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VBMS 324 > lecture 4- muscle physiology > Flashcards

lecture 4- muscle physiology Flashcards

1
Q

3 muscle types

A

skeletal, cardiac, smooth

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2
Q

T or F: muscles make up 42-50% of body weight

A

T

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3
Q

T or F: smooth muscle is the only non-striated kind

A

true

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4
Q

T or F: most muscle is skeletal

A

T

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5
Q

organization of muscle fibre

A

muscle -> muscle fiber -> myofibril -> thick/thin filaments

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6
Q

T or F: thick filament is myosin & thin filament is actin

A

T

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7
Q

A band

A

always the same

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8
Q

H zone

A

distance between ends of 2 filaments

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9
Q

M line

A

support thick filaments, middle of A band

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10
Q

I band

A

portion of thin filaments that don’t overlap with thick filaments

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11
Q

Z line

A

connects thin filaments together

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12
Q

sarcomeres

A

function unit measured from z to z lines & can expand in size

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13
Q

muscle

A

parallel bundles of fibres held together by connective tissue

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14
Q

cross bridges

A

extension of thick filaments towards thin filaments

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15
Q

T or F: resting state of cross bridge is when filaments are not in contact

A

T

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16
Q

T or F: 1 thick filament is surrounded by 6 thin and 1 thin is surrounded by 3 thick filaments in a cross bridge

A

T

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17
Q

what is myosin made of

A

2 identical subunits wth heads that face away from each other

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18
Q

what is the thin filament regulated by

A

tropomyosin & troponin

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19
Q

T or F: titin anchors myosin in place

A

T

20
Q

tropomyosin function

A

blocks actin cross bridge sites & prevents interactions required for muscle contraction

21
Q

troponin function

A

exposes myosin binding sites

22
Q

T or F: Ca regulates actions between thick & thin filaments

A

T

23
Q

what happens muscle is relaxed

A

troponin stabilizes interactions with action

24
Q

what happens when muscle is excited

A

muscle fibers release calcium

25
Q

T or F: Ca binding to troponon allows corss bridge interactions with actin & myosin

A

T

26
Q

power stroke mechanism

A

myosin bends to pull thin filaments in, detaches & then rebinds later on fibre to pull it more

27
Q

cross bridge cycling

A

repeated motions that drive thin filaments in towards each other

28
Q

sliding filament mechanism

A

muscle fibers contract when myosin pulls actin closer & causes sacromeres to shorten

29
Q

T or F: muscle contraction causes a change in filament length

A

F, only changes position

30
Q

T or F: power stroke is asynchronous

A

T - b/c it its synchronous then thin filament will be released back to relax position & it cannot grab it fast enough again - no movement would occur

31
Q

T tubules function

A

wrap around myofibrils so an action potential can be rapidly transferred from surface into muscle centre

32
Q

T or F: T tubules run perpendicular to fibre

A

T

33
Q

How does the SR store Ca

A

uses Ca-ATPase pump

34
Q

What do foot proteins act as

A

act as Ca release channels

35
Q

ryandione receptors

A

locks foot proteins + proteins open

36
Q

how do foot receptors & foot proteins interact?

A

like a zipper - 1 receptor takes in 2 proteins

37
Q

what will the opening of 1st voltage gated sensor do

A

activate 1/2 of Ca channels

38
Q

what does ATP power?

A

cross bridge cycles

39
Q

T or F: ATP hydrolysis only during excitation period

A

T

40
Q

what happens if ATP is depleted?

A

muscles get locked in contraction position = rigor

41
Q

what must be removed to allow relaxation?

A

Ca - this is b/c it is used during excitation

42
Q

increase in SR volume = ( ) in contraction speed = ( ) in force

A

increase, decrease

43
Q

twitch - longer or shorter than AP?

A

longer than AP but too weak to be useful

44
Q

how is a twitch initiated

A

1 power stroke = chemical input = twitch

45
Q

how to make a twitch stronger

A

more signalling input = more action potentials = extended contraction time

VBMS 324 (15 decks)

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