Karius: Physio of Smooth Muscle Flashcards Preview

Cardiopulmonary Exam 1 > Karius: Physio of Smooth Muscle > Flashcards

Flashcards in Karius: Physio of Smooth Muscle Deck (29):
1

When skeletal muscle is stretched, what happens to it's ability to generate tension (force) ?

decreases

2

When skeletal muscle is stretched, what happens to it's ability to generate tension (force) ?

WHY?

the cross bridges don't have enough overlap

3

Considering skeletal muscle loses the ability to generate force the longer the muscles get, what would happen if the GI track were made of skeletal muscle?

the more it distended because of food, the less it would have the ability to recoil (retract)

4

muscles of the GUT, vasculature, and respiratory tract must be able to do 5 things

a. contract and maintain contraction for long periods of time, so they have to be energy efficient

b. contract periodically to mix contents of organ

c. maintain shape of organ

d. continue to generate active tension even when stretched

e. use relatively little ATP

5

in what locations do we find smooth muscle?

vasculature
GI
respiratory tract
urogenital tract

6

Skeletal muscles are innervated by

alpha motor neurons

7

smooth muscles are innervated by

intrinsic innervation
(GUT and TRACHEA)
neurons (Sensory and motor)
independent of CNS & PNS

extrinsic innervation
Autonomic nervous system allows CNS to control viscera

8

NT of Skeletal M.

acetylcholine

9

norepinephrine or epinephrine

causes contraction of vascular smooth muscle

inhibits gut smooth muscle

10

nitric oxide (NO)

major inhibitory influence on smooth muscle
acts via cGMP mechanism

11

from the slides

"one major difference between skeletal and smooth muscle is that smooth muscle can be..."

directly inhibited (caused to relax)

12

Varicosities

swellings in the axon where NT is released

13

muscarinic receptors are both

cholinergic and adrenergic (alpha and beta)

14

NO uses what kind of receptor?

it doesnt, it's believed to diffuse across the membrane and act on the cGMP system

15

Skeletal muscle vs smooth m.

innervation

SK : alpha motorneurons
SM: multiple sources, intrinsic, AND, and sensory

16

Skeletal muscle vs smooth m.

NT

SK: acetylcholine
SM: ACh, Epinephrine/Norepinephrine, NO, others

17

Skeletal muscle vs smooth m.

excitatory or inhibitory

SK: ACh is exclusively +
SM: May be + or -

18

Skeletal muscle vs smooth m.

Specialized NMJ

SK: specialized NMJ
SM: varicosities, no motor end plate

19

Skeletal muscle vs smooth m.

ACh receptor is located at the...

SK: motor end plate
SM: Multiple receptor types located over cell membrane

20

Skeletal muscle vs smooth m.

activation

SK: only activated at NMJ
SM: may be activated by blood-borne substances

21

Control of Smooth muscle contraction

hormonal control, blood borne pathogens

22

Control of Smooth muscle contraction

Paracrine signaling in SM

endothelia secrete endothelium derived relaxing factor (NO), causing smooth muscle to contract

23

Control of Smooth muscle contraction

"other forms of activation"

STRETCHING!

SOME smooth muscle cells can be activated by stretch including some vasculature

24

The Latch Mechanism

4 steps

1. dephosphorylation of light chain
2. cycle proceding very slowly
3. any attached crossbridges are still generating tension
4. way of increasing tension and decreasing ATP usage

25

Tension/STRETCH curves for skeletal muscle

as active tension increases, passive tension increases due to the elasticity of the muscle membranes

as active tension decreases, passive tension increases
due to the elasticity of the muscle membranes

26

Tension/STETCH curve for smooth muscle



as the muscles stretch there is a momentary increase in passive tension due to the elasticity, followed quickly by dissipation because of the rearrangement of the actin-myosin fibers

as smooth muscle is stretched, the myosin heads, once free from the actin, will interact with a different thin filament

27

what is attached to the membrane in smooth muscle, thin or thick filaments?

thin

28

what is the purpose of thin and thick filaments randomly associating/dissociating?

it decreases passive tension build up by reducing tension build up on points of the membrane

allows the smooth muscle cell to continue to generate active tension over a wide range of length: there is always actin available for myosin heads to bind to

29

which maintains a longer muscle length: skeletal or smooth?

smooth (slide #40 of lecture)