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188 Cards in this Set
- Front
- Back
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Name 4 broad functions of skeletal muscle
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contraction, metabolic, protective, thermoregulation
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Give 2 examples of how skeletal muscle regulates temperature
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shivering and dissipation of heat
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name 2 things skeletal muscle protects
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joints and abdominal viscera
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Name 3 ways that the skeletal muscle functions metabolically
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1. major site for glucose disposal (major insulin target tissue)
2. Major storage depot for glycoge 3. major store of body protein; supplies gluconeoginc amino acis for gluconeogenesis |
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Name 3 contractional functions of skeletal muscle
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Movement of skeleton (force production
2. Respiration, contraction of the diapharm 3. Skeletal muscle pump (postural sway) |
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what is gluconeogenesis? Give an example of a precursor
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synthesis of glucose from noncarbohydrate precursors; protein
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What is the function of the postural sway
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enhances veinous blood making sure it returns to the heart
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What intervates skeletal muscle for the contraction of the diaphram? What spinal cord leve is it?
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somatic alpha motor neurons, SC level C4
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What are the 3 types of muscle?
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skeletal, cardiac, and smooth
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which of the muscle types are striatd
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skeletal and cardiac
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what does it mean to be striated?
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that the sarcomere is the basic unit
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where is skeletal muscle located?
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attached to the skeleton
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Where is smooth muscle located?
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lines all hollow tubes/ organs
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What is the function of smooth muscle?
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propells contents
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What is the function of cardiac muscle?
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to pump the blood
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Where is cardiac muscle located?
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in the heart
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What innervates skeletal muscle?
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somatic alpha motor neuron
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What is the transmitter for smooth muscle
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Acetylcholine
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What innervates smooth muscle?
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Pacemaker ANS motdifices inherent properties
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What intervates cardiac muscle
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pacemaker-ANS modifies inherent pacemaking
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what are the neurontransmiters for cardiac muscle?
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ACh,norepi, and epi
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What is the contratile mechanism for skeletal muscle
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Actin binds to myosin
Calcium regulated through troponin and tropomyosin |
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What is the contractile mehcanism for smooth muscle?
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actin and myosin react
Calcium binds to MLCJ |
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What is the contractile mechanism for cardiac muscle
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Actin binds to myosin
Calcium regulated thru troponin and tropomyosin |
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What is the growth/repair of cardiac musle?
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hypertrophy only
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what is the growth/repair of smooth muscle
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hypertrophy and hyperplasia
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How does the skeletal muscle of children grow?
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By addink sarcameres at the ends
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How does the skeletal muscle of adults grow?
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hypertrophy
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How is skeletal muscle repaired?
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fixed post-mitotic, repaired by??
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myofiber
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muscle/cell fiber
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myofibril
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long strand w/ in a muscle fiber, that make muscle look straited. run parallel making up individual myofibers
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How does the size of myofibrils increase?
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w/ exercise and more protein the gerth grows
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sarcomere
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repeating unit (each single one) that gives the muscle stration. (functional unit)
Runs from1 z line to the next |
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What are the 3 broad categories of proteins that help muscle function
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contractile, calcium regulatory, cytoskeletal
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What are the proteins for contractile muscle functions?
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actin and myosin
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What are the muscle proteins for calcium regulatory muscle function?
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troponin and tropomyosin
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What are 2 jobs of the cytoskeletal muscle function?
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1.Organization-provides a scaffold for muscle structure
2. Plays a key role in providing the force for muscle contraction |
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Which function are most dystrophies and myopathies a distruption of
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cytoskeletal
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Name 3 types of connective tissue
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epimysium, perimysium, endomysium
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Epimysium
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surrounds/sits upon the whole muscle
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Perimysium
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surrounds muscle bundles
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Endomysium? fxns?
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surrounds individual muscle cell/fiber
interacts w/ other endomysium for organization helps to transmit force |
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What are 4 properties of skeletal muscle?
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excitability, relaxation, contraction, elasticity
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What is the electrical switch that triggers excitability in skeletal muscle?
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calcium
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Which homeostasis system must be in order for proper excitation of skeletal muscle?
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homeostasis of electrolytes
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What part of skeletal muscle is excitable?
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excitable plasma membrane with voltage regulated channels
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Why is elasticity of skeletal muscle necessary?
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so it can return to its post contractile/pre-streteched state
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Which part of skeletal muscle is responsible for elasticity?
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cytoskeleton
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What is relaxation of muscle dependent upon?
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a pump to remove calcium
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What does relaxing a muscle do?
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it stops the contraction
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Where are costameres found?
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connected to the sarco lamina
@ all z discs @ all m line regions @ muscle tendon junctions |
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What does a sarcomere contain?
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transmembrane and extracellular membrane proteins
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Which part of the muscle extends the entire length of the myofibril?
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titin
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Which protein is most important for elasticity
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titin
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Where does desmin connect?
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w/ in the sarcomrere and w/ in the plasma membrane @ the z lines
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What does desmin connect?
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adjacent myofibrils at z lines`
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What disease is a result of mutation of Distrophin?
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Jerry's kids and 1 other?
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What is distrophin?
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Intracellular protein that connects thin filament to SL
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What is the fxn of distrophin?
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maintain the integrity of the SL
maintain the integrity of contractions |
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Why is the relation ship btwn strucutre and function important?
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Mutation of proteins can lead to dystrophies and myopathies
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2 facts about force
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1. Force transmitted laterally, as well as length
2. 50% of foce goes out into extra cellular matrix |
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Name 3 thick fillament proteins?
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myosin, titin, myosin binding proteins
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What is the fxn of each myosin head?
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binding site for nucleotide and actin
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What is a nucleotide on myosin?
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enzymatic site that hydrolyzes
-ATP: ATP→ ADP + Pi |
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What do myosin binding proteins do?
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stabilize myosin filament
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what compacts together forming the backbone?
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myosin
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what spans half the sarcomere?
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titin
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What is on Each side of PVEK? What happens when you unfold this?
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Ig; stretch PEVK
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What are IG & PEVK. #
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1. Elastic element that gives passive tension ( w/ out calcium/nerve intervention)
2. Scaffold for myofibillogenesis 3. Kinase activity @ M-line-signals |
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Name thin fillament proteins
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1. Actin
2. Troponin-calcium 3. Tropomyosin-calcium 4. Nebulin |
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What is nebulin
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· Prolocates in thin filament
· Molecular ruler: runs from z-line to thin filament, limiting the length of the actin filament |
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What makes up the z disc? Where is it located?
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1. Titin, actin, desmin
2. in the thin fillament |
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What is the fxn of the z-disc?
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Signaling molecules/development of muscle
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What are the cell organelles?
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1.Sarcoplasmic Reticulum
2.Mitochondria 3.T tubules |
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What is the fxn of the sarcoplasmic reticulum?
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Stores, releases, sequesters clacium
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What is the plasma membrane?
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Transveres tubule
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What is the fxn of the mitochondria? what determines its plasticity?
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1.Takes transferred energy and produces ATP
2. Plasticity based on exercise, pattern, usage |
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What determines the density of the capallaries
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Density is Plastic, changes w/ aerobic training
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What is myonuclei?
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“nuclear domain" that can sustain and support a limited area of the myofiber
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Describe the relationship between hypertrophy and myonuclei
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If you hypertrophy, you need more myonuclei, which are fixed post mitotic, so you must get it from stem cells
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What are satellite cells?
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source of stem cells for myonuclei
§ Mitosis of satellite cells→ formation of another satellite cell and a new myonuclei |
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Where are satelite cells located? what must be intact for them to work?
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Located outside the SL in the Basal Lamina,basal lamina
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Name 7 functions of the basement membrane?
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1. Morphogenic and trophic role in development
2. Site for attachment of growth factors and hormone 3. Scaffold for development and repair 4. Maintain membrane (SL) integrity 5. Keep the satellite cell in close proximity to myofiber 6. Basal Lamina for peripheral nerve regeneration 7. Proteins function as important signaling proteins |
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Name 2 intracellular proteins that connect intrasarcomeric proteins w/ the basement membrane
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Dystrophin-anchors thin fillament to plasma membrane
costameres |
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Name 4 proteins of the basememnt membrane
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1. Lamin
2.Integrin 3. Dystroglycans 4. sarcoglycans |
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What happens when there are mutations in Dystroglycans?
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limb-girdle/ facial scapalithies?
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What kind of proteins is Sarcoglycan? What is the result of mutations of sarcoglycan?
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Transmembrane
progressive muscle weakness ie tible gerty? |
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What kind of protein is Integrin? What are it's fxns? What are the results of mutations in Integrin?
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Transmembrane proteins
Signaling/adhesion Myopaties |
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What kind of protein is Lamin ? What is its xn? what are the results of mutations of Lamin
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1. Extracellular matrix protein
2. Signaling 3. Mutation→ myopathies |
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Describe the sliding fillament mechansim
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Force at one end, length at the other
Too long/short=lose all overlap |
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What is a powerstroke?
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movement of myosin head, allowing form movement of muscle
-Only 1 head of each myosin can attach @ 1 time, although there are 2 head |
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Describe the Early experiment :Length Tension Relationship of muscle
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-Length muscle is placed @ where it correlates w/ tension.
- Found point of maximum tension, Lo, which is the point of maximum overlap of actin and myosin -Isolated myofiber→ tethered to force transducer (measures force) and a mechanism to change the length -Isometric contractions: @ fixed length giving max. stimulus -Measured the tension of contactions |
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What is the approx. Lo of a frog?
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Lo in a frog is approx. 2.2
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What does the length the muscle is placed at correlate w/
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tension
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What is Lo?
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The point of max. tension, which is the point of optimal overlap of actin and myosin
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What are isomeric contractions?
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Isometric contractions: @ fixed length giving max. stimulus
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Name the 3 early experiments
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Lenght tension relationship of muscle
Electron micrographs Enzyme treatment of myosin |
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What did the enzyme treatmeant of myosin do?
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Find points where myosin is flexible/breaks easily
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What are the 2 later experiments?
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Sliding fillament assay
Xray-Crystallography of Contractile proteins |
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What was discovered from Xray-Crystallography of Contractile proteins
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1. See both actin binding site & ATP
2. Exist bound to either of those sites 3. ATP types can hydrolyze it also (fast and slow) 4. Light chains play a role in modifying ATP pocket in hydrolysis |
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Describe the Actin and myosin interaction
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1.A+M•ATP→(ATP hydrolysis) A+M*•ADP•Pi
· Energized head still not attaced to myosin 2. A+M*•ADP•Pi→ (calcium) A•M*•ADP•Pi 3. A•M*•ADP•Pi → A•M + ADP + Pi (release hydroylsis products→ A•M (Rigor State) 4. A•M + ATP→ (ATP binding) A + M• ATP |
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What represent the rigor state? what is the rigor state?
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A bound to M; Can't be detached by external forces
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What is the net result of 1 power stroke?
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hydrolysis of one ATP
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What 2 things can myosin exist bound to?
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nucleotide or actin
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What does the state of A•M*•ADP•Pi represent?
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a pre-power stroke state where actin is weakly “docked” to myosin
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What happens during maximal contraction?
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15-30% of crossbridges are attached at any one time
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What is the rate limiting step? What does this step allow?
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The release of Pi is the rate-limiting step in myofibrillar ATPase reaction. The release of Pi allows myosin to proceed to a force-generating state
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Each cross-bridge action requires
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1 ATP
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When does eschemic burn occur?
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once over 50% of maximum effort of contraction
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The binding of ATP @ the end of the power stroke causes ?
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a dramatic decrease in the affinity of myosin for actin
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Name 4 Calcium release units
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1. Dihydropyridine Receptors
2. Ryanodine Receptors 3. Calsequestrin 4. SERCA |
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What is SERCA?
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Calcium pump that pumps calcium back into SR
Requires ATP/energy |
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What is calsequestrin?
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Binding protein that binds and stores calcium
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What do Ryanodine Receptors
do? |
allow calcium out
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Describe Dihydropyridine Receptors and their fxn
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-On the T-tubule
-Forms calcium release unit w/? -Voltage synsetive -When calcium is released it gates open Ryanodine Receptors |
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What is malignant hypotherma?
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genetic mutation of Calcium release, get too much calcium, creating a lot of contractions/heat→ potentially lethal
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What are 3 fxns of ATP dealing w/ Actin myosin interaction
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1.Provides energy for power stroke
2. Breaks rigor state when binds to ? 3. Pumps calcium so muscle can relax (when muscles fatigue it takes longer for them to relax |
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Name 2 calcium regulatory proteins
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Troponin and Tropomyosin
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What do troponin and tropomyosin have in common when it comes to inhibition?
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Convey an inhibitory conformation onto the contractile proteins that prevents actomyosin interaction
Inhibition can be removed in the presence of calcium |
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What does tropomyosin look like? How big is it?Where is it?What does it do in the abscence of calcium? What happens when calcium is added?
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-Rod shaped protein
-Spans the length of about 7 actin molecules -Attached end to end forming a chain that is intimately associated w/ F-actin -Covers myosin binding sites on actin in the absence of calcium -When calcium is added tropomyosin moves and releases myosin binding sites |
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What happens when calcium binds to troponin?
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-Induces conrormational change in torpomysin
-Tropomyosin moves so that actin binding sites are exposed -Allows formation cross bridges-actomyosin complexes |
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What does troponin look like? Where is it? What is its function? special feature?
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-Small gobular protein
-Bound to actin and tropomyosin -Helps secure tropomyosin position covering actin sites for yosin -Contains a binding site that reversible binds calcium |
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Describe an alpha motor neuron
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-There is 1 alpha motor neuron/ myofiber
-An alpha motor neuron may branch and innervate a number of neighboring myofibers |
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What is the motor end plate? What happens when ACh is released?
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-Site where alpha motor neuron synapses onto the myofiber
-ACh release results in local potential change called an EEP |
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What is the neuromuscular junction NMJ?
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Where neuron comes in and connects to motor end plant
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What 3 things make up the NMJ?
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1. Presynaptic axon terminal
2. Synaptic cleft 3. Postsynaptic membrane on the myofiber |
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What is the postsynaptic receptor of the NMJ?
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nicotine
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What is this a discription of?
-Ligand operated-won’t open unless it has 2 Ach bound to it -Allow local conductance to small cations (mainly sodium) |
NMJ
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Describe the process of Excitation Contraction Coupling
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LOONG-see notes
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What stops contraction in the presence of calcium?
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1. Cesation of neural drive to contract (release ACh)
2. The enzyme Acetylcholinesterase degrades ACh. ACh→ choline + acetate 3.the sarcoplasmic reticulum by the calcium ATPase |
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What happens when ceasing contraction in the absence of calcium?
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1. In the absence of calcium, calcium regulatory proteins confer an inhibitory conformation that prevents actomyosin interaction
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What is a twich contraction?
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mechanical response of muscle to a single stimulus
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What is the latent period? What can affect it?
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-Period between when action potential is propogated and when there is
-Can be affected by fiber type and how quickly ATP can be developed |
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When does contraction begin to relax?
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right after it reaches peak
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What stops contraction in the presence of calcium?
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1. Cesation of neural drive to contract (release ACh)
2. The enzyme Acetylcholinesterase degrades ACh. ACh→ choline + acetate 3.the sarcoplasmic reticulum by the calcium ATPase |
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What stops contraction in the presence of calcium?
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1. Cesation of neural drive to contract (release ACh)
2. The enzyme Acetylcholinesterase degrades ACh. ACh→ choline + acetate 3.the sarcoplasmic reticulum by the calcium ATPase |
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What happens when ceasing contraction in the absence of calcium?
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1. In the absence of calcium, calcium regulatory proteins confer an inhibitory conformation that prevents actomyosin interaction
2.Serca (calcium pumps) pump calcium back inside the muscle |
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What is a twich contraction?
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mechanical response of muscle to a single stimulus
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What is the latent period? What can affect it?
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-Period between when action potential is propogated and when there is
-Can be affected by fiber type and how quickly ATP can be developed |
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What happens when ceasing contraction in the absence of calcium?
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1. In the absence of calcium, calcium regulatory proteins confer an inhibitory conformation that prevents actomyosin interaction
2.Serca (calcium pumps) pump calcium back inside the muscle |
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When does contraction begin to relax?
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right after it reaches peak
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What is a twich contraction?
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mechanical response of muscle to a single stimulus
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What is the latent period? What can affect it?
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-Period between when action potential is propogated and when there is
-Can be affected by fiber type and how quickly ATP can be developed |
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What stops contraction in the presence of calcium?
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1. Cesation of neural drive to contract (release ACh)
2. The enzyme Acetylcholinesterase degrades ACh. ACh→ choline + acetate 3.the sarcoplasmic reticulum by the calcium ATPase |
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When does contraction begin to relax?
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right after it reaches peak
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What happens when ceasing contraction in the absence of calcium?
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1. In the absence of calcium, calcium regulatory proteins confer an inhibitory conformation that prevents actomyosin interaction
2.Serca (calcium pumps) pump calcium back inside the muscle |
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What is a twich contraction?
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mechanical response of muscle to a single stimulus
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What is the latent period? What can affect it?
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-Period between when action potential is propogated and when there is
-Can be affected by fiber type and how quickly ATP can be developed |
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When does contraction begin to relax?
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right after it reaches peak
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What is required for relaxation?
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ATP is required to pump calcium back in (relax)
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Which take longer: building up tension or relaxing
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relax
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What makes it harder to relax?
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being fatigued
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How do u determine the size of a motor unit? In a hand? In a leg? Why
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Size-based on the # of myofibers; 300; 1000; less myofibers if it need so do more specific movements
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what is a motor unit
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1 alpha motor neuron and all the myofiber that innervates it
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What happens to subsequent tensions w/ no relaxation inbetween? Why?
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• Tension increased when relaxation is not allowed b/c the calcium has not been uptaken, therefore there is more available
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Skeletal muscle force is porportional 2?
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intracellular calcium concentration & the PCSA-physiological cross sectional area of muscle
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Increase in action potential does what to the myofiber?
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increases calcium inside the myofiber
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What is teatnus?
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the maximal response of muscle to high frequency
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What are 2 ways to increase the force of contraction of the whole muscle?
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1. Increase action potential frequency
2. Recruitment of more motor neurons |
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What is the approx. Lo for humans?
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Many times it is beneficial to begin w/ a decline
-Optimal operating range for Human muscle is 2.6 micron meters; sometimes it is beneficialto begin w/ the decline |
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What happens@ maximum isometric tension
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zero velocity, you can't move
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What is MVC maximum isolated/voluntary contraction
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-Can hold, but not shorten
-Can hold a little more until all of a sudden you can’t hod at all |
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When is power the greatest?
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@ 30% load b/c power=work/time
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What are the 3 major myofiber classifications?
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FO; FOG, SO
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Name 4 sources of ATP
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1.Stored in ATP cell
2. Creatine Phospate 3. Oxidative Phosphorylation (aerobic metabolism) 4.Substrate Phosphorylation (anaerobic metabolism) |
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How much aTP stored in the cell? How fast is it depleted?
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very limited, used quicly
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What is creatine phosphate? What does it do to make ATP? What enzyme is involved? How much is it/how long does it last? What happens when there excess?
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-Muscle protein loses phosphate b/c of enzyme creatine kinase
-Phosphate binds to ADP to make ATP -Very limited/ depleted quickly -Excess draws water into muscle cell (giving the appearance of hypertrophy) |
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How does oxidative phosyphorylation work? efficient?How long does it last? What is the negative part?
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-Aerobic metabolism
-Completely oxidize fuels-krebs cycle and electron ttransport chain -Very efficient- lots of ATP for little fuel -Long lasting, but takes time to begin |
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How does substrate phosphorylation work?
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anerobic metabolism
glucose to pyruvate to lactate |
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what is glycolysis
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glucose to pyruvate
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How does Myosin ATPase distinguish myofiber classifications?
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-fast vs. slow muscle
-Hyrolysis site and myosin nature of alpha motor neuron makes the distinction |
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What does Succinate Dehydrogenase distinguish between in myofiber classification?
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oxidative vs. nonoxidative fibers
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What does Alpa-glycerophosphate dehydrogenase distinguish between?
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glycolytic potential
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What is Immunohistochemical clastification of MHC (myosin Heavy chain) do?
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identifies 4 major fiber types?
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what are the 4 major fiber types identified by Immunohistochemical clastification of MHC (myosin Heavy chain) ? Describe them
|
Type 1: similar to slow oxidative
Type 2: similar to fast oxidative Type 2B: similar to fast glycolitic Type 2X: in between |
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Where is there evidence of fiber type conversions?
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-Cross Innervation Studies of the Cat Hindlimb
-Training Induced Changes |
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What is the only way change from a slow fiber to a fast fiber?
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denerverate and renerverate
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If you do a lot of aerobic work your fibers are more...?
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oxidative
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If you do a lot of sprinting/lifting your fibers are more...?
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glycolitic
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What kind of pathways can fast fibers have?
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oxidative or glycolitic
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What kind of pathways can slow fibers have?
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oxidative
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Can a motor unit have different myofiber characteristics?
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• 1 motor unit will have all the same myofiber characteristics
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What is the order of recruitment of motor units?
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1. Recruit ones that last a long time
2. Then fast oxidation 3. Finally fast glycolitic -Therefore 1→2A→2B |
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Which fibers are most easily brought to threshold?
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smaller oxidative
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Rank the fibers based on Maximum Contraction Velocity expressed as fiber length/sec
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2B>2X>2A>1
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Rank the fibers based on Maximum Tension expressed as force/unit area
o |
-Fast muscle slight>slow muscle (smaller)
-2B>2A>1 |
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what is the best predictor of maximum force?
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the size of the myofiber, Force is proportional to the PCSA of fiber size
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Rank the fibers based on endurance
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SO>FOG>FG
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