EX1; Smooth Muscle Flashcards Preview

AU14 Physiology > EX1; Smooth Muscle > Flashcards

Flashcards in EX1; Smooth Muscle Deck (38):
1

True or False
Smooth muscles are very large

False; they are very small (2-10µm in diameter)

2

Why are smooth muscle cells considered smooth

the striations are not present; have relatively little SR

3

True or False
The thick and thin filaments are similar, but not identical to those in skeletal and cardiac muscle

True

4

Smooth muscle cells have these; homologous to Z lines of started muscle

dense bodies

5

What is attached to the dense bodies

thin filaments

6

This is NOT expressed in smooth muscle

troponin

7

All the neural innervation of the smooth muscle is from what

the autonomic nervous system; therefore control is involuntary

8

Compared to cardiac and skeletal, there is a greater range of cell lengths over which what can occur

over which force can be generated; accommodates large changes in volume of organs that are designed to move fluids such as the bladder

9

The rate of ATP splitting by myosin in activated smooth muscle fibers is how many times lower than in skeletal muscle

10-100 times

10

Due to the extremely low rate of splitting of ATP, what is the virtually no of regarding smooth muscle

there is virtually no fatigue; the economy is much higher

11

The economy of muscle contraction equals what

force/ATP consumed
in smooth muscle, the force/cross sectional area is about the same as in skeletal muscle, but the ATP splitting is so much lower

12

In smooth muscle, a stimulus leads to what

increase in intracellular Ca concentration

13

The Ca is coupled with what in smooth muscle

Ca + calmodulin ⃗ Ca-calmodulin

14

The Ca-calmodulin is bound with what

myosin light chain kinase (MLCK) (inactive)

15

When the Ca calmoduin is bound with MLCK, what occurs

it becomes an active form

16

The Ca-calmodulin-MLCKacive then does what

it interacts with phosphatase and then either relaxes (Pi + myosin) or contracts (myosin + P)

17

This is continuously active, of which activation results when the MLCK activity is greater than its activity

phosphatase

18

This prevents the reattachment of myosin to actin

dephosphorylation

19

ATP causes this of myosin from actin, as with striated muscle

dissociation

20

Dephosphorylated myosin cannot bind actin, however, myosin bound to actin in smooth muscle can be dephosphorylated and what

remains attached in a rigor state with no movement of the cross bridges

21

This course of Ca is relatively sparse; there are no T tubules in smooth muscle

sarcoplasmic reticulum

22

There is some SR that is associated with what in the membrane can cause release of Ca from this DR

plasma membrane and SP

23

Ca ions enter from this through channels in the plasma membrane

extracellular fluid/extracellular space

24

APs in smooth muscle; the inward flow of positive charge is carried by what

Ca ions during the rising phase of AP

25

True or False
Some cells in the smooth muscle spontaneously generate APs; the resting potential is never steady

True

26

These cells cause membrane potential to reach threshold

pacemaker potential

27

Endings of motor neurons of autonomic nervous system release what in the vicinity of smooth muscle cells

neurotransmitters; may be excitatory or inhibitory

28

True or False
There are neuromuscular junctions in smooth muscle

False; there are not

29

These act similarly to neurotransmitters in control smooth muscle activation

hormones

30

What are three mechanisms that remove Ca from the smooth muscle

Ca pump in sarcolemma
Na/Ca exchanger
Sarcoplasmic reticulum

31

What are the two type smooth muscle

single unit
multi unit

32

Which one, single unit or multi unit contains gap junctions for electrical synapses

single unit

33

Which one, single unit or multi unit is spontaneously activated

single unit

34

Which one, single unit or multi unit is stretch activated

single unit

35

Which one, single unit or multi unit has each cell activated independently

multi unit

36

Which one, single unit or multi unit innervation is primarily restricted to pacemaker cells

single unit

37

Which one, single unit or multi unit smooth muscle is found in large arteries and large airways

multi unit

38

Which one, single unit or multi unit smooth muscle is found in the intestinal tract, uterus, and small diameter blood vessels

single unit