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22 spring: Physiology > exam 1 lecture 8 Smooth muscle > Flashcards

exam 1 lecture 8 Smooth muscle Flashcards

1
Q

Primary pathologies of smooth muscle in veterinary medicine are very ___ and have yet to be identified

A

rare

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2
Q

many diseases result in changes in smooth muscle activation or ___, resulting in pathology AND

A

relaxation

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3
Q

smooth muscle can be innervated by ___

A

Additionally, neurotransmitters and endocrine and paracrine factors can both stimulate and inhibit contraction

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4
Q

smooth muscle contracts quickly or slowly?

A

slowly

anatomy and chemistry of smooth muscle has eliminated speed as a characteristic of excitation-contraction coupling

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5
Q

what type of muscle has an all or nothing response

A

skeletal

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6
Q

where to find smooth muscle

A

Lines hollow organs

GI tract

Urinary Bladder

Endothelium

Uterus

Vas Deferens

Bronchioles ………

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7
Q

smooth muscle is normally is sheet shapes, where is it in bundles?

A

eye

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8
Q

smooth muscle is always covered by ___

A

protective cell layer- epithelium

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9
Q

muscle cell shape

A

spindled

single cell

single nucleus

shorter and smaller than skeletal muscle

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10
Q

why irregular pattern in smooth muscle?

A

generate force over huge changes in length

example: urinary bladder- works if a drop or is a liter of urine is present

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11
Q

___ muscle undergoes extensive tissue damage if stretched and also doesn’t generate force if the overlap between the thick and thin filaments is damaged.

A

Skeletal

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12
Q

___ help transfer force from thick and thin filaments onto the surface of smooth muscle cells

A

dense bodies

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13
Q

Z lines in skeletal muscle are similar to ___ in smooth muscle

A

dense body

distribute force

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14
Q

smooth muscle is stimulated to contract by affecting either calcium or ___

A

myosin light chain kinase or phosphatase

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15
Q

two distinct sources of neural stimulation of smooth muscle

A

extrinsic: ANS

Intrinsic: within the organ (enteric NS)

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16
Q

extrinsic innervation of smooth muscle

A

Autonomic Nervous System

Parasympathetic and Sympathetic

Organ specific (Vascular smooth muscle almost exclusively sympathetic)

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17
Q

intrinsic innervation of smooth muscle

A

Neural plexuses within organs

Motor, sensory and interneurons

Allows function if CNS input lost - doesn’t need brain to tell it what to do

example: Myenteric plexus

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18
Q

Generally ___ neural stimulation provides primary control of the smooth muscle and ____ input modifies activity

A

intrinsic

extrinsic

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19
Q

describe multi-unit neural stimulation of smooth muscle

A

each muscle cell has its own nerve and acts independently of other smooth muscle cells

1:1 muscle to nerve

(eye muscles: iris, piloerector muscles, some vascular smooth muscle)

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20
Q

describe single unit neural stimulation of smooth muscle

A

Gap junctions between smooth muscle cells exist to allow direct signaling between muscle cells

1 nerve impulse gets spread to other cells by gap junctions

(urinary bladder, GI, uterus, vascular smooth muscle)

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21
Q

example for single unit neural stimulation of smooth muscle

A

urinary bladder

Gap junctions between smooth muscle cells exist to allow direct signaling between muscle cells

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22
Q

example for multi-unit neural stimulation of smooth muscle

A

eye muscle

each muscle cell has its own nerve and acts independently of other smooth muscle cells

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23
Q

True or false

smooth muscle have motor endplates

A

false

no motor endplates, they have synaptic troughs, the axon released neurotransmitters to many muscle cells through varicosities

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24
Q

what neurotransmitter is released for parasympathetic stimulation of smooth muscle

A

acetylcholine

(rest and digest)

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25
Q

what neurotransmitter is released for sympathetic stimulation of smooth muscle

A

Norepinephrine

(fight or flight)

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26
Q

what are some neurotransmitters released at the synaptic troughs of smooth muscle?

A

Acetylcholine (parasympathetic- rest and digest)

Norepinephrine (sympathetic- fight or flight)

Nitric oxide

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27
Q

two types of receptors for acetylcholine

A

muscarinic- smooth muscle, CNS, G-protein linked (slower)

Nicotinic- skeletal muscle, CNS, no second messenger (fast)

28
Q

which acetylcholine receptor is used in smooth muscle and why?

A

muscarinic

CNS

second messenger system- G protein linked

makes it a slower reaction

29
Q

example of paracrine stimulation of smooth muscle

A

(particularly vascular smooth muscle)

Nitric oxide

Prostacyclin

Adenosine

Endothelin

30
Q

endocrine stimulation of smooth muscle is by ___

A

Epinephrine

Angiotensin

31
Q

all smooth muscle cells have ___ cell surface receptors

A

many different

(muscarinic, adrenergic, nitric oxide etc.) meaning that smooth muscle can respond appropriately to many different physiological stimuli, and that some conditions will result in an over-expression of the receptors.

32
Q

Some factors will cause contraction of ___ in one tissue and relaxation in another (i.e. histamine and epinephrine/norepinephrine) Balancing these effects will be critical in therapeutic use of the drugs.

A

smooth muscle

33
Q

example of a factor that causes contraction in one type of smooth muscle and relaxation in another smooth muscle

A

histamine

contractions- bronchi

dilation- blood vessels

34
Q

where does smooth muscle get calcium?

A

Sarcoplasmic reticulum

extracellular calcium

35
Q

there is more calcium inside or outside the cell?

A

outside- if you open a gate calcium will flow into the cell

36
Q

two types of calcium channels

A

ligand-gated calcium channels

voltage-gated calcium channels

-calcium induced calcium release (no voltage gated sodium channels)

37
Q

how is myosin in smooth muscle different than smooth muscle in skeletal muscle

A

smooth muscle:

2 regulatory myosin light chains

these control activation

38
Q

how do regulatory myosin light chains work in smooth muscle

A

4 calcium bind to calmodulin which activates myosin light chain kinase which phosphorylates (adds a phosphate) to the Regulatory myosin light chain. When this happens the myosin heavy change undergoes a conformation change and allows actin-myosin interaction

39
Q

myosin light chain kinase does what in smooth muscle?

A

adds phosphate group/ phosphorylates the regulatory myosin light chain which causes the myosin heavy chain to change shape and allow for actin-myosin interactions

40
Q

in smooth muscle, calcium binds to ___ to cause actin-myosin interactions

A

calmodulin

calmodulin triggers myosin light chain kinase

phosphylated Regulatory myosin light chain causes

myosin heavy chain to change shape

this allows actin-myosin interactions

41
Q

when regulatory myosin light chain is phosphorylated, the smooth muscle is ___

A

contracted

42
Q

when regulatory myosin light chain is not phosphorylated, smooth muscle is ___

A

relaxed

43
Q

what enzyme relaxes smooth muscle

A

myosin light chain phosphatase

44
Q

what % of myosin is working at maximum?

A

50%

never fully relaxes- 5% still working

45
Q

Calcium, through Calmodulin only affects MyLC ___ activity. It does not affect MyLC ___.

A

kinase (only forward to contraction)

phosphatase (relaxation)

46
Q

increased myosin light chain kinase leads to what in smooth muscle

A

more contracting from the regulated myosin light chain.

balance between kinase and phosphatase= amount of force generated by the smooth muscle

47
Q

why does smooth muscle not have an all or none response

A

some always have to work or else they would just pull on the relaxed one and nothing would move

example: heart and vessels, if they all relaxed- blood would pool and not move

48
Q

tonic form of myosin heavy chain encodes for a ___

A

slower, more energy efficient contraction (aorta)

49
Q

phasic form of myosin in smooth muscle produces a ___

A

faster contracting muscle (bladder)

50
Q

phasic smooth muscle is much __ than slow skeletal muscle

A

slower

phasic is fast contracting smooth muscle but even so it is much slower than skeletal muscle

51
Q

the aorta has what isoform of myosin heavy chain

A

tonic

slower, more energy efficient

52
Q

the bladder has what isoform of smooth muscle myosin heavy chain?

A

phasic

faster contracting

53
Q

Enzymatic inhibition of ___ results in a shift towards muscle contraction, with no change in calcium

A

MyLC phosphatase

(stop the relaxation of a smooth muscle)

54
Q

explain latch mechanism for smooth muscle

A

Actin-myosin complexes remains attached and force generating despite the loss of ATP from the myosin pocket

55
Q

explain calcium sensitization of smooth muscle

A

keep a smooth muscle contracted without using calcium but stopping/inhibiting the backwards reaction by myosin light chain phosphatase

56
Q

true or false. a drug will affect all smooth muscle the same way.

A

false

can have different reactions/side effects in different tissues or different areas of the body.

57
Q

Feline asthma is a type I hypersensitivity reaction to an inhaled allergen, that causes the the immune system to release histamine which causes constriction of ___

A

smooth muscle: bronchus/airways

can breathe in but oxygen can’t transfer

58
Q

treatment of asthma

A

glucocorticoids (suppress immune system)- primary problem

bronchodilators (relax smooth muscle of airways)- secondary response

59
Q

in a long term obstruction of the urinary bladder what can happen?

A

atonic(flaccid bag) bladder due to massive distension of bladder wall.

damage is actually to the nerves, which do not stretch as well as the smooth muscle of the bladder wall

60
Q

treatment for urinary tract obstruction

A

bethanechol- muscarinic agonist with selective activity in the detrusor muscle

help bladder contract

muscarinic- type of acetylcholine receptor for smooth muscle- second messanger- g protein linked

does not effect skeletal muscle

61
Q

dystocia

A

abnormal delivery of pups

long delivery-

uterus uses up all the extracellular calcium→ decrease in calcium influx into the muscle cell

↓ Calcium calmodulin complex→ ↓ MLC kinase activation → ↓ Myosin activation and force

treatment: give calcium slowly

similar to milk fever

62
Q

milk fever is similar to ___ in dogs

A

dystocia

63
Q

Early in heart failure, increasing vascular resistance is a good thing, maintaining tissue perfusion. Eventually the resistance exceeds the hearts ability to adequately push blood out of the ___. Death ensues rapidly

A

ventricles

64
Q

treatment for canine heart failure

A

nitroprusside → decrease blood pressure, heart doesn’t have to work as hard

paracrine transmitter to smooth muscle- cNOS is an enzyme that causes vasodilation through a second messenger signaling pathway that lowers intracellular calcium

65
Q

what kind of muscle lack all-or-none response?

A

smooth

allows either pharmacological increase or decrease in smooth muscle activation

66
Q

The ability to generate force over tremendous changes in fiber ___ are critical to smooth muscle function

A

length

67
Q

Tissue ___ activation or relaxation is critical to therapeutic success

A

specific

have to know what drug will do to different types of smooth muscle throughout the body, can have bad side effects.

22 spring: Physiology (34 decks)

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