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Z 331 final Flashcards

1
Q

motor unit

A

motor neuron and all the muscle fibers it supplies;
fibers spread throughout muscle;
contract asynchronously to prevent fatigue

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2
Q

muscle twitch

A

motor unit’s response to single action potential of motor neuron; simplest contraction observable in lab

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3
Q

3 phases of muscle twitch

A

latent: events of excitation-contraction coupling, no muscle tension
period of contraction
period of relaxation: tension declines to zero

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4
Q

graded muscle responses

A

contractions are smooth and vary in strength depending on demands

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5
Q

2 ways muscle contractions can be graded

A

changing frequency of stimulation, changing strength of stimulation

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6
Q

wave (temporal) summation

A

result of increase frequency of stimulation; muscle doesn’t completely relax between stimuli; second contraction of greater force; main function is smooth contractions

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7
Q

unfused (incomplete) tetanus

A

result of wave summation

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8
Q

fused (complete) tetanus

A

muscle reaches maximum tension, from very quick stimuli; no muscle relation, muscle fatigue

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9
Q

recruitment

A

multiple motor unit summation (from increased strenth of stimulus), controls force of contraction

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10
Q

size principle

A

motor units with smallest fibers recruited first, larger fibers recruited as stimulus intensity increases

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11
Q

isometric contraction

A

no shortening, tension increases but does not exceed load, cross bridges generate force but do not move actin filametns

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12
Q

isotonic contraction

A

muscle shortens, tension exceeds load

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13
Q

concentric contraction

A

muscle shortens and does work

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14
Q

eccentric contraction

A

muscle generates forces as it lengthens

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15
Q

muscle tone

A

constant slightly contracted state of all muscles, due to spinal reflexes

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16
Q

spinal reflexes

A

groups of motor units alternately activated in response to input from stretch receptors in muscles, responsible for muscle tone

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17
Q

force of muscle contraction depends on

A

number of myosin cross bridges attached.

  1. number of muscle fibers stimulated
  2. relative size of fibers
  3. frequency of stimulation
  4. degree of muscle stretch
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18
Q

the only energy source for contractile activities

A

ATP

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19
Q

3 ways ATP can be regenerated

A

direct phosphorylation of ADP by creatine phosphate
anaerobic glycolysis (glucose to lactic acid)
aerobic respiration

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20
Q

muscles store enough ATP to

A

start contraction

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21
Q

creatine kinase

A

catalyzes creatine phosphate + ADP –> creatine + ATP

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22
Q

creatine phosphate provides maximum muscle power for ? seconds

A

~15

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23
Q

where does CP come from?

A

some made from ATP at rest (reversible reaction with creatine phosphokinase), some stored in muscle

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24
Q

more pyruvate than mitochondria can use results in

A

lactic acid production from anaerobic pathway

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25
aerobic respiration equations
glucose + oxygen --> carbon dioxide + water + ATP
26
aerobic respiration substrates can be
glucose (pyruvic acid), amino acids, or fatty acids
27
anaerobic threshold
point at which muscle metabolism converts to anaerobic glycolysis
28
muscle fatigue
inability to contract even though muscle may stil be receiving stimuli
29
causes of fatigue
ATP/CP shortage, depletion of metabolic reserves, damage to sarcolemma and SR, low pH (lactic acid) inhibits enzymes and effects CNS, motor nerve fibers deplete Ach, unable to release Ca, muscle exhaustion and pain
30
excess post-exercise oxygen consumption (EPOC)
extra oxygen the body must take in for restorative processes, difference between amount of oxygen needed for total aerobic activity and amount actually used
31
slow oxidative fibers
high endurance, aerobic metabolism, smaller, more mitochondria, little power, high blood supply, contain myoglobin, red
32
fast glycolytic fibers
quick, no oxygen, large, few mitochondria, large glycogen reserves, strong, fatigue quickly, little myoglobin, white
33
fast oxidative (intermediate) fibers
mid sized, intermediate power, contract quickly, oxygen dependent, some myoglobin, more capillaries than fast
34
muscle fibers of a motor unit are
same type
35
aerobic/endurance exercise
increase # of capillaries surrounding muscle, increase # of mitochondria, more myoglobin may convert fast glycolytic fibers to fast oxidative
36
resistance exercise (high intensity/aerobic)
hypertrophy, increase size of fibers, more mitochondria, more myofilaments, store more glycogen, fast oxidative to fast glycolytic
37
2 layers of smooth muscle
longitudinal and circular
38
smooth muscle fibers
spindle shaped, thin, short, one nucleus, no striations/sacromeres, less developed SR, no myofibrils, no T tubules
39
Ca in smooth muscles from
SR, most through channels from extracellular space
40
caveolae
pouch like infoldings of sarcolemma, Ca infulx
41
longitudinal layer
fibers parallel to long axis, contraction dilates and shortens
42
circular layer
fibers in circumference of organ, contraction constricts lumen and elongates
43
varicosities
bulbous swellings of nerve fibers store and release neurotransmitters into diffuse junctions
44
innervation of smooth muscle
no NMJ, automatic nerve fibers at diffuse junctions
45
myofilaments in smooth muscle
ratio of thick to thin 1:13 spiraly arranged - contract like corkscrew thick have long heads along entire length - as powerful as skeletal of same size
46
calmodulin
instead of troponin, binds Ca, interacts with myosin kinase to phosphorylate and activate myosin
47
intermediate filaments
resist tension, between dense bodies
48
dense bodies
proteins that anchor noncontractile intermediate filaments to sarcolemma at regular intervals (like z disks)
49
gap junctions
actions potentials transfer from fiber to fiber
50
pacemakers (smooth)
some cells self-excitatory, depolarize without external stimuli
51
regulation of smooth muscle contraction
nerves, hormones, local chemical changes
52
stress-relaxation response
smooth muscle adapts to new length/stretch and relaxes, can still contract on demand
53
length and tension changes in smooth muscle
great force even when stretched, can stretch and relax to normal length
54
hyperplasia
smooth muscle cells can divide and increase numbers
55
types of smooth muscles
unitary (visceral) and multi unit
56
unitary (viseral) smooth muscle
hollow organs, opposing sheets, innervated by varicosities of autonomic nerve fibers, rhythmic spontaneous APs, gap junctions (no recruitment), respond to chemical stimuli; contract as single unit
57
multiunit smooth muscle
large airways, arteries, arrector pilli, iris; rare gap junctions, rare spontaneous depolarization, has independent muscle fibers, innervated by autonomic NS, graded contractions, motor units, responds to hormones
58
cardiac muscle cells
cardiocytes, cardio myocytes
59
cardiac cell characteristics
striated, short, branched, sacromeres, single nucleus, lots of mitochondria, t tubules, intercalated disks, aerobic
60
intercalated disks
anchor cardiac cells, myofibrils anchored together desmosomes: prevent separation gap junctions: ions pass from cell to cell, allow heart to be functional syncytium (single unit)
61
cardiac has long absolute refractory period to
prevent tetanic contractions
62
cardiac depolarization wave opens
slow Ca channel in sarcolemma, surge prolongs depolarization phase
63
pacemaker/autorhythmic cells
unstable resting membrane potentials, due to opening of slow Na channels, continuously depolarize
64
4 major functional characteristics of cardiac tissue
automaticity variable contraction speed and tension extended contraction time/longer refractory period prevent wave summation and tetanic contractions
65
relative contraction speeds
fast-slow: skeletal, cardiac, smooth
66
sarcomeres?
skeletal and cardiac
67
require neural signal to contract?
skeletal, some smooth
68
t tubules?
skeletal, small in cardiac
69
Ca source for each
skeletal: SR cardiac: 80 SR 20 ECF smooth: SR and ECF
70
gap junctions to connect cells?
cardiac, some smooth
71
capable of tetanus?
skeletal and smooth
72
components of lever system
lever/fulcrum, effort, load
73
mechanical advantage
power lever, load close to fulcrum, effort far from fulcrum
74
mechanical disadvantage
speed lever, load far from fulcrum, effort close, load moved rapidly over large distance,
75
1st class lever
fulcrum between load and effort (load, fulcrum, effort) | ex: scissors, seesaw, raise head
76
2nd class lever
load between fulcrum and effort (fulcrum, load, effort) | ex: wheelbarrow, standing on toes
77
3rd class lever
effort between fulcrum and load (fulcrum, effort, load) most common in body, mechanical disadvantage, speed lever, tweezers
78
prime mover
agonist, major responsibility for movement
79
antagonist
opposes movement
80
synergist
help prime movers
81
fixator
immobilizes bone or muscle's origin, stable base
82
circular arrangement
fascicles in concentric rings | ex: orbicularis oris
83
convergent arrangement
broad origin, converge towards tendon insertion | ex: pectoralis major
84
parallel arrangement
fascicles parallel to long axis | ex: sartorius
85
fusiform arrangement
spindle shaped, parallel fibers | ex: biceps brachii
86
pennate arrangement
``` short fascicles attached obliquely to central tendon running length of muscle unipennate - one side ex: extensor digitorum longus bipennate - opposite sides of tendon ex: rectus femoris mutipennate - feathers into one tendon ex: deltoid ```

Anatomy (16 decks)

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