Muscle Flashcards
1
Q
describe the main function of muscle
A
contraction, which leads to a lot more functions
2
Q
list and describe the 4 functional properties of muscle
A
- contractility: the ability of muscles to shorten forcefully
- excitability: the ability of muscles to respond to a stimulus
- extensibility: the ability of muscle to stretch beyond its normal resting point and can still contract
- elasticity: the ability of muscle to recoil to its original resting length after being stretched
3
Q
list the 3 muscle types
A
- skeletal muscle
- cardiac muscle
- smooth muscle
4
Q
describe skeletal muscle
A
striated, multi-nucleated= much longer cells that run the length of the muscle, voluntary muscle contraction
5
Q
describe cardiac muscle
A
also striated, found only in the heart, mono-/di/nucleated cells that are connected via intercalated disks, involuntary muscle contraction
6
Q
describe smooth muscle
A
nonstriated, mononucleated, shorter cells, involuntary muscle contraction
7
Q
what tissue are the tendons of skeletal muscle made of?
A
dense regular connective tissue
8
Q
what is the origin and its location in skeletal muscle tendons?
A
the less mobile, fixed attachment, usually on the proximal end of the muscle
9
Q
what is the insertion and its location in skeletal muscle tendons?
A
the more mobile attachment, usually on the distal end of the muscle
10
Q
what is the epimysium of skeletal muscle?
A
dense regular connective tissue that surrounds the entire muscle and is continuous with the tendons of that muscle
11
Q
what is the perimysium of skeletal muscle?
A
dense regular connective tissue that surrounds bundles of muscle fibers
12
Q
what is the endomysium of skeletal muscle?
A
dense regular connective tissue that surrounds individual muscle fibers, allows for smoother movement and contraction
13
Q
describe the sarcolemma of skeletal muscle fibers
A
the cell membrane
14
Q
describe the sarcoplasm of skeletal muscle fibers
A
the cytoplasm
15
Q
describe the sarcoplasmic reticulum of skeletal muscle fibers
A
specialized endoplasmic reticulum
16
Q
describe the terminal cisterns of skeletal muscle fibers
A
contained in sarcoplasmic reticulum, have voltage-gated Ca2+ channels
17
Q
describe transverse (T) tubules of skeletal muscle fibers
A
tubes that run from sarcolemma into cell
18
Q
describe triads in skeletal muscle fibers
A
one T tubule plus two terminal cisterns
19
Q
describe myofibrils of skeletal muscle fibers
A
bundles of proteins called myofilaments
20
Q
list the 2 components of myofilaments of skeletal muscle fibers
A
- thick filaments
2. thin filaments
21
Q
what are thick filaments composed of?
A
myosin
22
Q
what are the two components of myosin?
A
a tail and a head
23
Q
what do myosin heads contain? (2)
A
an actin binding site and and ATP binding site
24
Q
what 3 proteins make up thin filaments?
A
- actin
- tropomyosin
- troponin
25
describe the structure of actin proteins
2 strands spiraled around each other
26
describe the location and function of tropomyosin
spirals around actin, covers myosin head binding sites on actin
27
describe the location and function of troponin
attached to tropomyosin along thin filament, has Ca2+ binding sites
28
what is a sarcomere? where is it found?
the basic unit of contraction, found within myofibrils, runs from one Z disc to another
29
during a contraction, what moves, what shortens, and what remains the same in the sarcomere?
myosin pulls actin toward M-line, and the entire sarcomere shortens, the I band and the H zone also shorten, and the A band remains the same
30
what is a motor unit?
one motor neuron and all the muscle fibers it innervates
31
how do the muscle fibers of the same motor unit contract?
simultaneously
32
how many muscle fibers does a typical motor neuron innervate?
150
33
list the first 5 steps of muscle contraction
1. motor neuron releases a neurotransmitter (ACh) at neuromuscular junction
2. ACh binds to receptor on sarcolemma of muscle fiber
3. Na+ channels open on sarcolemma, resulting in depolarization, leading to an action potential along sarcolemma
4. (happening at the same time as 3) excess ACh at neuromuscular junction is broken down by Acetylycholinesterase on sarcolemma
5. action potential travels along sarcolemma and down the Transverse tubules
34
list steps 6-12 of muscle contraction (beginning after the action potential travels along sarcolemma and down T tubules)
6. when action potential reaches voltage-gated Ca2+ channels on T tubules, those channels are pulled away from Ca2+ release channels on terminal cisterns of sarcoplasmic reticulum
7. Ca2+ leaves sarcoplasmic reticulum via Ca2+ release channels and enters sarcoplasm
8. Ca2+ diffuses into myofibrils
9. Ca2+ binds to troponin on thin filament
10. a conformation change in the troponin/tropomyosin complex will expose myosin head binding sites on actin
11. myosin head will bind to ATP and hydrolyze it to ADP and a phosphate group
12. myosin head orients itself to bind to actin (getting to the ready position)
35
list steps 13-17 of muscle contraction (beginning after the myosin head orients itself to bind to actin)
13. myosin head binds to actin
14. myosin head pivots toward center of sarcomere and pulls actin toward center of sarcomere with it = power stroke
15. ADP is released from myosin head and a new ATP binds, and myosin head releases from actin
16. myosin head will hydrolyze ATP and orient itself to bind to a new myosin head binding site on actin, process repeats
17. myosin head walks along actin, shortening sarcomere
36
when does muscle relaxation occur?
when ACh is no longer released at neuromuscular junction
37
list the 4 steps of muscle relaxation
1. cessation of action potential results in voltage-gated Ca2+ channels covering Ca2+ release channels
2. Ca2+ that was released returns to sarcoplasmic reticulum via Ca2+ ATPase pump (which requires energy)
3. Ca2+ diffuses away from troponin, tropomyosin covers myosin head binding sites on actin
4. sarcomere returns to resting length
38
list the 3 ways muscles can obtain ATP
1. from creatine phosphate
2. from anaerobic glycolysis
3. from aerobic respiration
39
when does muscle obtain energy from creatine phosphate and how long does it last?
when contraction begins, lasts about 15 seconds
40
in what form can muscle store glucose and how is it released when needed?
as glycogen, glucose is released from glycogen during contraction and that glucose is broken down to create ATP
41
where else can muscle get glucose to break down to form ATP?
from the bloodstream
42
what are the products of anaerobic respiration?
ATP and lactate
43
how long does the energy provided from anaerobic respiration (glycolysis) last?
2 minutes
44
where does aerobic respiration occur and what does it require?
only in the mitochondria, requires oxygen
45
list 3 substrates that can be used to produce ATP via the Krebs cycle/citric acid cycle in aerobic respiration?
1. pyruvate
2. fatty acids
3. amino acids
46
how are the 3 muscle fiber types classified?
based on respiration type
47
list the 3 muscle fiber types
1. slow oxidative fibers
2. fast glycolytic fibers
3. fast oxidative-glycolytic fibers
48
what are slow oxidative muscle fibers also called?
slow twitch fibers/type I
49
how does the myosin head hydrolyze ATP in slow oxidative muscle fibers?
slowly
50
why do slow oxidative muscle fibers appear red/dark?
they contain a lot of myoglobin, which stores oxygen
51
what type of respiration do slow oxidative muscle fibers perform?
aerobic respiration
52
what type of movements are slow oxidative muscle fibers good for?
movements that happen over a long period of time, like posture maintenance and endurance
53
where can slow oxidative muscle fibers be found in chicken, and in what type of horse are these most predominant?
dark meat in chicken, Arabian horses
54
what are fast glycolytic muscle fibers also called?
fast twitch/type IIA
55
how does the myosin head hydrolyze ATP in fast glycolytic muscle fibers?
quickly
56
what do fast glycolytic muscle fibers lack and what does this mean for their color and respiration type?
they lack myoglobin = no oxygen = rely on anaerobic respiration = appear white
57
what are fast glycolytic muscle fibers good for?
short bursts of activity
58
what are fast oxidative-glycolytic muscle fibers also called?
fast twitch/type IIB
59
do fast oxidative-glycolytic muscle fibers have any myoglobin? what does this mean?
they have SOME myoglobin, which means they can utilize *some* aerobic respiration
60
where are fast oxidative-glycolytic muscle fibers found in chickens and in what type of horse are they predominant?
chicken breasts, white meat, in Quarter Horses
61
what color are fast oxidative-glycolytic muscle fibers?
slightly pink
62
what is summation? what does it determine?
adding things together, determines contraction strength
63
list the 2 types of summation
1. motor unit summation
| 2. temporal summation
64
describe motor unit summation
when multiple motor units contract at the same time, the contraction is stronger
65
describe temporal summation
when the frequency of the stimulus to contract increases, the contraction is stronger
66
what is tetany?
when further increases in the frequency of the stimulus to contract will not result in a stronger contraction, the contraction has reached a steady state
67
does tetany always occur as a result of pathology?
no not always
68
what is tetanus?
when clostridium tetani produces a neurotoxin that results in tetany of muscles, prevents inhibitory signals, so only activating signals are released, neurotoxin can get through blood-brain barrier
69
what is fatigue?
decrease in work capacity caused by work itself
70
what causes muscular fatigue?
caused by decrease in available ATP and a buildup of metabolites in muscle such as lactate or phosphate
71
what is muscle rigor?
when ATP is depleted, the myosin head cannot detach from actin and stays in a painful contracted state
72
what is rigor mortis? how does is affect meat?
muscle rigor that occurs after death, has a negative effect on meat tenderness after slaughter
73
what is Hyperkalemic Periodic Paralysis (HYPP)
high blood potassium (K+), caused by defective Na+ channels in muscle that randomly open, leading to depolarization, causing random muscle contraction, can be mild or severe, linked to Impressive's genes
74
list 3 drugs that effect muscle contraction
1. anticholinesterase
2. curariform
3. botulinum toxin
75
how does anticholinesterase effect muscle contraction?
inhibits acetylcholinesterase so acetylcholine will not be broken down, prolonging muscle contraction due to no removal of stimulus to contract
76
what is anticholinesterase used in and why is that bad?
insecticides, if animals get into it can lead to asphyxiation and death
77
how does curariform effect muscle contraction?
binds to acetylcholine receptors, keeping acetylcholine from binding, inhibiting contraction, leading to asphyxiation
78
how is curariform used in a good way?
in small doses during surgery to prevent certain muscles from contracting and fucking things up
79
what is botulinum toxin produced by and where is it found?
clostridium botulinum, found in some soils
80
how does botulinum toxin effect muscle contraction?
inhibits release of acetylcholine from motor neuron, inhibiting contractions and can lead to asphyxiation
