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Human Physiology > Week 2 - Muscle Tissue > Flashcards

Week 2 - Muscle Tissue Flashcards

1
Q

List types of muscle fiber and state:

  • whether or not they are striated in appearance
  • how many nuclei each muscle cell contains
  • voluntary/involuntary control
A

skeletal muscle - striated, multiple nuclei, voluntary
smooth muscle - non-striated, single nucleus, involuntary
cardiac muscle - striated, usually single nucleus, involuntary

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2
Q

Skeletal muscle attaches to _______

Smooth muscle attaches to ________

A
  • bone, skin, fascia

- hair follicles in skin, walls of hollow organs – blood vessels, GI tract

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3
Q

Cardiac muscle cells are branched cylinders usually w/ one central nucleus; intercalated discs made up of _____ and ______ join neighboring cells

A

gap junctions

desmosomes

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4
Q

Gap junctions allow action potentials to spread between cardiac cells by ___________

A

permitting the passage of ions between cells, producing depolarization of the heart muscle

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5
Q

When muscle fibers contract, in what direction(s) do they shorten?

A

skeletal muscle - linear
cardiac muscle - linear
smooth muscle - all directions

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6
Q

List functions of muscle tissue

A
  • Producing body movements
  • Stabilizing body positions
  • Regulating organ volumes - sphincters
  • Movement of substances w/in body - blood, lymph, urine, air, food, fluids, sperm
  • Producing heat (thermogenesis) - shivering
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7
Q

List properties of muscle tissue

A
  • Excitability
  • Conductivity
  • Contractility
  • Extensibility
  • Elasticity
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8
Q

Superficial fascia is _______

Deep fascia is _________

A
  • loose connective tissue & fat underlying the skin

- dense irregular connective tissue around muscle - epimysium, perimysium, endomysium

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9
Q

All deep fascia extend beyond the muscle belly to form _______

A

the tendon

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10
Q

Each skeletal muscle is supplied by ______. Each motor neuron supplies ____ muscle cell(s).

A
  • a nerve, artery, and two veins

- multiple

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11
Q

Nerve fibers and capillaries are found in the _______ between individual muscle cells

A

endomysium

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12
Q

Sarcolemma is ______
Sarcoplasm is red due to _________
Transverse Tubules are _____

A
  • plasma membrane of a muscle cell
  • presence of myoglobin
  • tiny invaginations from surface toward the center of each muscle fiber. Allows the action potential to travel from the sarcolemma throughout muscle fiber
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13
Q

Define sarcoplasmic reticulum. In relaxed muscles it stores ______

A
  • A fluid filled system of tubules that surround each myofibril
  • calcium
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14
Q

Myofibrils are ______. They contain three smaller structures called _______

A
  • contractile elements of skeletal muscle

- thin filament (actin), thick filament (myosin), elastic filament (titin)

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15
Q

_______ are considered to be the contractile unit of the skeletal muscle. They are defined as _____

A
  • Sarcomeres

- arrangement of myofilaments into compartments w/in muscle fiber

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16
Q

List the different types of protein present in a sarcomere, give examples for each type

A

contractile - actin, myosin
structural - titin, nebulin
regulatory - troponin, tropomyosin

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17
Q 
During muscle contraction describe how the length of each area below changes:
A band
Zone of overlap
H zone
I band
A
  • no change
  • increases
  • decreases
  • decreases
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18
Q

The number of cross bridges (overlap of thick & thin filaments) determines ____. What will decrease the number of cross bridges?

A
  • the amount of force that the muscle fiber can produce

- muscle stretching past optimal, muscle shortened past optimal

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19
Q

Describe the process of muscle contraction/relaxation

A
  • Nerve impulse reaches synaptic end bulbs, stimulating release of acetylcholine
  • Acetylcholine bind to receptors on muscle cell, stimulating opening of gated ion channels
  • Na+ travels down its electrochemical gradient into the cell, causing depolarization
  • depolarization causes an action potential to travel across the cell, opening Ca2+ channel to open on the sarcoplasmic reticulum
  • Ca2+ binds to and activates troponin, which moves tropomyosin away from binding site on actin molecules
  • myosin binds to actin, hydrolyzes ATP and uses the energy from hydrolysis to ratchet towards the Z disc
  • Action potential stops
  • Acetylcholine is broken down, Ca2+ channels in sarcoplasmic reticulum close
  • Ca2+ is pumped back into sarcoplasmic reticulum via active transport
  • troponin/tropomyosin covers actin binding site
  • muscle relaxes
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20
Q

A single motor neuron makes contact w/ an average of ______ muscle fibers

A

150

21
Q

The neuromuscular junction is usually located near ______ of the muscle fiber since _______

A

the midpoint

skeletal muscle fibers often are vey long

22
Q

List structures of the neuromuscular junction

A

synaptic end bulbs
synaptic cleft
motor end plate

23
Q

List 3 sources of ATP production w/in muscle cells

A

creatine phosphate
anaerobic respiration
aerobic respiration

24
Q

Muscle contraction requires huge amounts of ATP for _______

A
  • powering contraction
  • pumping Ca2+ into SR
  • other metabolic reactions
25
Q

In anaerobic respiration:
one glucose molecule yields __ ATP (net)
glucose is broken down into _____ which is then coverted into ______ which diffuses into the blood then to ______

A

2
2 pyruvic acid
lactic acid
liver for conversion back to glucose

26
Q

In aerobic respiration:
one glucose molecule yields __ ATP (net)
a typical fatty acid molecule yields ___ ATP

A

36

>100

27
Q

Muscle has 2 sources of oxygen, which are _____

A

oxygen diffused from blood

oxygen released from myoglobin w/in muscle

28
Q

What factors are thought to contribute to muscle fatigue?

A
  • inadequate release of Ca2+ from SR
  • decline of Ca2+ concentration in SR
  • depletion of creatine phosphate
  • O2 depletion
  • lactic acid/ADP buildup
29
Q

Increasing strength requires ____

A

increasing motor unit recruitment

30
Q

______ is a sheath of connective tissue that groups muscle fibers into bundles (anywhere between 10 to 100 or more) or fascicles

A

perimysium

31
Q

List the various periods of muscle tension in sequential order

A

latent period
contraction period
relaxation period
refractory period

32
Q

Describe wave summation of muscle tension/stimulation

A

If 2nd stimuli occurs after refractory period but before muscle has relaxed, the second contraction will be stronger than the first

33
Q

Describe unfused tetanus of muscle tension/stimulation

A

sustained but wavering contraction when skeletal muscle is stimulated at rate of 20-30x/second

34
Q

Describe fused tetanus of muscle tension/stimulation

A

sustained contraction in which individual twitches cannot be discerned when skeletal muscle is stimulated at rate higher than 80-100x/second

35
Q

Describe the 2 types of isotonic contraction

A

concentric isotonic contraction - muscle shortens and pulls on another structure
eccentric isotonic contraction - muscle length increases during contraction

36
Q

Describe isometric contraction

A

myosin cross-bridges generate tension but muscle doesn’t shorten because force of load equals muscle tension

37
Q

What is muscle tone?

A

the small amount of tautness or tension in muscle due to weak involuntary contraction of motor units

38
Q

Skeletal muscle fibers can be categorized into __ main types: namely ______. List applications of each type

A

3

slow oxidative fibers - posture, endurance activities
fast oxidative-glycolytic fibers - walking, sprinting
fast glycolytic fibers - short-duration/intense strength

39
Q

Describe slow oxidative skeletal muscle fibers

A

smallest in diameter
large myoglobin content
many large mitochondria
create ATP mainly via aerobic cellular respiration
very fatigue resistant
capable of prolonged, sustained contractions for many hours

40
Q

Describe fast oxidative-glycolytic skeletal muscle fibers

A

intermediate diameter
large myoglobin content & high glycogen content
create ATP via aerobic cellular respiration/glycolysis (anaerobic)
moderately fatigue resistant

41
Q

Describe fast glycolytic skeletal muscle fibers

A 
largest diameter
generate most powerful contractions
low myoglobin & few capillaries
high glycogen content
create ATP via anaerobic cellular respiration
fatigue quickly
42
Q

Compared to skeletal muscle, cardiac muscle has:

A 
more sarcoplasm, mitochondria
larger t-tubules at Z-discs
less well-developed SR
limited intracellular Ca2+ reserves
prolonged delivery of Ca2+ to sarcoplasm
43
Q

Cardiac muscle contains ______ which contract w/o stimulation

A

autorhythmic cells

44
Q

Describe visceral smooth muscle

A

found in walls of hollow viscera & small blood vessels
autorhythmic
contains gap juctions which cause fibers to contractin unison

45
Q

Describe multiunit smooth muscle

A

individual fibers w/ own motor neuron ending

found in large arteries, large airways, errector pili muscles, iris ciliary body

46
Q

In smooth muscle, troponin is replaced by ______

A

calmodulin

47
Q

Can skeletal, cardiac and smooth muscle undergo hypertrophy and/or hyperplasia?

A

skeletal - hypertrophy
cardiac - hypertrophy
smooth - hypertrophy, hyperplasia

48
Q

Sarcomeres are separated from each other by _______

A

Z discs

49
Q

Movement in a sagittal plane which decreases the angle of a joint usually taking the body foward is ______

A

Flexion

Human Physiology (9 decks)

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