Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

DPT 503 > Muscle Physiology > Flashcards

Muscle Physiology Flashcards

1
Q

What is the only source of energy for contractile activities?

A

ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

characteristics of muscles tissue

A

excitable: can be stimulated; able to receive stimulus and respond

contractible: able to contract and become shorter

extensible: able to lengthen

elastic: able to go back to og shape/length after being deformed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

muscle functions

A

produce movement

maintain posture/position

stabilize joints: more active than tendons and ligaments

generate heat: when muscles contract it creates heat (glycolysis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

skeletal muscle anatomy

A

connective tissue sheath: epimysium, endonysium

attachment

motor fibers innervate muscle fibers

blood supplies O2 and nutrients and removes waste products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

sarcolemma

A

around the whole fiber

muscle fiber plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

sarcoplasm

A

muscle fiber cytoplasm

structure for metabolism

contains:
- glycosome: storage for glycogen (energy source for muscles contraction)
- myoglobin: carry O2 in muscle
- ribosome: synthesizes protein (RNA, DNA)
- mitochondria: creates ATP which produces energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

myofibril

A

densely packed, rod-like elements

a single muscle fiber can contain 1000s

has myofilaments, striations, and sarcomeres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

myosin

A

thick filaments (16 nm diameter)

motor protein in all types of muscle

globular head and myosin tail

converts chem energy (ATP) to mechanical energy (contraction)

has actin binding sites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

actin

A

thin filament (8 nm diameter)

double helix formation

has indentation for myosin head

tropomyosin: string

troponin: at regular intervals binds to tropomyosin and actin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

myofibril striations

A

repeating series of dark and light bands along length of myofibril

A band, H zone, M line, I band, and Z disc

myosin and actin in hexagonal arrangement with myosin filaments surrounded by 6 actin filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

A band

A

dark region-dark bc of the density of myosin and actin filaments

length of thick filament (myosin)

myosin and actin

has H zone and M line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

H zone

A

lighter area in A band w/only myosin and no thin filaments (actin)

contains M line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

M line

A

connects myosin vertically within the H zone in the A band

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

I band

A

light region

thin filaments (actin) only

actin extends across the I band and partway into the A band

has the Z disc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Z disc

A

anchors actin together within the I band

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

sarcomere

A

smallest contractile unit

area b/w Z discs

align along myofibril

A band and 1/2 I band on each side

shortened muscle=less sarcomeres in series (less=can’t lengthen)

2 sarcomeres connect at the Z disc

titan filament

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

sarcomeres and muscles length

A

less sarcomeres=shorter

add sarcomeres=lengthen muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

titan filament

A

acts as spring tethering myosin to Z disc

contributes to stability of myosin

doesn’t contribute to contraction of muscles but is important to MUSCLE TONE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

contractile proteins

A

myosin and actin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

regulatory proteins

A

tropomyosin and troponin

21
Q

tropomyosin

A

covers binding sites, blocks the cross bridge

22
Q

troponin

A

holds tropomyosin in place

high affinity for calcium

23
Q

sarcoplasmic reticulum (SR)

A

web like structure
fluid filled intracellular organelle

spans the sarcomere and wraps up the contractile myofilaments

stores and releases Ca2+ which binds to troponin, moving tropomyosin off myosin binding sites so actin is ready to bind to it

has terminal cistern (cisterna)-enlarged space where the sarcomere ends.

24
Q

T tubules

A

vertical; overlies Z disc

continuation of sarcolemma

allows AP to reach deep into each muscle fiber

b/w terminal cistern

25
Q

triad

A

2 terminal cistern and 1 T-tubule

transmission of AP along T-tubules cause Ca2+ release from the SR (terminal cistern)

26
Q

Why is Ca2+ important?

A

troponin has calcium binding sites and high affinity for calcium

when Ca2+ binds to troponin, it moves the tropomyosin and uncovers myosin binding sites on actin so it’s ready to bind

27
Q

sliding filament theory

A

relaxation and contraction is caused by actin and myosin sliding past each other

relaxation: filaments only overlap slightly
- H zone wide in middle of A band
- lighter band is wider

contraction: thin filaments slide past thick filaments
- myosin fits into spaces made by actin
- in fully contracted muscle, everything comes together and fully overlap
- no/very little I band bc actin and myosin overlap more
- light region gets much shorter, dark region remains pretty unchanged
- sarcomere shortens
- progressive pulling of actin towards myosin

28
Q

what triggers muscle contractions?

A

AP in somatic motor neurons

AP arrives at axon terminal

voltage-gated calcium channels open

release ACh into synaptic cleft
- acetylcholinesterase degrades ACh later

ACH binds to receptors on sarcolemma that surrounds the fiber

opens voltage-gated ion channels

end plate potential (EPP) (local depolarization/excitation) triggers an AP

AP propogates along sarcolemma and T-tubules

voltage sensitive proteins in tubules stimulate Ca2+ release from SR

Ca2+ binds to troponin, moves tropomyosin off binding sites so myosin can bind to actin

29
Q

activation of cross-bridges

A

cross bridge formation: high energy myosin head with ADP and P attaches to actin

power (working) stroke: myosin head pulls actin towards in at the M line
- ADP and P detach from myosin

cross bridge detachment: ATP attaches to myosin head, causing bridge to detach

cocking of myosin head: energy from hydrolysis of ATP “cocks” myosin head into high energy state
- hydrolysis of ATP-ADP and P that’s ready to attach to myosin head and allow it to attach to actin and start cycle again

30
Q

role of ATP in muscles

A

both contraction and relaxation

31
Q

what does no ATP do to muscles

A

rigid muscles (rigor mortis)

32
Q

relaxation phase

A

APs of motor neurons stop

Ca2+ pumped back into SR
- requires ATP (active transport)
- prevents myosin cross bridge formation

33
Q

muscle innervation

A

each muscle innervated by one motor nerve (bundle of motor neurons axons)

34
Q

motor unit

A

one motor neuron and all muscle fibers it supplies

fibers innervated are dispersed throughout muscle, so an AP would only contract those fibers (very weak contraction)

35
Q

motor unit innervation ratio

A

muscle fibers per motor neuron

36
Q

low motor unit innervation ratio

A

20:1 for example

fine motor control

finger muscles, extraocular muscles, face muscles, larynx

need great amount of precision, control, and stabilization

37
Q

high motor unit innervation ratio

A

2000: 1 for example

gross motor controls

quads, hamstrings, thigh muscles, gastrocs, etc.

38
Q

muscle twitch

A

brief activation of a single motor unit w/a single action potential

just 1 AP lasts only a couple hundred milliseconds

VERY small force generated

summation of twitches makes things functional

latency period: (2 ms)
contraction period (10-100 ms) -max tension
relaxation period: (10-100 ms)

contracts faster than relaxes

39
Q

frequency (temporal) summation

A

muscle response to increases in stimulus frequency

increased frequency (decreased interval b/w twitches)=twitches summate

b4 motor unit completely relaxes, give another stimulus

high frequency=high force

40
Q

unfused tetanus

A

high tension w/ wave-like pattern (quiver) on top

20-40 Hz

41
Q

fused tetanus

A

over 20-40 Hz

max tension that can be generated from that motor unit

no quiver, one smooth contractions

42
Q

multiple motor unit summation

A

muscle response to increased stimulus strength

increased strength=increased motor units recruited

subthreshold stimulus: below 5 volts; not going to recruit

threshold stimulus: 5 volts; start to recruit

max stimulus: no more motor units to recruit

high stimulus=high recruitment= high force

43
Q

what determines which motor units are recruited 1st vs later?

A

size principle

44
Q

size principle

A

smaller motor units recruited 1st, larger motor units recruited later w/stronger stimulus

smallest, highly excitable (lower threshold) motor neurons innervate the smaller muscle fibers with small amount of force generated

larger, less excitable (higher threshold) motor neurons innervate larger muscle fibers with larger amount of force generated

45
Q

benefit of recruiting motor units asynchronously

A

helps reduce muscle fatigue

46
Q

isometric muscle contraction

A

tension at cross bridge is equal to resistance

constant muscle length

exercise when holding a a position (holding a dumbbell for a few minutes)

47
Q

isotonic muscle contraction

A

muscle tension remains constant

concentric and eccentric contractions

48
Q

concentric muscle contraction

A

tension at cross bridges is enough to overcome resistance

muscle shortens: biceps shorten with bicep curls

49
Q

eccentric muscle contraction

A

tension at cross bridges is less than resistance

muscle lengthens: slowly lower down the dumbbell, the biceps contracts eccentrically

DPT 503 (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions