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Cardiopulmonology Final > (8) Smooth Muscle Physiology (Rogers) > Flashcards

(8) Smooth Muscle Physiology (Rogers) Flashcards

1
Q

What is a major problem with skeletal muscle?

A

Once tension exceeds a certein length (stretch), the muscle looses tension (force)

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2
Q

What are the two types of smooth muscle?

A

Multiunit Smooth Muscle

Unitary Smooth Muscle

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3
Q

Describe multi unit smooth muscle

A
  • Fibers operate individually
  • Innervated by single nerve

Example: ciliary muscles of eye, iris, piloerector muscles

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4
Q

Describe unitary smooth muscle

A
  • Syncytial or visceral
  • Works together as a unit
  • Cell membranes adere and contain gap junctions

Example: GI tract, Bile ducts, uterus

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5
Q

Skeletal vs. Smooth Muscle

Innervation?

A

Skeletal = alpha motor neurons

Smooth Muscle = Intrinsic (no direct innervation from CNS or PNS) , Extrinsic (ANS)

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6
Q

Skeletal vs. Smooth Muscle

Neurotransmitters?

A

Skeletal = Acetylcholine

Smooth Muscle = ACh, NE, E, (NO-)

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7
Q

Skeletal vs. Smooth Muscle

Transmission Specialization?

A

Skeletal = Neuromuscular junction (NMJ)

Smooth Muscle = No NMJ - varicosities

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8
Q

Skeletal vs. Smooth Muscle

NT receptors?

A

Skeletal= nAChR

Smooth Muscle= mAChR, Adrenergic

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9
Q

Skeletal vs. Smooth Muscle

Other forms of activation?

A

Skeletal= None!!!

Smooth Muscle= Blood-borne, paracrine, intrinsic

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10
Q

[Contraction of smooth muscle]

State the 5 steps!!!

A
  1. Ca2+ enters cytosol through PM Ca2+ channels
  2. Ca2+ binds reversibly to CaM
  3. CaM-Ca2+ complex activates myosin light chain kinase (MLCK)
  4. Phosphorylated MLCK allows myosin and actin binding
  5. Relaxation
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11
Q

Function of myosin phosphatase?

A

Key regulator for relaxation of smooth muscle

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12
Q

What is the latch mechanism with smooth muscle?

A

Myosin phosphatase removes the phosphate from myosin, however STILL LATCHED!!!!

Low affinity for ATP

Continues generating active tension

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13
Q

Draw the length tension relationship graphs for skeletal muscle vs smooth muscle

(include active tension and passive tension)

A
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14
Q
A

C. Elevation of intracellular [Ca2+] for excitation contraction coupling

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15
Q

What are the two major types of smooth muscle?

A

Multi-unit

Unitary

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16
Q

Multi-unit Smooth Muscle Type

Describe:

Innervated by how many nerves?

Examples:

A

Describe: Fibers operate individually

Innervated by how many nerves? Single nerve

Examples: Ciliary muscles of eye, iris, piloerector muscles

17
Q

Unitary Smooth Muscle Type

Describe:

How is it innervated?

Examples:

A

Describe: Works together as unit

How is it innervated?:One nerve–> Cell membranes adhere and contain gap junctions

Examples: GI tract, bile ducts, uterus

18
Q

Describe how contraction of smooth muscle occurs

A

*Different than skeletal muscle!!!

  • No true sarcomere structures
  • Actin attaches to dense bodies/adherens juhctions
  • Myosin heads have bi-directional arrangement
19
Q

Cycling of myosin cross-bridges is ______ than skeletal muscle

A

Slower

20
Q

The time myosin and actin are attached in smooth muscle is ________

A

Greater

*makes for greater force

21
Q

The ATP demand in smooth muscle in comparison to skeletal muscle is…

A

LOWER

22
Q

Excitation slows in smooth muscle, contration remains…

This is known as:

A

Latch mechanism

23
Q

What major molecule does Ca2+ interact with in smooth muscle to induce a muscle contraction?

A

Calmodulin (CaM)

24
Q

How does Ca2+ enter cytosol?

A

Through plasma membrane Ca2+ channels

*release from SR is minor

25
Q

How does Ca2+ exit?

A

SERCA

3Na+/Ca2+ antiporter

Sarcolemmal Ca2+ ATPase

26
Q

After Ca2+ is in the cytosol, what does Ca2+ do to continue the pathway to initiate a muscle contraction?

A

Ca2+ binds reversibly to CaM

27
Q

What activates the myosin light chain kinase?

A

Calmodulin-Ca2+ complex

28
Q

Contraction strength is generally proportaional to….

A

Ca2+ levels

29
Q

What needs to occur to cause muscle relaxation?

A
  • Calcium pumps remove Ca2+
  • Myosin light chain phosphatase removes phosphate group on myosin light chain
30
Q

Describe the summary of contraction in smooth muscle

A
31
Q

What is a varicosity?

A

Varicosities serve as neurotransmitter release sites

32
Q

NO is a

A

Vasodilator

33
Q

What are enviornmental ques that control smooth muscle?

A
  1. Hypoxia
  2. Excess CO2
  3. Increased H+
  4. Adenosine

*EXERCISE!!!

34
Q

What are the major drawers of Ca2+ in this image?

A

VDCC

GPCR

35
Q

What is the resting membrane potential of smooth muscle?

A

-50 to -60mv

36
Q

Describe the difference in skeletal vs smooth muscle activity

A

(Left) Skeletal

(Right) Smooth

37
Q
A
38
Q
A

Cardiopulmonology Final (21 decks)

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