4b. Smooth Muscle

Question 1

Smooth muscle

Answer 1

autonomic nervous system

Question 2

smooth muscle located

Answer 2

vasculature
airways
gut

Question 3

blood vessel outside

Answer 3

smooth muscle

Question 4

blood vessel inside

Answer 4

endothelial cells

Question 5

multi-unit

Answer 5

each cell is innervated separately
so each behaves independently
not coordinated

Question 6

single-unit

Answer 6

innervated in series
gap junctions permit coordinated contraction
spontaneous action potential

Question 7

single unit smooth muscles

Answer 7

walls of hollow organs
airways
uterus
visceral smooth muscle

Question 8

multi-unit smooth muscles

Answer 8

airways
larger arteries
ciliary muscle of eye

Question 9

smooth muscle structure

Answer 9

smaller than skeletal
single nucleated
no striations
actin and myosin

Question 10

smooth muscle contraction speed

Answer 10

slower
duration longer

Question 11

3 types of muscle cells

Answer 11

skeletal - voluntary
cardiac - involuntary
smooth - involuntary

Question 12

smooth muscle membrane potential

Answer 12

-50 to -60 mV

Question 13

smooth muscle depolarization rising phase

Answer 13

VG Ca++ channels
+ some Leak Ca++ channels

some smooth muscle can contract w/graded potential

Question 14

Ca++ pathways into cell in smooth muscle contraction

Answer 14

1. VG Ca++ channel
2. stretch-activated Ca++ channel
3. NT/hormones Gprotein complex
4. CICR
5. SOCE

Question 15

How does the G-protein complex induce Ca++ release into Cytosol?

Answer 15

G protein complex stimulates Phospholipase C to release IP3

IP3 binds to SR Ca++ channels
Ca++ released from SR into cytosol

Question 16

how does CICR release Ca++ into cytosol?

Answer 16

Ca++ from cytosol binds to the CICR
CIRC pumped from SR to cytosol

(positive feedback)

Question 17

how does Store operated calcium entry (SOCE) work?

Answer 17

SR Ca++ stores become depleted
signal triggers SO Ca++ channel to open
Ca++ flows into Cytosol

Question 18

smooth muscle contraction

Answer 18

1. increase intracellular Ca++
2. Ca++ binds to calmodulin (CaM)
3. Ca++/CaM activates Myosin Light Chain Kinase (MLCK)
4. MLCK phosphorylates light chain in myosin heads (incr ATPase activity)
5. cross bridge cycling creates muscle tension

Question 19

what inhibits MLCK?

Answer 19

cAMP

Question 20

conformation change

Answer 20

1) increases ATP activity
2) allows myosin/actin interaction

Question 21

increase cAMP

Answer 21

inhibits MLCK
muscles cannot contract

Question 22

smooth muscle relaxation

Answer 22

decrease intracellular Ca++
increase MLCP activity

Question 23

MLCP

Answer 23

myosin light chain phosphatase

Question 24

how do you activate MLCP?

Answer 24

cGMP

Question 25

Nitric Oxide (NO)

Answer 25

released by endothelium causes smooth muscle relaxation vasodilator

Question 26

first signs of vascular disease

Answer 26

decrease in NO

Question 27

how does NO cause smooth muscle relaxation?

Answer 27

NO released by endothelium NO stimulates guanylyl cyclase GTP convert to cGMP increased cGMP causes relaxation of smooth muscles

Question 28

cGMP

Answer 28

inhibits Ca++ entry activates MLCP

Question 29

adrenergic receptors

Answer 29

alpha 1 alpha 2 beta 1 beta 2

Question 30

cholinergic receptors

Answer 30

muscarinic : M1-M5 nicotinic: N1-N2

Question 31

blood vessels receptors

Answer 31

most blood vessels have only adrenergic receptors some have bothh cholinergic and adrenergic

Question 32

adrenergic receptors cause

Answer 32

mostly vasoconstrictions some vasodilations

Question 33

cholinergic receptors cause

Answer 33

only vasodilations

Question 34

vascular smooth muscle (BV) alpha 1

Answer 34

NE binds to alpha 1 G-protein complex Phospholipase C produces IP3 IP3 binds to Ca++ Ca++ released into cytosol increase Ca++ smooth muscle contraction (vasoconstriction)

Question 35

vascular smooth muscle (BV) beta 2

Answer 35

NE or Epi binds to Beta 2 increase cAMP inhibits MLCK smooth muscle contraction (Vasodilation)

Question 36

B2 receptors in BV location

Answer 36

BV that support organ/tissue: coronary skeletal muscle pulmonary

Question 37

BV mainly innervated by

Answer 37

sympathetic nerves

Question 38

some BV innervated by

Answer 38

parasympathetic nerves

Question 39

Parasympathetic effects on vasculature

Answer 39

Ach releases NO from endothelium NO is vasodilator

Question 40

if you have a damaged endothelium

Answer 40

less NO would be released?

Question 41

Sympathetic effects on smooth muscles in bornchioles

Answer 41

Epi>NE NE or Epi binds to beta 2 cAMP increased inhibits intracellular Ca++ release decrease Ca++ decrease smooth muscle contraction (bronchodilation)

Question 42

parasympathetic effects on smooth muscles in bronchioles

Answer 42

Ach binds to muscarinic receptor G protein complex phospholipase C releases IP3 increases cytosol Ca++ increase smooth muscle contraction (bronchoconstriction)

Question 43

bronchodilation receptor

Answer 43

Beta 2

Question 44

bronchoconstriction receptor

Answer 44

M3

Question 45

Paracrine factors in smooth muscle vasodilation

Answer 45

High CO2 High H+ NO

Question 46

paracrine factors in smooth muscle vasoconstriction

Answer 46

Low O2 (hypoxic pulmonary vasoconstriction)

Question 47

endocrine vasoconstrictors

Answer 47

angiotensin II endothelin vasporessin serotonin

Question 48

endocrine vasodilators

Answer 48

histamine

Question 49

Stretch (in gut)...

Answer 49

increases contraction