Exam 3 Study Guide
Exam 3 Study Guide Bio 1144
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This 12 page Study Guide was uploaded by Carly Miller on Sunday November 1, 2015. The Study Guide belongs to Bio 1144 at Mississippi State University taught by Thomas Holder in Spring 2015. Since its upload, it has received 207 views. For similar materials see Biology II in Biology at Mississippi State University.
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Date Created: 11/01/15
Starts with chapter 40 Levels of Organization Cellular: phylum Porifera - very simple Tissue : aggregation of cells for a common function: Phylum Cnidaria and Ctenophora Organ: tissues aggregate to perform a common function Organ systems: organs working together to achieve a common goal (10 organ system) 1. Integumentary: external protection 2. Digestive: breakdown of food and elimination of solid waste 3. Nervous: regulation and coordination of bodily activities (communication system of the body) 4. Muscular/Skeletal (Musculoskeletal): muscular allows movement; skeletal helps with support, movement, and protection 5. Circulatory: transport of solutes through the body (blood ﬂow) 6. Respiratory: gas exchange (oxygen in, carbon dioxide out) 7. Excretory (Urinary): body ﬂuid regulation and elimination of soluble waste (gasses/ions) 8. Endocrine: regulation and coordination of most body processes (hormonal control) 9. Reproductive: production of gametes (eggs and sperm), and the reproductive path 10. Immune/Lymohatic: internal defense system (against pathogens) All tied together through the organism. Example: endocrine and immune system produce materials through the circulatory system. Materials broken down by digestive system transported through body via circulatory system, then excreted using digestion and excretory systems. Main focus is the structure and function. Structure affects function! Concentrate on the complexity and size increase in the heart and brain. Mainly focused on vertebrates, then mammals, then humans. Tissues 1. Epithelial tissue A. Most of the time, epithelial tissues are found as sheets of cells that cover or line surface or cavities. cells are tightly packed together in sheets or lines to form a massive network. Even though they are tightly packed, they are separated from underlying connective tissue by the basement membrane (basal lamina). B. Two classiﬁcation factors: number of cell layers and cell shape a. Number of Cell Layers: 1. one layer is simple 2. more than one layer is stratiﬁed (multiple layers) b. Cell Shape: 1. Squamous: ﬂattened cells 2. Cuboidal: cube shaped 3. Columnar: rectangular and the nucleus is usually in the lower portion of the cell c. Combination of these two factors determine its function. (Consider all combinations- 6) C. Simple Squamous Epithelium: a single layer of ﬂattened cells a. Functions: absorption, secretion, and exchange of materials D. Simple Cuboidal Epithelium: single layer of cube shaped cells with a centrally located nucleus a. Functions: absorption, secretion, and exchange of materials E. Simple Columnar Epithlium: single layer of rectangular cells a. Functions: absorption, secretion, and exchange of materials F. Pseudostrtiﬁed Columnar Epithelium: "Falsely Startifed," simple epithelium (single layers for cells) just looks stratiﬁed, but not really! All cells are in fact in contact with basement membrane, cells are different heights. a. Functions: absorption, secretion, and exchange of materials G. Stratiﬁed Squamous Epithlium: multiple layers of ﬂattened cells. In this case, multiple layers of cells but the cells on the outer edge are dead in maturity. The cytoplasm is replaced by keratin which is very strong and provides support and protection. Less keratin as the depth increases. a. Functions: protection (very important for the integumentary system) H. Stratiﬁed Cuboidal and Straiﬁed Columnar: both are 2-3 cells thick (stratiﬁed but not extensively). Diffusion uses concentration gradient, 2-3 cells are better and holding a gradient than 1 cell but also thin enough to allow diffusion to take place a. Functions: transportation and barrier I. Transitional Epithlium: cells are stretchable and ﬂexible, by deﬁnition it is stratiﬁed (4-5 cells thick). Not rigid, most are halfway between cuboidal and columnar; think short rectangular. Do not have a thick membrane, allows for ﬂexibility. When the organ is ﬁlled up, the transitional epithelium ﬂatten to allow the organ to stretch (covers the bladder to allow it to stretch to hold urine). Very important feature to mammals 2. Connective tissue A. As a group, they connect, bind, anchor, or support structures (mainly organs). B. Loose Connective Tissue (Areolar): basically a mesh of loosely connected ﬁbers that hold internal organs in place. Looks like a massive network of spider webs (lots of webbing). C. Dense Connective Tissue: tightly/densely packed ﬁbers. Used for strength and support. (Ex. Tendons and ligands) D. Cartilage: provides support and ﬂexibility. Think phylum Chordata and the vertebral column: bony pieces separated by cartilaginous remnants of the notochord; cartilage serves as a shock absorber - support) E. Bone Tissue: serves as protection and support. F. Adipose Tissue: primarily stores fat, functions include protection, support, and insulation G. Blood: involved in transport, protection (immune system transported via bloo stream), binds and connects organs (blood ﬂows through all organs). 3. Muscle tissue A. Skeletal Muscle: composed of elongated, tube-like ﬁbers. Skeletal muscle is attached to bone, usually referred to as a voluntary muscle (consciously controlled movement of the skeleton). B. Smooth Muscle: composed of lots of tightly packed ﬂat cells that form sheets. Typically smooth muscle is found as sheets in the walls of many internal organs. Involuntary (not consciously controlled) controlled by the nervous system. C. Cardiac Muscle: only associated with the heart, composed of tubular cells called ﬁbers (superﬁcially similar to skeletal muscle). Involuntarily controlled by electrical signals from the nervous system. 4. Nervous tissue A. Bulk of nervous tissue found in nervous system. B. Neurons: nerve cells- carry the signals within the nervous system but not most abundant cells in the tissue. C. Neuroglial cells: much more numerous than neurons; functions include cleaning up of the nervous tissues (damaged cells are removed), provide nutrition and support for neurons, can also produce neurons. Absolutely required for nervous tissue to perform correctly Organ Systems Organs contain several tissues; example: stomach has connected tissue, smooth muscle tissue, ner out tissue and epithelial tissue. Structure predicts/determines function. (If you know the structure, you can predict the function and the complexity of that function- might be an applied exam question) Integumentary System 1. Deﬁnition: skin and all accessory structures (hair, glands, feathers, scales, etc.) 2. Largest vertebrate organ! 3. Functions: A. External protection (stratiﬁed squamous epithelium- scratches don't make you bleed to death) B. Water regulation: monitoring the absorptio or release of water C. Some protection against UV light rays D. Temperature regulation (heat escapes the body primarily though the integument) E. Sensory organ: sense of touch F. Limited excretion: some ions can pass through 4. Consists of two layers: **See handouts of MyCourses** A. Epidermis: outermost and thinner layer. a. Mostly Straiﬁed squamous epithelium (multiple layers of ﬂat cells) b. Lamgerhans Cells: defense cells somewhat associated with the immune system c. Melanocytes: provide some protection against UV light d. Merkel Cells: touch receptors, found throughout but also found in clusters around hair or feathers e. Keratinocytes: most abundant cells; loaded with keratin, produces keratin in the outer layers. Eventually the cytoplasm of these cells will completely die and be replaced by keratin. B. Dermis: inner and thicker layer a. Highly vascularized (blood vessels) b. Many sensory structures, glands, and nerves c. Hair (or feathers, or scales) orgin d. Meissner's Corpuscles: associated with light touch sensation (advanced mammals) e. Pacinian Corpuscles: deep pressure touch f. Sweat Glands: involved with temperature regulation (evaporative cooling). Lose liquid (water+waste ions) and disipate heat g. Sebaceous Glands: secret sebum. Found on entire human body except the palms of hands and soles of feet. Most enhanced in the face, neck, and check regions. Sebum is the oil secrete by glands and it lubricates and softens hair and skin. Some mammals produce this so they can swim in the water in the winter because they don't lose heat. C. Subcutaneous layer/Hypodermis: technically not part of the skin but very important to the provides basal support to the skin, loaded with adipose tissue (fat storage=energy), provides insulation (trapping heat). Softer skin, more adipose tissue. Digestive System 1. Heterotrophs: "ingest feeding" 2. Two types of Gut tracts: A. Blind gut: no cavity between gut and body wall. One opening B. Tube within a tube arrangement: ﬂow through digestive tube; ﬂuid ﬁlled body cavity (coelom) between the gut and the body wall. Allows expansion of the gut tract, gut tract can be composed of larger organs. Characterized by separate openings. 3. Digestive enzymes: special group of proteins that help speed up chemical reactions at regular biological temperatures. Hydrolases: enzymes that catalyze a reaction by adding a water molecule. A. Carbohydrases: break down carbs and sugars B. Proteases: break down proteins C. Lipases: break down lipids D. Nucleases: break down Nucleic acids 4. Functions of digestive system: A. Digestion: break down of large molecules into smaller forms a. Chemical digestion: breaking the bonds of large molecules b. Mechanical digestion: physically breaking down large items into smaller ones B. Absorption: uptake of nutrients along the gastrointestinal tract C. Transport: digestive tract (particularly the tube) moves digested food through the body D. Elimination/Excretion: removal of undigested and unabsorbed materials 5. Alimentary canal: gastrointestinal tract or digestive tube or digestive tract. Lower animals with simpler systems may not have the organs that higher animals have. Broken into regions: A. Region of Reception: a. Buccal cavity: mouth and all accessory structures, site of both chemical and mechanical digestion. b. Includes jaw, teeth, tongue, salivary glands to sink amylase and other enzymes into the food. c. Pharynx the point at which the respiratory and digestive systems cross paths (back of the mouth). The esophagus is posterior to the windpipe. B. Region of Conduction: a. Esophagus: conducts food from the mouth to the stomach. Lined with simple epithelium. Outside of the simple epithelium is smooth muscle which assists in moving food down the esophagus via peristalsis. b. Peristalsis: rhythmic, wave-like contractions to push food through the alimentary canal C. Region of Storage and Digestion: a. Crop: enlarged lower portion of esophagus for short term storage seen in birds and insects b. Stomach: major storage sac seen mostly in vertebrates; lined with simple epithelium tissue (easy for absorption); outside is smooth muscle. 1. Rugae: temporary folds in the lining of the stomach when it's empty (simple epithelium) 2. Walls of the stomach are smooth muscle. There are three layers associated with the wall. Innermost layer cells run vertically, middle layer cells are horizontal, out layer is vertical. Function is to churn the stomach. The contractions cause the stomach to function like a big mixer. By churning, every part of the stored food interacts with the enzymatic juices. 3. Enzymatic juices lead to chemical digestion. Digestion of proteins begins in stomach. Carbohydrate digestion begins in the mouth. 4. Inner lining of the stomach (simple Epithlium) has pits and glands. Mucous cells: secrete moisture to soften the food and providing water for the enzymes. Chief cells: secrete pepsinogen (inactive enzyme-needs to be activated). Parietal cells: secrete hydrochloride acid which activates pepsinogen. When they combine the form pepsin which breaks peptide bonds of proteins. Theorized that hydrochloric acid helps regulate bacteria in the stomach. 5. Lumen (cavity of stomach): location where pepsin is formed so proteins can be digested. 6. Very minimal absorption. Lipid soluble material (aspirin, alcohol, etc). D. Region of Terminal Digestion & Absorption: a. Midgut: seen in insects b. Small intestine: seen in vertebrates, where most of absorption is done. 1. Chemical digestion of lipids and Nucleic acids begins and ends in this region. Chemical digestion of carbs and proteins continued and completed. If not broken down enough to be absorbed here, it won't be. Same width as esophagus, need lots of time for absorption so need more length. 2. Average small intestine is 8x the organisms height. 3. Duodenum: many secretions in this regions. Beginning region, attached to stomach. Make sense to secrete enzymes at the beginning. Absorption of small molecules can be absorbed here. Jejunum is the middle section. Ileum is the end of absorption. 4. Surface (lining of the small intestine) modiﬁcations can increase surface area: A. Plicae circulares: folds of the inner lining of the small intestine. Increase surface area 2-3x. B. Villus (pl. villi): ﬁnger-like projections off the surface. Increase surface area by 10x. C. Microvilli: folding of the plasma membranes of the cells lining the villus. (Folding of the cell membranes of the simple epithelial tissue). increase surface area by 20x. E. Region of Water Absorption & Concnetration of Solids (Waste packaging) a. Vertebrate animals = large intestine b. Large intestine lined with simple epithelium, average length is about 1.5 m. No need for extra surface area, so just simple epithelium. c. Water absorbed to package waste. Average absorption of water is about 1 L per day. d. When water is absorbed, feces is compacted and eliminated. e. In humans, waste is 75% water, 5% inorganic substances, 5% fats, 7% undigested proteins, dead cells and bile, and 8% roughage (material that cannot be digested). f. In the large intestine, there is vitamin synthesis by bacteria that live in the new intestine. Enter newborns via the anus and live there. Some bacteria are necessary. g. Anus: opening at the end of the large intestine. Most animals exhibit anus, those that don't exhibit cloaca: chamber receiving the contents of the digestive, urinary, and reproductive tracts. Think birds, amphibians, and reptiles. Cloacal vent that releases those contents to the outside. 6. Accessory Digestive Glands (not part of the digestive tube but associated with the digestive system) A. Pancreas: pancreatic duct is connected to duodenum. Pancrease secretes enzymatic juices that break down all biomolcules, travels through the pancreatic duct and into the duodenum. B. Liver: produces bile which is necessary for the breakdown of fat. Bike emptied into the duodenum to increase ingestion and absorption of fat. Constant trickle C. Gallbladder: stores bile from liver. When a high fat material passes through the system, the liver is still producing its bile, but the gallbladder helps concentrate the bile to break down the fatty contents 7. Page 945 shows the digestive system in entirety, 8. Carbohydrates (sugars) are big polysaccharides that cannot be absorbed as they are. Must be broken down (usually into sucrose, fructose, and even disaccharides like maltose) 9. Proteins are broken down by pepsin to amino acid which are absorbed by the small intestine to the blood stream 10. Fats are broken down by bile to glycerol and fatty acids 11.Nucleic acids are broken down into nucleotides (phosphate, nitrogenous base, and 5 carbon sugar) 12. All requires enzyme activity! Muscular System 1. Information on muscle tissue in general: A. Specialized for contraction B. Function is movement, no matter the type C. Characteristics: a. Irritability: muscle responds to stimuli b. Contractility: muscle ﬁbers contract or shorten c. Extensibility: muscle ﬁbers stretch d. Elasticity: return to relaxed state after stretching or contracting D. Classiﬁed according to structure (how many nuclei, striated, etc) function, and control mechanisms E. Types: Skeletal, cardiac, and smooth 2. Skeletal Muscle: A. Formed by fusion of multiple cells in the embryo B. Muscle ﬁbers = cells and they are parallel to each other C. Characteristics: long, multinucleated (nuclei are pushed toward the outside of the cell), voluntary, striated (banded appearance) D. Level of organization: ﬁgure 44.3 a. Epimysium: covers the surface of a muscle b. Perimysium: invades muscle and organizes muscle ﬁbers into groups called Fasicles c. Endomysium: invades muscle Fasicles and surrounds each muscle ﬁber E. Muscle: organ composed of muscle cells and other tissues (blood vessels, nerves, etc) F. Fasicle: collection of muscle ﬁbers bound by connective tissue (perimysium) G. Muscle Fiber: individual muscle cell H. Myoﬁbrils: cylindrical bundle of contractile proteins that interact with each other to allow the muscle cells to contract I. Composition of Myoﬁbril: myoﬁlaments --> actin (thin) and myosin (thick) tightly packed inside a myoﬁbril a. Thin ﬁlaments are composed of three proteins: actin, troponin, and tropomyosin 1. Actin: actin ﬁlaments form two intertwined helical chains. Each actin molecule contains a binding site for myosin (thick ﬁlament). 2. Tropomyosin: rope-like protein that wraps around he actin ﬁlament. Blocks binding sites during relaxed state. 3. Troponin: complex of three subunits (Figure 44.6) A. Troponin I (TnI) attached to actin ﬁlament B. Troponin T (TnT) binds to tropomyosin C. Troponin C (TnC) binds calcium which is required for contraction of skeletal muscle b. Thick ﬁlaments are composed of the contractile protein myosin. Individual myosin molecules are shaped like a golf club with a head region and a tail region. The head region interacts with actin of the thin ﬁlament, also binds ATP. The tail regions are facing inward. c. Figure 44.9: shifting of tropomyosin when calcium binds to troponin to reveal actin's binding sites. J. Muscle ﬁbers are organized into Sarcomeres: structural and functional unit of muscle. a. Sarcomeres composed of thick and thin ﬁlaments that overlap a little bit which causes the striation b. Actin ﬁlaments are anchored to the Z disk/line (collection of proteins) c. Sarcomere is the region of muscle ﬁbers that extended from one z disk to another d. Sarcomere shortens during contraction. K. Reading Striations: a. Z disks: appear as a dark line within the I band; system of proteins that serves as an attachment for the actin ﬁlaments (point of stabilization) b. I band: light region of striation caused by the thin ﬁlaments rotating light; portions of thin ﬁlaments are not overlapping with thick ﬁlaments in the sarcomere c. A band: dark band caused by overlapping thick and thin ﬁlaments d. H zone: narrow region between two sets of thin ﬁlaments, center of the A band, only thick ﬁlaments e. M line: in center of H zone, very thin, dark line caused by proteins that link the myosin tails together L. Mechanisms of Skeletal Muscle Contraction a. Sarcolemma: plasma membrane of muscle ﬁber b. Transverse tubules (T tubules): invaginations in the sarcolemma; allow for a muscle action potential to be rapidly internalized by the muscle ﬁbers c. Sarcoplasmic Reticulum (SR): stores calcium ions and releases when needed d. Triad: one t tubule and two adjacent dilated regions of the SR. As the muscle action potential, calcium ions will be immediately released so that muscle contraction can begin M. Sliding Filament Mechanism a. When skeletal muscle ﬁbers contract, thick ﬁlaments do not move but pull the think ﬁlaments closet together. The sliding of the thin ﬁlaments leads to the shortening of the sarcomere. b. Step 1: binding of calcium ions to troponin C. Muscle action potential internalized = calcium released to sarcoplasm. Calcium ions bind to thin ﬁlaments (TnC) which shifts tropomyosin to reveal myosin binding sites on actin ﬁlament. Once shifting occurs, myosin binds to actin. Myosin heads bind to the actin. c. Step 2: power stroke. Before all this, ATP attached to myosin then hydrolyzed (so ADP + phosphate group). During power stroke, the phosphate group is released from myosin head. Myosin head then swivels inward pulling actin ﬁlaments inward. Then ADP is released from the myosin head d. Step 3: detachment. Myosin head needs to release actin ﬁlament. Requires ATP. ATP now binds to myosin head --> change in shape to release the actin. Myosin is still swiveled inward.. e. Step 4: resetting. ATP has phosphate removed, then myosin head is repositioned. ADP and phosphate remain attached to myosin head at this point f. Figure 44.8 3. Neuromuscular Junction: A. Synapse: region of communication between a motor neuron and skeletal muscle ﬁbers (deﬁnition for this section only) B. Motor neuron: nerve cell that delivers a signal from central nervous system for muscle contraction C. Synaptic Cleft: space between motor neuron and sarcolemma of muscle ﬁber D. Axon: extension of the cell body of the neuron, relays action potential to skeletal muscle membrane and neurotransmitters mediate the signal. Neurotransmitters are released by the axon across the synaptic cleft and bind to receptors on the skeletal muscle ﬁbe E. Figure 44.11 F. Events a. Action potential (nerve impulse) spreads to axon terminal of a motor neuron b. Vesicles containing acetylcholine (neurotransmitter) are released from axon into synaptic cleft 1. Calcium is required c. Acetylcholine binds to receptors on muscle ﬁber sarcolemma 1. Sodium ion channels open (Na rushes into muscle ﬁber) which leads to a contraction of a muscle d. Acetylcholine is degraded by acetylcholine esterase (enzyme) 4. Cardiac Muscle A. Involuntary, striated, branched, one or two centrally-located nuclei B. Contraction is intrinsic, generates its own contraction; spontaneous and rhythmic C. Cardiac Muscle ﬁbers cannot divide or regenerate (no mitosis) D. Location: myocardium of heart E. Intercalated disks: special junctional complexes between cells; equipped with gap junctions which allow for muscle action potential to spread very rapidly through the heart (almost contracts as a single unit) 5. Smooth Muscle A. Unbranched, no striations, involuntary, single centrally located nucleus, spindle shaped B. Location: walls of hollow organs, blood vessels, respiratory passages C. Dense bodies a. Analogous to Z disk in skeletal muscle b. Attached to the sarcolemma (usually) c. Intermediate ﬁlaments (no troponin) and thin ﬁlaments inserted into dense bodies d. When a smooth muscle cell contracts, the cell assumes a corkscrew shape due to interactions between dense bodies, thin ﬁlaments, and intermediate ﬁlaments Nervous System • Central Nervous System (CNS): brain and the spinal cord • Peripheral Nervous System (PNS): all neurons outside of central nervous system, off of the midline nervous system, projections (nerves in the ﬁngertips) • Invertebrates have a simple nervous system, but sometimes it's difﬁcult to distinguish between central and peripheral nervous systems • Neurons: nerve cell, structural and functional units of the nervous system ◦ Function is to send and receive electrical and chemical signals from other neurons throughout the body ◦ Soma: cell body with nucleus (big) and organelles ◦ Dendrites: extensions of the plasma membrane, ﬁnger-like projections; receive incoming signals ◦ Axons: extensions of the plasma membrane, ﬁnger-like projections; sending signals ◦ Figure 41.2 ◦ Not the most important, and not the most abundant • Glial cells: provide support functions for nervous tissue; absolutely necessary; over 1000x more abundant than neurons ◦ Oligodendrocytes (CNS) and Schwann cells (PNS): produce myelinated sheath around the axon ◦ Microglial cells: remove cellular debris (cleaner cells) ◦ Astrocytes: metabolic support; basically provide nutrition for neurons (feeder cells) ◦ Radial glial cells: provide a track for neuron migration during embryonic development; layout the blueprint for the peripheral nervous system as the embryo develops ◦ Stem cells: astrocytes and radial glial cells because they can produce (replace) new neurons and new glial cells • Types of Neurons ◦ Sensory (Afferent): transmitting the signal to the CNS. Information detected from external or internal signals, that message is transported by sensory neurons to the spinal cord/brain ◦ Motor (Efferent): sending signals away from the CNS to elicit a response; after an original signal is interpreted, a new signal is sent by motor neurons to give a response. To remember: efferent=e il bc they try to elicit a response from the body & Afferent=away from the body ◦ Interneurons: form complex interconnections between other neurons • Reﬂec Arc: involuntary act - not consciously controlled • Electrical Properties: ◦ Membrane potential: "gatekeeper," selectively permeable; only neurons and muscle cells can generate electrical signals ◦ Because of the membrane selectivity, there is a charge difference between inside and outside the cell. ◦ Also the concentration of ions differ between inside and outside the cell, associated with ions is a positive or negative charge, so the membrane can select based on charge and chemical. ◦ Cell is polarized. ◦ Ions can move through channels in the membrane if they are open. It is possible that some ions have easier movement through the membrane than other. ◦ Resting Membrane Potential: neurons are not sending signals ‣ Selectively permeable to cations (+) and anions (-) ‣ Inside the membrane is more negative ‣ Outside the membrane is more positive ‣ Anions inside are drawn to cations on outside (opposites attract) but membrane keeps them separate unless the channels are open • Three Factors Contributing to Resting Potential: ◦ Sodium-Potassium pump ‣ ATP is expended ‣ 3 Na+ out for every 2 K+ pumped in ◦ Ion speciﬁc channels allow for passive ion movement ‣ Membrane is biased to potassium, so it moves easier. To get potassium concentration in equilibrium, pump it in ◦ More negatively charged ions inside the cell • Electro-chemical Gradient: combined effect of electrical. Harte and chemical ions ◦ When there's no net movement (no K out, not Na in), opposing forces of electrochemistry can cause almost equilibrium but not completely (no potassium ﬂow) ◦ Ion movement: cations or anions are moving in/out ◦ Chemical movement focuses on K+, Na+, and Cl- ◦ Because of movement or lack thereof, imbalance created between inside and outside of membrane • Neuron Signaling: Changes in membrane permeability = changes in the degree of polarization ◦ Depolarization: membrane becomes less polarized (negative) to the surrounding solution; gated channels for sodium open so increase the charge inside the cell. Membrane is less polarized. ◦ Hyperpolarization: membrane becomes more negative to surrounding solution; potassium moves out of the cell. Membrane is more polarized (more distinct difference in inside/outside charges). • All cells exhibit membrane potential • Use of gated ion channels: ◦ Voltage gated means they open/close in response to charges. ◦ Ligand (chemical) gated channels open/close in response to chemicals • Nerve impulse ◦ Frequency: language of the impulse. Higher frequency = greater excitation ◦ Resting potential: imbalance between potassium and sodium = charge Imbalance (gradient) between inside and outside of the axon ‣ Membrane is selectively permeable to potassium = will diffuse through membrane, sodium and chloride are held out (gates closed) ◦ Action potential: electric potential of the impulse: rapid, brief change of the nerve ﬁber ‣ Self-propagating ‣ After the impulse passes, the membrane returns to the resting potential ‣ At any given point, sodium channels open, sodium diffuse in, potassium diffused out due to electrical gradient changes. ‣ Greater the imbalance, the faster the diffusion ◦ Sodium potassium pump: expenditure of ATP, aided by a complex of proteins in the membrane: ‣ Pump out 3 sodiums, carry back in 2 potassiums • Impulse conduction rate ◦ Sea anemones (phylum Cnidaria): 0.1 m/sec ◦ Mammals: 120 m/sec ◦ For invertebrates: the speed is directly related to the axon diameter ◦ Vertebrates: the size of the axon and the layers of myelin sheath effect speed • Synapse: junction or gap where the nerve terminal meets a neuron, muscle cell, or a gland. Gaps between neurons or effector sites ◦ Axon,p has gaps in the myelin sheath . As the impulse travels down the axon, it jumps these gaps (nodes of Ranvier). Each time the gap is jumped, the impulse speeds up (like sending it down a hill). ◦ Electricalsynapse: ionic currents ﬂow across the gaps, fastest conduction rates. Associated with cardiac muscle pumping the heart ◦ Chemical synapse: neurotransmitters cross the gaps. Acetylcholine is a major neurotransmitter. Evolution of the Nervous System • Phylum Cnidaria: ◦ Simplest neural organization ◦ Protoneurons: primitive nerve cells ◦ Nerve net: impulses are not one way, travel bidirectionally • Phylum Platyhelminthes: ◦ 2 anterior ganglia: each ganglion has a network branching from it ◦ Weakly developed CNS and PNS but without a brain, no nervous system so basically they have something that is like a simpliﬁed CNS and PNS ◦ Mostly one way impulses • Phylum Annelida: ◦ Motor and sensory neurons (true neurons) ◦ Brain ◦ Ventral nerve cord ◦ Primitive CNS • Phylum Molluska: ◦ Squids and octopi have been studies extensively ◦ It's thought that their nervous system is equivalent to ﬁsh ◦ Most complex of invertebrates (nonchordates) • Phylum Arthropoda ◦ Similar to Annelida ◦ Insects (social insects) must have well developed brains for social behavior, learning, division of labor, and communication Vertebrate Nervous System • Brain and dorsal, hollow spinal cord = CNS • Spinal cord: dorsal, hollow, within vertebral column, surrounded by three layers (meninges) ◦ Dura mater: outer ◦ Arachnoid: middle ◦ Pis mater: inner ◦ Between each layer and in hollow canals is cerebrospinal ﬂuid • Brain: increased in size and complexity with vertebrate evolution ◦ Changes in embryonic development: entire nervous system develops from neural fold in embryo ◦ Changed in sections of brain: greatest increase in size is in the cerebrum (forebrain) ◦ Hindbrain, midbrain, and forebrain ◦ Overall, increase in brain size, speciﬁcally the forebrain ◦ See ﬁgure 42.9 & Table 42.1 The Circulatory System • Function: transport of gases, nutrients, hormones, etc. to the cells and transport wastes away the cells • Three Types: Gastrovascular cavity, Open Circulatory System, Closed Circulatory System • Gastrovascular Cavity: body cavity single opening to the outside ◦ Fluid with food particles circulated in cavity. Ciliated cells or contraction of cell wall causes a water current for movement ◦ Food digested and absorbed by lining cells ◦ Waste excreted into cavity ◦ Cnidarian • Open Circulatory System: ◦ Basic components: ‣ Hemolymph: mixes directly with interstitial ﬂuid (extra cellular ﬂuid) ‣ Open ended vessels ‣ One or more hearts to pump the ﬂuid through the open ended vessels ◦ vessels openinto the animals body cavity ◦ Nutrients and waste products are exchanged by diffusion between hemolymph and cells of the organism ◦ Metabolically inexpensive (cheap). As the organism becomes more active, increased circulation rate, hemolymph is moved through vessels at a faster rate ◦ Hemolymph cannot be selectively delivered to certain body regions (or tissues) ◦ Anthropods and Mollusks • Closed Circulatory Systems 3 Types) ◦ Fluid connective tissue is completely separated from interstitial ﬂuid (Blood stays inside the vessels) ◦ Larger, more active animals need a higher pressure to pump blood to all body cells ◦ One or more hearts ◦ Solutes are exchanged between cells and blood ◦ Blood contains disease-ﬁghting cells and other molecules ◦ Earthworms, cephalopods, and all vertebrates ◦ Blood ﬂow can be selectively controlled: ‣ Adjusted to meet metabolic needs ‣ Vessels can heal themselves when wounded (blood clotting factor) ‣ System grows as animal grows 1. Single Circulation Closed Circulatory System (think ﬁsh) A. Single atrium: collects oxygen poor blood from tissues B. Single ventricle: pumps blood out of the heart C. Arteries carry blood away from the heart to the gills a. Blood is oxygenated and carbon dioxide is released D. Oxygen rich blood transported to tissues 2. Intermediate Circulatory System (think frog) A. Rely on lungs and skin for gas exchange B. Heart pumps blood to either: a. Respiratory surfaces of the lungs and skin (pulmocutaneous circuit) b. Body tissues (systemic circuit) C. Right atrium receives blood from the body (deoxygenated except blood from the skin --> mixed) D. Left atrium receives blood from lungs (oxygenated blood) E. Single ventricle has ﬂaps that keep oxygenated blood and deoxygenated blood mostly separated F. When the ventricle contracts, mixing of blood occurs, then that blood is directly to lungs and skin. Anytime there is is a mixing of oxygenated and deoxygenated blood, decreases the efﬁciency of oxygen transport G. Noncrocodilian reptiles (snakes and lizards) still have one ventricle, but has a partial septum (partially separated), so efﬁciency of oxygen delivery is higher than amphibians 3. Double Circulation (think crocodiles, birds, mammals) A. Mammalian heart is four chambered a. Right and left atria: upper, thinner walls b. Right and left ventricles: lowers thicker walls B. Right and left sides are completely separated by a septum: no mixing of deoxygenated and oxygenated blood, also allows the heart to act as a double pump C. Two circuits allow for two pressures in two systems: a. Systemic circulation: higher pressure 1. Left ventricle --> all body tissues (except lungs) --> right atrium b. Pulmonary circulation: lower pressure 1. Right ventricle --> lungs --> left atrium D. Pathway of blood through the heart: a. Oxygen poor blood from systemic circuit 1. Vena cavae: largest veins in body, superior and inferior 2. Right atrium 3. Right AV valve: atrioventricular; prevents back ﬂow 4. Right ventricle 5. Pulmonary semi-lunar valve: between ventricle and pulmonary trunk/artery, prevents back ﬂow 6. Pulmonary Trunk/Artery 7. Lungs (blood gets oxygenated) b. Oxygen rich blood from the lungs 1. Pulmonary veins 2. Left atrium 3. Left AV valve 4. Left ventricle 5. Aortic semi-lunar valve: between ventricle and aorta; prevents back ﬂow 6. Aorta: largest artery 7. Systemic circuit • Types of Heart Tissue ◦ Myogenic Hearts: ‣ Electrically excitable, generates own action potential ‣ Nervous input can increase or decrease the force and rate of contraction. It not required to start the contentio ‣ All vertebrates ◦ Neurogenic Hearts ‣ A single from the nervous system is required for the heart to contract ‣ Not able to generate their own electrical impulse ‣ Many arthopods, decapod crustaceans • Blood Vessels ◦ Arteries ‣ Conduct blood away from the heart ‣ Thicker layer of smooth muscle than veins of similar size ‣ High pressure vessels ‣ Arterioles: very small arteries that control blood ﬂow through capillary beds ◦ Capillaries ‣ Site of gas and nutrient/waste exchange ‣ Wall composed of a single cell ‣ Smallest and narrowest vessels in the body ‣ Arteriolar end of the capillary has high pressure and high protein concentration ‣ Venus end has low pressure and high protein concentration ‣ Extra water and solutes that could not re-enter the capillary will enter Lymohatic vessels and later be directed to the heart ◦ Veins ‣ Conducts blood back to the heart (oxygenated or deoxygenated) ‣ Thinner and less muscular than arteries ‣ Low pressure vessels, require assistance to move blood • Skeletal muscle contractions propel blood forward • Valves inside veins prevent back ﬂow • Pressure changes thoracic cavity during ventilation ‣ Varicose veins: • Twisted large veins near the surface of the skin • Valve is permanently distorted, allows for back ﬂow and pooling of blood • Blood ◦ Fluid connective tissue ◦ Functions: ‣ Transport of nutrients my gases, waste, and hormones ‣ Protection from disease causing agents ‣ Hemostasis: blood clotting ‣ Regulation of body temperature ◦ Composition: ‣ Plasma ‣ Formed Elements • Erythrocytes • Leukoctyes • Platelets ◦ Plasma ‣ Fluid portion of the blood ‣ Accounts for 55% of the total blood volume ‣ Composed of water, plasma proteins (albumins & globulins), and solutes ◦ Erythrocytes ‣ Red blood cells ‣ Develop in bone marrow, before it exits the Bone marrow and enters the circulatory system, the cell loses its nucleus and organelles so they live about 120 days, then removed by the spleen ‣ Hemoglobin found inside blood cells, multimeric protein used for oxygen transport. Each polypeptide (4 of them) contains an iron heme group which binds oxygen ◦ Leukocytes ‣ White blood cells ‣ Must exit blood and enter connective tissues to provide biological function: protection from disease causing agents ‣ Neutrophils: Active phagocytes, engulf bacterium ‣ Eosinophils: protection against parasitic worms ‣ Basophils: enhance immune response ‣ Lymphocytes: associated with acquired immunity ‣ Monocytes: active phagocytes, number increases during chronic infections ◦ Platelets ‣ Fragments of bone marrow cells: megakarytocytes ‣ Fragments enter circulation and called thrombocytes ‣ Function: blood clotting (hemostasis) Evolutionary history of the Heart 1. Increase number of chambers 2. Decrease number of pseudo chambers 3. Increase in size of heart relative to body (same as increase of brain compared to spinal cord Fish • Two chambers (atria/ventricle) • 2 pseudo chambers (conus arteriosis & sinus venosus) Amphibians • Three chambers (2 atria/1 ventricle) • 2 pseudo chambers Reptiles • 3 chambers (2 atria/1 ventricle) • Some with SV only some with no CA • Exception is crocodilians: they have a four chambered heart (2 atria/2 ventricles) and no pseudo chambers Birds and Mammals • Four chambered hearts (2 atria/2 ventricle) lack pseudo chambers • Remnant of SV is a tiny patch of cells in the right atrium ◦ Function is the "pacemaker of the heart" sinistral node (SA node): initiates each heart beat • Heart diagrams The Skeletal System In higher animals: endoskeleton; only Echinoderms and chordates have endoskeleton • Functions: ◦ Locomotion- movement ◦ Support ◦ Protection ◦ Blood cell production (somewhat) ◦ Calcium and other mineral storage • Bone is a strong, lightweight, and ﬂexible tissue (collagen ﬁbers) • Depository of minerals: calcium and phosphorus salts provides the strength associated with bones • Formation ◦ Endochondral formation (within cartilage): Bone replaces cartilage. Majority of bone formation. ◦ Intramembranous formation: bone forms within the membranes of connective tissues. Usually produces thin, ﬂattened bones. Basically the bone is ﬁlling in the gaps • Bone tissue: ◦ Compact bone: ground bone, dense bone- special type of connective tissue that is hardened and organized into osteons ◦ Osteon: structural and functional unit of compact bone; provide strength and support ◦ Spongy bone: bony spikes, lots of air spaces, lacks osteons, looks like a lattice structure ◦ Bones are combinations of compact and spongy bones to provide strength and ﬂexibility • Long bone anatomy (concentrating on femur- longest bone in body) • Bone cells: ◦ Osteoprogenitor cells: future bone cells, found in the periosteum, differentiate into osteoblasts ◦ Osteoblasts: bone forming cells, secrete the ﬁbers to create bone tissue ◦ Osteocytes: mature osteoblasts which are trapped within the bone tissue they produced ◦ Osteoclasts: bone resorbing cells, breakdown old bone tissue and absorb the tissues to be reused (recyclers) ‣ Keep proper bone density • Microscopic anatomy of compact bone ◦ Osteons tractors land functional unit of compact bone; most oriented parallel to long axis of the bone ◦ Osteonic canal: passageway for blood vessels, Lymohatic ducts, and nerves; also provides strength by allowing microfractures to be stopped at the canal. If the force is strong enough to, it will pass through the osteonic canal and onto another osteon and continue on and on ◦ Lamellae: concentric rings of bone tissue ◦ Lacuna: spaces between lamellae where osteocytes are located ◦ Canaliculi: microscopic canals that connect lacunae to another and lacunae to the osteons century canal; waste, nutrients, and gases diffuse through canaliculi to the osteocytes Skeleton: • Two regions: axial and appendicular ◦ Axial: all bone associated with mid-axis of the body (skull, ribs, sternum, vertebral column, etc.) ◦ Appendicular: all bone associated with appendages (arms, legs, etc.) • Axial Skeleton ◦ Vertebrae- ‣ Cervical (neck) ‣ Thoracic (upper back/check) ‣ Lumbar (lower back) ‣ Sacral (hip) ‣ Caudal (tail) *coccyx in humans- tail bone* ◦ Vertebrae provide ﬂexibility and support/protection for nerve cord • Appendicular Skeleton: ◦ Pectoral girdle (shoulder): attached front limbs to vertebral column ‣ Scapula (2) ‣ Clavicle (2) ◦ Pelvic girdle (hip): attaches hind limbs to the vertebral column ‣ Fused to lower vertebral column ‣ Composed of fused pelvic bones ◦ Appendage Bones (limbs/ﬁns) ‣ Forelimb bones: (pectoral girdle) • Humerus: upper arm • Radius and ulna: forearm • Carpals: wrist • Metacarpals: hand • Phalanges: ﬁngers/digits ‣ Hind limb Bones: (pelvic girdle) • Femur: upper leg • Patella: kneecap • Tibia and Fibula: lower leg • Tarsals: ankle • Metatarsals: foot • Phalanges: toes/digits • Joints: provide better contact with the substrate, enhanced movement, provide ﬂexibility • Combine joints with bone with enhanced skeletal muscle gives advanced locomotive skills (better movement) • Skeleton on page 904 but only have to know what we talked about • Exam 3: chapters 41-47
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