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Physio > Physio Ch 08 > Flashcards

Physio Ch 08 Flashcards

1
Q

2 major types of smooth muscles

A

multi-unit smooth muscle and unitary (or single-unit) smooth muscle

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2
Q

discrete, separate smooth muscle fibers

A

multi-unit smooth muscle

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3
Q

major share of control is exerted by non-nervous stimuli

A

unitary smooth muscle

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4
Q

Where are some locations of multi-unit smooth muscle

A

ciliary muscle of the eye, iris muscle of the eye, piloerector muscles

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5
Q

mass of hundreds to thousands of smooth muscle fibers that contract together as a single unit

A

unitary smooth muscle

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6
Q

present in cell membrane of unitary smooth muscle wherein ions can flow freely from one muscle to the next

A

gap junctions

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7
Q

also known as syncytial smooth muscle because of its syncytial interconnections among fibers

A

unitary smooth muscle

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8
Q

visceral smooth muscle are found in these organs

A

GI tract, bile duct, ureter, uterus, blood vessels

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9
Q

It is mainly through these bonds that the force of contraction is transmitted from one cell to the next

A

dense bodies

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10
Q

serve the same role as the Z discs in skeletal muscle

A

dense bodies of smooth muscles

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11
Q

sidepolar of crossbridges in smooth muscles allows it to contract how many percent of their length

A

80 percent

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12
Q

major factor that determines the force of contraction in smooth muscles

A

fraction of time

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13
Q

these organs maintain muscle contraction indefinitely

A

intestines, urinary bladder, gallbladder

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14
Q

a typical smooth muscle reach full contraction in

A

0.5 seconds later

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15
Q

reaches full contraction about 0.5 second later, and then declines in contractile force in another

A

1 to 2 seconds

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16
Q

contraction time of typical smooth muscle

A

1-3 seconds

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17
Q

True or False. Contraction of some types
can be as short as 0.2 second or as long as 30 seconds

A

TRUE

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18
Q

maximum force of contraction of smooth muscle

A

4-6 kg per cm squared cross-sectional area

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19
Q

maximum force of contraction of skeletal muscles

A

3-4 kg

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20
Q

great force of smooth muscle contraction results from

A

prolonged period of attachment of the myosin cross bridges to the actin filaments

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21
Q

maintain prolonged tonic contraction in smooth muscle for hours with little use of energy

A

latch mechanism

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22
Q

Another important characteristic of smooth muscle, especially the visceral unitary type of smooth muscle of many hollow organs

A

stress relaxation of smooth muscle

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23
Q

allow a hollow organ to maintain about the same amount of pressure inside its lumen despite long-term, large changes in volume

A

stress relaxation or reverse stress relaxation

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24
Q

Factors that influence the increase of calcium ions in intracellular fluid

A

nerve stimulation, hormonal stimulation, stretch of the fiber, change in chemical environment of the fiber

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25
Q

In place of troponin, smooth muscle cells contain a large amount of another regulatory protein

A

calmodulin

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26
Q

calmodulin initiates contraction by?

A

activating myosin cross-bridges

27
Q

the chain present in the light chains of myosin heads, that once phosphorylated attachment-detachment of myosin head with actin filament occurs

A

regulatory chain

28
Q

calmodulin calcium complex binds with this enzyme that causes regulatory chain to be phosphorylated

A

myosin light chain kinase

29
Q

located in the cytosol of the smooth muscle cell, which splits the phosphate from the regulatory light chain

A

myosin phosphotase

30
Q

allows longterm maintenance of tone in many smooth muscle organs without much expenditure of energy

A

latch mechanism

31
Q

innervate smooth muscle located on top of a sheet of muscle fibers

A

autonomic nerve fibers

32
Q

autonomic nerve fibers forms this complex in order to secrete their transmitter subtance into the matrix through

A

diffuse junctions

33
Q

axons in smooth muscle fiber do not have branching end feet type but have this instead distributed along their axes

A

varicosities

34
Q

function in much the same way as the skeletal muscle neuromuscular junction

A

contact junction

35
Q

rapidity of contraction of these smooth muscle fibers is considerably faster than that of fibers stimulated by the diffuse junctions

A

contact junction

36
Q

most important transmitter substances secreted by the autonomic nerves innervating smooth muscle

A

ACH, norepinephrine

37
Q

normal resting state of smooth muscle

A

negative fifty to negative sixty

38
Q

action potential of this smooth muscle do not normally occur the same way as skeletal muscles

A

multi-unit smooth muscle

39
Q

action potentials of visceral smooth muscle occur in one of two forms

A

spike potentials, action potential with plateus

40
Q

spike potential duration

A

10 to 50 milliseconds

41
Q

its importance account for the prolonged contraction that occurs in some types of smooth muscles

A

plateau

42
Q

flow of these cations to the interior of smooth muscle fiber is mainly responsible for the action potential

A

calcium ions

43
Q

a local property of the smooth muscle fibers that make up the muscle mass

A

slow wave rhythm

44
Q

caused by waxing and waning of the pumping of positive ions outward through the muscle fiber membrane

A

slow wave rhythm

45
Q

when strong enough, can initiate action potentials

A

slow wave rhythm

46
Q

approximate threshold for eliciting action potentials in most visceral smooth muscle

A

negative 60 to about negative 35 millivolts

47
Q

repetitive sequences of action potentials elicit rhythmical contraction of the smooth muscle mass

A

pacemaker waves

48
Q

when stretched sufficiently, spontaneous action potentials generate

A

unitary smooth muscle

49
Q

Excitation of visceral smooth muscle by muscle stretch is a result from

A

normal slow wave potentials; decrease in overall negativity of the membrane potential caused by the stretch itself

50
Q

how many fibers must depolarize simultaneously before action potential ensues in multi-unit smooth muscle

A

30 to 40 smooth muscle fibers

51
Q

local depolarization of multi unit smooth muscle caused by the nerve
transmitter substance

A

junctional potential

52
Q

2 types of non nervous and non action potential stimulants

A

local tissue chemical factors, hormones

53
Q

cause vasodilation

A

Adenosine, lactic acid, increased potassium ions, diminished calcium ion concentration, and increased body temperature

54
Q

hormones affecting smooth muscle contraction in some degree

A

norepinephrine, epinephrine, acetylcholine, angiotensin, endothelin, vasopressin, oxytocin, serotonin, and histamine

55
Q

hormone causes contraction of a smooth muscle when the muscle cell membrane contains

A

hormone gated excitatory receptors

56
Q

time required for this diffusion of calcium ions into the cell occur averages 200 to 300 milliseconds before contraction begins

A

latent period

57
Q

latent period is greater by how many times in smooth muscle compared to skeletal

A

50 times

58
Q

Small invaginations of the cell membrane in smooth muscle

A

caveolae

59
Q

rudimentary analog of the transverse tubule system of skeletal muscle

A

caveolae

60
Q

When the extracellular fluid calcium ion concentration falls down into this number, smooth muscle contraction ceases

A

1/3 to 1/10 normal

61
Q

removes calcium and pumps back into ECF or sarcoplasmic reticulum

A

calcium pump

62
Q

Smooth muscle of each organ is distinctive from that of most other organs in several ways

A
  1. physical dimension
  2. organization into bundles or sheets
  3. response to different types of stimuli
  4. characteristics of innervation
  5. function
63
Q

Major differences of smooth and skeletal muscles

A
  1. physical organization
  2. excitation-contraction coupling
  3. control of the contractile process by calcium
    ions
  4. duration of contraction
  5. amount of energy required for contraction
64
Q

Control factors that influence smooth muscle contraction in response to local tissue chemical factors

A
  1. Lack of oxygen in the local tissues causes smooth muscle relaxation and, therefore, vasodilatation
  2. Excess carbon dioxide causes vasodilation
  3. Increased hydrogen ion concentration causes vasodilation

Physio (6 decks)

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