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CPR Exam 1 > smooth muscle > Flashcards

smooth muscle Flashcards

1
Q

Compare and contrast Skeletal muscle and smooth muscle: histology, and sarcoplasmic reticulum

A

skeletal muscle: Large, multinucleate striated cells
-large well developed SR with triads, well developed T tubules

smooth muscle: small, single nucleus, no striations
-poorly developed SR, T tubles have membrane with caveoli

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2
Q

Compare and contrast Skeletal muscle and smooth muscle: Thin filaments, thin filament number,

A

Skeletal muscle: actin, tropomyosin, toponin
lower number of thin filaments

smooth muscle: actin and tropomyosin
more number of thin filaments

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3
Q

Compare and contrast Skeletal muscle and smooth muscle: Thick filament, composition, number

A

Skeletal muscle: myosin, ATPase activity is faster
-greater number of thick filaments

smooth muscle: Myosin, ATPase activity is slow, myosin light chain prominence
-lesser number thick filaments

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4
Q

Compare and contrast Skeletal muscle and smooth muscle: Innervation, neurotransmitters, and neurotransmitter receptors

A

skeletal muscle: alpha motor neurons

  • Acetylcholine-excitatory
  • nicotinic cholinergic

smooth muscle: multiple including intrinsic and autonomic nervous system

  • acetylcholine, epinephrine, norepinephrine (excitatory/inhibitory)
  • muscarinic cholinergic, adrenergic, and others
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5
Q

Compare and contrast Skeletal muscle and smooth muscle: Transmission specialization, other forms of activation

A

skeletal muscle: Neuromuscular junction
-zero

smooth muscle: No NMJ- varicosities (pre-synaptic swelling) no endplate specialization
-blood-borne, paracrine, intrinsic

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6
Q

Compare and contrast Skeletal muscle and smooth muscle: Action potential, source of calcium, and role of calcium

A

skeletal muscle: Required

  • release from SR
  • Binds to troponin C

Smooth muscle: No-pacemaker activity, hormonal

  • Release from SR and ECF influx
  • binds calmodulin, activates MLCK
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7
Q

Compare and contrast Skeletal muscle and smooth muscle: Mechanism to allow actin and myosin binding, Relaxation

A

Skeletal muscle: Tropomyosin moved by troponin
-REmoval of Ca+ from troponin

Smooth muscle: Phosphorylation of myosin light chain
-Activation of light chain phosphatase, dephosphorylation

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8
Q

what are the two major types of Smooth muscle and how can they be arranged

A

Multi unit smooth muscle
Unitary smooth muscle

arrangements:

  • Circumferential
  • Circumferential and longitudinal
  • Varied
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9
Q

Characteristics of Multi-unit smooth muscle

A
  • Fibers operate individually
  • Innervated by single nerve
  • allows for more fine control
  • examples: ciliary muscle of eye, iris, piloerector muscles
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10
Q

characteristics of Unitary smooth muscle

A
  • Visceral smooth muscle or syncytial
  • works together as a unit
  • cell membranes adhere and contain gap junctions
  • Examples: GI tract, bile ducts, uterus
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11
Q

what component on the smooth muscle allows for the muscle to pull together

A

since their are no true sarcomere structures

smooth muscle has actin attach to dense bodies/adherens junctions

these serve as anchors for the muscle that come together during contraction

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12
Q

what is the difference in smooth muscle for, cycling, force, and ATP demand compaired to skeletal muscle

A

in smooth muscle the cycling of myosin cross bridges is slower than skeletal muscle

but, the time myosin and actin are attached is greater making a greater force

and the the ATP demand for contraction is lower

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13
Q

Mechanism of COntraction of SMooth muscle

A

Ca+ enters cell via

  • Sarcolemmal: L type voltage gated Ca+ or receptor activated Ca+ channels
  • via the SR from Ryanodine receptors
  • IP3 receptors

calcium binds reversibly CaM (calmodulin)

calmodulin-calcium complex activates the myosin light chain kinase
-contraction strength proportionate to Ca+ levels

the myosin light chain kinase (activated) will phosphorylate the myosin light chains so that now it can bind to actin to cause contraction

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14
Q

How does the relaxation process occur for smooth muscle

A

calcium pumps remove calcium from the cell

myosin light chain phosphatase removes the phospate from the myosin light chain which will stop binding to actin

need both to occur to stop contraction

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15
Q

what are the 4 stimulations of smooth muscle

A

nerves
hormones
stretch
environmental Ques

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16
Q 
effects on smooth muscle:
Norepinephrine/epinephrine?
Acetylcholine?
Angiotensin II, vasopressin, endothelin?
Adenosine?
Nitric oxide?
Antidiuretic hormone?
A

Norepinephrine/epinephrine: excitatory or inhibitory depending on organ

Acetylcholine: excitatory or inhibitory depending on organ

  • contraction is direct effect
  • relaxation can be indirect effect

Angiotensin II, vasopressin, endothelin: contraction

Adenosine: relaxation

Nitric oxide: inhibitory = relaxation

antidiuretic hormone: vasoconstrict

17
Q

other neurotransmitters and hormones that control smooth muscle and how?

A

Cholecystokinin (CCK)
Oxytocin
Serotonin
Histamine

actions through own receptors influence Ca+ channels

(all major role in GI tract not much in cardio)

18
Q

How does increased metabolic activity affect smooth muscle, and what are some of those ques

A 
Hypoxia
Excess CO2
Increased H+
increased K+
Prostoglandins

lead to increase in Vaso dilation

19
Q

how does an increase in sympathetic tone affect the smooth muscle

A

cause Vasoconstriction

20
Q

how does Atrial natriuetic peptide affect smooth muscle

A

ANP released by atrium

tells body to vasodilate

21
Q

how does the latch mechanism work

A

binding of slow fatigue myosin ATPase that can contract without burning though large amounts of AtP

After the initial depolarization with Ca+ to get the contraction started, the muscle can go to a tonic contraction by not releasing all the calcium to still hold the force for longer periods of time

attached cross bridges are still generating tension at 20/30 percent even after dephosphorylation of the light chain, thanks to the ca+

22
Q

what is the resting membrane potential of smooth muscle

A

-50 to - 60 mv

23
Q

what are the two forms of action potentials for smooth muscle activity

A

plateaus (hold force for long periods of time at specific increases of mv or by different agents increasing Ca+ concentrations)

Spike potentials (typical over threshold to increase contraction strength,)

24
Q

how are spike potentials stimulated

A

stimulated by hormones
neurotransmitters
stretch
spontaneous

25
Q

how are slow waves controlled

A

oscillating Ca+ influx (L-type VGCC) and
K+ efflux (Ca+ activated K+ channels)
-has pacemaker capabillities

26
Q

How are plateaus controlled

A

stimulated by neurotransmitters, stretch

27
Q

significance of the length tension relationship of smooth muscle

A

as smooth muscle stretches has the abillity to manipulate its self to still get optimum tension even when the muscle is fully stretched

this is because it can move its dense bodies around to take in account the stretch of lets say our stomach after a big meal and still be able to function and not tear

CPR Exam 1 (26 decks)

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