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Muscle Physiology > smooth muscle > Flashcards

smooth muscle Flashcards

1
Q

is smooth muscle voluntary or involuntary control?

A

involuntary

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2
Q

smooth muscle contractions produce __________

A

constriction

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3
Q

smooth muscle is organized in _______________

A

multidirectional contractile units

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4
Q

how many nuclei do smooth muscle have?

A

one

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5
Q

how is smooth muscle classified?

A

1 - by location
2 - by contraction pattern
3 - by their communication with neighboring cells

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6
Q

what are the 2 contraction patterns of smooth muscles?

A

1 - phasic (ex. peristalsis)
2 - tonic (ex. sphincters)

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7
Q

what are the 2 classifications of communication between neighboring cells

A

1 - single-unit/unitary/visceral smooth muscle
2 - multiunit smooth muscel

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8
Q

__________ smooth muscle cells are connected by gap junctions, and the cells contract as a single unit

A

single-unit

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9
Q

_______ smooth muscle cells are not linked, and each cell must be stimulated independently

A

multi-unit

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10
Q

what is an example of a phasic smooth muscle that is usually relaxed?

A

esophagus

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11
Q

what is an example of a phasic smooth muscle that cycles between contraction and relaxation?

A

intestine

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12
Q

what is an example of a tonic smooth muscle that is usually contracted?

A

sphincter

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13
Q

what is an example of a tonic smooth muscle whose contraction is varied as necessary

A

vascular smooth muscle

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14
Q

smooth muscles are the _______ to contract and relax

A

slowest
(skeletal is the fastest and cardiac is in the middle)

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15
Q

T or F: smooth muscle has no sarcomeres

A

T

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16
Q

T or F: actin is more plentiful in smooth muscle

A

T

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17
Q

T or F: smooth muscle lacks troponin

A

T, but actin is still associated with tropomyosin in smooth muscle

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18
Q

T or F: myosin filaments are longer in smooth muscle and the entire surface of the filament is covered with myosin heads

A

T

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19
Q

T or F: smooth muscle has an extensive cytoskeleton consisting of intermediate filaments and dense bodies

A

T

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20
Q

T or F: in smooth muscle the amount of SR varies and is less organized

A

T

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21
Q

T or F: smooth muscle has t-tubules and caveolae

A

F, smooth muscle only has caveolae

22
Q

_______ initiates smooth muscle contraction

A

calcium

23
Q

increased _____________ is the signal for smooth muscle contraction

A

cytosolic calcium

24
Q

describe the events for smooth muscle contraction

A

1 - intracellular Ca+ concentration increases
2 - Ca binds to calmodulin
3 - Ca-calmodulin activates myosin light chain kinase
4 - MLCK phosphorylates light chains
5 - active myosin crossbridges slide along actin (crossbridge cycling)

25
Q

____________ is the first step in smooth muscle relaxation

A

removal of Ca+ from the cytosol

26
Q

describe the steps of smooth muscle relaxation

A

1 - free Ca in cytosol decreases
2 - Ca unbinds from calmodulin
3 - myosin phosphatase removes phosphate from myosin light chains
4 - less myosin ATPase activity

27
Q

contraction caused by chemical signaling is ________________ coupling

A

pharmacomechanical

28
Q

what are the 3 different types of cell membrane ca entry in smooth muscle

A

1 - voltage gated
2 - ligand gated or receptor- operated ca channels (ROCC)
3 - stretch-activated

29
Q

some smooth muscles have unstable membrane potentials including ________ and __________ potentials

A

slow-wave and pacemaker

30
Q

membrane potentials _______ in smooth muscles

A

vary

31
Q

_____________________: chemical signals change muscle tension through signal transduction pathways with little or no change in membrane potential

A

pharmacomechanical coupling

32
Q

what are some ways chemical signals influence smooth muscle activity

A
  • autonomic neurotransmitters and hormones
  • paracrine signals
33
Q

antagonistic control

A

both sympathetic and parasympathetic neurons
influence smooth muscle

34
Q

tonic control

A

only a single autonomic branch controls smooth muscle

35
Q

chemical signal

A

different effects in different tissues with different receptors (hormonal control)

36
Q

most neurotransmitters and hormones act through:

A

G protein-linked receptors

37
Q

what are two examples of paracrine signals that influence smooth muscel

A

histamine constricts airways. nitric oxide dilates

38
Q

sympathetic + epinephrine + alpha receptor =

A

constriction of blood vessels, dilates etes, GI/bladder sphincters

39
Q

sympathetic + epinephrine + beta 2 receptors =

A

relaxes airways, wall of stomach, small intestine, and bladder, some blood vessels

40
Q

parasympathetic + acetylcholine + M receptors =

A

contracts airways
relaxes GI/bladder sphincters
relaxes via NO or CIP some blood vessels

41
Q

__________ must operate over a range of lengths

A

smooth muscle

42
Q

T or F: within an organ, the layers may run in several directions

A

T, like the stomach

43
Q

smooth muscles contract and relax more ________ than skeletal muscle

A

slowly

44
Q

smooth muscle uses ________ energy to generate and maintain a given force than skeletal muscle

A

less

45
Q

T or F: smooth muscle can sustain contractions for extended periods without fatiguing

A

T

46
Q

T or FL smooth muscles have small, spindle-shaped cells with multiple nuceli

A

F - single nucleus

47
Q

T or F: smooth muscle contractile fibers are arranged in sarcomeres

A

F

48
Q

Contraction in smooth muscle may be initiated by:

A

electrical or chemical signals or both

49
Q

T or F: smooth muscle is controlled by the somatic nervous system

A

F: autonomic

50
Q

T or F: smooth muscle lacks specialized receptor regions

A

T

51
Q

T or F: the Ca+ for contraction comes from the extracellular fluid as well as from the SR

A

T

52
Q

T or F: the Ca+ signal initiates a cascade that ends with phosphorylation of myosin light chain and activation of myosin ATPase

A

T

Muscle Physiology (19 decks)

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