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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
Describe anaerobic glyolysis
When CP stores are depleted, glucose is covered into pyretic acid to generate ATP
26
Describe cellular respiration
under aerobic conditions, pyruvic acid can enter the mitochondria and go through the Krebs cycle to generate large amounts of ATP
27
What are the two sources of oxygen in muscle tissue?
oxygen that diffuses into muscle fibers from the blood oxygen released by myoglobin within muscle fibers
28
What is muscle fatigue? What causes it?
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
What is central fatigue?
central fatigue occurs due to changes in CNS and generally results in cessation of exercise - feeling of tiredness, desire to cease activity
30
What's oxygen debt?
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
What happens to most of the lactic acid after exercise?
it gets converted back into pyruvic acid and used to ATP production via aerobic cellular respiration
32
What are the three reasons for oxygen consumption after exercise?
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
What is a motor unit? How does it affect the strength of a muscle contraction?
Motor unit - consists of a somatic motor neuron and the muscle fibers it innervates more activated = stronger contraction
34
What are the variables that affect muscle tension?
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
How are motor units are recruited?
weakest first, followed by stronger motor units motor units contract alternately to sustain contractions for longer periods of time
36
What are the periods of contraction for a muscle fiber?
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
what is wave summation
when an action potential triggers muscle contraction before the first contraction has finished - stimuli arrive at different times - results in a stronger contraction
38
What is unfused and fused tetanus?
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
What is tone
small amount of tension of muscles at rest | - established by alternating, involuntary activation of small group of motor units in a muscle
40
Describe isotonic vs isometric contraction
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
Describe the slow oxidative muscle fibers. Where are they found? What are their functions?
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
Describe the fast oxidative glycolytic fibers. Where are they found? What are their functions?
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
Describe the fast glycolytic fibers
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
What affects the distribution of the three different muscle fibers?
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
what is the order for recruitment for the different motor units?
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
What determines the relative radiation of fast glycolic and slow oxidative fibers in each muscle?
determined genetically - accounts for individual differences in physical performance
47
What is hypertrophy and how is it affected by endurance exercises?
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
What are characteristics of cardiac muscle?
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
What makes smooth muscle weird?
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
What are things that cause smooth muscle to relax?
autonomic nervous system, stretching hormones like epi - pH, oxygen, Co2 levels, ion concentration
51
What are the connective tissue that surrounds the three muscular tissues?
skeletal - endomysium, permimysium, epimysium cardiac - enodmysium, perimyseum smooth - endomysium
52
what are the regulatory proteins for smooth muscle tissue?
calmodulin and myosin light chain kinase
53
Describe the first class lever, second class lever, and third class lever
first class - fulcrum in the middle second class - load in the middle third class - effort in the middle
54
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
calsequestrin
55
What are the regulatory proteins that switch contraction process off?
troponin, tropomyosin
56
What are myofibrils?
contractile organelles of skeletal muscles that extend the entire length of the muscle fiber
57
What are the 4 elastic components of muscle?
titin molecules Titin connective tissue around muscle fibers tendons that attach to muscle to bone
58
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
tendon
59
What is the cytoplasm of the sarcolemma?
sarcoplasm
60
The sarcoplasm contains large glucose molecule called ____ and a red color protein called ____
glycogen | myoglobin
61
What is the basic functional unit of a myofibril?
sarcomere
62
Muscle contraction cycle starts when the SR releases ____ ions into the sarcoplasm and binds to _____.
Calcium | Troponin
63
What are the 4 functions of muscular tissue
movement stabilizing structure storing and mobilizing energy generating heat
64
What is a fascicle?
bundles of muscle fibers wrapped in perimysium
65
The force of a muscle contraction depends on the _____ in a muscle prior to contraction
length of sarcomeres
66
what are the 2 functions of the fascia?
allows free movement of muscles | fills spaces between muscles

BIOL 430 (14 decks)

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