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Molecular and Cellular Physiology > MCP 30: Muscles II > Flashcards

MCP 30: Muscles II Flashcards

1
Q

length-tension relationship (for sarcomere)

A

maximal force of contraction for sarcomere determined by degree of overlap between actin and myosin, when at optimal overlap, sarcomere at resting potential

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2
Q

isometric contraction

A

length stays the same, but tension changes, i.e. pushing against a wall

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3
Q

isotonic contraction

A

muscle tone stays the same but length changes; i.e. lifting free weights

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4
Q

combination of isometric and isotonic contractions

A

usually isometric contraction followed by isotonic contraction; isometric to counteract load of weight then isotonic to move it forward

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5
Q

force-velocity relationship (muscle)

A

as force increases, the velocity of shortening decreases, for isotonic contractions

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6
Q

ways to increase contraction speed

A

1.) faster ATPase 2) changing the force on the muscle (force-velocity relationship)

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7
Q

ways to increase muscle tension

A

1.) optimizing length tension relationship 2.) hypertrophy 3.) increasing number of stimuli 4.) increasing the # and type of motors units involved

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8
Q

length tension relationship (muscle)

A

total tension is the sum of the active and passive elements

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9
Q

active tension

A

due to myosin/actin crossbridges

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10
Q

passive tension

A

due to the elasticity of muscle components

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11
Q

parallel elastic element

A

passive tension

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12
Q

hypertrophy

A

increasing the size of muscle fibers by increase the number of sarcomere

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13
Q

hyperplasia

A

increasing the number of muscle fibers

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14
Q

tetany

A

mutiple action potentials at a high frequency allow for plentiful Ca2+ release and not enough time for the SR to uptake the calcium; leaders to maximal muscle force

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15
Q

series elastic element

A

accounts for delay between calcium release and contraction, think of fishing line that needs to be taut before able to reel it in, twitches can’t cause maximal tension because of series elastic element

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16
Q

motor unit

A

group of muscle fibers that are all innervated by the same alpha neuron and therefore will twitch all at the same time by an AP; increasing number of fibers innervated in a motor unit will increase strength

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17
Q

type I motor unit (muscle cell)

A

Properties of muscle cell: small number of innervated fibers, moderate fiber diameter, low force, oxidative metabolism, moderate conduction velocity and low fatiguabiity, high myoglobin and lots of mitochondria, low ATPase activity, used for endurance activities, burn fat

18
Q

type II motor unit (muscle fiber)

A

Properties of muscle cell: many innervated fibers, large fiber diameter, large output force, fast ATPase activity, low excitability, anaerobic exercise, use glycolytic metabolism leading lactic acid behind, high glycogen content, low number of mitochondria, increased fatigue

19
Q

red fibers

A

part of type I motor units

20
Q

white fibers

A

part of type II motor units

21
Q

innervation ratios

A

ratio of muscle fibers to an innervating neuron; low ratios are used for fine muscle tasks and high ratios used for tasks that require immense strength

22
Q

mutiunit smooth muscle

A

require fine motor movement, cells electrically isolated from each other, each cell separately innervated, neurogenic

23
Q

unitary smooth muscle

A

less precision, more muscle fibers innervated per motor neuron, cell connect via gap junctions, forms syncitium, contains pacemaker smooth muscle cell where innervation is, myogenic, also called visceral muscle

24
Q

single spike

A

AP caused by electrical stimulation, hormone/neurotransmitter action or muscle stretch

25
Q

plateau shaped AP

A

typical pattern of AP but repolarization delayed

26
Q

slow wave APs

A

extremely slower than other APs, Ca2+ channels close very slowly

27
Q

smooth muscle

A

composes internal contractile organs except heart, used to expel contents, change cross sectional area of organ, change dimensions, movement (piloerection), smooth muscle cells are small and unstriated, innervated by autonomic nervous system

28
Q

syncytium

A

group of cells in unitary smooth muscle

29
Q

dense bodies

A

point of attachment for actin in smooth muscle

30
Q

neurogenic

A

requires a nerve impulse for contraction; has characteristics that resemble skeletal muscle and each fiber completely insulated from each other

31
Q

myogenic

A

innervation isn’t required for the initiation of a contraction on visceral smooth muscle, the innervation serves to modulate the intrinsic pacemaker ability

32
Q

caveloi

A

indentations on the smooth muscle cell membrane which contain voltage-gated Ca2+ channels

33
Q

voltage gated Ca2+ channels

A

on caveoli, open in response to AP and allow calcium from extracellular space into muscle cell

34
Q

calcium induced cacium release channels

A

Ca2+ or secondary messager binds to calcium induced calcium release channels on SR and allow Ca2+ to flow in cytosol

35
Q

store-operate channels

A

allow influx of calcium from extracellular space into cystol

36
Q

IP3 gated Ca2+ release

A

G protein system that causes release of Ca2+ from channels on SR

37
Q

contractions in smooth muscle

A
  1. ) intracellular Ca2+ concentration rises, and Ca2+ binds to calmodulin (CAM)
  2. ) Ca-CAM complex binds to myosin light chain kinase (MLCK)
  3. ) MLCK phosphorylates myosin
  4. ) phosphorylated myosin forms cross-bridges with actin, contraction occurs
  5. ) Myosin light chain phosphatase (MLCP) dephosphorylates myosin, stops the cross bridge cycle
38
Q

latch mode

A

the smooth muscle can remain contracted without using ATP which is great when you really have to pee otherwise you’d be burning through calories to keep from peeing on yourself.

39
Q

type 1 motor unit (nerve cell)

A

Properties of nerve: small cell diameter, fast conduction velocity, high excitability

40
Q

type II motor unit (nerve cell)

A

Properties of nerve: large cell diamter, very fast conduction velocity, low excitability,

41
Q

type 1 motor unit (nerve cell)

A

Properties of nerve: small cell diameter, fast conduction velocity, high excitability

42
Q

type II motor unit (nerve cell)

A

Properties of nerve: large cell diamter, very fast conduction velocity, low excitability,

Molecular and Cellular Physiology (14 decks)

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