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Physiology Block 1- Cardiovascular Physiology > Cardiac and Smooth Muscle > Flashcards

Cardiac and Smooth Muscle Flashcards

1
Q

What is the mitochondria and vascularity content of cardiac muscle relative to skeletal muscle?

A

More mitochondria and vascularity in cardiac muscle

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2
Q

What structures allow for cell-to-cell propagation of the action potential in cardiac muscle?

A

Gap junctions

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3
Q

What is the length of cardiac muscle’s refractory period relative to skeletal muscle’s?

A

Cardiac muscle has a longer refractory period

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4
Q

What is the physiologic advantage a longer refractory period in cardiac muscle?

A

The cardiac muscle cannot be excited again, preventing it from contracting again, and giving the heart time to fill

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5
Q

What facilitates the re-uptake of Ca++ into the sarcoplasmic reticulum?

A

Phosphorylation of phospholamban

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6
Q

What is the normal action of phospholamban?

A

Inhibition of Ca uptake into the SR

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7
Q

True or false: cardiac muscle cannot be modulated by hormones

A

False

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8
Q

What physiologic event results in the plateau phase of the cardiac muscle action potential?

A

Slow opening of voltage-gated L-type Ca++ channels [DHP]

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9
Q

To what kind of receptor on cardiac tissue will norepinephrine released by the sympathetic nervous bind

A

Beta 1 adrenergic receptor

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10
Q

What serves as regulatory proteins in smooth muscle?

A

Myosin Light Chain Kinase and Myosin Light Chain Phosphatase

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11
Q

What molecules modulate the rate of ATPase activity in smooth muscle?

A

Calponin and Caldesmon

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12
Q

What is the pattern of smooth muscle filament arrangement?

A

Diagnonal orientation

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13
Q

What is the equivalent of Z lines in smooth muscle?

A

Dense bodies

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14
Q

True or false: smooth muscle cells contain T tubules?

A

False

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15
Q

What is the size of smooth muscle sarcoplasmic reticulum relative to skeletal muscle SR? What is the significance of this?

A

Smooth muscle cells have a smaller volume of SR, which means smaller calcium storage; Smooth muscle relies on extracellular calcium for contraction

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16
Q

Which types of muscle contain gap junctions?

A

Cardiac and smooth muscle

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17
Q

What are the two functional types of smooth muscle?

A

Single unit and multiunit

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18
Q

What is the main type of visceral muscle?

A

Single unit smooth muscle

19
Q

What type of smooth muscle has rich ANS innervation?

A

Multiunit

20
Q

What is the result of stretching single unit smooth muscle?

A

Stretch produces tension which leads to contraction

21
Q

What is the relative level of gap junctions in multiunit smooth muscle compared to unitary smooth muscle?

A

Fewer or no gap junctions in multiunit smooth muscle

22
Q

What type of smooth muscle has a more stable membrane potential?

A

Multiunit

23
Q

What does the contractile response of multiunit smooth muscle depend on?

A

Number of muscle fibers activated and frequency of nerve stimulation

24
Q

What mechanisms can stimulate smooth muscle contraction and relaxation?

A

Electrical depolarization, chemical stimuli, and mechanical stimuli (stretching)

25
Q

True or false: An action potential is required for smooth muscle contraction?

A

False

26
Q

What are the two types of smooth muscle action potentials?

A

Spikes and plateaus

27
Q

True or false: an increase in cytosolic calcium is necessary for smooth muscle contraction?

A

True

28
Q

What are store operated channels in smooth muscle cells?

A

Channels that sense when the SR stores of Ca++ are insufficient and can activate the influx of additional Ca++

29
Q

What can activate RyR channels in smooth muscle?

A

Ca++ induced Ca++ release or IP3 activation

30
Q

To what molecule will calcium bind in smooth muscle?

A

Calmodulin

31
Q

What are the actions of the calcium-calmodulin complex in smooth muscle?

A

It activates Myosin Light Chain Kinase as well as CaCM-dependent kinase (CAMK)

32
Q

What is the function of activated myosin light chain kinase?

A

It phosphorylates myosin light chain, activating it and increasing myosin ATPase activity

33
Q

What phosphorylates calponin? What is the effect of this phosphorylation?

A

CaCM-dependent kinase; blocks inhibition of myosin ATPase

34
Q

What is the activity of Myosin Light Chain Phosphatase?

A

Continuously decreases MLC phosphorylation

35
Q

What are the two ways to cause smooth muscle relaxation?

A

Dephosphorylation of myosin light chain through myosin phosphatase or removal of cytosolic calcium

36
Q

What molecule is responsible for the phosphorylation and inactivation of myosin phosphatase?

A

Rho-Kinase

37
Q

During pregnancy, what is the effect of an increase in estrogen?

A

Smooth muscle hypertrophy and increase in gap junction expression

38
Q

What is the effect of oxytocin on smooth muscle contraction

A

Potent stimulator of smooth muscle contraction

39
Q

What is the effect of nitric oxide in smooth muscle? What is the pathway/mechanism of this action?

A

Nitric oxide activates guanylyl cylcase, increasing the amount of cGMP, and enhancing smooth muscle relaxation

40
Q

What is the effect of Protein Kinase G activation?

A

Smooth muscle relaxation

41
Q

What is the mechanism of viagra?

A

Inhibition of cGMP breakdown

42
Q

What is the mechanism of amlodipine?

A

Calcium channel blocker that blocks calcium influx

43
Q

What is Raynaud’s Syndrome?

A

When exposed to cold temperature, patients’ digits become pale and cold because of vasoconstriction of blood vessels

Physiology Block 1- Cardiovascular Physiology (17 decks)

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