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Exercise Physiology > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

what are the functions of skeletal muscle?

A
  • force production of locomotion and breathing
  • force production for postural support
  • heat production during cold stress
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2
Q

composition of skeletal muscle

A

75% water, 20% protein (myosin, actin, tropomyosin), and 5% salts (carbohydrates/calcium)

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3
Q

epimysium

A

surrounds entire muscle

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4
Q

perimysium

A

surrounds bundles of muscle fibers

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5
Q

endomysium

A

surrounds individual muscle fibers

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6
Q

sarcolemma

A

muscle cell membrane

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7
Q

what is the role of satellite cells?

A
  • key role in muscle growth and repair (can increase the # of nuclei in mature muscle fibers)
  • detect microtears and begin to repair by filling in the gaps with proteins, why you feel sore
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8
Q

myonuclear domain

A
  • volume of cytoplasm surrounding each nucleus
  • each nucleus can support a limited myonuclear domain
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9
Q

myofibrils

A

contain contractile proteins

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10
Q

actin filament

A
  • thin filament
  • contains actin, troponin, and trypomyosin
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11
Q

myosin

A
  • thick filament
  • globular head region
  • long alpha-helical tail
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12
Q

sarcomere

A

repeating contractile unit in the myofibril bounded by Z lines

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13
Q

what bands are in the sarcomere?

A

Z line, M line, H zone, A band (myosin), I band (actin)

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14
Q

sarcoplasmic reticulum

A

surrounds myofibrils, storage site for calcium

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15
Q

what triggers muscle contraction?

A

calcium

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16
Q

what triggers muscle contraction?

A

calcium

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17
Q

transverse tubules

A

extend from sarcolemma to SR, maintains the SR calcium store under control of membrane depolarization

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18
Q

role of tropomyosin

A
  • regulates muscle contraction
  • during rest, prevents myosin from forming cross-bridges
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19
Q

role of troponin

A

during excitation contractions, calcium binds with troponin and interacts with tropomyosin to unblock active sites between myosin filaments and actin

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20
Q

role of troponin

A

during excitation contractions, calcium binds with troponin and interacts with tropomyosin to unblock active sites between myosin filaments and actin

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21
Q

what does the SERCA pump do?

A

transports calcium ions from cytoplasm to SR.

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22
Q

what is the sliding filament theory and what role does it play in contraction?

A

Muscle fibers contract by a shortening of their myofibrils due to actin sliding over myosin, results in reduction in distance from Z disc to Z disc.

Actin and myosin slide across each other during contraction due to cross-bridges extending from myosin and attaching to actin. Results in myosin cross-bridge moving actin towards the center of sarcomere.

Energy for muscular contraction comes from the breakdown of ATP by the enzyme myosin ATPase located on the “head” of the myosin cross-bridge.

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23
Q

what role does ATP play in the formation of cross-bridges?

A

breaks the myosin-actin cross-bridges freeing the myosin for the next contraction.

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24
Q

what is the length tension relation in regards to sarcomere length and force generation?

A

optimal sarcomere length = optimal overlap

too short = little force generation

too stretched = no force generation

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25
Q

neuromuscular junction (NMJ)

A
  • where the motor neuron and muscle fiber meet
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26
Q

what effect does acetylcholine have on the receptor?

A

allows for muscle contraction

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27
Q

how does myosin head bind to actin?

A

at binding site on the globular actin protein

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28
Q

what role does Ca play on troponin?

A

troponin changes shape, removing tropomyosin from the binding sites

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29
Q

when does ATP come into play?

A

chemical energy is converted to mechanical energy when ATP is hydrolyzed during cross-bridge cycling (to ADP)

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30
Q

Type 1 fibers

A
  • slow oxidative/slow twitch
  • large # of oxidative enzymes and are surrounded by more capillaries
  • aerobic/oxidative metabolism
  • most efficient
  • less resist to fatigue
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31
Q

Type 2x fibers

A
  • fast twitch/fast glycolytic
  • glycolytic metabolism
  • large anaerobic capacity
  • fastest muscle in humans
  • highest power output of all muscle fiber types
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32
Q

Type 2a fibers

A
  • mixture of type 1 and type 2x
  • intermediate/fast-oxidative glycolytic fibers
  • oxidative metabolism
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33
Q

muscarinic receptors

A

excitatory or inhibitory

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34
Q

nicotinic

A

excitatory, accepts acetylcholine

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35
Q

steps of excitation

A

Nerve impulse arriving at neuromuscular junction.

Synaptic vesicles release acetylcholine that diffuses across the synaptic cleft and binds to receptors on the sarcolemma of the muscle fiber. This opens ion channels on the sarcolemma that results in the movement of sodium into the fiber.

Inward movement of positive sodium ions depolarizes the fiber and sends waves of depolarization through the T-tubules.

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36
Q

steps of contraction

A

Depolarization of T-tubules results in release of calcium from SR into cytosol of muscle fiber.

Calcium ions bind to troponin (on actin molecule). This results in a shift in the position of tropomyosin so myosin binding sites on actin are exposed.

Energized myosin cross-bridge binds to active site on actin and pulls the actin molecule to produce movement. Occurs repeatedly as long as stimulation to muscle continues.

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37
Q

steps of relaxation

A

Motor neuron stops to fire. When neural stimulation to muscle ceases acetylcholine is no longer released and the muscle fiber is repolarized.

After cease, calcium is pumped from cytosol to SR for storage. No free calcium in cytosol = troponin moves tropomyosin back into position to cover myosin binding sites on actin. Prevents myosin-actin cross-bridge formation causing muscle relaxation.

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38
Q

isometric action

A

action in which the muscle develops tension, but does not shorten, aka static contraction. No movement occurs.

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39
Q

dynamic exercise

A

exercise involves movement of body parts. Two kinds (concentric and eccentric)

40
Q

concentric action

A

muscle action that results in muscular shortening with movement of a body part.

41
Q

eccentric action

A

when a muscle is activated and force is produced, but muscle lengthens.

42
Q

hypertrophy

A
  • increase in size of muscle fibers
  • result from addition of protein & new myofibrils making them linger
  • needs additional myonuclei
43
Q

hypertrophy

A
  • increase in size of muscle fibers
  • result from addition of protein & new myofibrils making them linger
  • needs additional myonuclei
44
Q

proprioception

A

ability to identify where limbs and joints are in place.

45
Q

effects of endurance training

A
  • increase in delivery of oxygen to muscle (increase in capillaries, myoglobin, capillary density)
  • enhanced ability for aerobic metabolism (increase size and # of mitochondria)
46
Q

muscle spindles

A
  • proprioceptors in skeletal muscle
  • monitors stretch of muscle
  • initiates a contraction when muscle is stretched
47
Q

stretch reflex

A

quickly stretched muscle intiates immediate contraction due to being stretched.

48
Q

what are the two parts of the nervous system?

A
  • central nervous system
  • peripheral nervous system
49
Q

central nervous system

A
  • brain and spinal cord
  • receives stimuli concerning touch, pain, temp. change, and chemical stimuli
  • controls intelligence, memory, personality, emotion, speech and ability to feel and move
50
Q

peripheral nervous system

A
  • outside spinal cord and brain
  • has two portions sensory (effector organs transmit neuron impulses to CNS) and motor (impulses from CNS to effector organs)
51
Q

cerebrum

A
  • cerebral cortex (complex movement, learned experiences, sensory information)
  • motor cortex (motor control and voluntary movement)
51
Q

cerebrum

A
  • cerebral cortex (complex movement, learned experiences, sensory information)
  • motor cortex (motor control and voluntary movement)
52
Q

cerebellum

A
  • coordinates and monitors complex movement
  • connections to motor cortex, brain stem, and spinal cord
  • may initiate fast ballistic movements
53
Q

brain stem

A
  • medulla, pons, midbrain, reticular formation
  • responsible for: metabolic functions, cardiorespiratory control, complex reflexes
54
Q

structure of neuron and their functions

A
  • cell body (nucleus)
  • dendrites (receives info, conducts impulses toward the cell body)
  • axons (sends info, carries electrical impulses away from cell body, may be covered by Schwann cells)
  • synapse (contact points between axons of one neuron and dendrite of another neuron)
55
Q

Schwann cells

A

forms discontinuous myelin sheath along length of axon

56
Q

what does it mean if an axon has a large myelin sheath?

A

conducts impulses more rapidly that small, nonmyelinated fibers

57
Q

Excitatory Postsynaptic Potentials (EPSPs)

A

causes depolarization

58
Q

Inhibitory Postsynaptic Potential (IPSP)

A

inhibitory transmitters cause hyperpolarization (increased negativity) of the postsynaptic membrane.

59
Q

threshold

A

membrane voltage that must be reached in an excitable cell during depolarization to generate an action potential

60
Q

action potential

A

caused by sodium channels rapidly opening

61
Q

repolarization

A

sodium channels close and potassium channels stay closed

62
Q

all or none principle

A

when threshold is reached, all muscle fibers in motor unit are activated.

if not reached, none of the muscle fibers are activated.

63
Q

myelinated nerves

A

conduct impulses using saltatory conduction

64
Q

unmyelinated nerves

A

uses local conduction

65
Q

role of schwann cells

A

maintaining the PNS

66
Q

saltatory conduction

A

jumps, if previously myelinated axons become unmyelinated, signals shoot everywhere, ability to do things decreases

67
Q

oligodendrocytes

A

create myelin in CNS

68
Q

Nodes of Ranvier

A

small gaps in myelin sheath that allow action potential to jump from node to node along axon, site of saltatory conduction

69
Q

motor neurons

A

somatic neuron that innervates skeletal muscle fibers, allows signal to reach skeletal muscle cells

70
Q

motor unit

A

each motor neuron and the muscle fibers it innervates, provides electrical input to a muscle in order to generate a muscle contraction

Type S (slow) type 1

Type FR (fast, fatigue resistant) type 2a

Type FF (fast, fatigable) type 2x

71
Q

motor unit recruitment

A

recruitment of more muscle fibers through muscle unit activation

72
Q

afferent fibers

A

conducts toward CNS

73
Q

efferent fibers

A

conducts impulses away from CNS

74
Q

autonomic nervous system

A

plays important role in maintaining homeostasis

75
Q

sympathetic nervous system

A

tends to activate an organ (ex. increases heart rate)

“fight or flight”

76
Q

parasympathetic nervous system

A

tends to inhibit an organ (ex. slows heart rate)

helps control body’s response during times of rest

77
Q

how is the autonomic nervous system regulated?

A

integrated reflexes through the brainstem to the spinal cord and organs

78
Q

motor end plate

A

chemical synapse formed at the sites where branches of axons contact a target muscle.

AcH from pre-synaptic neurons into synaptic cleft activates nicotinic receptors on the motor end plate

79
Q

somatic nervous system

A

allows you to move and control muscles throughout your body

feeds smell, sound, taste, touch to brain

80
Q

What role do neurotransmitters play on the excitation/ inhibition? Receptors?

A

by binding to postsynaptic receptors, neurotransmitter can cause excitatory or inhibitory postysynaptic potentials by depolarizing or hyperpolarizing the postsynaptic membrane.

81
Q

How does exercise play a role in neural adaptations?

A

stimulates formation of new neurons

improves brain vascular function

82
Q

function of endocrine system

A

made up of glands that secrete hormones in the body to regulate the activity of cells or organs

83
Q

hormones

A

substances released into the blood from endocrine glands

84
Q

basal secretion

A

almost all endocrine cells secrete small amounts of hormones 24/7

85
Q

negative feedback

A

secreted hormone acts to decrease its secretion from gland
ex. testosterone

86
Q

positive feedback

A

secreted hormone acts to increase its secretion from gland
ex. oxycotin

87
Q

What role does the circadian rhythm play in the release of hormones? How are hormones cleared?

A

SCN controls the production of melatonin which plays a role in conveying info about light/dark cycles

cleared by plasma membrane recycling, metabolizing in blood, and kidney/liver

88
Q

What is the role of the hypothalamus/pituitary gland in the release of hormones?

A

hypothalamus: controls function of pituitary gland, hormones promote & inhibit pituitary hormone release

pituitary: “master gland”, hormones influence many physiological functions of the body

89
Q

beta cells

A

secrete insulin to lower glucose when high

90
Q

alpha cells

A

secrete glucagon to increase glucose when low

91
Q

aldosterone

A

controls sodium reabsorption and potassium secretion

regulates blood volume & pressure

stimulated by increasing potassium concentration and decreased plasma volume

92
Q

cortisol

A

maintenance of plasma glucose (stimulates FFA mobilization, glucose synthesis, blocks glucose uptake into cells)

released by exercise

93
Q

thyroid hormones

A

decreased thyroid function = slower metabolism

regulation of thyroid through hypothalamus

94
Q

thyroxine (T4) secretion

A

raises metabolism except in brain, spleen, testes, uterus, and thyroid gland

causes sluggishness

regulates growth/development, skeletal & nervous system formation, and maturation/reproduction

95
Q

triiodothyronine (T3) secretion

A

facilitates neural reflex activity

regulates growth/development, skeletal & nervous system formation, and maturation/reproduction

96
Q

growth hormone

A

released from anterior pituitary gland

builds and repairs lean tissue

loosing adipose tissue

stimulates release of insulin-like growth factors (IGFs)

spares plasma glucose (opposes insulin action to reduce use of plasma glucose)

Exercise Physiology (5 decks)

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