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ANSC 310 > Week 4 midterm 2 > Flashcards

Week 4 midterm 2 Flashcards

1
Q

What causes muscle contractions?

A

Myosin and actin

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2
Q

What is the main structure for contraction?

A

sarcomeres (fundamental unit of myofibrils)

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3
Q

What are fascia?

A

connective tissue that covers muscle

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4
Q

Where is the epimysium located?

A

it surrounds groups of fascicles

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5
Q

Where is the perimysium located?

A

Surrounds individual fascicles

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6
Q

What are fascicles?

A

they hold muscle fibers (discrete bundle of muscle cells)

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7
Q

Where is endomysium?

A

It separates individual muscle fibers

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8
Q

What is the sarcolemma?

A

the plasma membrane of a muscle fiber

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9
Q

What are muscle fascicles?

A

bundles of muscle tissue held together by connective tissue

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10
Q

What are muscle fibers composed of? (x4)

A

myofibrils (muscle fibre contractile strucutres), sarcoplasmic reticulum (aka smooth ER, stores and sequesters calcium), t tubules and mitochondria (E)

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11
Q

What are t tubules?

A

tubular infoldings of the sarcolemma which penetrate through muscle cells and emerge on the other side
-associate with the ends of the sarcoplasmic reticulum

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12
Q

What composes the triad?

A

2 lateral sacs and the t tubule

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13
Q

What gives skeletal and cardiac muscles striations and what are striations composed of?

A

myofibrils – due to thick and thin filaments which run parallel to the long axis

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14
Q

What creates thick and thin filaments?

A

thick: myosin
thin: actin
- both contractile proteins

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15
Q

What are tropomyosin and troponin and what do they do?

A

regulatory proteins that regulate muscle cells

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16
Q

What are titin and nebulin and what do they do

A

they are accessory proteins and they anchor myosin and actin into the sarcomere

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17
Q

What are transverse tubules?

A

a system of tubules that provides channels for ion flow throughout the muscle fibers to facilitate the propagation of an action potential.

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18
Q

What is the H zone and what is it composed of?

A

H = helles = the clear band (within the A band) – made up of myosin, gets shorts during muscle contraction

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19
Q

What is the A band?

A

A = anisotropic = darkest coloured band (length stays the same) – contains myosin

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20
Q

What is the I band?

A

I = isotropic = lightest coloured band (length decreases) – contains actin

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21
Q

What is actin and what is the binding site for?

A

a contractile protein with a binding site for myosin

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22
Q

What regulates skeletal muscle contraction?

A

calcium binding to troponin

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23
Q

What is the Z line?

A

the line formed by the attachment of actin filaments between two sarcomeres of a muscle fiber in striated muscle cells (links thin filaments)

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24
Q

What is the M line?

A

supporting proteins that hold the thick filaments together in the H zone. myosin tail is toward this (links thick filaments)

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25
Q

What is the hinge region?

A

it enables the myosin head to move (thick filament where the length decreases)

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26
Q

What is g actin (globular)?

A

a globular subunit of F actin with an active site for binding a myosin head

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27
Q

What is f actin (filament)?

A

linear polymer of G actin units (G actin is single globular unit)

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28
Q

What is TnT?

A

a component of troponin that binds and attaches to tropomyosin

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29
Q

What is TnI?

A

a component of troponin that attaches to actin and inhibits binding with myosin

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30
Q

What is TnC?

A

a component of troponin that binds to calcium ions (reversibly)

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31
Q

What are cross bridges

A

aka myosin heads, they bridge the gap between thin and thick filaments

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32
Q

What is titin?

A

a long and elastic accessory protein that anchors thick filaments between the M and Z line, also provides structural support and elasticity

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33
Q

What is nebulin?

A

a protein that lies along the thin filament that attaches to a Z line but not the M line – regulates thin filament length during sarcomere assembly

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34
Q

What is the sliding filament theory?

A

a theory that actin filaments slide toward each other during muscle contraction, while the myosin filaments are still; neither thick/thin filaments shorten, filaments slide past each other

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35
Q

What is the cross bridge cycle?

A

a cyclical formation and breaking of cool bridges (how muscles generate force)

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36
Q

What is excitation contraction coupling?

A

how muscle contractions are turned on and off – a sequence of events when an AP in the sarcolemma causes contraction (requires calcium release)

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37
Q

What are sarcomeres?

A

a functional unit of muscle, spans from Z line to Z line and shortens during contraction (composed of actin and myosin)

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38
Q

What shortens during contraction?

A

I band, H zone and sarcomeres

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39
Q

What is rigor mortis and what causes it?

A

stiffness of the body that sets in several hours after death; occurs due to myosin heads being frozen in their 90 degree position

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40
Q

What happens in high energy form for myosin heads?

A

its at 90 degrees, ADP and Pi are bound to myosin and it has a high affinity for actin

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41
Q

What happens in low energy form for myosin heads?

A

its at 45 degrees, ADP is bound to myosin and it has a low affinity for actin

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42
Q

What is a power stroke for myosin heads?

A

movement of the myosin head that pushes the thin filament toward the center of the muscle, after which thick + thin filaments detach and the myosin head returns to its initial potential

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43
Q

What role does calcium play in contraction?

A

it binds to troponin, causing movement of troponin, causing movement of tropomyosin, exposing binding sites for myosin on actin

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44
Q

What opens calcium channels and where?

A

DHP receptors of t tubules in lateral sacs of sarcolemma

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45
Q

What is the heart?

A

a hollow muscular organ that pumps blood throughout the body

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46
Q

What does the cardiovascular system transport (x3)?

A
  1. O2 from nutrients to cells
  2. removes waste from tissues to liver and kidney (Co2 and urea)
  3. hormones, immune cells and clotting proteins to their specific target cells
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47
Q

What are blood vessels?

A

tubelike structures that carry blood throughout the body

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48
Q

What is blood?

A

a connective tissue with a fluid matrix called plasma where red and white blood cells, and platelets (cell fragments) are suspended

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49
Q

What are the 2 valves?

A

atrioventricular and semilunar

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50
Q

How many chambers does the heart have?

A

4

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51
Q

What is the inter ventricular septum?

A

it separates ventricles

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52
Q

Which way does the electrical signal flow through the heart?

A

from the apex to the base

53
Q

What is the strucuture of the cardiovascular system called?

A

vasculature

54
Q

What is the order blood flows in the heart?

A

heart, arteries, arterioles, capillaries, venules then veins

55
Q

What are arteries?

A

large, branching vessels that conduct blood away from the heart

56
Q

What are arterioles?

A

small branching vessels that conduct blood away from the heart?

57
Q

What are capillaries?

A

sites of exchange between blood and tissue

58
Q

What are venules?

A

small converging vessels

59
Q

What are veins?

A

large converging vessels that conduct blood to the heart

60
Q

What kinda system is the cardiovascular system?

A

a closed system

61
Q

What are erythrocytes?

A

red blood cells that transport oxygen and CO2`

62
Q

What are leukocytes?

A

white blood cells that defend the body against pathogens

63
Q

What are platelets?

A

cell fragments that are important in blood clotting

64
Q

What is plasma?

A

the fluid part of blood (water) + solutes (ex. carbs, minerals, lipids, vitamins, etc.)

65
Q

What are the 2 ways the blood circulates?

A
  1. series flow through the cardiovascular system

2. parallel flow within the systemic or pulmonary circuit

66
Q

What is the pulmonary circuit?

A
  • supplied by the right heart

- blood vessels from the heart to the lungs and lungs to the heart

67
Q

What is the systemic circuit?

A
  • supplied by the left heart

- blood vessels from the heart to systemic tissues and tissues to the heart

68
Q

What colour is oxygenated and deoxygenated blood?

A

oxy: red
deoxy: blue

69
Q

How does blood becomes oxygenated?

A

When it passes through the lungs, oxygen diffuses through the tissues into the blood

70
Q

Why is parallel blood flow great?

A

it allows for independent regulation of blood flow to organs

71
Q

Where does the right atrium receive blood from (x2)?

A

venae cavae and coronary sinus

72
Q

What is the right atrioventricular valve?

A

aka the tricuspid valve, blood leaving the R atrium flows into the L ventricle through it

73
Q

What does the right ventricle do?

A

pumps deoxygenated blood to the lungs

74
Q

What does the left atrium do?

A

receives oxygenated blood from the lungs

75
Q

What does the left atrioventricular valve do?

A

(mitral or bicuspid valve) Blood leaving the left atrium flows into the left ventricle through this valve; most commonly replaced due to more pressure on left side of the heart

76
Q

What does the left ventricle do?

A

pumps oxygenated blood to the body

77
Q

What does the aorta do?

A

the large arterial trunk that carries blood from the heart to be distributed by branch arteries through the body

78
Q

What is the pulmonary semilunar valve?

A

the heart valve opening from the right ventricle to the pulmonary artery

79
Q

What is the aortic semilunar valve?

A

the valve located between the left ventricle and the aorta

80
Q

Where is the heart located?

A

in the thoracic cavity

81
Q

What is the phragmdia?

A

it separates the abdominal cavity from the thoracic cavity

82
Q

What is the pericardium?

A

a membranous sac that surrounds the heart and lubricates it to decrease friction

83
Q

What is pericarditis?

A

inflammation of the pericardium in cows that swallow nails

84
Q

What are the 3 layers of the heart wall?

A
  1. endocardium (inner)
  2. myocardium (middle)
  3. epicardium (outer)
85
Q

What is the endocardium?

A

inner layer of the heart wall, composed of endothelial cells

86
Q

What is the myocardium?

A

the middle layer of the heart wall, composed of cardiac muscle

87
Q

What is the epicardium?

A

the outer layer of the heart wall, external membrane

88
Q

Which ventricle is thicker and why?

A

the left as it pumps bloods to the longer systemic circuit

89
Q

What are intercalated disks?

A

structures that connect cardiac muscle cells to each other

90
Q

What do gap junctions do?

A

they cause the heart to contract as a unit

91
Q

What are desmosomes?

A

tough connective tissue that resist stress in the heart muscles

92
Q

What does the fibrous skeleton do? (x2)

A

separates atria and ventricles and anchors the heart valves

93
Q

What does an aerobic muscle mean?

A

that it uses oxygen to generate ATP

94
Q

What type of growth occurs after infancy?

A

hypertrophy (increase in cell size, not number)

95
Q

What are the majority of cardiac muscles? And what is the other tiny bit?

A

majority: contractile

minority (1%): autorhythmic cells (self generate APs)

96
Q

What cells set the rate of heart beat?

A

autorhythmic cells

97
Q

What generates heart pumping action?

A

rhythmic contraction and relaxation

98
Q

What pushes blood out of the heart and into the vasculature?

A

contractions

99
Q

When does the heart fill with blood?

A

during relaxation

100
Q

What is a heartbeat?

A

a wave of contraction through cardiac muscled

101
Q

What is the flow of blood and what drives it?

A

atria to ventricles to arteries, driven by pressure difference

102
Q

What opens valves?

A

they open passively due to the pressure gradient (no going backwards only forwards)

103
Q

What do the papillary muscles and chordae tendinae do together?

A

they keep the AV valves from turning outwards

104
Q

What are the semilunar valves?

A

aortic and pulmonary

105
Q

What is autorhythmicity?

A

the hearts ability to generate its own rhythm

106
Q

What are autorhythmic cells? and what are the 2 types?

A

set the rate of the heartbeat – pacemaker cells and conduction fibers

107
Q

What are pacemaker cells?

A

spontaneously depolarizing membrane potentials to generate APs – coordinate and provide rhythm to the heartbeat (fastest cells) – never rest so their potential is called “pacemaker potential” rather than resting potential

108
Q

What are conduction fibers

A

they rapidly conduct APs initiated by pacemaker cells to the myocardium (faster than regular muscle fibers)

109
Q

What is the sinoatrial node?

A

the pacemaker of the the heart

110
Q

What is the atrioventricular node?

A

a specialized mass of conducting cells located at the atrioventricular junction in the heart

111
Q

What are internodal pathways?

A

specialized conductile cells within the atria that transmit the impulse from the SA node throughout the myocardial cells of the atrium and to the AV node

112
Q

What is the bundle of His?

A

a conduction fiber of the myocardium, modified heart muscle that transmits the cardiac impulse from the atrioventricular node to the ventricles causing them to contract

113
Q

What are bundle branches?

A

branches of the AV bundle that divide to the right and left sides of the interventricular septum

114
Q

What are purkinje fibers?

A

fibers in the ventricles that transmit impulses to the right and left ventricles, causing them to contract

115
Q

What links cardiac cells and why?

A

gap junctions, used for electrical coupling

116
Q

What are intercalated disks?

A

junctions between adjacent myocardial cells (for electrical coupling)

117
Q

What are the steps of the interatrial pathway?

A

from sinoatrial node - to right atrium - to left atrium (rapidly) causing simultaneous contraction of the right and left atria

118
Q

What is the internodal pathway?

A

the spread of excitation from sinoatrial node to the atrioventricular node

119
Q

What is the AV node transmission pathway?

A

the only pathway from atria to ventricles, slow conduction where atria contract before ventricles do

120
Q

What is ventricular excitation?

A

the spread of excitation down the bundle of His, right and left bundle branches and up the purkinje fibers

121
Q

What causes spontatnous depolarization/

A

closing of K channels and opening of If (funny) and Ca (t-type) channels (sodium is greater than potassium)

122
Q

What are L type channels

A

fast calcium channels that generate an action potential in pacemaker cells by depolarizing it to the threshold

123
Q

What is the resting membrane potential of a contractile (myocardial cell)

A

-90mv

124
Q

What do cardiac cells and skeletal muscle have in common?

A

sarcoplasmic reticulum calcium, T tubules, troponin-tropomyosin regulation

125
Q

What do cardiac cells and smooth muscle have in common?

A

extracelular calcium and gap junctions

126
Q

How does cardiac muscle relaxation occur?

A

through the removal of calcium from the cytosol

127
Q

What is calcium ATPase?

A

pumps for the removal of calcium in the sarcoplasmic reticulum and plasma membrane

128
Q

What is the sodium-calcium exchanger?

A

pumps that remove calcium from the cytosol that are present in the plasma membrane

129
Q

What do troponin and tropomyosin cover?

A

myosin binding sites

ANSC 310 (6 decks)

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