Smooth muscle physiology Flashcards Preview

FHB Exam 1 - Cardiovascular Physiology > Smooth muscle physiology > Flashcards

Flashcards in Smooth muscle physiology Deck (24)
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1
Q

Which type of smooth muscle is continuously active (tonic):

single or multi unit?

A

SINGLE

2
Q

Is this a description of Single Unit or Multi Unit:

electrically coupled; stimulate one cell is followed by stimulation of adjacent smooth muscle cells; this results in a wave of contraction, as in peristalsis. The electrical signal may be initiated by a pacemaker cell.

A

Single

3
Q

Is this a description of Single Unit or Multi Unit:

not electrically coupled. Eg. Vas deferens of the male genital tract and the iris of the eye.

A

Multi Unit

4
Q

What are the 4 main differences of smooth muscle and skeletal?

A
  1. Apparatus attaches to DENSE BODIES
  2. No t-tubules
  3. Sarcolemma contains
    caveolae, which represent invaginations of SL
  4. Gap junction for electrical coupling and chemical communication
    - smooth & skeletal both have actin & myosin
5
Q

Instead of calcium induced muscle contraction, what does smooth muscle rely on?

A
  1. Calcium Calmodulin complex & phosphates & Kinases
6
Q

State the general events that occur during SMOOTH muscle contraction

A

AP (doesn’t need one tho)

open voltage gated Calcium channels

increase Ca

Calcium binds to calmodulin( instead of troponin like in skeletal muscle)

Ca-Calmodulin activates Kinase

light chain activated

Myosin activated

Cross bridge formation
Tension

7
Q

Does smooth muscle require an AP like skeletal muscle?

A

NO!

  • but uses myosin
8
Q

How can contraction be turned off?

A
  • increase phosphates activity
  • decrease kinase activity
  • decrease amount of calcium
9
Q

What are 3 excitation pathways involving Calcium?

A
  1. Hromon or NT IP3 gated
  2. Voltage gated - SR releasing calcium
  3. Ligand gated (Hormone or NT)
10
Q

The 3 regulatory pathways in smooth muscle all result in what?

A

Increase in calcium

11
Q

Describe the areas that fall under these categories:

  1. Normally contracted
  2. Normally partially contracted
  3. Phasically active
  4. Normally relaxed
A
  1. Sphincters
  2. Blood vessels, airways
  3. Stomach, intestines
  4. Esophogus, Urinary Bladder
12
Q

What pathways DO NOT require membrane depolarization?

A

hormone receptor stimulation leading to formation of IP3, cAMP, cGMP or the activation of a ligand operated Ca2+ channel

13
Q

How does NO cause smooth muscle relaxation?

A
  • No released by endothelial cells in response to ACh

- causes VASODILATION

14
Q

What are pathways that require alterations in membrane potential?

A
  • Depolarization -induced Calcium entry into smooth muscle cells
  1. Voltage gated Ca
  2. Ligand Bound
  3. Ca entry by CA-CAM & MLCK
    - spread of depolarization via gap junctions is important in SINGLE unit smooth muscle
15
Q

What causes smooth muscle activation? Relaxation?

A
  1. Alpha-adrenergic stimulation

2. Beta - adrenergic = relaxation

16
Q

What do all pathways require for smooth muscle activation?

A

activation of MLCK

- myosin light chain kinase to phosphorylate –> leading to cross-bridge formation (uses ATP)

17
Q

What regulates phosphates?

A

cGMP

  • regulated by NO release from endothelial cells
  • if high = relaxation of blood vessels (viagra)
18
Q

Name 3 ways to regulate smooth muscle:

A
  1. regulate calcium
  2. Regulate phosphotase
  3. Regulate kinase
19
Q

What is the function of Angiotensin II?

A

CONTRACTION

20
Q

What is the second messages for alpha-adrenergic receptors? Beta-adrenergic?

A
  1. IP3 (stimulate contraction)

2. cAMP ( stimulate relaxation)

21
Q

What type of muscle requires somatic neural input? (not autonomic)

A

SKELETAL

  • voluntary (the rest involuntary)
22
Q

What type of hormonal control does the heart use?

A

EPINEPHRINE

23
Q

What type of regulatory protein do the following bind:

  1. smooth muscle
  2. skeletal
  3. Cardiac
A
  1. Smooth = CALMODULIN
  2. Troponin
  3. Troponin
24
Q

What two muscle types both have gap junctions?

A
  1. Cardiac
  2. Single-unit smooth muscle (NOT MULTI UNIT)
  • both have pacemaker ability