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BIOL 430 > Unit 3 Lecture > Flashcards

Unit 3 Lecture Flashcards

1
Q

The ability of muscular tissue to stretch, within limits without being damages is called

A

extensibility

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2
Q

The ability of muscular tissue to return to its original length and shape after contraction or extension is called

A

elasticity

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3
Q

What is the dark middle part of the sarcomere? How long does it extend?

A

Dar middle part of sarcomere - A band

A band extends entire length of THICK myosin filaments

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4
Q

What are the 4 steps of muscle contraction in order?

A
  1. ATP hydrolysis by myosin
  2. attachment of actin to myosin - cross bridge
  3. power stroke - myosin head pivots, pulls thin past thick towards center of sarcomere
  4. detachment of actin from myosin
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5
Q

What are the neurons that stimulate skeletal muscles to contract?

A

somatic motor neurons

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6
Q

How do the muscles contribute to homeostasis?

A

producing heat, body movement, moving substances

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7
Q

What zone in the middle of the A band contains only thick filaments?

A

H zone

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8
Q

When connective tissue elements extend as broad, flat sheet, its called

A

aponeurosis

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9
Q

Define Transverse tubules

A

tiny invaginations in the sarcolemma of a muscle cell that tunnel in from the surface toward the center of each muscle fiber

when an AP goes down a T tubule, it stimulates the voltage gated Ca channels that stimulate the Ca release channel of the sarcoplasmic reticulum

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10
Q

a dense sheet or broadband or irregular connective tissue that lines the body wall and limbs, supports and surrounds muscles and other organs of the body is called

A

fascia

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11
Q

Threadlike contractile elements within sarcoplasm of muscle fibers that extend the entire length of the fiber, composed of filaments are

A

myofibrils

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12
Q

List the 3 connective tissues surrounding the muscle fibers in order from outer to inner most layer

A

epimysium

perimysium

endomysium

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13
Q

What does the M line do?

A

supporting protein in the middle of the sarcomere

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14
Q

Long cylindrical cell covered by endomysium and sarcolemma are called

A

muscle fibers

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15
Q

What are the contractile proteins os muscles?

A

Actin (thin) and myosin (thick)

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16
Q

Describe skeletal muscle. What are its 4 functions?

A

surrounds skeleton, multi nucleated and striated, Voluntary

producing movement, stabilizing body parts, storing/mobilizing substances, generating heat

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17
Q

What are the 4 properties of muscular tissue?

A
  1. electrical excitability - ability to respond to AP
  2. contractibility - ability to contract forcefully when stimulated bu an AP
  3. Extensibility - agility of muscular tissue to stretch
  4. Elasticity - returns to original shape after being stretched
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18
Q

Describe the following: epimysium, perimysium, endomysium

A

epimysium - dense irregular CT that encircles entire muscle

perimysium - dense irregular CT that surrounds 10-100 muscle fibers, separates them into FASCICLES

endomysium - reticular fibers that separate individual fibers from each other

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19
Q

What are the regulatory muscle proteins?

A

troponin - binds with Ca and changes shape to move tropomyosin away from myosin binding site

tropomyosin - covers actin to prevent myosin from binding

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20
Q

What are Titian, nebulin, alpha actin, myomesin and dystrophin?

A

structural muscle protein

tinning - connects Z to M, helps with elasticity and extensibility

alpha actin - part of Z disc that attaches to actin

nebulin - wraps around filament

dystrophin - links actin to membrane proteins in sarcolemma

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21
Q

What happens to the Z discs, H zone and I band when a muscle contracts? A band?

A

Z discs - come closer together

H and I - get smaller/disappear bc of actin/myosin overlap

A - size stays the same, actin and myosin overlap more depending on strength of contraction

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22
Q

What does a triad consist of?

A

one transverse tubule and two terminal cistern of 2 different SR

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23
Q

What is the length-tension relationship?

A

the force of a muscle contraction depends on the length of sarcomeres in a muscle prior to contraction

under stretched < 1.8 um-2.2 um < overstretched

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24
Q

How does creatine phosphate help derive ATP necessary for the contraction cycle?

A

Creatine kinase transfers the P from creatine P to ADP

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25
Q

Describe anaerobic glyolysis

A

When CP stores are depleted, glucose is covered into pyretic acid to generate ATP

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26
Q

Describe cellular respiration

A

under aerobic conditions, pyruvic acid can enter the mitochondria and go through the Krebs cycle to generate large amounts of ATP

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27
Q

What are the two sources of oxygen in muscle tissue?

A

oxygen that diffuses into muscle fibers from the blood

oxygen released by myoglobin within muscle fibers

28
Q

What is muscle fatigue? What causes it?

A

inability to maintain force of contraction after prolonged activity

caused: 
inadequate release of Ca from SR
depletion of CP, oxygen and nutrients
build top of lactic acid and ADP
insufficient release of ACh at NMJ
29
Q

What is central fatigue?

A

central fatigue occurs due to changes in CNS and generally results in cessation of exercise
- feeling of tiredness, desire to cease activity

30
Q

What’s oxygen debt?

A

the added oxygen, over and above the resting oxygen consumption that is taken into the body after exercise

breathing heavily to get extra oxygen for:

  • replenishing CP stores
  • converting lactate into pyruvate
  • reloading O2 onto myoglobin
31
Q

What happens to most of the lactic acid after exercise?

A

it gets converted back into pyruvic acid and used to ATP production via aerobic cellular respiration

32
Q

What are the three reasons for oxygen consumption after exercise?

A
  1. elevated body temperature causes faster reactions and more ATP use, need more O2 for more ATP
  2. the heart and muscles used for breathing still working hard - consume more ATP
  3. tissue repair occurs more quickly
33
Q

What is a motor unit? How does it affect the strength of a muscle contraction?

A

Motor unit - consists of a somatic motor neuron and the muscle fibers it innervates

more activated = stronger contraction

34
Q

What are the variables that affect muscle tension?

A

frequency of stimulation - number of impulses a second

amount of stretch before contraction

nutrient/oxygen availability

number of muscle fibers that are contracting in unison

35
Q

How are motor units are recruited?

A

weakest first, followed by stronger motor units

motor units contract alternately to sustain contractions for longer periods of time

36
Q

What are the periods of contraction for a muscle fiber?

A

latent - AP sweeps over sarcolemma and Ca ions released

contraction - Ca binds troponin, myosin binding sites on actin are exposed, cross bridges form

relaxation - Ca actively transported back to SR, myosin binding sites covered by tropomyosin, myosin detaches from actin, tension decreases

refractory - period of lost excitability - if two stimuli are applied immediately after the other, the muscle will not respond to 2nd stimulus

37
Q

what is wave summation

A

when an action potential triggers muscle contraction before the first contraction has finished

  • stimuli arrive at different times
  • results in a stronger contraction
38
Q

What is unfused and fused tetanus?

A

unfused - sustained but wavering contraction
- stimulated at a rate of 20-30/sec

fused - sustained contraction in which individual twitches cannot be detected
- stimulated at 80-100 - does not relax at all

both have larger peals because of the buildup of Ca
- tautness/partial contraction enables force of another contraction to be greater than one before

39
Q

What is tone

A

small amount of tension of muscles at rest

- established by alternating, involuntary activation of small group of motor units in a muscle

40
Q

Describe isotonic vs isometric contraction

A

isotonic - tension is constant while muscle length changes

  • concentric: becomes shorter
  • eccentric: becomes longer

isometric - muscle contracts but does not change length
- tension generated is not enough to exceed the resistance of the object to be moved

41
Q

Describe the slow oxidative muscle fibers. Where are they found? What are their functions?

A

deep color

  • large amount of myoglobin, mitochondria, capillaries
  • high capacity for generating ATP via aerobic respiration
  • slow rate of ATP hydrolysis and contraction velocity
  • high fatigue resistance
  • recruited first
  • low glucose and creatine

postural muscles (neck)

maintains posture and aerobic endurance activities

42
Q

Describe the fast oxidative glycolytic fibers. Where are they found? What are their functions?

A

medium color

  • large amount of mitochondria, myoglobin and capillaries
  • perfumes aerobic and anaerobic
  • fast ATP hydrolysis and contraction
  • intermediate fatigue

location: lower limb muscles
walking, sprinting

43
Q

Describe the fast glycolytic fibers

A

white

  • smallest amount of myoglobin, mitochondria and capillaries
  • anaerobic glycolysis
  • fast ATP hydrolysis, contraction, fatigues quickly
  • highest amount of creatine and glycogen
  • 3rd in recruitment
location - extraocular muscles 
function - rapid, intense movements of short duration
44
Q

What affects the distribution of the three different muscle fibers?

A
  1. action of the muscle
  2. person’s training
  3. genetics

most muscle is a mix of all 3, about half of typical skeletal muscle fiber are SLOW OXIDATIVE

45
Q

what is the order for recruitment for the different motor units?

A
  1. slow oxidative - weak contractions
  2. fast oxidative glycolytic - more force
  3. fast glycolytic - max force

activation of motor units is controlled by the brain and the spinal cord

46
Q

What determines the relative radiation of fast glycolic and slow oxidative fibers in each muscle?

A

determined genetically - accounts for individual differences in physical performance

47
Q

What is hypertrophy and how is it affected by endurance exercises?

A

increased thickened of muscle due to increased synthesis of thick and thin filaments

  • cardiovascular changes: cause skeletal muscles to receive better oxygen and nutrients

greater elasticity contributes to a greater degree of flexibility, increasing range of motion

48
Q

What are characteristics of cardiac muscle?

A

striated, central nucleus, branched

INTERCALATED DISCS - contain desmosomes and gap junctions that allow muscle AP’s to spread from one muscle fiber to another

have more mitochondria and contractions lats 15x longer than skeletal

49
Q

What makes smooth muscle weird?

A

can shorten and lengthen to greater extent - get smaller in response to stretch

contain thin, thick, and intermediate filaments that are not arranged orderly
- thin and intermediate attach to dense bodies

lack transverse tubules

caveolae - small spaces that contain extracellular Ca that help with small SR storage of Ca

when it contracts, it rotates like a corkscrew
- starts more slowly and lasts much longer

no contractile proteins

contains gap junctions

50
Q

What are things that cause smooth muscle to relax?

A

autonomic nervous system,
stretching
hormones like epi
- pH, oxygen, Co2 levels, ion concentration

51
Q

What are the connective tissue that surrounds the three muscular tissues?

A

skeletal - endomysium, permimysium, epimysium

cardiac - enodmysium, perimyseum

smooth - endomysium

52
Q

what are the regulatory proteins for smooth muscle tissue?

A

calmodulin and myosin light chain kinase

53
Q

Describe the first class lever, second class lever, and third class lever

A

first class - fulcrum in the middle
second class - load in the middle
third class - effort in the middle

54
Q

Inside the SR, molecules of a calcium-binding protein called _____ bind to the Ca, enabling more Ca to be sequestered or stored within the SR

A

calsequestrin

55
Q

What are the regulatory proteins that switch contraction process off?

A

troponin, tropomyosin

56
Q

What are myofibrils?

A

contractile organelles of skeletal muscles that extend the entire length of the muscle fiber

57
Q

What are the 4 elastic components of muscle?

A

titin molecules
Titin
connective tissue around muscle fibers
tendons that attach to muscle to bone

58
Q

All three connective tissue layer surrounding muscle fibers may extend beyond the muscle fibers to form a roselike structure called ______ that attaches the periosteum to the bone

A

tendon

59
Q

What is the cytoplasm of the sarcolemma?

A

sarcoplasm

60
Q

The sarcoplasm contains large glucose molecule called ____ and a red color protein called ____

A

glycogen

myoglobin

61
Q

What is the basic functional unit of a myofibril?

A

sarcomere

62
Q

Muscle contraction cycle starts when the SR releases ____ ions into the sarcoplasm and binds to _____.

A

Calcium

Troponin

63
Q

What are the 4 functions of muscular tissue

A

movement
stabilizing structure
storing and mobilizing energy
generating heat

64
Q

What is a fascicle?

A

bundles of muscle fibers wrapped in perimysium

65
Q

The force of a muscle contraction depends on the _____ in a muscle prior to contraction

A

length of sarcomeres

66
Q

what are the 2 functions of the fascia?

A

allows free movement of muscles

fills spaces between muscles

BIOL 430 (14 decks)

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