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MCAT Biology Review Chapter 1 Molecular Biology Cellular Respiration Water Majority of Cell Mass Solvent in which most Rxn s take place Cohesive forces squeeze hydrophobic molecules away from water Hydrophilic molecules dissolve easily in water bc their negatively charged ends attract positively charged hydrogens of water Most molecules broken by hydrolysis and formed by dehydration Lipids any biological molecule that has low solubility in water and high solubility in nonpolar organic solvents Fatty Acids Building blocks for most complex lipids 9 long carbon chains truncated at one end by carboxylic acid Saturated Only single C C bonds Unsaturated At least one CC double bond Triglycerides 9 Constructed from 3C backbone called glycerol which is attached to three fatty acids function in cell is to store energy provide insulation and padding as well Adipocytes Specialized fat cells Phospholipids 9 Constructed from 3C backbone as well but a polar phosphate group replaces one of the fatty acids Serve as major component of membranes 9 have both polar and nonpolar ends amphipathic Steroids 9 four ringed structures including hormones vitamin D and cholesterol Proteins built from Amino Acids linked by peptide bonds sometimes referred to as Polypeptides Amino Acids differ only in side chains R Group Primary Structure Number and sequence of AA s in a polypeptide Secondary Structure Once primary structure is formed can twist into alpha helix or lie along side itself to form a Beta sheet Both Alpha Helix and B Sheets are reinforced by Hydrogen Bonds between carbonyl Oxygen and hydrogen on amino group Tertiary Structure 3D shape formed when peptide chain curls and folds Reinforced by disulfide bonds electrostatic interactions hydrogen bonds van der waal forces and hydrophobicphilic interactions Quaternary Structure When 2 or more polypeptide chains bind together Denaturation When a conformation is disrupted Carbohydrates Made from carbon and water Glucose most common almost all carbs absorbed by humans reaching body cells have been converted to glucose by liver or enterocytes Cell can oxidize glucose transferring chemical energy to ATP 9 if cell has sufficient ATP glucose is polymerized to glycogen or converted to fat Glycogen found in all animal cells but especially concentrated in muscle or liver cells 9 Liver regulates blood glucose so liver cells are capable of reforming glucose from glycogen and releasing it back into blood stream Plants form starch and cellulose from glucose 9 Cellulose has Blinkages and animals can only digest alpha linkages of starch and glycogen but not blinkages of cellulose Nucleotides Made up of a five carbon sugar a nitrogenous base and a phosphate group Most common bases are adenine guanine cytosine thymine and uracil CUT the PY CUT Pyrimidines GA Purines Nucleotides form polymers to create nucleic acids DNA and RNA 9 linked by phosphodiester bonds 9 nucleotides always written 5 93 A2T 9 Adenine and Thymine form 2 hydrogen bonds C36 9 Cytosine and Guanine form 3 hydrogen bonds Enzymes Typically globular proteins 9 Act as catalysts to lower energy of activation for a rxn and increase the rate of rxn 9 They are not consumed nor permanently altered 9 only small amnt required for any rxn Note They do not alter equilibrium of any rxn Reactants Substrates Substrates are generally smaller than enzyme 9 attach to active or allosteric site Enzymes follow enzyme specificity 9 LE One enzyme has a specific shape that fits a specific substrate Enzyme Kinetics As concentration of substrate increases rate of rxn also increases but to a lesser and lesser degree until Vmax is reached 9 Vmax is proportional to enzyme concentration Km Substrate concentration at which rxn rate is equal to 12 Vmax 9 acts as a way to measure an enzyme s affinity for its substrate Some enzymes need cofactors or coenzymes to function Enzyme Inhibition Competitive Inhibitors 9 Compete with substrate by binding REVERSIBLY with noncovalent bonds to the active site 9 They only typically bond for a fraction of a second so they block substrate during that time 9 Thus they raise Km but do not change Vmax 9 You can obtain the original Vmax by adding substrate Noncompetitive Inhibitors 9 Bind at allosteric site and change the conformation of the enzyme 9 do not prevent substrate from binding but do change conformation 9 Vmax is lowered but they don t lower enzyme affinity for substrate so Km remains the same Enzyme Regulation Enzymes control what rxns take place within cell so cell must regulate activity Proteolytic Cleavage AKA irreversible covalent modification 9 Many enzymes released in inactive form called a Zymogen or a proenzyme Look for 39ogen ending Allosteric Interactions 9 Modification of enzyme configuration resulting from the binding of activator or inhibitor at specific binding site on the enzyme Many allosteric inhibitors or activators are NOT noncompetitive inhibitors bc many alter Km without affecting Vmax Cellular Respiration Glycolysis Respiration in which oxygen is NOT required Occurs in the Cytosol First stage of both aerobic and anerobic respiration Breaks down Glyucose into two 3C molecules of pyruvate Other products Net production of 2 ATP 2 NADH Phosphate and Water If no oxygen is present 9 Leads to Fermenation Fermentation is anerobic 9 Reduces pyruvate to ethanol in yeast OR lactic acid in humans NADH is oxidized back to reform NAD in order to undergo glycolysis again If oxygen is present 9 Products go to Matrix of Mitochondria 9 Pyruvate is converted to Acetyl CoA in a rxn that also products NADH and C02 Kreb Cycle Acetyl CoA is a coenzyme that transfers 2C s to the 4 carbon oxaloacetic acid to begin the Kreb Cycle Each turn produces 1ATP 3NADH 1FADH2 During cycle two carbons are lost as C02 ETC Series of proteins in the inner membrane of the mitochondria First protein oxidizes NADH by accepting high energy electrons 9 Electrons are then passed down the protein series and ultimately accepted by oxygen to form water As electrons are passed protons are pumped into the intermembrane space for each NADH establishing a proton gradient which propels protons through ATP synthase to make ATP Production of ATP in this fashion oxidative phosphorylation Chapter 2 Genes Gene Series of DNA nucleotides that codes for the production of a single polypeptide Entire DNA sequence of an organism genome Central Dogma DNA 9 RNA 9 Protein DNA Deoxyribonucleic acid Polymer of nucleotides 9 nucleotides differ only by nitrogenous base Each nucleotide is bound to next by a phosphodiester bond between 3 Carbon of one deoxyribose and the phosphate backbone of a single strand of DNA with a 5 93 directionality 5 and 3 indicate the carbon numbers on the sugar DNA strands lie side by side in opposite directions Antiparallel bound by hydrogen bonds between nitrogenous bases to form a double stranded struction This hydrogen bonding base pairing lenth is measured in Base Pairs Matching strands complementary Complementary strands bound together double helix Replication One time per life cycle a cell replicates its DNA DNA replication is semi conservative when new double strand is created it contains one strand from the original DNA and one newly synthesizes strand Begins at Origin of Replication ORI and proceeds in both directions producing leading and lagging strands DNA helicase unwinds double helix separating strands DNA polymerase builds new strand from requires an RNA primer to start Reads strand 3 95 and synthesizes 5 93 5 Key steps Helicase unzips the double helix RNA polymerase builds an RNA primer DNA polymerase assembles leading and lagging strands Primers are removed Okazaki fragments are joined by DNA ligase P PPP DNA replication is FAST and ACCURATE RNA Ribonucleic Acid Just like DNA but carbon 2 is not deoxygenated It is single stranded and contains uracil in place of thymine Summary of DNA vs RNA 1 DNA made from deoxyribose RNA made from Ribose 2 DNA is double stranded RNA is single stranded DNA has thymine RNA has uracil DNA produced by replication RNA produced by transcription DNA only in nucleus and mitochondrial matrix RNA is also in cytosol DNA One major type RNA three major types 991 Transcription Occurs in Nucleus Starts with initiation 9 Requires promotor which is a series of DNA nucloetides that designates a beginning point for transcription 9 The start point is part of the promotor After binding to promotor RNA pol unzips the DNA double helix and makes a transcription bubble The complex then initiates elongation mode where RNA pol transcribes only one strand of the DNA nucleotide sequence into a complementary RNA nucleotide sequence The strand that is transcribed is the template strand or antisense strand Transcription is slower than replication and RNA pol does not have a proofreading mechanism so has a higher rate of error than replication These errors in RNA are called mutations End of transcription is called termination and requires a special termination sequence to dissociate RNA pol from DNA Most regulation of gene expression occurs at level of transcription via proteins called activators and repressors which bind to DNA close to the promotor and either active or repress the activity of RNA pol The amount of a given type of protein within a cell is likely to be related to how much of its mRNA is transcribed Post Transcriptional Processing Initial mRNA nucleotide sequence arrived at through transcription Primary Transcript aka premRNA It is processed in three ways Addition of nucleotides Deletion of nucleotides Modification of nitrogenous bases Before euk mRNA is completely transcribed 5 cap is added using GTP 5 cap serves as an attachment site in protein synthesis and protection against degradation 3 end is polyadenylated with a poly A tail also to protect from exonucleases Primary transcript is very long and gets cleaved into Introns and Exons by sn RN PS 39Snurps Introns remain in nucleus and EXons EXit to be translated DNA Technology After denaturing DNA separated strands will spontaneously associate with original parter or other complementary nucleotide sequences so DNA DNA DNA RNA or RNA RNA can be formed through nucleic acid hybridization Restriction Enzymes Cut DNA at certain sequences along chain cleaving ends unevenly leaving complementary single stranded ends sticky ends that can be reconnect through hybridization Once pairs phosphodiester bonds can be joined by DNA ligase Two DNA fragments cleaved by same endonuclease can be joined together regardless of the origin of DNA this DNA is called recombinant DNA Recombinant DNA can be made long enough for a bacteria to replicate and then placed within bacteria using a vector typically a plasmid Bacteria is then grown in large quantity forming a close of cells containing vector with recombinant DNA with your DNA fragment Can screen and find desired DNA sequence from a library by radioactively labeling complementary sequences of desired dNA Radiolabeled clones are identified PCR Double strand of DNA to be cloned or amplified is placed in a mixture with many copies of two DNA primers one for each strand Mixture then heated to denature the DNA Mixture is cooled 9 primers hybridize or anneal to complementary ends of DNA strand Heat resistant polymerase is added with a supply of nucleotides and mixture is heated to activate the polymerase 9 polymerase amplifies the complementary strands doubling the amount of DNA 2 to the nth Southern Blot DNA to be identified is cleaved in restriction fragments which are resolved according to size via gel electrophoresis large fragments move more slowly through gel Gel is made alkaline to denature the DNA fragments Gel is blotted which and a radio labeled probe with a complementary nucleotide sequence is added to the membrane The probe hybridizes with and marks the target fragment Radiographic film then reveals the location of probe and target fragment Northern Blot Same as southern blot but for RNA Western Blot Detects a mixture of proteins in same fashion starting with electrophoresis 9 If it shows up on MCAT recognize that this is the one that detects a protein with antibodies Genetic Code mRNA nueclotides are strung together to form a genetic code which translates DNA nucleotide sequences into an amino acid sequence The code is degenerative but unambiguous and is universal Start Codon AUG Stop codons UAA UAG and UGA Three consecutive nucleotides make up a codon Stop codons signal an end to protein synthesis the start codon AUG also codes for amino acid methionine Translation process of protein synthesis directed by mRNA Each of the major types of RNA plays a unique role in translation tRNA contains a set of nucleotides that is complementary to the codon called the anticodon tRNA sequesters the amino acid that corresponds to its anticodon rRNA with protein makes up ribosome providing site for transaltion Ribosome has small and large subunits Prok ribosomes smaller than Euks ribosomes Nucleolus is the quotribosome factory After post transcriptional processing in euks mRNA leave the nucleus through nuclear pores and enters cytosol for translation 5 end attaches to small subunit of a ribosome and a 5 CAU3 ANTICODON sequesters the AA methionine and enters the P side signaling the large subunit to join and form initiation complex 9 elongation now begins A tRNA with corresponding amino acid attaches to the A site at expense of two GTPs Translocation causes the ribosome to shift 3 nucleotides along the mRNA toward the 3 end the tRNA that carried methionine moves to the E site where it can exit the ribosome then the tRNA carrying the newly formed dipeptide moves to P site clearing the A site for the next rRNA 9 translocation requires the expenditure of another GTP When stop codon is reached the polypeptide is freed from tRNA and ribosome Translation can occur on free floating ribosomes in cytosol or a ribosome may attach to rough ER 9 proteins from rough ER are destined to become membrane bound proteins lysosomes or to be secreted from cell Mutations Mutations may occur at the chromosomal level or the nucleotide level Gene mutation alteration in the sequence of DNA nucleotides in a single gene Chromosomal mutation Occurs when the structure of a chromosome is changed Mutagen Any physical or chemical agent that increases the frequency of mutation above frequency of spontaneous mutations f Mutation changes a single base pair of nucleotides it is called a point mutation Base pair substitution one base pair replaced by another Insertion or Deletion Remove or add base pair 9 Cause frameshift mutation Missense Mutation A mutation that may alter amino acid sequence can change an AA and may or may not have serious effects on protein Nonsense Mutation A mutation that creates a stop codon 9 VERY serious mutation bc they prevent translation of a functional protein entirely Silent Mutation A mutation that does not cause a change in AA Cancer Cancer is the unrestrained and uncontrolled growth of cells 9 normal cells divide 20 50 times before death but cancer cells continue to grow and divide indefinitely Mass of cancer cells Tumor Proto oncogenes stimulate normal growth in human cells Protooncogenes can be converted to oncogenes or genes that cause cancer by mutagens that cause cancer that we call carcinogens Chromosomes DNA is wrapped tightly around globular proteins called histones 9 8 histones wrapped in DNA form a nucleosome which eventually is packed and wrapped even tighter into supercoils 9 entire DNAprotein complex chromatin Inside the nucleus of human somatic cells there are 46 double stranded DNA molecules 9 the chromatin associated with each one of these molecules is called a chromosome and each chromosome contains hundreds or thousands of genes In human cells each chromosome possesses a partner that codes for the same traits as itself these two chromosomes are called homologous chromosomes or homologues Although the traits are the same the genes may be different LE 9 Trait Eye color but eye color gene on one chromosome may code for blue eyes and eye color on the other may code for brown eyes Any cell that contains homologous pairs is said to be diploid Cell that does not contain homologues is haploid Cell Life Cycle 9 Every cell has a life cycle beginning with birth of the cell and ends with death or division of cell 61 S 62 Mitosis or Meiosis and Cytokinesis 61 S 62 are collectively called interphase G0 nongrowing state distinct from interphase 9 some cells stay in GO permanently neurons and muscle cells 61 Cell has just split and begins to grow producing new organelles and proteins 9 areas of heterochromatin have been unwound and decondensed into euchromatin 9 RNA synthesis and protein synthesis are VERY active 9 Cell is growing Synthesis 5 Cell replicates its DNA 9 Each chromosome is exactly duplicated 9 By convention cell is still diploid and still contains the same number of chromosomes but they are now sister chromatids 62 Cell prepares to divide 9 cellular organelles continue to duplicate RNA and protein are actively synthesized Mitosis Nuclear cell division without any genetic change resulting in identical daughter cells Remember quotIPMATquot Interphase Prophase Metaphase Anaphase Telophase Prophase 9 Condensation of chromatin into chromosomes Centrioles move to opposite ends of cell nucleolus and nucleus disappear spindle apparatus begins to form consisting of asters and microtubules growing from centromeres and spindle microtubules connecting centrioles Metaphase 9 Chromosomes align along center quotMetaphase Plate Anaphase 9 Sister chromatids split at attaching centromeres and move toward opposite ends of cell 9 Cytokinesis begins Telophase 9 nuclear membrane reforms followed by the reformation of the nucleolus 9 chromosomes decondense and cytokinesis continues 9 Cell split apart and two identical daughter cells are formed Meiosis Double nuclear division which produces 4 haploid gametes aka germ cells 9 In humans ONLY spermatogonium and the oogonium undergo meiosis After replication occurs in S phase the cell is called a primary spermatocyte or primary oocyte In females replication takes place before birth and life cycle of germ cells are arrested at the primary oocyte stage until puberty Just before ovulation a primary oocyte undergoes the first meiotic division to become a secondary oocyte 9 Secondary oocyte is released upon ovulation and penetration of the secondary oocyte by sperm stimulates anaphase2 and meiosis 2 of the second meiotic division Prophase 1 homologous chromosomes line up along side each other matching their genes exactly At this time they may exchange sequences of DNA nucleotides in a process called crossing over 9 crossing over causes genetic recombination The duplicated chromosomes appear as X side by side exhibiting 4 chromatids called a tetrad Genes located close together on a chromosome are more likely to cross over together and are deemed quotlinkedquot Metaphase 1 Homologues remain attached and move to the metaphase plate 9 UNLIKE MITOSIS TETRADS LINE UP IN MEIOSIS AT THE PLATE Anaphase 1 Separates the homologues from their partners Telophase 1 Nuclear membrane may or may not form cytokinesis may or may not occur 9 If cytokinesis occurs new cells are now haploid with 23 replicated chromosomes and are secondary spermatocytes or secondary oocytes In females one of the ooytes called the first polar body is much smaller and degenerates in order to conserve cytoplasm Meiosis 2 9 proceeds almost exactly like normal mitosis producing a final product of haploid gametes each with 23 chromosomes For spermatocytes 4 sperm cells are formed For oocyte only a single ovum is formed Females Telophase 2 produces one gamete and a second polar body Nondisjunction If during anaphase 1 or 2 the centromere of any chromosome does not split this is called nondisjunction resulting in one cell having two extra chromatids and the other missing a chromosome if in anaphase 1 Nondisjunction in anaphase 2 results in one cell having an extra chromatid and one lacking one chromatid Chapter 3 Microbiology Viruses Small infectious agents which most basically contain Protein coat called a capsid One to several hundred genes in form of DNA or RNA inside capsid Some most commonly animal virsuses have a lipid rich envelope 9 often taken from host cell or synthesized in host cell cytoplasm They require host cells to reproduce Use ATP made available from host Bacteriophage Attaches to membrane of bacteria via a membrane receptor 9 Attaches to membrane 9 tail contracts 9 penetration and injection of virus occurs Lytic Cycle virus commandeers cells reproductive machinery and produces new viruses until it lyses and releases reproduced viruses Lysogenic Virus Viral DNA incorporated into host genome then when host cell replicated its DNA the viral DNA is replicated as well with it Host cells infected may show no symptoms and be dormant or latent this is called a provirus Provirus can be activated by some type of stress Types of Viruses Plus strand RNA quotPlus Strand indicates that proteins can be directly translated from RNA Minus strand RNA quotMinus strand indicates that the RNA is the complement to mRNA and must be transcribed to plus RNA before being translated Defense Against Viruses Vaccination Injection of antibodies or an injection of a non pathogenic virus with same capsid or envelope allowing the body to create its own antibodies Prokaryotes No membrane bound nucleus 9 split into two domains Bacteria and Archaea Archaea have much in common with Euks but are Proks Carbon sources can be organic or inorganic 9 Most sources also contribute oxygen and hydrogen Autotrophs Organisms that are capable of using C02 as their sole source of carbon Heterotrophs use preformed organic molecules as their source of carbon 9 typically coming from other organisms both living or dead All organisms acquire energy from one of two sources 1 Light 2 Oxidation of organic or inorganic matter Organisms that use light as energy source are called phototrophs and those that use oxidation of organic or inorganic matter are called chemotrophs Structure of Prokayotes Structure is more simple than that of Euks 9 No nucleus have single circular double stranded molecule of DNA DNA is twisted into supercoils and associated with histones in Archaea and with proteins that are different from histones in Bacteria Three shapes of bacteria Cocci bacilli and spirilla Proks have no membrane bound organelles 9 Have DNA and RNA and have prokaryotic ribosomes which are smaller than Euk ribosomes Membranes 9 Cytosol of nearly every prok is surrounded by a phospholipid bilayer called the plasma membrane Phospholipid is composed of a phosphate group two fatty acid chains and a glycerol backbone often drawn as a balloon with two strings 9 balloon phosphate group strings fatty acids Phosphate group is polar and fatty acids are nonpolar Amphipathic n aqueous solution amphipathic molecules spontaneous aggregate turning polar hydrophilic ends toward the solution and nonpolar hydrophobic ends away from solution Resulting structure micelle Plasma membrane is embedded with proteins and steroids like cholesterol in euks 9 membrane proteins act as transporters receptors attachment sites and enzymes Membrane Transport Membrane acts as barrier and creates differences in compositions of solutions Molecules without an electric charge move down their concentration gradient Molecules with a charge there is an electrical gradient pointing in the direction that a positively charged particle will tend to move 9 the two together form a single electrochemical gradient Two aspects of a compound affect its semipermeability Size and polarity The larger the molecule the less permeable the membrane is to that molecule Greater polarity the less permeable the membrane to the molecule Large lipid soluble nonpolar molecules like steroid hormones can move right through the membrane Movement through the membrane due to random motion without aid of a protein passive diffusion When molecules are too large or too charged to passively diffuse specific proteins can assist called transport or carrier proteins this is called facilitated diffusion Movement of compounds against its electrochemical gradient requires active transport 9 accomplished by the direct expenditure of ATP f ATP used indirectly to create electrochemical gradient and then using the energy of the gradient to acquire or expel a molecule is called secondary active transport Bacterial Envelope 9 Bacteria plasma membrane and everything inside protoplast Surrounding the protoplast is the bacterial envelope 9 component of envelope adjacent to plasma membrane is the cell wall Cell wall made of peptidoglycan Many antibiotics attack the amino acid crosslinks of peptidoglycan Lysozyme attacks the disaccharide linkage in peptidoglycan 9 both cases causes disruption of cell wall Gram Staining Gram Positive 9 Thick peptidoglycan cell wall 9 show up purple 9 Gram positive bacteria have a cell wall that is four times thicker than the plasma membrane 9 space in between the plasma membrane and cell wall periplasmic space Gram Negative 9 Thin peptidoglycan cell wall 9 show up pink 9 outside cell wall gram negative bacteria have a phospholipid bilayer this second membrane is more permeable than the first 9 in gram negative bacteria the periplasmic space is between two membranes Bacterial Flagella 9 long hollow cylinders made from globular protein 9 rotate counterclockwise to propel bacteria in single direction or rotate clockwise to allow bacteria to tumble and change orientation Bacterial Reproduction Bacteria do not undergo meiosis or mitosis nor can they reproduce sexually but have 3 alternate methods of genetic recombination conjugation transformation and transduction Can also undergo cell division via binary fission a type of asexual reproduction 9 in binary fission circular DNA is replicated similar to replication in Euks 9 two DNA pols begin at same point on the circle ORI and move in opposite directions making complementary strands that combine to form two complete DNA double stranded circles cell then divides leaving one circular chromosome to each daughter cell Conjugation Requires one bacterium to have a plasmid with genes that code for the sex pilus aka conjugation bridge F plasmid is called the Fertility factor or F factor a bacteria with F factor is F and one without it is F Transformation Process by which bacteria may incorporate DNA from external environment into genome 9 may be added in lab or may occur to to lyses of other bacteria Transduction DNA transferred VIA viruses Endospore 9 Bacteria can form endospores endospores used to resist extreme environments Fungi 9 Distinct kingdom of organisms with tremendous diversity 9 They are considered Saprophytic and do not distinguish between living and dead matter and can be potent pathogens Most posses cell walls called septa made of polysaccharide chitin Fungi are multicellular with the exception of yeast which is unicellular They are euk heterotrophs and spend most of their lives in the haploid state Fungi alternate between haploid and diploid states 9 diploid states predominate Hyphae are haploid Yeasts asexual reproduction occurs by bidding Chapter 4 Euk Cell and Nervous System The Nucleus 9 Contains all the DNA except for small amount in mitochondria Wrapped in a membrane called nuclear envelope or nuclear membrane Perforated with holes called nuclear pores for passage Within nucleus is nucleous where rRNA is made and subunits of ribosomes are assembled Membrane 9 Besides transport cells can acquire substances from extracellular environment via endocytosis there are a few types of endocytosis Phagocytosis Cell membrane protrudes outward and engulfs matter Pinocytosis Extracellular fluid is engulfed Receptor Mediated Endocytosis Specific uptake of macromolecules such as hormones and nutrients in this process the ligand binds to a receptor protein Exocytosis Reverse of endocytosis Rough ER 9 Studded with ribosomes translation here makes secretory proteins that are moved through golgi Golgi apparatus organizes and concentrates proteins as they are shuttled by vesicles outward 9 Golgi can also alter or change proteins chemically by glycosylation or removing amino acids End product of golgi is a vesicle full of proteins 9 protein filled vesicles can be expelled as secretory vesicles Secretory vesicles may contain enzymes growth factors or extracellular matrix components and release their contents through exocytosis Lysosomes 9 contain acid hydrolases which are enzymes capable of breaking down all major types of macromolecules within the cell Lysosomes generally have an interior pH of 5 and fuse with endocytotic vesicles and digest their contents 9 any material NOT degraded by lysosome is ejected from cell via exocytosis Smooth ER 9 Production of triglycerides cholesterol formation and subsequent conversion to steroids production of most phospholipids oxidation of foreign substances detoxifying drugs Smooth ER 9 THINK LIPID SYNTHESIS Peroxisomes 9 vesicles in cytosol grow by incorporating lipids and proteins from cytosol they do not budd off membranes and instead selfreplicate Involved in production and breakdown of hydrogen peroxide and inactivate toxic substances such as alcohol regulate oxygen concentration Cellular Filaments Structure and motility of a cell is determined by a network of filaments known as the cytoskeleton Cytoskeleton anchors some membrane proteins and other cellular components moves components within the cell and moves the cell itself Two major types microtubules and microfilaments Microtubule 9 larger than microfilaments 9 Rigid hollow tubes made from a protein called tubulin mitotic spindle is made from microtubules Flagella and Cilia are specialized structures also made from microtubules Cilia are found in fallopian tubes and respiratory tract Microtubles have and ends end attaches to MTOC in cell and it grows away at its end 9 major MTOC in animal cells is called the centrosome Microfilaments 9 Smaller than microtubules 9 Actin is a microfilament Microfilaments produce contracting force in muscle as well as being active in cytoplasmic streaming Cellular Junctions Tight Junctions Form watertight seal cell to cell blocking water ions and other molecules Tissue held together by tight junctions acts as complete fluid barrier Epithelial Tissue in organs like bladder intestines and kidney are held together by tight junctions Desmosomes Join two cells at a single point do not prevent fluid circulation Gap Junctions Small tunnels connecting cells together allowing small molecules and ions to move between cells Gap junctions in cardiac muscle provide for spread of AP from cell to cell Mitochondia power house of euk cells 9 home of kreb cycle 9 mitochondrial DNA passed maternally Inner membrane holds the ETC Between inner and outer membrane is the intermembrane space Organization in Multicellular Euks Cells that work together with each type of cell performing unique function Tissue Epithelial Tissue Separates free body surfaces from surroundings Paracrine System 9 local mediators are released by a variety of cells into interstitial fluid and act on neighboring cells a few millimeters away 9 mediators could be proteins AA derivatives or fatty acids Nervous System 9 Rapid and direct communication between specific parts of the body Functional unit neuron Neuron is highly specialized cannot divide and relies on glucose for chemical energy Dendrites of the neuron receive signal to be transmitted 9 cytosol of cell is highly conductive and any electrical stimulus creates a disturbance in the electric field that is transferred immediately to the axon hillock where an action potential is generated and moves down the axon to the synapse Action Potential 9 Disturbance in electric field across the membrane Resting Potential Established by equilibrium between passive diffusion of ions across the membrane and NaK pump 3 Na out 2K in making the positive chage along the membrane outside the cell more charged As Na electrochemical gradient becomes greater the force pushing Na back into the cell also increases 9 the rate at which Na passively diffuses back into cell increases until it equals the rate at which it is being pumped out of the cell and the same happens for potassium when all rates reach equilibrium the inside of membrane has a negative potential difference voltage Resting Potential Membrane of Neuron contains proteins called voltage gated sodium and potassium channels that change config when the voltage across membrane is disturbed 9 They allow Na to flow through membrane for a fraction of a second as they change config 9 as Na flows into cell the potential goes up inside and in a process called depolarization Voltage gates potassium channels take longer to open and allow K to flow out of cell making inside more negative in a process called repolarization and because they are slower the potential gets even lower than that of the resting potential in hyperpolarization ACTION POTENTIAL IS ALL 0R NOTHING 9 Membrane completely depolarizes or no action potential is generated and in order for an action potential to occur the stimulus of the membrane must be greater than the threshold stimulus The Synapse Neural Impulses are transmitted one cell to another via synapses 9 Electrical synapses are composed of gap junctions between cells IE cardiac muscle visceral smooth muscle Chemical Synapse 9 unidirectional Small vesicles filled with neurotransmitter release into the cleft Membrane has a large number of Ca2 voltage gated channels and Ca flows into cell causing neurotransmitter vesicles to be released The neurotransmitter attached to receptor for only a fraction of a second and is then released back into synaptic cleft Receptors may be ion channels themselves that open when the neurotransmitter attaches or they may act via a second messenger system activating another molecule inside the cell to make changes G Proteins commonly initiate a second messenger system G Proteins are attached to receptor proteins along the inside of the postsynaptic membrane 9 when a receptor is stimulated by a neurotransmitter part of the Gprotein called the alpha subunit breaks free The Alpha subunit may active separate specific ion channels activate a second messenger CAMP or CGMP activate intracellular enzymes activate gene transcription Support Cells 9 Myelin created by Schwann Cell increases the rate at which an axon can transmit signals gaps between myelin are called Nodes of Ranvier when an AP is generated down a myelinated axon the AP jumps from one node of Ranvier to the next as quickly as the disturbance moves through the electric field is a process called salutatory conduction Structure of the Nervous System 1 Sensory afferent Neurons 9 receive signals from a receptor cell that interacts with environment then transfers this signal to other neurons Interneurons 9 transfer signals from neuron to neuron Moter Neurons 9 Carry signals to a muscle or gland called the effector Sensory neurons are located dorsally toward back from the spinal cord while motor neurons are located ventrally toward the front Two divisions of the nervous system Central Nervous System 9 Consists of interneuron s and support tissue function of CNS is to integrate nervous signals between sensory and motor neurons For the MCAT think of CNS as Brain and Spinal Cord Peripheral Nervous System PNS 9 Connects CNS to peripheral parts of body Can be further divided into two two more systems Somatic Nervous System Primarily to respond to external environment contains motor and sensory neurons Somatic motor neurons ONLY innervate skeletal muscle 9 neurons synapse directly on their effectors and use acetylcholine for their neurotransmitter When you see Somatic think of conscious control Somatic VOLUNTARY Autonomic Nervous System ANS The sensory portion of the ANS receives signals from the viscera organs of ventral body cavity 9 Motor portion of ANS conducts these signals to smooth muscle cardiac muscle and glands Motor Portion divided into two sections Sympathetic and Parasympathetic Sympathetic 9 Signals originate in neurons whose cell bodies are found in spinal cord 9 postganglionic neurons use epinephrine or norepinephrine Parasympathetic 9 originate in neurons whose cell bodies are found in both brain and spinal cord 9 postganglionic neurons use acetylcholine IF YOU SEE AUTONOMIC THINK INVOLUNTARY The Central Nervous System Consists of some spinal cord lower brain and all the higher brain Medulla BreathingDigestionHeart Rate regulation Hypothalamus Maintain homeostasis Cerebellum Fine Movements coordination The Eye Light reflects off an object and strikes the eye on the cornea 9 from cornea enters the anterior cavity and then enters the Lens the lens has suspensory ligaments that flatten it and it is connected to ciliary muscle The Retina covers inside and back of the eye contains rods and cones These cells are named for characteristic shapes Cones for Color Cones distinguish color Rods for Light The Iris is the colored portion of the eye that creates the opening called the pupil Chapter 5 The Endocrine System Endocrine vs Exocrine Exocrine 9 Exocrine glands release enzymes to external environment through ducts Ex sweat oil mucous digestive glands Endocrine 9 Release hormones directly into body fluids As a comparison look at the Pancreas Exocrine glands of pancreas release digestive enzymes through pancreatic duct Endocrine Glands ductless releasing insulin and glucagon directly into blood Hormones 9 Act by binding to protein receptors each receptor being highly specific for its hormone there are three types of hormones 1 Peptide Hormones 9 May be large or small sometimes have carb portions 9 All peptide hormones are manufactured in the rough ER and cleaved in the ER lumen to become a prehormone 9 transported to Golgi where it is cleaved and modified to final form and packaged into secretory vesicles and released via exocytosis a Peptide hormones bind to a receptor on the membrane may act as ion channel increasing permeability to a specific ion or may activate or deactivate other membrane proteins 9 may also activate a intracellular second message such as cAMP or cGMP Peptide Hormones to know 9 From Anterior Pituitary FSH LH ACTH HGH TSH Prolactin quotFLATPiGquot from Posterior Pituitary ADH and oxytocin Parathyroid Hormone PTH and Glucagon and Insulin 2 Steroid Hormones 9 Since they are lipids they require a protein transport molecule in order to dissolve into the blood stream 9 Being lipid soluble steroids diffuse through the cell membrane of their effector and once inside they combine with a receptor in the cytosol a Important Steriods for the MCAT i Glucocorticoids and mineral corticoids of the adrenal cortex Cortisol and Aldosterone ii The Gonadal hormones estrogen progesterone and testosterone 3 Tyrosine Derivative Hormones T3 T4 Epinephrine and Norepinephrine Functions of Specific Hormones Hypothalamus controls the Pitutary release of hormones 9 Anterior Pituitary quotFLATPiGquot HGH Peptide Stimulates growth in all cells of body 9 increases episodes of mitosis increases cell site increase protein synthesis mobilizes fat storage increase use of fatty acid for energy decreasing use of glucose ACTH Peptide Adrenocorticotropic Hormone Stimulates adrenal cortex to release glucocorticoids via second messager system using cAMP 9 release of ACTH is stimulated by stress TSH Peptide Stimulate thyroid to release T3 and T4 Prolactin Peptide promote lactation by breasts Posterior Pituitary Composed of support tissue for nerve ending extending from hypothalamus Produces Oxytocin and ADH Oxytocin Peptide Increases uterine contractions during pregnancy and causes milk to be ejected from breasts ADH Peptide Also known as vasopressin causes collecting ducts of kidney to become more permeable to water reducing amount of urine and concentrating the urine 9 bc fluid is reabsorbed ADH also increases blood pressure Adrenal Cortex Has adrenal glands located on top of the kidney 9 Cortex is the outside portion and only secretes steroid hormones mineral corticoids and glucocorticoids Mineral Corticoids Effect electrolyte balance in blood stream Aldosterone Glucocorticoids Increase blood glucose concentration and have a greater effect on fat and protein metabolism Aldosterone Steriod 9 acts in distal convoluted tubule and collecting duct to increase Na reabsorption and K excretion 9 causes increase in blood pressure Cortisol Steroid 9 glucocorticoid that increases blood glucose levels by stimulating gluconeogenesis in liver Gluconeogenesis creation of glucose and glycogen from amino acids glycerol andor lactic acid Adrenal Medulla Released epinephrine and norepinephine 9 similar effects to their effects in the sympathetic nervous system but much longer lasting 9 they are vasoconstrictors Thyroid T3 and T4 Tyrosine derivatives act like steroids 9 general effect is to increase the basal metabolic rate BM R Calcitonin Peptide Released by thyroid 9 decreases blood calcium by decreasing osteoclast activity and number Pancreas 1 Insulin Peptide hormone Released from B cells of pancreas released when carbs or proteins are high in blood In presense of insulin carbs are stored as glycogen in liver and muscles and fat is stored in adipose tissue and amino acids are taken up by the cells of the body and made into proteins Effect is to lower blood glucose levels 2 Glucagon Peptide Hormone Release by A cells of pancreas Opposite effect of insulin 9 stimulates gluconeogenesis in the liver in an effort to raise blood glucose level Parathyroid Hormone PTH Peptide Works to increase blood calcium level by increasing osteoclast activity Male Reproduction Male gonads Testes 9 Production of Sperm occurs in Seminiferous Tubules ertoi Cells stimulated by FSH surround and nurture spermatocyte and spermatids and then spermatozoa Leydig Cells stimulated by LH release testosterone Testosterone Primary androgen male sex hormone and stimulate germ cells to become sperm 9 Also responsible for secondary sex characteristics Spermatid has characteristics of a typical cell however as a spermatozoon it loses its cytoplasm and forms the head midpiece and tail 9 The head has the nucleus and the acrosome the acrosome has lysosomelike enzymes for penetrating the egg during fertilization Spermatozoon is carried to epididymus to mature 9 upon ejaculation they are propelled through the vas deferens and into the urethra and out of the penis Semen is the complete mixture of spermatozoa and the fluid that leaves the penis upon ejaculation Semen is composed of fluid made from seminal vesicles prostate and bulbourethral glands Female Reproductive System Oogenesis begins in ovaries of the fetus 9 All the eggs of the female are arrested as primary oocytes at birth puberty FSH stimulates the growth of granulose cells around the primary oocyte and makes the zona pellucida 9 the stucture is called a primary follicle 9 NEXT theca cella grow around the follicle to form a secondary follicle Theca cells are stimulated by LH to secrete androgen which is converted to estradiol A type of estrogen by the granulosa cells Typically estradiol inhibites LH secretion but before ovulation the estradiol level rises rapidly causing a dramatic increase in LH secretion called the luteal surge Luteal Surge causes the follicle to burst and release the egg into a body cavity 9 Egg is swept into Fallopian tube or oviduct by the fimbriae 9 The corpus luteum secretes esradiol and progesterone throughout pregnancy or if NO pregnancy occurs for about 2 weeks until the corpus luteum degrades Fertilization and Embryology Once in fallopian tube egg is swept toward the uterus by cilia Fertilization occurs in Fallopian tubes and the enzymes of the acrosome in the sperm are released upon contact with the egg and digest a path for the sperm through the granulose cells and zona pellucida Cell membranes of sperm head and ooctye fust upon contact and the sperm nucleus enters the cytoplasm of the oocyte The entry of sperm causes the cortical reastion which prevents other sperms from fertilizing the same egg 9 AT THIS POINT THE OOCTYE GOES THROUGH MEIOSIS 2 TO BECOME AN OVUM Fertilization occurs when the nuclei of the ovum and sperm fuse to form the zygote Zygote goes through several cycles of mitosis and once it is eight or more cells is called a morula which continues to divide for 4 days eventually forming a blastocyst and it is the blastocyst that lodges in the uterus in a process called implantation on the 5th to 7th day post ovulation Upon implantation the egg begins secreting a peptide hormone called HCG which prevents the degeneration of the corpus luteum and mains secretion of estrogen and progesterone 9 HCG in blood and urine of the mother is first sign of pregnancy Formation of gastrula occurs in second week after fertilization in process called Gastrulation Cells begin to slowly move about the embryo for the first time three layers are formed 1 Ectoderm outer coverings skin nails cells of nervous system 2 Endoderm lining of digestive tract and into much of the liver and pancreas 3 Mesoderm Muscle bone and rest Gastrula develops into Neurula in the third week As the embryo develops past the eight cell stage the cells become different from each other due to cell cell interaction This process is called determination 9 The specialization that occurs at the end of development forming a specialized tissue cell is called differentiation Chapter 6 The Digestive System Excretorv System Quick Anatomy Overview Digestion begins in mouth with salivary amylase 9 Amylase breaks down starch which is the long carb in human diets 9 Breaks the food into polysaccharides 9 Create Bolus and moves down esophagus via peristaltic action 9 performed by smooth muscle The Stomach 9 Flexible pouch that further breaks down mixes and stores food reducing it to a semifluid mass called chyme Stomach contains exocrine glands Begins protein digestion with Pepsin Four Cells in Stomach important for MCAT Mucous Cells 9 Secrete Mucus 9 Protect epithelial lining from acidic environment Chief Cells 9 Secrete Pepsinogen which is activated to Pepsin by HCl Parietal Cells 9 Secrete HCI G Cells 9 Secrete Gastrin which stimulates parietal cells to secrete HCI Small Intestine 9 90 of digestion and absorption occurs in small intestine Most digestion occurs in the duodenum Most absorption occurs in jejunum and ileum Wall of small intestine contains villi and microvilli which increase surface area Within each villus is a capillary network and a lymph vessel called a lacteal Nutrients absorbed through the wall of the small intestine pass into capillary network and the lacteal Fuzzy border of small intestine is called brush border which secretes digestive enzymes 9 Brush border also completes the digestion and breaking down of proteins and carbs Some of the epithelial cells are goblet cells that secrete mucus to lubricate the intestine and protect the brush border The Pancreas 9 Semifluid Chyme is squeezed out of the stomach through the pyloric sphincter and into the duodenum 9 Fluid in duodenum has a pH of 6 due to the bicarbonate ion secreted by the pancreas In addition to the secretion of bicarbonate the pancreas acts as an exocrine gland releasing enzymes through the pancreatic duct into the small intestine these enzymes include Trypsin and Chymotrypsin Degrade proteins into smaller polypeptides Pancreatic Amylase which hydrolyzes polysaccharides to disaccharides and trisaccharides just like salivary amylase except much more powerful Lipase Degrades fats specifically triglycerides Lipase requires the fats to be emulsified by bile released by liver stored by gall bladder Large Intestine 9 Major function is water absorption and electrolyte absorption Also contains bacteria E Coli which produces vitamins and riboflavin 9 mutual symbiosis Carbohydrates 9 Most common carbs in human diet are sucrose lactose and starch Cellulose cannot be digested Sucrose glucose and fructose and Lactose glucose and galactose are disaccharides Starch is a LONG chain of glucose molecules Glucose is absorbed by secondary active transport mechanism down the concentration gradient of sodium All Carbs in the bloodstream are carried by the hepatic portal vein to the Liver 9 The liver works to try and maintain a constant blood glucose level The liver absorbs all the carbs and converts nearly all galactose and fructose into glucose and then glycogen for storage The formation of glycogen is called glycogenesis The breakdown of glycogen into glucose is called glycogenolysis notice lysis breaking down Almost all cells are capable of producing and storing some glycogen however only muscle cells and especially liver cells can store them in large amounts 9 When cells reach saturation of glycogen carbs are converted to fatty acids and then triglycerides Proteins 9 Protein digestion results in tripeptides dipeptides and amino acids Nearly all polypeptides are absorbed into an enterocyte Intestinal absorbative cell and are hydrolyzed to their constituents by enzymes within the enterocytes They are completely broken down to amino acids before being absorbed into the blood If you see Nitrogen THINK PROTEIN ON MCAT Fats 9 Most dietary fat consists of triglycerides 9 These are broken down to monoglycerides and fatty acids before shuttled to brush border by bile micelles Chylomicrons pick up fats and move them into lacteals Fat is insoluble in water and requires a carrier Lipoprotein albumin etc Associate fats with LONG term energy storage The Liver 9 Positioned to receive blood from the capillary beds of the intestines stomach spleen and pancreas via the hepatic portal vein The Liver has MANY functions but most importantly Carbohydrate metabolism Liver maintains normal blood glucose levels through gluconeogenesis making glucose and glycogen from noncarb substituents Makes Biles from cholesterol and converts carbs and proteins into fat 9 Oxidizes fatty acids for energy Protein Metabolism Deaminates amino acids forming urea from ammonia in the blood 9 also synthesizes plasma proteins such as fibrogen albumin and most globulins Prothrombin and Fibrinogen are important clotting factors Globulins are a group of proteins that include antibodies Detoxification 9 Detoxified chemicals are excreted by the liver Destruction of irregular erythrocytes Most are actually destroyed in spleen Vitamin Storage The Kidney The Function of the Kidney is Excrete waste products such as urea uric acid ammonia and phosphate Maintain homeostasis of the body fluid volume and solute composition Help regulate the plasma pH Made up of outer cortex and inner medulla Functional unit is the Nephron 9 Blood flows into the first capillary bed of the Nephron called the glomerulus Hydrostatic pressure forces some plasma through fenestrations of the glomerular endothelium and into Bowman s Capsule Moves into Proximal Tubule 9 Most reabsorption occurs here Secondary active transport proteins in apical membrane of proximal tubule responsible for most reabsorption of Cglucose protein and other solutes Drugs toxins are secreted Into filtrate by the cells of the proximal tubule Hydrogen ons are secreted through an antiport system with sodium Uric Acid bile pigments and antibiotics secreted in proximal tubule as well Filtrate then moves into Loop of Henle Loop of Henle dips into the medulla and water passively diffuses out of loop and into medulla In the ascending loop side 9 Salt diffuses out making the medulla more concentrated with salt The Distal Tubule Reabsorbs Na and Ca2 while secreting K H and HCO3 Aldosterone acts on the distal tubule to increase sodium reabsorbtion and potassium secretion Collecting Duct 9 Distal tubule empties into the collecting duct which carries the filtrate into the highly osmotic medulla s sensitive to ADH which makes the collecting duct permeable to water allowing more reabsorption of water Juxtaglomerular Apparatus Monitors filtrate pressure in distal tubule Granular cells secrete Renin 9 Renin initiates a cascade producing angiotensin 1 and 2 which ultimately stimulate the adrenal cortex to secrete aldosterone Chapter 7 Cardiovascular and Respiratory System Anatomy Blood flows through the left ventricle through the aorta and from the aorta it branches into smaller arteries which branch into smaller arteries called arterioles 9 These led to Capillaries Blood from capillaries goes into the venules which collect into larger veins which collect again into the superior and inferior vena cava which empties into the right atrium of the heart Blood from the right atrium is squeezed into the right ventricle which pumps blood into the pulmonary artery to arterioles and to the capillaries of the lungs 9 From these capillaries they collect once again into venules and then into veins and finally pulmonary veins leading to the heart Pulmonary veins empty into the left atrium which fills the left ventricle The Heart Heart is a large muscle 9 It s fibers form a net and contract upon itself squeezing blood into the arteries Systole 9 Occurs during the contraction of the ventricles Diastole 9 Occurs during the relaxation of the entire heart and then contraction of the atria Heart contracts automatically and is paced by a group of specialized cardiac muscle cells called the sinoatrial node SA node locatd in the right atrium 9 SA node is autorhythmic contracts by itself at regular intervals spreading it s contractions to surrounding cardiac muscles via electrical synapses made from gap junctions Pace of the SA node is faster than heartbeats but it is regulated by the vagus nerve parasympathetic system Action potential created by SA node spreads around both atria causing them to contract and at the same time spreads to the atrioventricular node AV node and the AV node is slower to contract creating a delay allowing the atria to finish their contraction and to squeeze their contents into the ventricles before the ventricles begin to contract From the AV Node the Action potential moves down conductive fibers called bundle of His wall separating ventricles and branches out through ventricular walls via conductive fibers called Purkinje fibers spreading through gap junctions through the cardiac muscles Arteries are elastic and stretch as they fill with blood 9 They are smooth muscle innervated by the sympathetic nervous system 9 Epinephrine works as a powerful vasoconstricter causing arteries to narrow Capillaries are microscopic blood vessels 9 capillary walls are only one cell thick with a diameter roughly equal to that of a single red blood cell Capillaries are found close to all cells of the body 9 as blood flows into a capillary the hydrostatic pressure is high and greater than osmotic pressure and net fluid flow is out of capillary and into the interstitium 9 Osmotic pressure remains relatively constant throughout the capillary but hydrostatic pressure drops from the arterial end to the venule end and thus osmotic pressure overcomes hydrostatic pressure near the venule end of the capillary and the net fluid flow is back into the capillary so only a small amount of fluid is loss into the interstitium 10 Venules and Veins are similar to arterioles and arteries 9 The lumen is larger than the lumen of comparable arteries and veins contain a far greater volume of blood 9 They hold most of the blood and act as a reservoir Veins have valves and are a lower pressure system than Arteries Random Fact to help on the MCAT Blood pressure increases near the heart and decreases to the lowest amount in capillaries Respiratory System Provides a path for gas exchange between the external environment and blood Air enters through nose and moves from 9 pharynx larynx trachea bronchi bronchioles and into alveoli where oxygen is exchanged with carbon dioxide with the blood Inspiration occurs when the medulla signals for diaphragm to contract Note The diaphragm is skeletal muscle and is innervated by the phrenic nerve When relaxed the diaphragm is dome shaped and flattens upon contraction expanding the chest cavity and creating negative gauge pressure Atmospheric pressure forces air into lungs Nasal cavity 9 Filters moistens and warms incoming air 9 Hair in the nasal cavity traps large dust particles Mucus 9 Secreted by goblet cells Cilia 9 Moves mucus and dust back toward pharynx Note that bc microtubules are found in cilia a problem in microtubule production may result in problems breathing ORDER 9 Nasal Cavity 9Pharynx 9 Larynx 9 Trachea 9 Bronchi 9 Bronchioles 9 Alveoli Alveoli 9 Site of gas exchange Oxygen diffuses into a capillary where it is picked up by red blood cells 9 Red blood cells release carbon dioxide which diffuses into alveolus and is expelled upon exhalation Oxygen binds with hemoglobin 9 Hemoglobin is located inside erythrocytes and is composed of 4 polypeptide subunits each with a single heme cofactor 9 Each can bind one oxygen molecule 9 Binding of one molecule promotes and accelerates further binding Cooperativity What Causes a Right Shift Increase in Carbon Dioxide Pressure hydrogen ion concentration lowering of pH or Temperature VERY MPORTANT Hypertension causes alkalosis Hypotension causes acidosis THINK C02 H20 9 H2C03 9 HC03 H Lymphatic System Collects interstitial fluid and returns it to the blood Proteins and large particles that cannot be taken up by capillaries are removed by the lymph system Is an open system fluid enters one end and leaves at the other Blood Contains cell and a matrix Plasma 9 Contains matrix of the blood and includes water ions urea ammonia proteins and other organic and inorganic compounds Also contains important proteins and clotting factors and albumin and immunoglobulin s Antibodies Erythrocytes bags of hemoglobin they DO NOT HAVE A NUCLEUS no organelles and do not reproduce or undergo mitosis Main job is to deliver oxygen and remove carbon dioxide All blood cells differentiate from a stem cell residing in the bone marrow 9 Erythrocytes lose their nucleus while still in the marrow Platelets are small portions of membrane bound cytoplasm they are important for stopping bleeding in coagulation processes Starts with Platelets and includes plasma proteins prothrombin and fibrin Immune System Injury to tissue results in inflammation 9 Inflammation is a dilation of blood vessels increased permeability of capillaries swelling of tissue cells and migration of granulocytes and macrophages to inflamed area Let s start from the beginning Infectious agents that pass through the skin or digestive defenses and enter the body are first attacked by local macrophages There are two types of immunity Humoral Bcell immunity and CellMediated Tcell Immunity Humoral Immunity 9 promoted by B lymphocytes B cells differentiate and mature in bone marrow and the liver Each B Cell can make a single type of antibody or immunoglobulin which it displays on its membrane Antibodies recognize antigens foreign particles The portion of the antibody that binds to the antigen is highly specific for that antigen Macrophages present the chopped up antigen particles on their surfaces and they present the antigen to B cells The B cells can now differentiate into memory B cells and plasma cells The plasma cells produce antibodies which are released into the blood to attack the bacteria The memory cells are preparation in the event that the same type of bacteria or antigen attack again Secondary immune response Blood Type Blood types are identified by A and B surface antigens Example Type A blood means that the red blood cell membrane has A antigens therefore if the erythrocytes have A antigens the immune system does not make A antibodies Type A blood cannot receive type B blood because they make A antibodies which would attack their A surface antigens Rh factors are surface proteins on red blood cells 9 Those that code for nonfunctional products of the Rh gene are Rh negative 9 Those that code for functional proteins are Rh positive Muscle Bone and Skin Three types of Muscle Skeletal Muscle Cardiac Muscle and Smooth Muscle Skeletal Muscle Voluntary muscle tissue Not directly attached to bone but attached via a tendon Tendons attach muscle to bone while ligaments attach bone to bone Muscles work in groups the agonist attaches while the antagonist stretches Skeletal Muscle Contraction Functional unit of skeletal muscle sarcomere Sarcomere composed of both thick and thin filaments which are positioned end to end to form a myofibril which is surrounded by the sarcoplasmic reticulum Lumen of sarcoplasmic reticulum filled with Ca2 Skeletal Muscle is multinucleate Thick Filament Myosin Thin Filament Actin Actin and Myosin 9 Work together to create the contractile force in skeletal muscle Tropomyosin covers an active site on the actin preventing binding of myosin Myosin head remains cocked back in high energy position Ca2 causes troponin to pull the tropomyosin back and reveal the actin active site Myosin head expels phosphate and ADP and bends into a low energy position dragging actin with it 9 This is the power stroke because it causes shortening of the sarcomere and the muscle contraction Next ATP attaches to the myosin head which releases the head from the active site Last ATP splits to a phosphate and ADP and cocks back into high energy position Muscle Contraction begins with action potential at the neuromuscular synapse 9 The Action Potential releases acetylcholine into the synaptic cleft 9 AP Travels down T Tubules and spreads throughout muscle for uniform contraction Skeletal Muscle does not undergo mitosis to create new cells 9 Grows via hypertrophy Cardiac Muscle 9 Involuntary 9 Striated Composed of Sarcomeres Just like Skeletal muscle but only one nucleus mononucleate Separated from neighbors by intercalated disks Action potential for cardiac muscle a bit different because has a slow voltagegated calcium ion channels which allow calcium to enter the cell and hold the membrane at a positive potential Smooth Muscle 9 Mainly involuntary lnnervated by autonomic nervous system Only contains one nucleus 9 Contains thick and thin filaments but not organized into sarcomeres Two types single unit and multi unit Single unit visceral 9 Connected by gap junctions spreading AP from a single neuron through a large group of cells Bone Living Tissue 9 protection assist in movement mineral storage and blood cell production and energy storage in the form of adipose cells in bone marrow Types of Cells Osteoblasts secrete collegen upon which bone is formed 9 Makes bone 9 assist in bone formation Osteoclasts resorb bone matrix 9 Break down bone 9 releasing minerals back into blood Spongy Bone Red Bone Marrow Location of Red Blood Cell development Compact Bone Yellow Bone Marrow contains adipose cells for fat storage Osteoclasts burrow tunnels called Haversian Canals Most Calcium in body is stored in the bone matrix as hydroxyapatite Cartilage Flexible resilient connective tissue 9 Composed of collegen and has no blood vessels and no nerves Skin Several Fxn s including Thermoregulation Blood conducts heat from core of body to skin and some of the heat is dissipated by endothermic evaporation of sweat but most by radiation Protection Skin is physical barrier to abrasion bacteria dehydration and chemical and UV Rays Sensory Input Gathers info from environment by sense Epidermis Avascular No blood vessels epithelial tissue 9 Has several layers continuously divide and peel off Dermis Connective tissue from mesodermal cell embedded with blood vessels nerves glands and hair follicles
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