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From Flashcardlet > Physiology Block 1 > Flashcards

Physiology Block 1 Flashcards

0
Q

What kind of transport system is the sodium-potassium pump an example of?

A

primary active transport

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1
Q

Which subunit of the sodium potassium pump acts as the ATPase?

A

alpha subunit

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2
Q

What are the three factors that regulate sodium-potassium pump activity?

A

intracellular ATP concentration
intracellular sodium concentration
extracellular potassium concentration

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3
Q

The sodium-potassium pump is the only ______ ________ ________ mechanism for Na+

A

primary active transport

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4
Q

The sodium-potassium pump is the primary mechanism for maintenance of ____ intracellular _____ concentration and ____ intracellular ____ concentration (relative to the outside of the cell).

A

low, Na+, high, K+

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5
Q

What are ouabain and digoxin?

A

cardiac glycosides

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6
Q

What can happen to the cell volume when the sodium-potassium pump is inhibited?

A

increase

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7
Q

Inhibition of the sodium-potassium can lead to membrane ___________.

A

depolarization

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8
Q

What is myasthenia gravis?

A

Autoimmune disease where antibodies attack and destroy acetylcholine receptors at the postsynaptic neuromuscular junction; causes muscle paralysis because patients are not able to trasmit enough signals from their nerve fibers to their muscle fibers

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9
Q

What are the steps for smooth muscle contraction?

A

1) calcium ions bind calmodulin
2) calcium-calmodulin complex activate myosin light chain kinase
3) myosin light chain kinase phosphorylated regulatory (light) chain of myosin head
4) myosin head can bind actin filament head repetitively and cause muscle contraction similar to skeletal

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10
Q

What is curare?

A

Curare is a muscle relaxant that blocks the gating action of acetylcholine on the acetylcholine channels by competing for the acetylcholine receptor sites. The end plate potential becomes very weak and depolarization does not reach threshold potential–>no AP–>muscle stays relaxed.

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11
Q

What is the antidote for curare?

A

Anti-cholinesterases; by blocking ACh degradation, the amount of ACh in the neuromuscular junction goes up, and the accumulated ACh will then correct for the effect of the curare by activating the receptors not blocked by toxin at a higher rate.

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12
Q

Skeletal muscle: What do the I bands contain?

A

only actin filaments

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13
Q

Skeletal muscle: What do A bands contain?

A

A band length = length of thick filament (myosin)

does not change in size during contraction

Guyton: A bands contain myosin and ends of actin filaments where they overlap the myosin

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14
Q

Skeletal muscle: What do H bands contain?

A

Only myosin (thick filament)

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15
Q

In skeletal muscle contraction, calcium binds _______ to initiate contraction.

A

troponin

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16
Q

In skeletal muscle, what causes contraction to cease?

A

Removal of Ca2+ from the cell via Ca2+ membrane pumps back into the SR

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17
Q

Skeletal muscle: What does I troponin bind?

A

actin

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18
Q

Skeletal muscle: What does T troponin bind?

A

Tropomyosin

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19
Q

Skeletal muscle: What does C troponin bind?

A

Ca2+

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20
Q

T-tubules in skeletal muscle system allow for uniform _____ release throughout the cell

A

Ca2+

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21
Q

What protein in the SR of skeletal muscle cells helps with the re-uptake of Ca2+?

A

calsequestrin

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22
Q

What is the ratio between nerve AP and motor AP in skeletal muscle cells?

A

1:1

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23
Q

Skeletal muscle: How does acetylcholine get released from the presynaptic nerve cell in the neuromuscular junction?

A

AP in the neuron causes Ca2+ channels to open, Ca2+ rushes in, binds to acetylcholine-containing vesicles, vesicles fuse with outer membrane and acetylcholine is released into the junction

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24
Q

Skeletal muscle: What effect does acetylcholine have on the postsynaptic muscle cell?

A

Acetylcholine binds to acetylcholine-gated cation channels and open them, causing Na+ to rush into the muscle cell to cause depolarization

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25
Q

How many acetylcholines need to bind to acetylcholine-gated cation channels to open them?

A

2

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26
Q

When does skeletal muscle contract with maximum force?

A

At resting (normal) length

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27
Q

Skeletal muscle: Fast vs slow twitch muscle

Which is red and which is white?

A

Fast is white and slow is red

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28
Q

Skeletal muscle: Fast vs slow twitch muscle

Which has more mitochondria?

A

Slow twitch muscle (red)

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29
Q

Skeletal muscle: Fast vs slow twitch muscle

Which has small fibers and which has large fibers?

A

Fast twitch has large fibers, slow twitch has small fibers

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30
Q

Skeletal muscle: Fast vs slow twitch muscle

Which is aerobic and which is anaerobic?

A

Slow twitch is aerobic and fast twitch is anaerobic

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31
Q

Skeletal muscle: Fast vs slow twitch muscle

Which has more blood supply?

A

Slow twitch

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32
Q

Skeletal muscle: Fast vs slow twitch muscle

Which has myoglobin?

A

Slow twitch

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33
Q

Smooth muscle: Single unit vs multi-unit

Which can be spontaneously activated?

A

single unit

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34
Q

Smooth muscle: Single unit vs multi-unit

Which is characterized as a functional syncytium?

A

single unit

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35
Q

Smooth muscle: Single unit vs multi-unit

Which are generally in visceral muscles (i.e., GI) and which are in vascular muscles (i.e., aorta)?

A

single unit is found in visceral muscles and multi-unit is found in vascular muscles

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36
Q

In smooth muscle, ________ provide sites for filament attachment.

A

dense bodies

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37
Q

Compared to skeletal muscle, smooth muscles lack _____ and _____.

A

troponin, sarcomeres

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38
Q

Smooth muscle vs. Skeletal muscle: Which has more actin?

A

Smooth muscle

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39
Q

Smooth muscle vs. Skeletal muscle: Which has greater contraction?

A

Smooth (80% vs. 30% of resting/normal length)

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40
Q

Smooth muscle vs. Skeletal muscle: Which has slower rate of contraction and why?

A

Smooth, because its myosin head has far less ATPase activity

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41
Q

Smooth muscle requires much _______ energy to sustain the same tension of contraction as skeletal muscle.

A

less

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42
Q

Smooth muscle: Explain the stress relaxation and reverse stress relaxation phenomena.

A

When smooth muscle is stretched or shortened, there is an initial increase or decrease in force, but then the myosin heads acommodate the stretch or shortening by interacting with new active sites on the actin, so the force returns close to normal.

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43
Q

How is smooth muscle contraction initiated?

A

1) Depolarization in the muscle cell causes voltage-gated Ca2+ channels to open
2) Ca2+ rushes into the cell
3) Ca2+ binds calmodulin
4) Ca2+ and calmodulin activate myosin light chain kinase
5) Myosin light chain kinase phosphorylates myosin regulatory light chain
6) Myosin head cleaves ATP into ADP and phosphate
7) Muscle contraction

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44
Q

How is smooth muscle contraction terminated?

A

When [Ca2+] goes down, myosin light chain phosphatase dephosphorylates the myosin regulatory light chain

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45
Q

Smooth muscle: Explain latch state

A

Cross-bridge cycling happens very slowly and long term force can be maintained with minimal energy expenditure

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46
Q

Unlike in skeletal muscle where depolarization is due to the opening of ____ channels, depolarization in smooth muscle is mainly due to the opening of ____ channels.

A

Na+, Ca2+

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47
Q

Smooth vs. Skeletal muscle:

Which has a less negative resting membrane potential and why?

A

smooth muscle, because the conductance/permeability of K+ is much lower in smooth muscle which means there is less current going across the membrane –> lower transmembrane potential

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48
Q

Smooth muscle: Single unit vs multi-unit

Which has action potentials?

A

single unit

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49
Q

Single unit smooth muscles have ___-dependent action potentials

A

Ca2+

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50
Q

What does an increase in K+ permeability do to a smooth muscle cell?

A

It causes relaxation, because K+ rushes out of the cell, causing hyperpolarization, and the voltage-gated calcium channels close

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51
Q

Although it is not common in in vivo situations, smooth muscle cells can increase contractile force without changing membrane potential. Explain.

A

The ratio between myosin light chain kinase and myosin light chain phosphorylase activity can alter the Ca2+ sensitivity of the contractile filaments.

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52
Q

Smooth muscle: outline the steps of generating a slow wave

A

1) Voltage gated Ca2+ channels open
2) Ca2+ rushes in –> depolarization
3) Ca2+ gated K+ channels open
4) K+ goes out of the cell –> slow hyperpolarization
5) Voltage gated Ca2+ channels close
6) Intracellular [Ca2+] goes down
7) Ca2+ gated K+ channels close

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53
Q

In order to open the aortic or pulmonary valves, you need to _______ the pressure in the ________.

A

exceed, vasculature

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54
Q

What happens if you have a leaky mitral valve?

A

Blood flows back into the atrium when ventricle contracts –> this can affect cardiac output

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55
Q

What is the first heart sound (S1, lub)?

A

Closing of mitral (left) and tricuspid (right) valves (aka A-V valves)

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56
Q

What is the first heart sound indicative of?

A

Beginning of systole, end of diastole

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57
Q

What does systole mean? What is blood doing during systole?

A

The contractile phase of the heart; blood is being pumped out

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58
Q

What does diastole mean? What is blood doing during diastole?

A

Relaxation phase of the heart; the heart is filling with blood

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59
Q

What is the second heart sound (S2, dub)? What also happens at this point?

A

Closing of aortic and pulmonary valves, opening of mitral and tricuspid valves

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60
Q

What is the second heart sound indicative of?

A

End of systole, beginning of diastole

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61
Q

Is diastole the filling or ejection stage of blood in the heart?

A

filling

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62
Q

Is systole the filling or ejection stage of blood in the heart?

A

Ejection

63
Q

In cardiac muscle, individual muscle cells are separated from each other by ______________; these are permeable communicating junctions called __________, this enables ________ spread of action potential from cell to cell.

A

intercalated disks, gap junctions, syncytial

64
Q

What is the A-V node/bundle?

A

It is a fibrous ring of conductive fibers that slows the conduction of action potentials from the atria to the ventricles to allow the important delay in contraction

65
Q

What do the Purkinje fibers do?

A

Transmit action potentials throughout the ventricles

66
Q

Where is the Bundle of His?

A

Between the A-V node and the Purkinje Fibers

67
Q

In cardiac muscle, ______ is the trigger for initiating contraction

A

Ca2+

68
Q

What is happening during the plateau in cardiac muscle action potential?

A

Ca2+ influx

69
Q

What is the resting membrane potential for cardiac muscle and what is it due to?

A

-85, potassium potential

70
Q

Unlike skeletal muscle where the size of action potentials can be increased by increasing ________ and _______, cardiac muscle action potentials have a ____________. It is not graded.

A

the number of motor units being stimulated, frequency of stimulation, absolute refractory period

71
Q

What is preload?

A
  • pressure during filling of the ventricle
  • degree of tension on the muscle when it begins to contract
  • the end-diastolic pressure when the ventricle has become filled
72
Q

What is afterload?

A
  • the arterial pressure against which the ventricle must contract
  • pressure in the aorta leading from the ventricle
  • corresponds to systolic pressure
  • load against which the muscle exerts its contractile force
73
Q

Active force in skeletal muscle and in smooth muscle _________ at very long muscle lengths, but this does not happen in cardiac muscle because of _________.

A

decreases, sympathetic nerve activity

74
Q

During sympathetic stimulation of the heart, _______ is released from neurons.

A

norepinephrine

75
Q

The rhythmicity of sinus nodal depolarization is caused by an _______ of ______ ions

A

influx, sodium

76
Q

The highest resistance vessels in a normal person are the __________

A

arterioles

77
Q

Arrange the following in decreasing order of cross-sectional area: aorta, capillaries, vena cava

A

capillaries, vena cava, aorta

78
Q

What is vasomotion?

A

Vasomotion is the intermittent contraction of precapillary sphincters and metarterioles. The contraction of these vessels causes capillary blood flow to be intermittent or pulsatile causing periods of low flow and resulting decreases in
local delivery of oxygen. Vasomotion can result in elevated peripheral resistance.

79
Q

What is the most likely route of transcapillary exchange of lipophilic substances?

A

transcellular

80
Q

What is the most likely route of transcapillary exchange of hydrophilic substances?

A

intercellular clefts

81
Q

What is the most likely route of transcapillary exchange of large hydrophilic molecules?

A

pinocytic vesicles

82
Q

What is the most likely route of transcapillary exchange of large amounts of fluid?

A

fenestrae and aquaporins

83
Q

What is cardiac output?

A

The rate at which blood is pumped from either ventricle; the amount of blood pumped into the aorta each minute

84
Q

What does Poiseuille’s Law indicate about the relationship between radius of a blood vessel and the resistance? Between radius and flow?

A

Even a small decrease in radius can increase the resistance a lot and therefore decrease flow.

85
Q

What is polycythemia?

A

A condition of having too many blood cells.

86
Q

How do you calculate pulse pressure?

A

Sytolic pressure - diastolic pressure

87
Q

What is stroke volume?

A

The volume of blood ejected from the heart in one beat.

88
Q

What is pulse pressure directly and indirectly proportionate to?

A

Directly proportional to stroke volume, inversely proportional to arterial compliance

89
Q

How are lipid soluble molecules transported across the capillary membrane, and what are some examples of lipid soluble molecules?

A

They diffuse directly through; O2, CO2, CO, NO

90
Q

How are water soluble molecules transported across the capillary membrane, and what are some examples of water soluble molecules?

A

Through “pores”; H2O, NaCl, glucose, other ions

91
Q

What three things determine diffusion rate?

A

concentration gradient, surface area, diffusion coefficient (determined by molecule and capillary type)

92
Q

What are the outward forces in Starling Forces?

A

Mean capillary pressure, interstitial fluid colloid osmotic pressure

93
Q

What are the inward forces in Starling Forces?

A

Interstitial free fluid pressure

Plasma colloid osmotic pressure

94
Q

Colloid osmotic pressure is determined by the _________ of molecules, not the _________ of molecules. _________ is the major contributor of colloid osmotic pressure in the blood.

A

number, mass, albumin

95
Q

The sympathetic nervous system has _______ fibers that travel in the ______ spinal cord

A

preganglionic, lateral

96
Q

For cardiac muscle:
Sympathetic stimulation is caused by _________
Parasympathetic stimulation is caused by _________

A

norepinephrine, acetylcholine

97
Q

What is the P wave?

A

A peak on the EKG representing the atria depolarizing

98
Q

What is the QRS wave?

A

A peak on the EKG representing the ventricles depolarizing before contraction

99
Q

What is the T wave?

A

A peak on the EKG representing repolarization of the ventricles

100
Q

What are the sources of calcium for skeletal muscle and what are they for smooth muscle?

A

Skeletal: SR
Smooth: primarily EXTRACELLULAR, less SR

101
Q

Sodium/calcium exchangers play a role in ______ and ______ muscle, but not at all in _____ muscle.

A

cardiac, smooth, skeletal

102
Q

List the following in decreasing permeability in capillaries:
Glucose, Hemoglobin, Albumin, Sucrose, NaCl

A

Albumin, hemoglobin, sucrose, glucose, NaCl

103
Q

List the following in decreasing cross-sectional area:

Vena cava, aorta, small veins, arterioles, capillaries

A

capillaries, small veins, arterioles, vena cava, aorta

104
Q

What is hooked up to limb lead I?

A

right arm and left arm

105
Q

What is hooked up to limb lead II?

A

Right arm and left leg

106
Q

What is hooked up to limb lead III?

A

Left leg and left arm

107
Q

What is Einthoven’s law?

A

Limb lead 1 + Limb lead 3 = Limb lead 2

108
Q

An increase in alpha causes _____ in the motor neuron

A

depolarization

109
Q

An increase in extracellular [Na] causes ______ in motor neuron

A

depolarization

110
Q

What is alpha?

A

Permeability of Na+ / Permeability of K+

111
Q

An equilibrium potential requires ________ for its maintenance.

A

no free energy expenditure

112
Q

What does it mean when a potential is “steady-state?”

A

It requires active transport for its maintenance, as in, a continual supply of metabolic energy is required to maintain it.

113
Q

Is resting membrane potential a steady state potential?

A

Yes, it requires energy to maintain normal transmembrane concentration gradients for each permeable ion NOT at equilibrium potential.

114
Q

Hypoxia can lead to a decrease in _______ activity causing _______ in CNS neurons.

A

Na/K pump, depolarization

115
Q

Under resting conditions in the motor neuron, permeability of Cl- is less than that of ______ and greater than that of ______.

A

Na, K

116
Q

_______ actively transports Ca2+ ions from cytoplasm back into the SR –> relaxation

A

SERCA

117
Q

The membrane potential of multi unit smooth muscle cells is ______ than that of single unit smooth muscle cells.

A

more negative

118
Q

The magnitude of developed tension in a cardiac myocyte is proportional to the _________ concentration.

A

intracellular Ca2+

119
Q

What is Laplace’s Law?

A

Wall tension = Pressure x Radius

120
Q

Blood flow to skeletal muscle during exercise is dominated by __________.

A

metabolic autoregulation

121
Q

What do renin and angiotensin do to total peripheral resistance?

A

They increase it by causing vasoconstriction

122
Q

What does positive feedback mean?

A

The initiating stimulus causes more of the same.

123
Q

What can a large injection of K+ cause?

A

cardiac arrhythmias

124
Q

Why are calcium channel blockers effective in dilating arteries and arterioles?

A

Because the smooth muscles around them need calcium to constrict. Recall: in SMOOTH muscle, extracellular Ca2+ is the major source of calcium.

125
Q

What does epinephrine cause?

A

Vasoconstriction, it is part of sympathetic stimulation

126
Q

Inhibition of Na/K pump causes _______ force of contraction

A

increased

127
Q

Beta adrenergic blockers cause what?

A

vasoconstriction

128
Q

How can the maximum veloctiy of isotonic contraction change in smooth muscle?

A

Changing the degree of phosphorylation of regulatory light chain on myosin.

129
Q

In skeletal muscle, what determines contraction velocity and ATPase activity?

A

Specific myosin isoforms (ex: slow twitch muscles have distinct myosin that hydrolyzes ATP more slowly)

130
Q

In smooth muscle, Ca2+ release from SR (its minor source of Ca2+) is related to ______ and _____, and not to ryanodine sensitive Ca2+ channels like in skeletal muscle.

A

IP3 and phospholipase C

131
Q

Is energy required to maintain the transmembrane equilibrium potential (Ex) of a cation?

A

No

132
Q

What is the equilibrium potential of a cation if its concentrations are the same intracellularly and extracellularly?

A

0

133
Q

The resting transmembrane potential of a mammalian nerve fiver is most dependent on the ___________ of ______, because ______ is very little in resting conditions.

A

concentration gradient, K+, permeability of Na+

134
Q

What is Fick’s Law of Diffusion?

A

J = (DA/thickness of membrane)(concentration gradient) = permeability x concentration gradient
Where J: flux, D: diffusion coefficient, A: surface area

135
Q

Cardiac glycosides like ouabain block ________ to ________ site of Na/K pump.

A

K+ attachment, extracellular site

136
Q

Outline the cardiac impulse (the order in which conduction occurs in different parts of the heart)

A

SA node –> atria –> AV node –> Purkinje fibers –> ventricles

137
Q

Thee aortic and pulmonary valves are ________ valves. Mitral and tricuspid are ________ valves.

A

seminlunar, A-V

138
Q

A chronotropic medication changes ________.

A

heart rate

139
Q

A positive inotropic agent _____________.

A

increases contractility, power of contraction

140
Q

Cardiac muscle velocity at fixed length is maximal when ____________.

A

afterload is zero

141
Q

List the following in decreasing blood volume: pulmonary circulation, heart, arteries, venous circulation

A

venous circulation, arteries, pulmary circulation, heart

142
Q

What does Poiseuille’s Law say about flow?

A

It is directly proportional to change in pressure, and radius to the fourth degree.

143
Q

Glucose can come into cells by _________ or _________.

A

facilitated diffusion, secondary active transport

144
Q

Angiotensin-renin is activated by __________ when renal perfusion pressure _________.

A

sympathetic nervous system, falls under 80 mmHg

145
Q

Smooth muscle: Single unit vs multi-unit

Which can conduct electrical currents from cell to cell?

A

single unit

146
Q

Smooth muscle vs. Skeletal muscle:

Which has greater velocity of contraction?

A

Skeletal

147
Q

Increase in pressure in carotid causes _______ afferent nerve activity and _______ efferent nerve activity, causing _______.

A

increased (in response to stretch), decreased, vasodilation

148
Q

What is active hyperemia?

A

An increase in blood flow due to increase in metabolic activity

149
Q

What is resistance to venous return dependent on?

A

arterial and venous compliance

150
Q

During excercise, sympathetic nerve activity is responsible for what?

A

increased cardiac function

151
Q

After a large hemorrhage, what happens to heart rate and why?

A

Heart rate increases above control because of a reduction of nerve activity in the vagus nerve

152
Q

What happens to each of these when blood volume is increased?
Sympathetic nerve activity
ADH
Renin

A

they all decrease, because they all cause vasoconstriction

153
Q

What happens after weeks or months of increased afterload?

A

Cardiac hypertrophy

154
Q

What is the immediate response to reduced carotid sinus pressure?

A

rapid increase in sympathetic outflow

155
Q

What would opening K+ channels do to a smooth muscle?

A

Cause it to hyperpolarize and thus relax

From Flashcardlet (20 decks)

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