Z 331 final Flashcards Preview

Anatomy > Z 331 final > Flashcards

Flashcards in Z 331 final Deck (86)
1

motor unit

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

2

muscle twitch

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

3

3 phases of muscle twitch

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

4

graded muscle responses

contractions are smooth and vary in strength depending on demands

5

2 ways muscle contractions can be graded

changing frequency of stimulation, changing strength of stimulation

6

wave (temporal) summation

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

7

unfused (incomplete) tetanus

result of wave summation

8

fused (complete) tetanus

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

9

recruitment

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

10

size principle

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

11

isometric contraction

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

12

isotonic contraction

muscle shortens, tension exceeds load

13

concentric contraction

muscle shortens and does work

14

eccentric contraction

muscle generates forces as it lengthens

15

muscle tone

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

16

spinal reflexes

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

17

force of muscle contraction depends on

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

18

the only energy source for contractile activities

ATP

19

3 ways ATP can be regenerated

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

20

muscles store enough ATP to

start contraction

21

creatine kinase

catalyzes creatine phosphate + ADP --> creatine + ATP

22

creatine phosphate provides maximum muscle power for ? seconds

~15

23

where does CP come from?

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

24

more pyruvate than mitochondria can use results in

lactic acid production from anaerobic pathway

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