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biological sciences year 1 > muscles > Flashcards

muscles Flashcards

1
Q

What is the location of smooth muscle?

A

internal organs, walls of blood vessels, around hollow organs, around tracts

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2
Q

What is the function of smooth muscle?

A

move food, urine and reproductive tract secretion, regulate diameter of blood vessels

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3
Q

What are the shape of smooth muscle cells?

A

spindle-shaped

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4
Q

What is the length and width of smooth muscle cells?

A

100-300 micrometers, 2.5 micrometres

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5
Q

Is smooth muscle striated or non-striated?

A

non-striated

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6
Q

What do varicosities do?

A

increase surface area of smooth muscle, close to effector cells so can communicate more easily

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7
Q

What do hormones/neurotransmitters do in smooth muscle excitation contraction coupling?

A

open voltage or ligand gated Ca2+ channels in the sarcolemma causing Ca2+ influx or bind to G-protein coupled receptors inducing IP3 generation

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8
Q

What does Ca2+ bind to in the sarcolemma (smooth muscle)?

A

calmodulin

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9
Q

What activates myosin light chain kinase (MLCK)?

A

Ca2+-calmodulin

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10
Q

What does MLCK do?

A

phosphorylates myosin light chains, enabling muscle contraction

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11
Q

What is single unit smooth muscle examples?

A

GIT, bladder

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12
Q

What is multi unit smooth muscle examples?

A

iris, airways, vasculature

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13
Q

What is phasic contraction?

A

relatively quick contraction with short durability

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14
Q

What is tonic contraction?

A

relatively slow contraction with long durability

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15
Q

Where do calcium ions come from in smooth muscle?

A

sarcoplasmic reticulum and extracellular fluid

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16
Q

How is the SR in smooth muscle compared to cardiac and skeletal?

A

less well organised and developed

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17
Q

What is the latch state?

A

an adaptation of smooth muscle which allows sustained muscle tone with low rate of cross-bridge cycling

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18
Q

What are differences between smooth muscle and cardiac and skeletal muscle?

A

smooth muscle contraction is thick filament regulated, contractions can be slow and sustained

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19
Q

What is the length and width of cardiac muscle?

A

10 and 100 um

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20
Q

What are mechanical junctions of cardiac muscle?

A

fascia adherens and desmosomes

21
Q

What are electrical junctions of cardiac muscle?

A

gap junctions

22
Q

What are the two types of action potentials in cardiac muscle?

A

slow response (pacemaker cells) and fast response (cardiac action potential)

23
Q

What cells undergo slow response?

A

SAN and AVN

24
Q

What cells undergo fast response?

A

atrial & ventricular myocytes and purkinje fibres

25
Q

What is stage 0-4 in fast response cells?

A

0 = Na+ entry, 1 = K+ efflux, 2 = Ca2+ entry, 3 = K+ efflux, 4 = RMP slightly more negative

26
Q

What is stage 0, 3 + 4 in slow response cells?

A

0 = slow inward current of Na+ and Ca2+, 3 = repolarisation due to K+ efflux and Ca2+ channels closing, 4 = RMP less negative - slow depolarisation

27
Q

What come first: action potential and contraction?

A

contraction force follows action potential

28
Q

What channels are in pacemaker cells?

A

funny channels: inward Na+ current

29
Q

What does the absolute refractory period allow?

A

heart to fully relax between beats

30
Q

What are I bands and A bands ad H zone?

A

I = light (thin filaments) A = dark (thin and thick filaments) H = thick filaments

31
Q

What are some important proteins in cardiac muscle?

A

scaffolding proteins (mermyosin, C protein, nebulin, alpha actin), titin (enables relaxation)

32
Q

What does Ca2+ bind to in cardiac muscle electrochemical coupling?

A

troponin which enables filament sliding

33
Q

What is not conformationally coupled in cardiac muscle?

A

DHPR and RyR

34
Q

What does ca2+ bind to which allows more Ca2+ release in cardiac muscle?

A

ryanodine receptor

35
Q

What shape channels does calcium come through in cardiac muscle?

A

L-shaped

36
Q

Does cardiac or skeletal muscle have a higher resistance to stretch?

A

cardiac

37
Q

What is the Frank-starling law?

A

stretching occurs at times of increased venous return, - Force of contraction is increased by stretch and enhanced by sympathetic stimulation

38
Q

What is positive chronotropy?

A

increase rate of contraction

39
Q

What is positive inotropy?

A

increase force of contraction

40
Q

What is positive lusitropy?

A

increased rate of relaxation

41
Q

What receptors are conformationally coupled in skeletal muscle?

A

DHPR and RyR

42
Q

What activates DHPR ?

A

propagation of action potential down into T-tubules

43
Q

What does calcium bind to in skeletal muscle in excitation coupling?

A

troponin which has a conformational change to tropomyosin

44
Q

What happens in the sliding filament theory?

A

1) binding to myosin to actin. Pi released. 2) power stroke - actin gets pulled towards middle of sarcomere. 3) rigor. ADP released 4) new ATP binds to myosin head 5) unbinding of myosin and actin 6) ATP is hydrolysed 7) cocking of myosin head

45
Q

What is Rigor Mortis caused by?

A

depletion of ATP

46
Q

What colour is fast twitch skeletal muscle?

A

white (lower myoglobin and capillary content)

47
Q

What colour is slow twitch skeletal muscle?

A

red (high myoglobin and capillary content

48
Q

At approximately what sarcomere length do skeletal muscle fibres usually function?

A

2 um

49
Q

What is tetanic fusion frequency?

A

frequency of action potentials that are needed to not see summation and produce a smooth graded contraction as seen in normal muscle contraction

biological sciences year 1 (16 decks)

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