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physiology > Exam 3- Muscles > Flashcards

Exam 3- Muscles Flashcards

1
Q

function of muscular system

A

movement

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2
Q

term for a single cell

A

muscle fiber

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3
Q

moving skeleton

A

skeletal muscle

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4
Q

moving contents, usually within a tube, it surrounds

A

smooth muscle

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5
Q

pumping blood

A

cardiac muscle

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6
Q

neurons who’s axons innervate SM fibers- somatic

A

motor neuron

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7
Q

somatic motor neurons and the skeletal muscle fibers it innervates

A

motor unit

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8
Q

allow contraction strength to vary due to number of motor units active

A

graded contractions

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9
Q

-Ca2+ enables ACh to be released across the space between the axon terminal and the motor end plate
-ACh binds to nicotinic ACh receptors
*Electrical excitation of a muscle results in muscle contraction
—Meaning: Nervous system stimulates muscle fiber, action potential in muscle fibers contracts it

A

excitation-contraction coupling

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10
Q

thick filaments: made almost entirely of __

A

myosin

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11
Q

polypeptide chains form two globular heads and a tail

A

thick filaments: myosin

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12
Q

area that exerts force on the thin filament

A

heads of myosin forms crossbridge

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13
Q

thin filaments: mostly made of the protein ___ and also includes the regulatory proteins ___ and ___

A

actin; troponin & tropomyosin

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14
Q

overlaps binding sites blocking cross bridge

A

tropomyosin

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15
Q

Ca2+ binding to _____ regulates skeletal muscle contraction bc it moves the tropomyosin away and allows myosin to interact with the actin

A

troponin

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16
Q
  • AP starts in Muscle Cell
  • T-tubule Voltage gated calcium channel: open when membrane is depolarization
  • Direct link to Ca2+ release channels in Sarcoplasmic reticulum
  • Relaxation results as Ca2+ is pumped into S. Reticulum when AP stop
A

the neuromuscular junction: post-synaptic-muscle cell

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17
Q
  • Initiated when excitation-contraction coupling increases cytosolic Ca2+ and binding sites on actin are exposed
A

the cross-bridge cycle

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18
Q

what step of the CBC?

the active site on actin is exposed as Ca2+ binds troponin

A

step 1

19
Q

what step of the CBC?

the myosin head forms a cross bridge with actin

A

step 2

20
Q

what step of the CBC?

during the power stroke, the myosin head bends, and ADP and phosphate are released

A

step 3

21
Q

what step of the CBC?

a new molecule of ATP attached to the myosin head, causing the cross bridge to detach

A

step 4

22
Q

what step of the CBC?

ATP hydrolyzes to ADP and phosphate, which returns the myosin to the “cocked” position

A

step 5

23
Q

what is happening in steps 1 & 2 of CBC

A

bind actin + myosin –> lose phosphate

24
Q

what is happening in step 3 & 4 of CBC

A

lose ADP powerstroke

25
Q

what is happening is step 5 & 6 in CBC

A

gain ATP & gain energy

26
Q

The overlapping thick and thin filaments in each sarcomere move past each other, propelled by movements of the cross-bridges. Filaments do not change length but slide.

  • I band decreasing in length
A

sliding filament mechanism

27
Q

excitation = contraction coupling __ Ca2+

A

decreases

28
Q

Excitation =. AP, depolarized, all from neuron up until _____

A

Ca2+ release

29
Q

fluid in skeletal muscle

A

sarcoplasm

30
Q

cell membrane

A

sarcolemma

31
Q
  • ______ muscles surround hollow structures and organs that undergo changes in volume with accompanying changes in the lengths of the smooth muscle fibers.

ex. stomach, intestines, blood vessels

A

smooth muscle

32
Q

in smooth muscle nerves are part of _____ division

A

autonomic

(instead of somatic division like other muscle types)

33
Q

in smooth muscle calcium bind to ____

A

calmodulin

(NO troponin in smooth muscle)

34
Q

how smooth differs from other muscle types

A
  • Smooth muscle cells (SMC) have a single nucleus and have the capacity to divide throughout the life of an individual.
  • The thick and thin filaments are not organized into myofibrils, and there are NO sarcomeres.
35
Q

sources of cytosolic Ca2+

(Two sources of Ca2+ contribute to the rise in cytosolic Ca2+ that initiates smooth muscle contraction)

A
  1. The sarcoplasmic reticulum
  2. Extracellular Ca2+ entering the cell through plasma-membrane Ca2+ channels.
36
Q

sources of cytosolic Ca2+: To relax, the Ca2+ has to be removed using the _______

A

Ca-ATPase pump

37
Q

action potentials spontaneously in the absence of any neural or hormonal input

A

pacemaker cells

38
Q

___ ___ holding Ca2+ concentrations high is termed latch state where muscle holds tension for long periods.
- Ex. sphincter muscles of the GI tract.

A

prolonged stimulation

39
Q
  • striated and use the sliding filament mechanism to contract
  • myocardium contracts fully every time its stimulated
  • hold the appearance of skeletal filaments & T-tubule
  • arranged like smooth muscle: around a hollow tube w/ gap junctions
A

cellular structure of cardiac muscle

40
Q

pacemaker potentials are regulated by ____ innervation

A

autonomic

41
Q

the heart cannot exhibit ___ & ____

A

summation & tetanus

42
Q

why cant the heart exhibit summation & tetanus

A
  • due to refractory period
  • due to filling heart with blood
43
Q

_____is initiated by one AP (one electrical followed by one mechanical event)

A

one heart beat

44
Q
  • The sequence of events from an action potential that activates force-generating mechanisms
  • This occurs in skeletal, smooth and cardiac muscles
  • In all muscles there is an increase in cytosolic Ca2+concentration
A

excitation-contraction coping in all muscle types

physiology (19 decks)

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