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Physiology > Cardiovascular Physiology II: Smooth Muscle (EXAM III) > Flashcards

Cardiovascular Physiology II: Smooth Muscle (EXAM III) Flashcards

1
Q

The main populations of smooth muscle surround:

(Category + specific locations)

A

Hollow organs
Blood vessels, airways, GI tract, Uterus, Fallopian tubes, Ureter, Bladder

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2
Q

In addition to surrounding hollow organs, smooth muscle is also important in _____ & ______

A

Ocular function & Piloerection

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3
Q

Contraction of smooth muscle may cause _____ or _____

A

Propulsion or resistance

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4
Q

Contracting smooth muscle around a hollow organ will ______ which may result in _____

A

Narrow the lumen; forcing contents through

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5
Q

The stimulus for contraction of smooth muscle may be ____ or _____

A

Extrinsic or intrinsic

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6
Q

The contraction of smooth muscle can be described as:

A

Involuntary

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7
Q

Involuntary smooth muscle contraction is regulated by (3):

A
  1. Autonomic neurons
  2. Hormones
  3. Autocrine/paracrine signals
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8
Q

Smooth muscle is comprised of ____ cells with a ____ nucleus

A

Smaller
Single

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9
Q

Describe the contraction of smooth muscle:

A

Slow, steady, forceful & long

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10
Q

What mechanism does smooth muscle use to generate ATP?

A

Primarily oxidative metabolism

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11
Q

The cellular shape of smooth muscle cells:

A

Elongated & tapered (pointed at each end)

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12
Q

Describe the striation of smooth muscle & why

A

Not striated because the sarcomere is NOT the functional unit

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13
Q

Smooth muscle lacks _____ and only has a ______ SR

A

T-tubules
Rudimentary

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14
Q

Compare the twitch duration of smooth muscle to skeletal & cardiac muscle:

A

By far the slowest

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15
Q

What are the two types of smooth muscle?

A
  1. Multi-unit
  2. Single-unit
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16
Q

What can single unit smooth muscle also be referred to as?

A

Unitary or visceral

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17
Q

Type of smooth muscle with no gap junctions resulting in an independent response per each cell

A

Multi-unit

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18
Q

What type of smooth muscle behaves as multiple units?

A

Multi-unit

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19
Q

The type of smooth muscle that is controlled mainly by nerve signals:

A

Mult-unit

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20
Q

The type of smooth muscle in which cells functions independently:

A

Multi-unit

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21
Q

Describe the muscle tone of multi-unit smooth muscle:

A

No tone

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22
Q

Type of smooth muscle in which the cells are extensively connected via gap junctions allowing them to behave as a functional syncytium

A

Single-unit

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23
Q

Single-unit smooth muscle is controlled by:

A

A variety of stimuli

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24
Q

What type of smooth muscle may be controlled by pacemaker cells?

A

Single-unit

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25
Q

The type of smooth muscle in which cells may be organized into sheets or bundles, often around lumen of a hollow organ:

A

Single-unit

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26
Q

Unlike multi-unit smooth muscle, single-unit smooth muscle can exhibit _____

A

Tone

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27
Q

Determine whether the following smooth muscle is single or multi-unit:

  1. Piloerector
  2. Gut
  3. Bladder
  4. Iris
  5. Uterus
  6. Ciliary muscles
  7. Blood vessels
A
  1. MU
  2. SU
  3. SU
  4. MU
  5. SU
  6. MU
  7. B
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28
Q

The gap junctions in single-unit smooth muscle permit:

A

Coordinated contraction

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29
Q

The electrical isolation of cells in mutli-unit smooth muscle allow for:

A

Finer motor control

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30
Q

An example of smooth muscle that spends most of its time in a relaxed state & when stimulated will briefly contract then return to relaxed state:

(Similar to skeletal & cardiac muscle)

A

Smooth muscle of the esophagus & urinary bladder

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31
Q

An example of smooth muscle that is completely contracted in its resting state & when stimulated it relaxes briefly & then returns to contracted state:

A

Sphincters

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32
Q

Sphincters are an example of a muscle with _____ because it is contracting in its resting state

A

Tone

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33
Q

Example of smooth muscle that is partially contracted in the resting state, but neither completely contracted nor relaxed & will fluctuate depending on its need:

A

Blood vessels & airway

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34
Q

Example of smooth muscle that is phasically active meaning that it will go through phases of contraction & relaxation:

A

Stomach & intestines

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35
Q

Smooth muscle myocytes contain:

A

Actin & myosin

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36
Q

The actin & myosin in smooth muscle myoctyes is NOT organized into:

A

Sarcomeres

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37
Q

Describe the actin in smooth muscle compared to cardiac & skeletal muscle: (4)

A
  1. Higher levels
  2. Longer
  3. Attached to dense bodies
  4. Arranged diagonally to long axis of cell
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38
Q

What is responsible for attaching actin to dense bodies?

A

Alpha-actinin

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39
Q

The dense bodies of smooth muscle myocytes may be located:

A

Intracellular and membrane bound

40
Q

Describe the myosin in smooth muscle myocytes compared to skeletal/cardiac myocytes:

A

Fewer myosin fibers

41
Q

The myosin filaments of smooth muscle are interspersed with:

42
Q

Smooth myocytes lack:

43
Q

Rather than the calcium binding to troponin (as it does in skeletal & cardiac muscle) in smooth muscle, calcium binds to:

A

Calmodulin

44
Q

What are the two actin binding proteins?

A

Calponin & Caldesmon

45
Q

What can Calponin & Caldesmon be described as?

A

Inhibitory proteins

46
Q

Both calponin & caldesmon are associated with:

47
Q

What needs to be removed from actin in order for the smooth muscle to be able to contract?

A

Calponin & Caldesmon

48
Q

_____ inhibits the myosin ATPase

49
Q

_____ inhibits myosin/actin bond

50
Q

What removes the calponin & caldesmon from actin?

A

Calcium-calmodulin complex

51
Q

Contraction of smooth muscle results in _______of the cell

A

Rounding up

52
Q

Smooth muscle contracts effeciently over:

A

Wide range of resting lengths

53
Q

What is the telelogical explanation for why smooth muscle can contract over a wide range of resting lengths?

A

Because we still want smooth muscle to contract efficiently even if its being stretched (such as a full stomach, or bladder)

54
Q

All three types of muscle need an increase in _____ in order for contraction:

A

Intracellular calcium

55
Q

_____ binds to calmodulin for contraction

56
Q

When calcium binds to calmodulin it then removes _____ & ____ from _____

A

Caldesmon & Calponin from actin

57
Q

In addition to calcium _____ in needed for smooth muscle contraction & this comes from _____

A

ATP
Myosin head ATPase

58
Q

In addition to calcium & ATP what is the third requirement for smooth muscle contraction?

A

Myosin light chain phosphorylation

59
Q

What specifically is the myosin light chain phosphorylation required for?

A

Required for myosin to be able to interact with actin

60
Q

What are the three requirements for smooth muscle contraction?

A
  1. Intracellular calcium
  2. ATP
  3. Myosin light chain phosphorylation
61
Q

What is responsible for phosphorylation of the myosin head?

A

Myosin light chain kinase (enzyme)

62
Q

What removes the phosphate from the myosin head to stop contraction?

A

Myosin light chain phosphatase (enzyme)

63
Q

Smooth muscle contraction can be stimulated by?

A
  1. Stretch
  2. Ligands
  3. Intrinsic activity
64
Q

The ligands that can stimulate smooth muscle contraction may include:

A
  1. Neurotransmitters
  2. Hormones
  3. Paracrines
  4. Autocrines
65
Q

The instrinsic activity that can stimulate smooth muscle contraction includes:

A

Pacemaker cells

66
Q

What are not necessarily required for increase in contractile force (AKA contraction)

A

Action potentials (Depolarization)

67
Q

When the concentration of calcium is high, the activity of the myosin light chain is ______ than the activity of the myosin light chain phosphatase so there will be a _____ in contraction

A

Greater than
Increase

68
Q

When the calcium concentration in the cytosol is low, the activity of the myosin light chain kinase is _____than the activity of the myosin light chain phosphatase so there will be a ______ in contraction

A

Less than
Decrease

69
Q

What are the three sources of cytosolic calcium?

A
  1. Voltage-gated calcium channel in cell membrane
  2. Ligand binding GQ-GPCR
  3. Calcium coming in from outside, stimulating SR
70
Q

What occurs when a ligand binds a GQ-GPCR?

A

The GQ-GPCR will generate IP3 which will lead to calcium release in the SR

71
Q

What is unique about increasing cytosolic calcium through a GQ-GPCR?

A

No action potential (depolarization) is required

72
Q

For a smooth muscle to relax _____ has to be removed:

73
Q

What are the two ways in which calcium is removed in order for smooth muscle to relax?

A
  1. Calcium ATPase (to SR or ECF)
  2. Na+/Ca+ Exchanger (To ECF)
74
Q

Both mechanisms to remove calcium in order for smooth muscle to relax are _____ processes

A

Active transport

75
Q

The muscle twitch tension in smooth muscle is:

76
Q

What is the mechanistic explantation to why the muscle twitch tension is graded in smooth muscle:

A

The force of contraction is dependent on how much calcium is released inside the cell

77
Q

What is the teleological explanation to why the muscle twitch tension is graded in smooth muscle:

A

We need to be able to vary the force at which our smooth muscles contract

78
Q

Smooth muscle will continue to contract as long as:

A

Myosin head stays phosphorylated

79
Q

The phosphorylated cross-bridges continue to cycle because:

A

The myosin ATPase is active

80
Q

In smooth muscle we probably never get complete relaxation unless we:

A

Remove calcium

81
Q

When myosin is dephosphorylated, myosin & actin may form:

A

Latch-bridges

82
Q

Allow tension to be maintained within smooth muscle even though the calcium concentration within the cell may be going down & the ATP usage to maintain those contractions goes way down:

A

Latch state

83
Q

In the latch state, tension is _____ although calcium levels in cytosol _____ & ATP usage ____

A

Maintained
Decrease
Decrease

84
Q

Sustained contraction at low cost

A

Latch state

85
Q

Dephosphorylation by the myosin light chain phosphatase can result in what two things?

A
  1. Relaxation
  2. Sustained contraction due to latch bridge
86
Q

Only smooth muscle cells can be _____ or _______

A

Stimulated or inhibited

87
Q

Input for smooth muscle can either be ____ or _____

Input to skeletal muscle & cardiac muscle are always _____

A

Excitatory or inhibitory

Excitatory

88
Q

Inputs to smooth muscle contractility inlclude (5):

A
  1. AP via pacemaker cells
  2. NTs via autonomic neurons
  3. Hormones
  4. Locally induced changes of ECF surrounding cell
  5. Stretch
89
Q

Give examples of locally induced changes of the ECF that act as an input to smooth muscle contractility: (5)

A
  1. paracrine factors
  2. acidity
  3. oxygen
  4. osmolarity
  5. ion concentrations
90
Q

Smooth muscle activation via autonomic neurons:

  1. Do not form ______
  2. Axons have _____
  3. NT released into _____
  4. Distribute to receptors on smooth muscle surface via ______
  5. Each smooth muscle cell may be influences by ______
  6. ____ or _____ contraction
A
  1. synapses
  2. varicosities
  3. interstitial fluid
  4. simple diffusion
  5. more than one varicosity
  6. stimulate or inhibit contraction
91
Q

In the case that the smooth muscle cells is being acted on by more than one varicosity which one yields the result:

A

The stronger stimulus

92
Q

Smooth muscle activation: Hormonal control

Dependent on the receptor there may or may not:

A

Induce a Vm change

93
Q

Smooth muscle activation: Hormonal control

Dependent on the receptor contraction can be:

A

Activated or inhibited

94
Q

In multi-unit smooth muscle, cells are activated:

A

Independently of other cells

95
Q

In single-unit smooth muscle you can activate some of the cells & due to the gap junctions ________ occurs

A

Propogation of signal

Physiology (11 decks)

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