ASCI 141 Exam #1 Study Guide
ASCI 141 Exam #1 Study Guide ASCI 141
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This 20 page Study Guide was uploaded by Katarina Fielding on Friday February 5, 2016. The Study Guide belongs to ASCI 141 at University of Vermont taught by Feng-Qi Zhao in Spring 2016. Since its upload, it has received 59 views. For similar materials see Anatomy and Physiology of Domestic Animals in Animal Science and Zoology at University of Vermont.
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ASCI 141: WEEK #1 READING NOTES CHAPTER #1: INTRODUCTION TO ANATOMY AND PHYSIOLOGY Anatomy and physiology are two complementary but different ways of looking at the animal body o Anatomy: deals with the form and structure of the body and its structure- what things look like and where they are located o Physiology: deals with the functions of the body and its parts- how things work and what they do Anatomy can be approached in different ways o Microscopic versus macroscopic Microscopic- deals with small structures that we need a microscope to see them, cells and tissues Macroscopic aka gross- deals with body parts large enough to be seen with the unaided eye; organs, muscles, bones o Regional versus systematic Regional- neck region (cervical): including all the cells, tissues, blood vessels, nerves, muscles, organs, and bones in the neck Problem is the overlapping of regions that are adjacent; example where does should end and neck start Systematic- deals with the systems of the body Skeletal- bones and joints Integumentary- skin, hair, nails, and hooves Nervous- central nervous system and peripheral nerves Cardiovascular- heart and blood vessels Respiratory- lungs and air passageways Digestive- gastrointestinal tube and accessory digestive organs Muscular- skeletal, cardiac, and smooth muscle Sensory- organs of general and special sense Endocrine- endocrine glands and hormones Urinary- kidneys, ureters, urinary bladder, and urethra Reproductive- male and female reproductive structures Basic anatomy terminology is based on planes of reference o 4 anatomic planes of reference Sagittal plane: plane that runs the length of the body and divides it into left and right parts that are not necessarily equal halves Median plane: a special kind of sagittal plane that runs down the center of the body lengthwise and divides it into equal left and right halves Transverse plane: a plane across the body that divides it into cranial (head end) and caudal (tail end) parts that are not necessarily equal Dorsal plane: plane at right angles to the sagittal and transverse planes. It divides the body into dorsal (towards the animals back) and ventral (toward the belly) parts that are not necessarily equal Called the frontal plane in humans Directional terms in anatomy provide a common language for accurately and clearly describing body structures regardless of the position of the animals body o Left and right refer to the animal’s left and right o Cranial and caudal refer to the ends of the animal as it stands on four legs Cranial- towards the head Caudal- towards the tail In humans superior takes place of cranial and inferior takes place of caudal o Rostral is only used for the head as cranial is the head so rostral means toward the nose o Dorsal and ventral mean “up and down” with the animal in the standing position Dorsal- towards the back (top surface) Ventral- towards the belly (bottom surface) In humans posterior takes place of dorsal and anterior takes place of ventral o Medial and lateral refer to positions relative to the median plane Medial is toward the median plane ( toward center) Lateral is away from the median plane o Deep and superficial refer to the position of something relative to the center or surface of the body or a body part Deep means towards the center of the body or a body part Internal sometimes used in place of deep Superficial means towards the surface of a body or body part External is sometimes used in place of superficial o Proximal and distal are used to describe positions only on extremities Proximal means towards the body Distal means away from the body o When it comes to the front and back surfaces of legs it comes to the carpus (equivalent to our wrist) as the dividing line for the front limbs and the tarsus (equivalent to our ankle) for the rear limbs Back surface of the front leg distally from the carpus is the palmar surface Front surface of the front leg proximal from the carpus is the caudal surface Back surface of the hind leg distally from the tarsus is the plantar surface Front surface of the hind leg proximal from the tarsus is the caudal surface Common regional terms Term Region Barrel Trunk of the body- formed by the rib cage and the abdomen Brisket Area at the base of the neck between the front legs that covers the cranial end of the sternum Cannon Large metacarpal or metatarsal bone of hoofed animals Fetlock Joint between cannon bone and the proximal phalanx of hoofed animals Flank Lateral surface of the abdomen between the last rib and hind legs Hock Tarsus Knee Carpus of hoofed animals Muzzle Rostral part of the face formed mainly by the maxillary and nasal bones Pastern Area of the proximal phalanx of hoofed animals Stifle Femorotibial/femoropatellar joint- equivalent to human knee Tailhead Dorsal part of the base of the tail Withers Area dorsal to scapulus Bilateral symmetry- left and right halves of an animal’s body are essentially mirror images of each other Body cavities are main spaces in the body- animals have two main body cavities o Dorsal body cavity- contains the brain and spinal cord (central nervous system) Two parts: spherical cranial cavity in the skull and the narrow spinal cavity running down the spine Cranial Cavity aka cranium: Formed from numerous bones of the skull and it houses and protects the brain Spinal cavity aka the spinal canal: formed from vertebrae of the spine and houses and protects the spinal cord o Ventral body cavity Much larger than the dorsal cavity Contains most of the soft organs (viscera) of the body Divided into the thoracic cavity (cranial) and the abdominal cavity (caudal) by the thin diaphragm muscle Thoracic cavity major structures are heart, lungs, esophagus, and man major blood vessels coming to and going from the heart All organs covered by pleura as well as the interior of the cavity Layer covering the organs is called the visceral layer Layer covering the cavity is called the parietal layer Abdominal cavity includes digestive, urinary, and reproductive organs Lined by a thin covering called the peritoneum which also covers all of is contents Visceral layers covers all the organs, parietal layer lines the cavity Levels of organization o Cells- basic functional units of animal life Cells must specialized in some functions and eliminate others in order to create and support an environment that allows all of its cells to live and function o Tissues- form when specialized cells group together Four basic tissue types in animals: connective, epithelial, muscle and nervous Tissue Characteristics Functions Epithelial Composed only of cells Covers and protects (surfaces), secretes (glands), absorbs (intestinal lining) Connective Composed of living and Binds cells and structures non-living intercellular together and supports substances the body Muscle Skeletal (voluntary), Movements Cardiac (heart), Smooth (involuntary) Nervous Composed of nerve cells Transmits information (neurons) and supporting around body; coordinates cells and controls activities o Organs- made up of groups of tissues that work together for a common purpose Examples: kidneys, eyes, lungs, brain, heart, uterus Some come in pairs while other are singular o Systems- most complex level of body organization, groups of organs that are involved in a common set of activities Example: digestive system- concerned with obtaining, digesting, and absorbing nutrients to fuel the rest of the body Includes organs made of the digestive tube such as the esophagus, stomach, and intestines as well as the accessory digestive organs such as the salivary glands, pancreas, and liver Health- state of normal anatomy and physiology o Complicated process as the health of the body as a whole depends on the health and proper functioning of all the systems, organs, tissues, and cells while the health of the body’s cells depends on the health and proper functioning of all the tissues, organs, systems, and the body as a whole o Body Health System Health Organ health Tissue health Cell health Homeostasis- maintenance of a dynamic equilibrium in the body o Whole body is responsible for the maintenance of homeostasis through the use of the body’s systems CHAPTER 3: ANATOMY OF THE CELL Cells that do not have a nucleus- prokaryotes Cells that do have a nucleus as well as DNA combined with protein to form chromosomes- eukaryotes Animal cells have a size limiting factor from 10 to 30 micrometers due to the relationship between surface area and the volume of the cell Cell size is also regulated by the governing capability of the nucleus o Single nucleus can control the metabolic activity of a small cell better than a larger one Some very large cells or cells that are very active have two or more nuclei Combination of increased nuclei and expanded surface area enables muscle cells to function at a very high metabolic rate Three structures found in mammalian cells regardless of their shape size and function o Cell membrane (plasmalemma)- cells are separated from their environment by this o The cytoplasm: cytosol, cytoskeleton, organelles Everything inside the cell membrane other than the nucleus and genetic material is known as the cytoplasm Cytoplasm includes cytosol- jam-like protoplasm that is highly structured and composed of proteins, electrolytes, and metabolites Flexible cytoskeleton Organelles which like the organs in our body work together to carry out necessary metabolic functions o The nucleus- contains vital genetic material in the form of chromosomes o No single cell includes all of these features and cells have a diverse array of shapes and sizes depending upon their function within the body o Nuclei have many shapes and that many of them are not positioned in the center of the cell Cell membrane- acts as a flexible barrier between the inner cytoplasm and the outside environment o Includes many infoldings and outpouchings which provide extra surface area, and continually removing and recycling parts of itself, updating surface receptors and renewing its sticky outer coating o Governs the movement of atoms and molecules in and out of the cell o Usually consists primarily of protein (55%) and phospholipids (25%) but also includes quantities of cholesterol (13%), miscellaneous lipids (4%0 and carbohydrates (3%) o Cell membrane is composed of two layers of phospholipid molecules arranged so that the hydrophilic heads are on the outside and the hydrophobic, fatty acid tails are on the inside- lipid bilayer o Proteins which are suspended in the bilayer can move easily throughout the membrane to create a constantly changing mosaic pattern – fluid mosaic Lipid-soluble materials (ex: oxygen, carbon dioxide) pass through the membrane with ease Ionized, water soluble molecules (ex. amino acids, sugars, proteins) are not lipid soluble and do not readily pass through o Membrane contains cholesterol molecules which wedge themselves between phospholipids and help stabilize the membrane Prevents lipids from aggregating, adds to oily nature of the internal layer which increases the membrane’s impermeability to water-soluble molecules o Structural and globular proteins are responsible for the membrane’s special functions Compact globular proteins can occur either inside the lipid bilayer or on the cell surface Integral proteins- within the bilayer o Span the entire width of membrane and can create channels through which other molecules can pass o Some are selective channels which can only permit certain substances from entering or exiting o Others are pores which allow substances to pass through with no resistance Peripheral proteins- bound to inside or outside of the cell membrane o Sometimes act as enzymes to catalyze specific chemical reactions and can be involved in changing the cell’s shape Proteins on inner surface of membrane- bound to components of cytoskeleton, keratin fibers, or peripheral proteins Proteins and lipids on the outer layer are attached to the sugar groups Glycoprotein- sugar and protein Glycolipid- sugar and phospholipid o Principal components of glycocalyx Provides improved cell-to-cell adhesion and represents an important biological marker for intercellular recognition and for the interactions between cell and antibodies or cells and viruses Composed of two families of cell adhesion molecules (CAMs) and membrane receptors CAMs- sticky glycoproteins which cover surfaces of almost all of cells in mammals; allow the cells to bond to extracellular molecules and to each other Important in helping cells move past one another and in signaling circulating cells to areas of inflammation or infection Membrane receptors- integral or glycoproteins that acts as binding sites on cell surface Play vital role in contact signaling Rafts- rigid areas or densely packed phospholipids, cholesterol and protein forming plaque-like structures Important in helping to organize functional areas on the cell surface, in initiating cytokinesis during cell division, and in forming depressions on the cell surface that may lead to involution and vesicle formation Caveolae- small invaginations of plasma membrane which often pinch off and migrate inside the cell to form tiny vesicles o Can form single vesicles or clusters depending upon the type of cell o Produced only from rafts in the plasma membrane that contain the integral protein caveolin Cells lacking caveolin, lack caveolae o Three types of caveolin All have a similar loop structure Calveolin-1 and 2 have been found in cell membranes of endothelial, fibrous and adipose cells Calveolin-3 found in striated and smooth muscle cells o Caveolin associated with cellular functions including endocytosis, transcytosis, and contact signaling Flagella and cilia extensions of plasma membrane which extend into the extracellular space o Energetic motile hairs structurally identical but functionally different o Composed of 9 pairs of microtubules which encircle a central pair of microtubules o Originate from the basal bodies (pair of centrioles) located at periphery of cell just under the plasma membrane o Cilia- large numbers on the exposed surface of some cells Shorter than flagella and move synchronously propelling fluid, mucus, and debris across the cell surface Used in upper respiratory tract and in oviduct o Flagella- occur singly and significantly longer Propel cell forward by undulating and attached to individual cells Sperm cell tail is a flagellum Cytoplasm- inner substance of the cell excluding nucleus, includes the cytosol, cytoskeleton, organelles, and inclusions o Cytosol- fluid of the cell Viscous, semi-transparent composed of dissolved electrolytes, amino acids, and simple sugars o Cytoskeleton- three dimensional frame for the cell Flexible, fibrous structure which changes in accordance with cell’s activities Gives support and shape to cell, enables it to move, provides direction for metabolic activity, and anchors the organelles Composed of three different types of fibers: microtubules, intermediate fibers, and microfilaments Microtubules- thickest fibers, long hollow tubes which grow out from the cell center near nucleus o Form secure cables which mitochondria, lysosomes, and secretory granules attach o Can be easily disassembled and then reassembled to form new paths or to take on new direction o Composed of a pair of spherical molecules called tubulins, linked in a spiral chain which provides strength and flexibility to cilia and flagella, as well as to the cell as whole Intermediate fibers- woven, ropelike fibers which possess high tensile strength and are able to resist forces pulling on the cell by acting as internal guy wires o Toughest and most permanent element of the cytoskeleton o Composed of different proteins, depending on the function of the cell and take on different names depending on which type of cell they are found in Ex: nerve cells- neurofilaments Microfilaments- located near the cell surface on cytoplasmic side of the plasm membrane and arranged in bundles and meshworks o Composed of contractile protein actin, together with the motor protein myosin which plays key role in cell’s ability to change shape, break apart during cell division, and form outpouchings and involutions o Assembled where and when they are needed- position and quantity in the cell vary depending on the cell’s activity o Centrosomes- important region of cytoskeleton located near the nuclear envelope Responsible for the coordination of building and breaking down microtubules in the cell and is composed of: centrioles, pericentriolar material, and asters Centrosome helps manufacture microtubules Centrioles ( pair of small cylinders) found in the central portion of the centrosome Composed of nine triplets of microtubules arranged like a pinwheel around a hollow core Asters- long rods of microtubules- radiate away from centrioles forming anchors to the centrosome Center of this region forms the pericentriolar material (PCM) where the formation of microtubules is initiated In order to get ready for cell division, centrioles must first duplicate Centrosome- plays an important role in the formation of microvilli, cilia, and flagella Organelles- membrane bound structures within the cytoplasm that possess specialized cellular functions o Compartmentalization of organelles crucial for effective metabolic processes, enables the cell to separate and control various molecular interactions Basis for food absorption, energy production and excretion o Largest or organelles- mitochondria “powerhouse” of the cell- produces 95% of the energy that fuels the cell Large nutrient molecules are processed and broken down into smaller ones to be used for fuel of most metabolic processes Respiration also takes place here as well as many other biochemical processes Active cells- have high energy demand and therefore great numbers of mitochondria o Ribosomes- most common and smallest organelle in the cell Flexible in their abilities to attach and detach from membranes and move freely throughout the cell o Endoplasmic reticulum- series of flattened tubes stacked on one another and bent into a crescent shape Walls composed of single lipid bilayer and are continuous with the membranes of the nucleus Rough ER and smooth ER Rough- ribosomes on the surface o Involved in the production of protein, assembled by ribosomes Smooth- lacks ribosomes o Active in the synthesis and storage of lipids, particularly phospholipids and steroids Proportion of smooth and rough ER varies depending on the synthetic activities of the cell o Golgi apparatus- composed of flat, crescent shaped cisternae Proteins modified in Golgi and then packaged into small spherical vesicles and travel to other parts of the cell Modification, distribution, and packaging center for molecules destined either for secretion or for intercellular use Functions in polysaccharide synthesis and in the coupling of polysaccharides to proteins to create glycoproteins found on the cell surface o Lysosomes- specialized vesicle formed by the Golgi apparatus Contains powerful enzymes enclosed in a single protective membrane which fuses with nutrient carrying vesicles, microbes or aged cellular parts Uses digestive enzymes Can digest large amounts of cellular debris at once o Proteasomes Small cylindrical structure composed of multiple protein subunits Assists with breakdown and removal of misfolded and unwanted protein in the cell Can only break down one protein at a time Barrel shaped composed of a stack of flattened protein subunits with a hollow core down the center Normal functioning is essential for healthy cells o Peroxisomes- membranous sacs containing enzymes that are found throughout the cell Formed by vesicles pinching in half via fission or pinching off from the ER Common in kidney and liver cells Important in detoxification of various molecules Use oxygen ex. alcohol and formaldehyde Assist in the removal of free radicals, normal products of call metabolism but can be harmful to the cell in large quantities because they interfere with the structure of proteins, lipids, and nucleic acids Contain peroxidases and catalases Peroxidases- assist in the conversion of free radicals to hydrogen peroxide Catalases- reduce hydrogen peroxide to water o Vaults- minute barrel-shaped structure with tapered ends which are hollow Extremely numerous in cells and may play a role in transporting molecules to and from the nucleus Attached to microtubules and seem to be acting as transportation pods Made of protein and small amount of RNA ( vault RNA= vtRNA) o Inclusions- packages units of metabolic products or substances that the cell has engulfed May be delineated by a surrounding, single-layer membrane as seen in secretory granules, vacuoles, and vesicles Non-membrane bound inclusions such as lipid droplets and fat globules Ex. vacuoles Nucleus- largest organelle of the cell, control center, “brain” of the cell o Maintain hereditary information of the species and control cellular activities through protein synthesis o Nucleus divided into four parts Nuclear envelope or membrane, nucleoplasm, chromatin, nucleoli CHAPTER 4: CELL PHYSIOLOGY Water is essential for life- 60% of animal’s body is composed of water Two thirds of total body water (TBW) is found inside cells as intracellular fluid Fluid outside cell is extracellular fluid and makes up last third of TBW o If found in blood and lymphatic vessels- intravascular fluid o If found outside vessels and surrounding cells- interstitial fluid Osmolality- measure of solute concentration in fluids o Ranges in mammals are 278 to 300 milliosmoles per kilogram o Ranges kept very narrow due to hormonal feedback loops Increase in osmolality triggers desire to drink and release of antidiuretic hormone Decrease in osmolality inhibits desire to drink and inhibits release of antidiuretic hormone Veterinarians request serum osmolality tests to better understand what is happening physiologically in sick patients: Problems with hydration status, dehydration (high osmolality) or over hydration (low osmolality) Presence of hyperglycemia caused by diabetes (high osmolality) Problems with the functioning of the hypothalamus in the brain, which produces ADH (low osmolality with trauma to the head) Poisoning by ethylene glycol (high osmolality) or excessive use of steroids ( low osmolality) o Osmolality comparable to normal blood or normal saline- isotonic o Osmolality fluids greater than that of blood- hypertonic o Osmolality fluids less than that of blood- hypotonic Summary of Membrane Processes Type of Description Substances Example Process Transported Passive Processes 1. Diffusion Kinetic movement of 1. Small molecules 1. Water molecules from higher diffuse through 2. Oxygen and to lower membranes carbon concentration 2. Lipid-soluble dioxide gases pass 3. Chloride through lipid and urea bilayer 3. Charged ions move through specialized channel proteins 2. Facilitated Selective carrier Some large molecules Movement of Diffusion proteins assist in and non-lipid-soluble glucose into muscle movement of molecules and fat cells molecules from higher to lower concentration; speed of diffusion is limited by saturation of carrier molecules 3. Osmosis Passive movement of Water Water moves from water through a stomach into semipermeable bloodstream membrane from dilute solution to more concentrated one 4. Filtration Hydrostatic pressure Water and small Filtration of blood in (caused by the molecular solutes but kidney enables beating heart) forces not large molecules small solutes and liquid and small such as proteins; liquid to pass molecules through a separates molecules by through it but not membrane size blood cells, proteins, and other large molecules Active Processes 1. Active Active movement of Molecules too large to Ions such as K+, transport molecules by specific pass through channels Na+, and Ca2+ carrier protein; or unable to penetrate molecules may move lipid bilayer because of against concentration polarity; may be on gradient wrong side of concentration gradient 2. Endocytos Cell engulfs solid Microinvaders and White blood cell or is substances foreign debris macrophage a. Phagocyt engulfs bacteria osis b. Pinocytosi Cell engulfs liquid Water and other solutes Absorptive cells in s substances small intestine take water into intracellular vesicles c. Receptor Specialized protein Hormones, iron, and Insulin, produced mediated receptors bind to cholesterol by pancreas, only ligands specific binds to cells with receptors insulin receptors 3. Exocytosi Excretion of waste Waste products, Digestive enzymes s products and secretory proteins, produced in secretion of hormones, and lipids pancreas and manufactured released into ducts substances; these connected to small substances are intestine packaged in secretory vesicles, which fuse with cell membrane; contents ejected to the extracellular space Isotonic- extracellular fluid has same concentration of dissolved solutes as the intercellular fluid Hypertonic- extracellular fluid more concentrated than the cytoplasm Hypotonic- extracellular fluid less concentrated then the cytoplasm Oncotic pressure- difference between osmotic pressure of blood and the osmotic pressure of interstitial fluid or lymph Symport system- all substances in an active system moving in the same direction Antiport system- some substances moved in one direction while other substances move in other directions in an active system Life cycle of the cell o Reproductive cells divide through the process of meiosis o Somatic cells divide through the process of mitosis o Interphase- period between cell divisions divided into three subphases Growth one (G1)- can last for variable periods, intensive metabolic activity and cellular growth Cell doubles in size and the number of organelles also doubles Centrioles begin to replicate in preparation for cell division Synthetic (S)- marked by DNA replication; new histones are formed and assembled into chromatin, forming new identical replicas of the genetic material Growth two (G2)- very brief, synthesis of enzymes and proteins necessary for cell division and continued growth of the cell Centrioles complete their replication o DNA Replication Nucleoplasm of the a cell, chromosomes uncoil from their superhelical and helical formations to form loose strands of chromatin ( DNA and histone proteins) The portion of DNA to be copied unwraps and separates from the histone proteins A special protein called helicase initiates the untwisting of the DNA helix and separates portions of the DNA into two nucleotide chains. Each region along the long strand where the DNA has separated is called a replication bubble. The spot where the bubble begins and ends is called a replication fork Free DNA nucleotides, which are dissolved in the surrounding nucleoplasm, are attracted to the exposed complementary nucleotides. These molecules pair to one another in complements. Purines, adenine and guanine, pair with pyrimidines, thymine and cytosine. Original DNA strand is a template for the formation of a complementary new strand. DNA replication is carried out by a kind of molecular “machine” called a replisome. The replisome is composed of a collection of proteins including two types of enzymes called primases and replicases. Replication process begins when the primases attach a short chain of RNA to the DNA template strand. These RNA primers are about 10 bases long. Once primer is in place, DNA replication can begin. DNA polymerase III places complementary nucleotides along the template strand and covalently links them together. Polymerase III is responsible for assembling the majority of the new nucleotide strand. DNA polymerase II moves in only one direction, so the first strand, the lead strand is made continuously while the second strands, the lagging strand, is made in segments and subsequently joined together by an enzyme called DNA ligase. DNA polymerase III finishes building a new strand, DNA polymerase I moves in and replaces the RNA primer with DNA nucleotides. Telomeres, nucleoprotein caps, are placed on the ends of each DNA strand to protect the ends from damage. In addition, histone proteins are imported into the nucleus from the cytoplasm, and DNA is wrapped around them, forming chains of nucleosomes. Identical DNA strands become chromatids, joined together at a central point called the centromere. Each chromatid is an exact replica of the other, each containing one strand of the original DNA molecule and one strand of the new complement. o Mitotic phase Time when the cell is actively dividing; broken up into four stages: prophase, metaphase, anaphase, and telophase and concludes with the division of the cytoplasm which is cytokinesis Prophase- chromatin condenses, coils, supercoils, and forms discrete X-shapers, formation of duplicate chromosomes essential for life and enables the cell to divide its genetic material, cytoplasm becomes more viscous, cell becomes rounds, two centrioles form anchors on microtubules and lengthen, concludes with disintegration of nuclear envelope Metaphase- lining up of chromosomes in the exact center of the spindle, known as the equator; form the anaphase plate Anaphase- centromere of each chromosome splits in half and each single strand becomes its own independent chromosome; each spindle fiber pulls chromosomes creating a V-shape Telophase- when the chromosomal movement stops; chromosomes have reached the poles, begin to unravel, elongate, and return to the chromatin form Control of cell division o Normal cells stop dividing when they come into contact with surrounding cells- contact inhibition o Growth-inhibiting substances are released from cells when their number reach a certain point o A number of checkpoints are reached during cell division (G1 and G2 interphase checkpoints) o Cyclins and cyclin-dependent kinases allow cell to enter mitosis Transcription- in nucleus o RNA polymerase binds to a DNA molecule and initiates separation of the double helix. A specific section of DNA, called a gene, is exposed o RNA polymerase moves along the DNA strand and coordinates the pairing of RNA nucleotides to corresponding DNA nucleotides. The RNA nucleotides are linked to one another to form a strand of mRNA. o When RNA polymerase reaches the end of the gene, the newly formed mRNA molecule is released and travels through the nuclear envelope to the cytoplasm o The separated strands of DNA are reunited to form a double helix once again Translation- in cytoplasm o A ribosome binds to the beginning of the mRNA strand. o Transfer RNA molecules move into the vicinity of the ribosome. The tRNA anticodon is paired with the appropriate codon on the mRNA molecule. o The amino acid carried by the tRNA molecule is released and linked to the neighboring amino acid. o The ribosome continues to move along the mRNA molecule until all of the codons have been paired. o As the developing chain of amino acids lengthens, it coils and folds into the structure of a functional protein. o When translation is complete, the new protein is released then later modified. The mRNA, tRNA and ribosome are free to repeat the process and form more of the same type of protein. Genetic error- mutation Specialization of cells leads to a morphologic or structural variation and influences the types and quantities of organelles contained within the various cell types CHAPTER 5: TISSUES: LIVING COMMUNITIES Epithelial tissue- composed of sheets of cells that cover and line other tissues o Have an exposed surface that affords access to the surrounding environment or to the inner openings of chambers or ducts o Acts as an interface layer that separates and defines the beginning and ending of different types of tissues o Protective of underlying tissues and frequently acts as a filter of biochemical substances o May be absorptive; can also detect changes in the environment and play an important role in the reception of sensory input o Common in secretion or excretion of biochemical substances; engage in manufacture and release of substances called glandular epithelial; some substances produced by glandular epithelial lubricates parts of the body or can play a vital role in producing biochemical substances produced by glandular epithelia o Excretions- substances that ultimately leave the body Ex. urine o Secretions- substances that remain within body ex: mucus o Vital functions of epithelial Protects, covers, and lines Filters biochemical substances Absorbs nutrients Provides sensory input Manufactures secretions Manufactures excretions General Characteristics of Epithelia o Polar, have a sense of direction relative to surrounding structures o Each has an apical and basal surface Apical- side of cell that faces the body cavity (lumen) Basal- side which faces the underlying connective tissue o Lateral surfaces which are connected to the neighboring cells by junctional complexes Bring the cells in close apposition to each other leaving little room for extracellular matrix o Lack blood vessels or capillaries (avascular); rely on underlying connective tissue to provide oxygen and nutrients o Most contain nerves and provide valuable sensory input Epithelial cells held together in many ways o Lateral surfaces are wavy and fit together like a jigsaw puzzle o Matrix filled channels between plasma membranes of adjacent cells transport nutrients from the underlying connective tissue Act as distribution routes for biological supplies and waste elimination routes o Junctional complexes- give epithelial tissue surprising strength Junctions include: tight junctions, desmosomes, and gap junctions Tight junction- fusion of outermost layers of the plasma membranes of adjoining cells; matrix filled space is lost; found in tissues where there is a risk of leaks ex. urinary bladder and digestive system Desmosomes- strong welded thickening which connects plasma membranes of adjacent cells; bond is mechanical coupling by filaments; tonofilaments (intermediate filaments) extend from plaque into cytoplasm of each cell in order to form stabilizing bases for the junction; found in tissue that undergo repeated episodes of tension and stretching such as the skin, heart, and uterus Gap junctions- linked by tubular channel proteins (connexons) which extend between the cytoplasm of one cell to another; allow for the exchange and passage of ions and nutrients; found in intestinal epithelial, heart and smoot muscle tissue; coordinate contraction of cardiac and smooth muscle Basement membrane- foundation of the epithelial cell o Meshwork of fibers which attaches the epithelial cells to the underlying connective tissue Epithelial cells surfaces vary depending on where the epithelium is located in the body and what role it plays in the function of the tissue o Ex. keratin on skin cells Classification of epithelial o Number of layers of cells- single layer= simple, two or more= stratified o Shape of cells- squamous, columnar, cuboidal o Presence of surface specializations- cilia or keratinized Types of epithelia o Simple squamous- delicate and thin- often found in lining surfaces involved with the passage of either gas or liquid, ca only occur in protected regions of the body; important in reducing friction and found in lining of blood and lymphatic vessels; lining cavity= mesothelium; lining blood an lymphatic vessels= endothelium o Simple cuboidal- provides little protection from abrasion; found in places of body where secretion and absorption occur; plays important roles in endocrine and exocrine functions o Simple columnar- relatively thick and more protective than simple squamous and cuboidal; aligned in a row at the base of the basement membrane; ex. line GI tract from stomach to rectum; associated with absorption and secretion o Stratified squamous- regions of body which are subject to mechanical and chemical stresses; ex: lining of mouth, rectum, vagina o Stratified Cuboidal- found primarily along large excretory ducts o Stratified columnar- rare and found in only certain spots ex. respiratory tract, reproductive, digestive o Pseudostratified columnar- not truly stratified; not all cells reach the luminal surface o Transitional- remarkable ability to stretch; found in regions of body which are required to expand and contract as part of their normal function; forms a leak proof membrane Glands- cell or group of cells which have the ability to manufacture and discharge a secretion o Glands classified by the following Presence or absence of ducts (endocrine or exocrine) # of cells that composed them (unicellular or multicellular) Shape of the secreting ducts (simple or compound) Complexity of glandular structure (tubular, acinar, tubuloacinar) Type of secretion produced (mucoid or serous) Manner in which secretion is stored and discharged (merocrine, apocrine, or holocrine) o Endocrine glands- no ducts or tubules, secretions distributed throughout the body; produce hormones o Exocrine glands- possess ducts, more common, discharge secretions via ducts directly into nearby areas; act locally and normally do not enter circulation Unicellular exocrine glands- goblet cells Multicellular exocrine glands- contain two parts- secretory units and a duct Simple glands= unbranched main gland Compound gland= branched main gland Tubular gland= long channel of even width Acinar/ Alveolar= round sac Tubuloacinar= both tubular and acinar Merocrine= secretory cells remain intact during the secretory process Apocrine= loss of the top part (apex) of the cell Holocrine= entire cell is lost Serous secretions= watery and high concentrations of enzymes Mucous secretions= thick, viscous, and composed of glycoproteins Mixed exocrine= both mucous and serous components Connective tissue- Tissue which connects epithelium to the rest of the body, provide structure, stores energy, transports materials and has no contact with the environment. o Composed of specialized cells and extracellular components: Vasculated o Ground substance: Medium through which cells exchange nutrients and waste with bloodstream. o Fibers of connect tissues. Collagenous fibers: Strong, thick and unbranched strands has tensile strength in order to resist pull forces. Reticular fibers: thin delicate and branched, form a mist net which provides support for organs. Elastic fibers: branched in complicated network, stretches and contracts like a rubber band. o Loose connective tissue: packing materials of body includes Adipose- Closely packed adipocytes filled with lipids, highly vascularized, white adipose tissue: throughout body, brown adipose tissue: in newborn and hibernating animals, functions as a thermoinsulator, important energy storage, and protection. Reticular- Uses only reticular fibers, arranged in an irregular network, only in limited number of sites including liver and bone marrow, provides internal skeleton for hematopoietic and lymphatic tissue. Areolar- Loose fibers suspended in ground substance, located throughout body under the basement membrane, provides nutrients to epithelial as well as supporting and forming barriers against microorganisms o Dense connective tissue: most of volume occupied by fibers includes Dense regular- Collagen fiber tightly packed in one direction, found in tendons and ligaments, tensile strength provides firm attachment and pulls muscles. Dense irregular- Collagen fibers stacked in different directions found in locations such as dermas of skin and organ capsules, provides strength to resist forces from multiple directions and helps prevent overexpansion of organs. elastic tissue- Dominated by extremely flexible elastic fibers, found between vertebrae of spinal column and walls of blood vessels, stabilizes position of vertebrae as well as cushion shock and permits expansion and contraction of organs o Cells of connective tissue proper Fixed cells: fibroblasts, adipocytes, and reticular. Wandering cells: mast cells, leukocytes and macrophages. o Fluid connective tissue Blood: carries oxygen and nutrients to tissues, transports waste products and gases for disposal Lymph: immune system o Supportive connective tissue: Cartilage: Located in chondrocytes, no nerves, avascular, uses collagen and elastic fibers as well as ground system supported by fibrous membrane Bone: provides support and protection, blood’s produced in marrow, provides storage for calcium and other minerals. CHAPTER 6: INTEGUMENTARY SYSTEM Be able to list its components, specify its general function, describe structure and function of the epidermis, dermis, and hypodermis layers, describe structure and unction of hair follicle, describe differences between sebaceous and sweat glands CHAPTER 7: THE SKELETON SYSTEM Describe skeletal system functions, classify bones according to their shape and structure’ compare structures and functions of compact and spongy bone, identify cell types in bones and list major functions, introduce intramembranous and endochondral ossification, describe the remodeling and homeostatic mechanisms of the skeletal system, contrast major categories of joints, describe dynamic movements of the skeleton
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