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56 Cards in this Set
- Front
- Back
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1. Where are muscular systems found?
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In all animals except sponges
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2. What are the functions of muscles?
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1. for contraction by converting energy as the contract
2. generates mechanical forces and motion necessary for life processes |
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3. What is so special about actin?
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Even though animals with simple body plans do not have a muscular system, they do contain contractile protein actin
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1. What is special about myosin?
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1. Protein that is functionally associated with actin
2. along with actin, myosin is most highly organized in muscle cells |
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Describe contractile tissue
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1. contain actin (thin) and myosin (thick)
2. work in pairs (antagonists and agonists) 3. always shorten by stimulus (contract) 4. elongated when relaxed |
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1. Describe muscular systems in cnidarians
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1. Contractile proteins located in bundles
2. Mostly epithelial-muscular cells 3. have nutritive-muscular cells 4. no muscle fibers |
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1. Describe muscular systems in platyhelminthes
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1. longitudinal muscle in single layers; antagonist
2. Circular 3. Diagonal - allow for alternative contractions side to side; antagonist |
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What is the antagonist of longitudinal muscles in playthelminthes?
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hydrostatic skeleton
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What is the antagonist of diagonal muscles in playthelminthes?
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the membrane bound cuticle
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1. Describe muscular systems in nematoda?
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1. Longitudinal muscle - single layers; antagonist (hydrostatic skeleton)
2. Antagonist - cuticle 3. weaving fibers |
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1. 1. Describe muscular systems in annelids
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1. Longitudinal and circular muscle
2. partitioned coelum (hydrostatic skeleton) 3. smooth muscle |
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1. Describe muscular systems in mollusks
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1. smooth and skeletal muscle for different functions
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What is the striated muscle in mollusks good for?
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rapid contractions - to swim and shut (bivalves) quickly
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What is the smooth muscle in mollusks good for?
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slow, sustained contractions - to remain closed for long periods of tie (bivalvia)
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1. Describe muscular systems in arthropods
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1. only skeletal muscle (striated)
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What is the skeletal muscle in arthropods used for?
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quick movement and digestive tract (makes arthropods unique)
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1. Describe muscular systems in echinoderms?
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1. circular
2. longitudinal 3. hydrostatic skeleton |
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What are muscles used for?
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1. Directed locomotion (flying, walking, jumping...)
2. Object manipulation and tool use 3. Propulsion - blood flow, peristalsis 4. elimination of wastes - bladder 5. reproduction - contraction of uterus 6. communication - production of sound 7. heat production - shivering |
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What are the types of contractile muscles in vertebrates?
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1. skeletal
2. cardiac 3. smooth |
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Describe skeletal muscle
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1. movement by pulling on tendons anchored to bone
2. most abundant tissue in body 3. organized in muscle fibers wrapped in connective tissue 4. striated 5. can only contract (can't push) - muscles act as antagonists to each other 6. voluntary control 7. elongated, cylindrical, blunt ends 8. multi-nucleated 9. rapid contractions 10. least resistance to fatigue |
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Describe cardiac muscle.
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1. involuntary; auto-regulatory
2. contracts and relaxes in alternating rhythm (propels blood) 3. striated (use gap junctions) 4. heart muscle 5. elongated, cylindrical, fibers that branch and fuse; 6. one or two nuclei per fiber 7. intermediate contractile speed 8. intermediate resistance to fatigue |
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Describe smooth muscle
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1. walls of stomach; intestines, etc...
2. involuntary control 3. elongated, spindle shaped, pointed ends 4. unstriated (actin and myosin not organized into fibrils or sarcomeres) 5. mononucleated 6. slowest speed of contraction 7. greatest resistance to fatigue 8. in sliding filament: cross bridge remains attacked longer 9. less ATP required to maintain high level of force |
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Microscopic anatomy:
1. Parts of a muscle cell? |
1. myofiber (whole cell)
2. myofibril (muscle bundle 3. myofilaments (actin and myosin) |
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Microscopic order of muscles
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muscle-->fascicle --> myofiber --> myofibril -->myofilaments
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Sarcolemma
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plasma membrane
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Sacroplasmic reticulum
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endoplasmic reticulum
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T-Tubule (transverse tubule)
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invagination of myofibrals
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Triad
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sarcoplasmic retic.-- t-tubule--sarcoplasmic retic.
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Sarcomere
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contractile unit; mycrofilaments; Z-line; I band (thin filament attached to Z-line), A band
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Troponin, Tropomyosin
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binding sites; sliding filament theory; calcium depolarization
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Z-line
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beginning and end of sarcomere (no change during contraction)
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I band
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thin filament attached to Z-band (shortens during contraction)
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H- zone
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contains only myosin (shortens during contraction)
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M-line
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stack of proteins holding the myosin together; center of H zone (does not change during contraction)
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Describe skeletal muscle contraction
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1. tropomyosin blocking myosin binding site
2. neuron synapse (Ach) 3. depolarization of muscle fiber 4. action potential sent down sarcolemma and propagates down t- tubule 5. depolarization of t-tubule triggers Ca release from sarcoplasmic reticulum 6. calcium binds to troponin, rotating tropomyosin 7. binding site exposed 8. hydrolysis of ATP(ADP and Pi) allows myosin head to undergo change into high energy state 9. myosin binds to actin, forming cross bridge 10. ADP + Pi are released (relaxes head) 11. when head relaxes (release of Pi), it rotates, causing a sliding movement (power stroke) and ADP is release during power stroke 12. Decreasing Ca will allow tropomyosin to cover binding site again |
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What is a motor unit?
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a motor neuron and the muscle fibers it controls
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Describe muscle strength
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1. the number of motor units recruited determines the complexity, while size of motor units determines strength and effort
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muscle twitch
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a single, quick contraction in response to a single, brief electrical stimulus
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what is summation?
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when two twitches are added together (when a second stimulus is reached before the first contraction)
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tetanus
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when summation results in a smooth, sustained contraction
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what is muscle tone?
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even when you're not moving, your muscles are in a state of partial contraction
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What are the three types of muscles fibers in vertebrates?
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1. slow oxidative fibers
2. fast oxidative fibers 3. fast glycolytic fibers |
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Describe slow oxidative muscle fibers
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1. specialized for endurance activities
2. contract slowly 3. fatigue slowly 4. aerobic respiration 5. many mitochondria 6. low intensity of contraction 7. high in myoglobin 8. red |
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Describe fast oxidative muscle fibers
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1. fast contraction speed
2. specialized for rapid response 3. intermediate rate of fatigue 4. aerobic respiration 5. many mitochondria 6. intermediate intensity of contraction 7. high myoglobin content 8. red |
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Describe fast glycolytic muscle fibers
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1. generate a great deal of power and carry out rapid movements but can sustain activity for only a short time
2. fast contraction speed 3. fast rate of fatigue 4. glycolysis 5. few mitochondria 6. high level of contraction 7. low myoglobin content 8. white |
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What types of skeletal fibers are used for sprinting and weight lifting?
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fast-glycolytic fibers
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What types of skeletal fibers are used for swimming, running long distances, or maintaining posture?
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slow-oxidative fibers
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Do muscles run out of ATP?
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no, in fact, only around 30% of ATP is used
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Describe fatigue
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1. depends on intensity and duration of exercise
2. composition of muscle 3. fitness of individual |
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what are spasms?
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uncontrolled muscle contractions
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Describe smooth muscle (at microsocopic)
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1. myosin: actin ratio - 1:13
2. myosin head group is along entire body (allows for stronger contraction) 3. tropomyosin 4. troponin absent 5. sarcomere absent 6. intermediate filaments and dense bodies 7. t-tubules absent 8. unstriated (filaments NOT in myofibrils) 9. calcium from extracellular spaces 10. caldesmon 11. controlled by myosin linked regulation 12. nerve impulse initiation OR self generated action potential |
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Why is a smooth muscle cell contraction stronger?
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`1. head groups line the entire length of the myosin body
2. more actin 3. more binding sites available |
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Smooth muscle contraction
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1. sheets of cells (unlike skeletal = bundles)
2. lack troponin, so active site always exposed 3. myosin knase activated when calcium binds to calmodulin 4. ATP hydrolyzes 5. myosin is dephosphorylated (can't interact with actin) 6. calcium drop -->relaxation |
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Describe smooth muscle (at microsocopic)
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1. myosin: actin ratio - 1:13
2. myosin head group is along entire body (allows for stronger contraction) 3. tropomyosin 4. troponin absent 5. sarcomere absent 6. intermediate filaments and dense bodies 7. t-tubules absent 8. unstriated (filaments NOT in myofibrils) 9. calcium from extracellular spaces 10. caldesmon 11. controlled by myosin linked regulation 12. nerve impulse initiation OR self generated action potential |
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Why is a smooth muscle cell contraction stronger?
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`1. head groups line the entire length of the myosin body
2. more actin 3. more binding sites available |
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Smooth muscle contraction
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1. sheets of cells (unlike skeletal = bundles)
2. lack troponin, so active site always exposed 3. myosin knase activated when calcium binds to calmodulin 4. ATP hydrolyzes 5. myosin is dephosphorylated (can't interact with actin) 6. calcium drop -->relaxation |
