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Physiology > Cardiovascular Physiology I: Excitation, Conduction, and Cardiac Cycle (Exam III) > Flashcards

Cardiovascular Physiology I: Excitation, Conduction, and Cardiac Cycle (Exam III) Flashcards

1
Q

The three principal components of the circulatory system are:

A
  1. the heart
  2. the blood vessels
  3. the blood
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2
Q

The pump:

The pipes:

The fluid to be moved:

A

Heart
Blood vessels
Blood

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3
Q

Cardiovascular function is regulated by ___ & _____ and strongly impacted by _____.

A

endocrine factors & autonomic nerves

renal function

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4
Q

Number one cause of death worldwide:

A

cardiovascular disease

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5
Q

____ & _____ are the most common cardiovascular diseases

A

atherosclerosis & HTN

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6
Q

Cardiovascular disease affects many organs including:

A

brain, eyes, and kidneys

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7
Q

Multiple risk factors of cardiovascular disease including:

A

smoking, obesity, DM, genetics

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8
Q

A build up of plaque in the wall of a vessel causing the narrowing of the lumen

A

atherosclerosis

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9
Q

The heart beats to generate ____ to push blood through the vessels

A

pressure

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10
Q

The heart beats to ultimately allow blood to reach the ____.

A

capillary system

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11
Q

Exchange at the capillary system occurs between:

A

plasma and interstitial fluid

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12
Q

Supplies O2 and nutrients to the tissues and removes waste

A

systemic circulation

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13
Q

Adds O2 and removes CO2:

A

pulmonary circulation

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14
Q

Blood always enters the heart through the:

A

atria

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15
Q

Blood always exits the heart through the:

A

ventricles

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16
Q

Blood vessels that return blood to the heart:

A

veins

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17
Q

Blood vessels that carry blood away from the heart

A

arteries

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18
Q

Blood vessels that are attached to the atria, returning blood to the heart:

A

veins

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19
Q

Blood vessels that are attached to the ventricles carrying blood away from the heart:

A

arteries

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20
Q

What is the pump for systemic circulation:

A

Left ventricle

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21
Q

What is the end goal for systemic circulation:

A
  1. supply O2 and nutrients to tissues
  2. removes waste
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22
Q

Describe the path of systemic circulation:

A

The left ventricle pumps the blood out into systemic vessels and then into systemic capillaries and then into systemic veins. The systemic veins then bring blood back to the right atrium (end of systemic circulation)

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23
Q

What is the pump in pulmonary circulation?

A

Right ventricle

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24
Q

Describe the pathway of pulmonary circulation:

A

The right ventrical pumps blood into vessels that will carry it into the pulmonary capillaries, from here, the pulmonary vein will bring it back to the left atrium (this ends pulmonary circulation)

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25
Q

What is the end goal for pulmonary circulation?

A

Add O2 and remove CO2

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26
Q

Function is to keep blood flowing in one direction:

A

heart valves

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27
Q

Heart valves open and close due to:

A

changes in pressure

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28
Q

When we see vessels colored in red, what type of vessels are these and describe the blood within them:

A

Systemic arteries and blood is high in O2 and low in CO2

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29
Q

When we see vessels color coated blue, what type of vessels are these and describe the blood within them:

A

systemic veins and blood is high in CO2 and low in O2

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30
Q

What is the one artery that is carrying blood that is low in O2 and high in CO2?

A

pulmonary artery

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31
Q

What is the one vein that is carrying blood high in O2 and low in CO2?

A

pulmonary vein

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32
Q

The blood flow out of the left ventricle into systemic circulation is ____ compared to the blood that is pumped out into the right ventricle into pulmonary circulation:

A

EQUAL

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33
Q

Unequal blood flow between pulmonary and systemic would result in:

A

blood pooling

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34
Q

oxygen is loaded and CO2 is unloaded in the:

A

pulmonary capillaries

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35
Q

oxygen is unloaded and CO2 is loaded in the:

A

systemic cappilaries

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36
Q

Veins attached to the left atrium:

A

pulmonary vein

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37
Q

Large systemic artery attached to the left ventricle:

A

aorta

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38
Q

Large vein attached to the right ventricle

A

Pulmonary trunk

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39
Q

The pulmonary trunk will branch into:

A

right and left pulmonary arteries

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40
Q

Attached to the right atrium (returns blood to the right atrium)

A

Vena Cava

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41
Q

Valves are not _____ but are considered ____.

A

muscles; passive structures

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42
Q

Passive structures that open and close based on pressure gradients and function to keep blood flowing in one direction:

A

Heart valves

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43
Q

Valves found between the atria and respective ventricles:

A

atrioventricular valves (AV)

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44
Q

What are the two AV valves?

A
  1. tricuspid valve
  2. mitral vavle (biscuspid)
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45
Q

Where is the the tricuspid valve located?

A

between right atrium and right ventricle

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46
Q

Where is the mitral (biscuspid) valve located?

A

between left atrium and left ventricle

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47
Q

Valve located between the right atrium and right ventricle:

A

triscuspid

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48
Q

Valve located between the left atrium and left ventricle:

A

bicuspid (mitral)

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49
Q

If P(A)> P(V)=

A

open

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50
Q

If P(A)<P(V)=

A

closed

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51
Q

Valves located between the ventricles and there respective arteries:

A

semilunar valves

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52
Q

Valve located between right ventricle and pulmonary trunk:

A

pulmonary valve

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53
Q

Valve located between the left ventricle and the aorta

A

aortic valve

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54
Q

Where is the pulmonary valve located?

A

between the right ventricle and pulmonary trunk

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55
Q

Where is the aortic valve located?

A

between the left ventricle and the aorta

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56
Q

If P(V)> P(art) =

A

open

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57
Q

If P(V) < P(art)=

A

closed

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58
Q

When semilunar valves are open, the blood will be:

A

ejected out into the arteries

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59
Q

Prevents the back flow of blood into the ventricles when ventricular pressure falls:

A

Closing of the semilunar valves

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60
Q

Two loops in the cardiovascular system:

A

systemic loop & pulmonary loop

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61
Q

loop that carries oxygen rich blood to the systemic capillaries and oxygen poor blood back to the heart:

A

systemic loop

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62
Q

The systemic loops carriers oxygen rich blood to the _____ and oxygen poor blood ____.

A

systemic capillaries; back to the heart

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63
Q

The systemic loop carries _____ blood to the systemic capillaries and ____ blood back to the heart.

A

oxygen-rich; oxygen poor

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64
Q

Loop that carries oxygen poor blood to the lungs and oxygen rich blood back to the heart:

A

pulmonary loop

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65
Q

The pulmonary loop carries oxygen poor blood to the _____ and oxygen rich blood ____.

A

lungs; back to the heart

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66
Q

The pulmonary loop carries _____ blood to the lungs and ____ blood back to the heart

A

oxygen-poor; oxygen-rich

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67
Q

What occurs between the plasma and interstitial fluid at the capillaries?

A

exchange

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68
Q

Exchange occurs between _____ & ______ at the ____

A

plasma & interstitial fluid; capillaries

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69
Q

How is blood supply to tissue arranged?

A

Parallel

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70
Q

The cardiovascular system is considered a _____ system

A

closed

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71
Q

What is considered “bad” due to the cardiovascular system being a closed system?

A

leaks

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72
Q

A bleeding paper cut would be considered a _____ in the cardiovascular system.

A

leak

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73
Q

What repairs leaks in the cardiovascular system?

A

hemostasis

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74
Q

Vessels and capillary beds have a _____ arrangement

A

parallel

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75
Q

Why is it significant that all capillaries in systemic circulation are arranged in parallel?

A

Allows the body to selectively change blood flow to a certain tissue without affecting the blood flow to another area

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76
Q

There is around _____ of blood moving through the body every minute at rest:

A

~5 liters

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77
Q

Each tissue gets a different amount of blood because you can regulate how much blood flow goes into each tissue and that is due to the:

A

parallel arrangment

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78
Q

During strenuous exercise, where might the body increase blood flow to?

A

Brain, heart, skeletal muscles, and skin

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79
Q

During strenuous exercise, where might the body decrease blood flow to?

A

kidneys, abdominal organs, etc.

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80
Q

List the types of arteries:

A
  1. elastic arteries
  2. muscular arteries
  3. arterioles
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81
Q

The largest arteries that are attached to the heart:

A

elastic arteries

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82
Q

Muscular arteries may also be called:

A

distribution arteries

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83
Q

Type of artery that branches off the aorta and function to distribute blood to and around different organs of the body:

A

muscular artery (distribution artery)

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84
Q

Where arteries come to an end (represent the end of arteries)

A

arterioles

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85
Q

Smallest arteries, connected to the capillaries

A

arterioles

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86
Q

Blood flows out of the arteriole system into the ___ through the ____

A

capillaries; arterioles

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87
Q

Function to carry blood to tissue capillaries from the heart:

A

arteries

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88
Q

What regulates blood pressure?

A

arterioles

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89
Q

What are the three types of veins?

A
  1. large veins
  2. medium-sized veins
  3. venules
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90
Q

large veins are attached to:

A

the heart

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91
Q

What are some examples of large veins?

A

Vena Cava; Pulmonary vein

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92
Q

Medium veins are considered ____ veins

A

collection

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93
Q

Collect blood from different tissues that the muscular arteries delivered it to:

A

medium-sized veins (collection veins)

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94
Q

Smallest of veins, that captures the blood that flows out of the capillaries:

A

venules

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95
Q

Represent the beginning of the venous system:

A

venules

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96
Q

Venules collect into _____

A

medium-sized veins

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97
Q

Carry blood to the heart from tissues capillaries

A

veins

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98
Q

The process of carrying blood to the heart from tissue capillaries:

A

venous return

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99
Q

Veins serve as:

A

reservoir of blood

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100
Q

Veins have a very high compliance and can hold a large volume of blood with very little change in pressure and this can be referred to as:

A

peripheral venous pool (PVP)

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101
Q

Describe what peripheral venous pool means:

A

The ability of veins to act as a reservoir of blood

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102
Q

At rest, how much of our blood volume is contained within the veins:

A

~60%

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103
Q

The aorta is an example of an:

A

elastic artery

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104
Q

The aorta is attached to the:

A

heart

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105
Q

Describe the blood flow through the aorta:

A

blood is ejected out at a forceful pressure

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106
Q

Muscular arteries branch off of the:

A

aorta

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107
Q

Example of muscular arteries:

A

renal artery and celiac artery

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108
Q

Muscular arteries enter into the ____ and get smaller and smaller until they become ____.

A

organs and arterioles

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109
Q

______ will end with capillaries and this is where exchange will occur

A

arterioles

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110
Q

Exchange occurs in the capillaries, and that blood will get picked up by:

A

venules

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111
Q

For every artery we have a ____ component to it

A

venous

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112
Q

The force exerted by a fluid in a tube

A

pressure (hydrostatic pressure)

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113
Q

Pressure is measured in:

A

mmHg

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114
Q

In the cardiovascular system we are measuring what pressure:

A

pressure of blood in blood vessels

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115
Q

The volume of fluid moved in a given amount of time:

A

flow

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116
Q

Flow is measured in:

A

ml/min

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117
Q

How difficult it is for blood to flow between two points at any given pressure difference:

A

resistance

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118
Q

Resistance is a measure of:

A

friction that impedes flow

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119
Q

Ohm’s law =

A

F= (Change in Pressure) / Resistance

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120
Q

Flow is directly related to ____; flow is inversely related to ____.

A

pressure gradient; resistance

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121
Q

What is the unit for resistance?

A

Poiseuille

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122
Q

If the change in pressure is constant and resistance increases, flow:

A

decreases

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123
Q

The driving force to move blood through the cardiovascular system

A

pressure gradient generated by the heart

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124
Q

From a mechanistic standpoint, which would be better to alter to change blood flow to specific tissues?

  1. Increase in pressure
  2. Decrease in resistance
A

Reduce resistance to flow because the driving pressure is your BP and we don’t want to alter that much

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125
Q

Flow will be regulated by_____, and NOT _____.

A

regulating resistance; NOT changing pressure

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126
Q

As blood flows through systemic circulation (aorta –> arteries –> arterioles –> capillares –> venules –> veins –> vena cava) What happens to the pressure and why?

A

Pressure decreases due to friction (resistance) as you move away from the heart

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127
Q

Where is pressure CV system the highest?

A

Immediately outside the left ventricle

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128
Q

Where is the biggest pressure drop in systemic circulation?

A

arterioles

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129
Q

The biggest pressure drop occurs in the arterioles due to:

A

most resistance/friction there

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130
Q

What are the three factors that contribute to cardiovascular resistance?

A
  1. blood viscosity (n)
  2. total blood vessel length (l)
  3. blood vessel radius (r)
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131
Q

Resistance is directly related to _____; resistance is indirectly related to _____.

A

blood viscosity (n) and total blood vessel length (l)

blood vessel radius (r)

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132
Q

How thick the blood is =

A

viscosity

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133
Q

Viscosity is determined by:

A

hematocrit

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134
Q

Percentage of red blood cells per unit of whole blood:

A

Hematocrit

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135
Q

The more red blood cells present per unit of whole blood =

A

higher viscosity

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136
Q

How much tubing is needed:

A

total blood vessel length

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137
Q

The longer the blood vessel, the _____ the resistance

A

greater

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138
Q

What determines blood vessel length?

A

genetics

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139
Q

Vasodilated blood vessels increase ____ and decrease _____.

A

radius; resistance

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140
Q

Vasoconstricted vessels decrease ___ and increase ____

A

radius; resistance

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141
Q

What is the main contributor to minute-to-minute control of resistance in the vascular system?

A

blood vessel radius

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142
Q

Small changes in blood vessel radius lead to:

A

big changes in resistance

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143
Q

If we want to increase blood flow to an area we can _____ the blood vessel; but if we want to reduce blood flow to an area we can _____.

A

dilate; constrict

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144
Q

What is poiseuille equation?

A

Resistance= 8nl / pi(r)^4

n= viscosity
l= length
r= radius

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145
Q

By combining poiseuille law and ohm law we get:

A

Q= P(pi)r^4 / 8nl

Hagen-poiseuille equation

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146
Q

When regarding pressure and flow in vessels, its not the ____ of pressure that is important, it is the ____ of the pressure that is important.

A

absolute values of pressure; differences in pressure

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147
Q

Diameter of a vessel is a major determinant of:

A

flow

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148
Q

A two-fold increase in radius will lead to a:

A

16 fold increase in blood flow

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149
Q

Describe the effects the following have on flow:

  1. Increased radius
  2. Decreased radius
  3. Increased tube length
  4. Decreased tube length
A
  1. increased flow
  2. decreased flow
  3. decreased flow
  4. increased flow
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150
Q

What is the equation for velocity regarding blood flow through vessels?

A

V = Q/A

V= velocity
Q= blood flow
A= total cross sectional area

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151
Q

How something happens:

A

mechanistic explanation

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152
Q

Why something happens:

A

teleological explanation

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153
Q

Velocity of blood flow is slowest through the capillaries, what is the mechanistic explanation for this?

A

greatest total cross-sectional area leads to the lowest velocity

(1 aorta = low cross sectional area compared to many capillaries= highest cross sectional area)

(V=Q/A)

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154
Q

Velocity of blood flow is slowest through the capillaries, what is the teleological explanation for this?

A

We want velocity to be slow at the capillaries to allow time for maximum exchange to occur

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155
Q

Describe the following at the aorta:

  1. total cross-sectional area
  2. velocity of blood
  3. blood pressure
A
  1. low cross-sectional area
  2. high velocity of blood flow
  3. high blood pressure
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156
Q

Describe the following at the capillaries:

  1. total cross-sectional area
  2. velocity of blood
  3. blood pressure
A
  1. large cross-sectional area
  2. low velocity of blood flow
  3. low blood pressure but higher than in the venules, veins and vena cava
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157
Q

Connective tissue cords that are attached to the AV valves on one end and papillary muscles located inside the ventricles on the other end:

A

chordae tendinae

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158
Q

What does the chordae tendinae connect to?

A

AV valves and papillary muscles

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159
Q

The walls of the atria are _____ compared to the walls of the ventricles.

A

thinner

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160
Q

What is the mechanistic explanation the walls of the atria being thinner than the walls of the ventricles:

A

The walls of the atria are thinner because the atria only have to contract to push blood into the ventricles (not a ton of work)

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161
Q

Compare the walls of the right ventricle to the left ventricle:

A

Wall of left ventricle is much thicker

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162
Q

What is the mechanistic explanation of the left ventricle wall being thicker than the right ventricle wall?

A

Left ventricle is responsible for systemic circulation, it has to forcefully contract to get blood all the way to the toes (a lot of work)

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163
Q

Separates the right ventricle from the left ventricle:

A

Interventricular septum

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164
Q

List the AV valves and where they are located:

A
  1. tricuspid valve (RA/RV)
  2. Bicuspid (mitral) valve (LA/LV)
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165
Q

The AV valves are supported by _______ when closed

A

Chordae tendinae and papillary muscles

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166
Q

When the AV valves are open, the semilunar valves are:

A

closed

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167
Q

When are all valves open at the same time?

A

NEVER

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168
Q

When AV valves are open, blood is flowing into the:

A

ventricles

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169
Q

Describe the chordae tendinae when the AV valves are open?

A

Lots of slack (not drawn tight)

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170
Q

When the AV valves are closed, the semi lunar valves are:

A

open

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171
Q

Describe the chordae tendinae when the AV valves are closed:

A

chordae tendinae stretched tight and supported by the papillary muscle

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172
Q

The function of the chordae tendinae is to:

A

prevent backflow

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173
Q

What would happen if the chordae tendinae were not functioning?

A

valve prolapse

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174
Q

Caused by weakened/stretch chordae tendinae and can be due to HTN:

A

Valve prolapse

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175
Q

Valve dysfunction creates:

A

heart murmurs

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176
Q

Valves open and close due to:

A

pressure gradients

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177
Q

Valves function to:

A

keep blood flowing in one direction

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178
Q

Which valve is considered the tricuspid valve?

A

Right AV valve

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179
Q

Which valve is considered bicuspid valve?

A

Left AV valve

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180
Q

Cardiac myocytes can also be called:

A

cardiocytes, cardiac muscle cells

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181
Q

There are two types of cardiac myocytes in cardiac muscle and these include:

A
  1. conductive muscle fibers (Autorhythmic cells (AR cells), Pacemaker cells)
  2. Contractile muscle fibers
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182
Q

Conductive muscle fibers may also be called:

A

autorhythmic cells (AR Cells)

pacemaker cells

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183
Q

Makes up 1% of cardiac myocytes:

A

conductive muscle fibers

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184
Q

Spontaneously generate AP that leads to heart beat:

A

conductive muscle fibers

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185
Q

______ stimulus an excitation (AP) which stimulates ______.

A

conductive muscle fibers; contractile cells

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186
Q

Type of cardiac myocyte that contract very weakly:

A

conductive muscle fibers

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187
Q

Conductive muscle fibers are located:

A

in conduction system of heart

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188
Q

99% of myocytes=

A

contractile muscle fibers

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189
Q

contract and generate heart beat:

A

contractile muscle fibers

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190
Q

What are the 2 types of contractile muscle fibers?

A
  1. atrial myocytes
  2. ventricular myocytes
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191
Q

cardiac muscle cell that contracts in response to the electrical signal that is generated by conductive muscle cells

A

Contractile muscle fibers

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192
Q

Contractile muscle cells located in the atria:

A

atrial myocytes

193
Q

contractile muscle cells located in the ventricles:

A

ventricular myocytes

194
Q

What stimulates SKELETAL muscle to contract?

A

action potentials and somatic motor neurons

195
Q

What are the steps for (simplified) to stimulating a SKELETAL muscle to contract?

A
  1. AP in somatic motor
  2. release of Ach
  3. Ach binds to nicotinic receptors on motor end plate
  4. Excitation leading to calcium entry (for contraction)
196
Q

Compare heart contraction to skeletal muscle contraction:

A

No outside electrical stimulus is needed for the heart to beat

197
Q

Where does the electrical signal that leads to heart contraction come from?

A

from WITHIN the heart

198
Q

What enables the heart to beat outside of the body?

A

internal stimulation from conductive muscle fibers

199
Q

The appearance of cardiocytes can be described as:

A

striated

200
Q

The functional unit of a cardiocyte:

A

sarcomere

201
Q

The _____ and _____ of cardiac muscle is similar to skeletal muscle

A

anatomy and function

202
Q

Cardiac muscle can be described as a _____.

A

syncytium

203
Q

group of cells that function as one:

A

syncytium

204
Q

What feature of cardiocytes allows them to function as a syncytium?

A

intercalated discs

205
Q

specialized connections between one cardiac muscle cell and another

A

intercalated disc

206
Q

Intercalated discs are composted of:

A
  1. interlocking plasma membrane
  2. gap junctions
  3. desmosomes
207
Q

Describe the interlocking plasma membrane of intercalated discs in cardiac muscle:

A

Little hooks locking the plasma membrane together

208
Q

Describe the function of the gap junction found in intercalated discs in cardiac muscle:

A

allows for rapid movement of ions from one cell to the next

209
Q

Describe the function of desmosomes found in intercalated discs in cardiac muscle:

A

Structural support cell connections

210
Q

Why is it so important that desmosomes are found in the intercalated discs in cardiac muscle?

A

Allows the cells to stay together under the extreme pressure of the heart

211
Q

In what ways are cardiac muscle cells linked?

A
  1. mechanically
  2. chemically
  3. electrically
212
Q

What are the two syncytiums of the heart?

A
  1. atrial
  2. ventricular
213
Q

The atrial syncytium and the ventricular syncytium function:

A

separate of eachother

214
Q

If the atrial syncytium is contracted, the ventricular syncytium is ____.

A

relaxed

215
Q

The arteries supplying the myocardium are the:

A

coronary ateries

216
Q

The blood flowing through the coronary arteries:

A

coronary blood flow

217
Q

Coronary arteries exit from behind the ____.

A

aortic valve cusps

218
Q

Coronary arteries exit form the behind the aortic valve cusps and lead to a branching network for:

A

small arteries, arterioles, capillaries, venues and veins

219
Q

Describe the drainage of most of the cardiac veins:

A

most of the cardiac veins drain into a single large vein- the coronary sinus

220
Q

After the cardiac veins drain into the single coronary sinus, this empties into the:

A

right atrium

221
Q

Coronary circulation is a part of:

A

systemic circulation

222
Q

because coronary circulation is part of systemic circulation it functions to:

A

provide O2 and nutrients to tissues of the body (including the heart)

223
Q

Systemic blood flow to the heart and prices fresh O2 and nutrients to the cells

A

coronary cirulation

224
Q

What does coronary circulation bypass?

A

vena cava

225
Q

The coronary sinus dumps directly into the:

Why is this unique?

A

right atrium; because it bypasses the vena cava

226
Q

The very 1st branch off the aorta is the:

A

coronary artery

227
Q

The coronary artery branches into:

A

right and left coronary arteries (which travel around the heart)

228
Q

Lack of blood supply to the left ventricle:

A

widow maker

229
Q

What is the artery involved in widow maker?

A

Left anterior descending artery (coronary artery??)

230
Q

What is the only thing that does not use the vena cava to dump blood back into the heart?

A

coronary sinus

231
Q

Contraction=

A

systole

232
Q

relaxation=

A

diastole

233
Q

atrial contraction=
atrial relaxation=
ventricular contraction=
ventricular relaxation=

A

atrial systole
atrial diastole
ventricular systole
ventricular diastole

234
Q

What is the term for the events occurring in a single heart beat

A

cardiac cycle

235
Q

The events of the cardiac cycle include:

A
  1. atrial systole
  2. ventricular systole/atrial diastole
  3. ventricular diastole
236
Q

What must occur before systole can happen? What must occur before diastole can happen?

A

heart muscle must depolarize before systole can happen and repolarize before diastole can happen

237
Q

What is the order of depolarization in the heart/conduction system?

A
  1. SA Node
  2. Internodal pathways
  3. AV node
  4. Bundle of His
  5. Down bundle branches
  6. Up purkinje fibers
238
Q

The SA node will generate AP which travel via gap junctions along _______ to the ______

A

internodal pathways; AV node

239
Q

The action potential is held up for 0.1s in the _____. This is known as the _____.

A

AV node; AV delay

240
Q

What is the teleological explanation for the AV delay?

A

The atria needs to contract before the ventricles fill with blood

241
Q

What is the mechanistic explanation for the AV delay?

A

The conduction velocity through the AV node is slower than elsewhere along the conduction system

242
Q

The AP travels from the AV node ______ the bundle of His, ____ bundle branches, ____ purkinje fibers

A

Down, down, up

243
Q

The purkinje fiberse also supply the ____

A

papillary muscles

244
Q

Contracts during ventricular contraction to tighten the chordae tendinae and prevent AV valves from prolapsing into the atria

A

Papillary muscles

245
Q

When do the papillary muscles contract?

A

during ventricular contraction

246
Q

The pacemaker cells with the _____ drive the heart

A

fastest rate of discharge

247
Q

In general, pacemaker cells have high _____.

What is an exception to this?

A

action potential conduction velocities

exception: AV node (due to AV delay)

248
Q

The reason that the action potential is held up for a fraction of a second at the AV node is because it has ____ which causes the AP to take longer to move through this area.

A

Very slow conduction velocity

249
Q

The speed at which the action potential moves

A

conduction velocity

250
Q

the number of APs the pacemaker cells can generate in a given amount of time

A

rate of discharge

251
Q

Why does the SA node drive the heart?

A

because it contains the pacemaker cells with the fastest rate of discharge

252
Q

Describe an ectopic focus

A

abnormal pacemaker cells (hijackers)

253
Q

If contractile cells convert into AR cells like after a long infection these would be considered:

A

ectopic focus

254
Q

Describe the events that occur when the action potential takes the internodal pathways?

A
  1. depolarization of atria
  2. AV delay
  3. atrial contractions
255
Q

Describe the events that occur when the AP is sent down the bundle branches and up purkinje fibers:

A
  1. depolarization of ventricle
  2. contraction of ventricles
256
Q

Atrial repolarization occurs at the exact same time as _____.

Describe the wave of atrial repolarization on an ECG.

A

Ventricular depolarization

Because it occurs at the same time as ventricular depolarization (it is dominated since the ventricles are bigger) and therefore is absent on an ECG

257
Q

Name the wave that is characterized by the following actions:

  1. atrial depolarization
  2. ventricular depolarization/atrial repolarization
  3. ventricular repolarization
A
  1. P wave
  2. QRS complex
  3. T wave
258
Q

The p wave itself does not represent atrial ______ but it represents atrial _____.

A

contraction; depolarization

259
Q

Does the QRS complex represent atrial repolarization? why?

A

No- It represents ventricular depolarization although atrial repolarization does occur at this time (just not represented on ECG)

260
Q

AV delay occurs during the PR interval, if AV delay is longer than normal = ________. If AV delay is shorter than normal = ________.

A

longer PR interval; shorter PR interval

261
Q

When would the Q- wave show up on an ECG?

A

Not normally, only on someone with previous cardiac event

262
Q

AR cells do not have a:

A

steady resting membrane potential

263
Q

Describe the resting membrane potential of AR cells:

A

unsteady

264
Q

depolarization to threshold in AR cells:

A

pacemaker potential

265
Q

What are the two channels of pacemaker potential?

A

F-type channels
T-type channels

266
Q

F-type channel=

A

Voltage gated sodium channel (funny channel)

267
Q

T-type channel=

A

Transient voltage gated calcium channel

268
Q

What are the two channels of AP?

A

L channel
K+ channel

269
Q

L Channel=

A

long-lasting voltage gated calcium channel

270
Q

Once the membrane potential hits the resting potential that will be stimulus for:

A

opening of F-type channel

271
Q

What happens when the F-type channel opens?

A

Sodium influx into the cell leading to depolarization to 3/4 of threshold

272
Q

At resting potential, sodium permeability is _____. But as soon as the F-type channel opens, ______.

A

low; Na+ permeability increases

273
Q

At 3/4 the way up to theshold what occurs?

A

Transient voltage gated calcium channels open

274
Q

Why doe we call them “transient” voltage gated calcium channels?

A

because they only open briefly

275
Q

The calcium flowing in due to the transient voltage gated calcium channels allows for:

A

depolarization to threshold (the final 1/4)

276
Q

What work together to get the cell to threshold?

A

F-type channel + transient voltage gated calcium channel

277
Q

Once we reach threshold, what occurs?

A

L-Type calcium channels open, calcium flows in = spike of depolarization

278
Q

Describe the opening of the L-type calcium channel:

A

Long lasting opening at threshold

279
Q

At the peak of deploarization the L type calcium channel _____, and the permeability of calcium ____.

A

closes; goes down

280
Q

When the L-type calcium channels close, _____ opens.

A

voltage gated potassium channels

281
Q

The increased permeability to potassium (opening of K+ channels) leads to:

A

repolarization to rest

282
Q

As soon as repolarization to rest occurs what happens?

A

process starts over again (with F channels opening)

283
Q

In skeletal muscle, the depolarizaiton of neurons is due to ______, while in cardiac muscle, the depolarization of AR cells is due to _____.

A

sodium; calcium

284
Q

Describe what neurotransmitters are involved in sympathetic control of AR cells:

A

Epi and NE

285
Q

Describe what neurotransmitters are involved in parasympathetic control of AR cells?

A

acetylcholine

286
Q

What receptors do NE and epi bind to?

A

beta 1 adrenergic

287
Q

What receptors do acetylcholine bind to?

A

muscarinic

288
Q

Describe the effects of NE and E binding to beta-1 adrenergic receptors to control AR cells:

A
  • Increase in probability of opening F-type channels and transient calcium channels
  • Decrease in time to threshold
  • Increase in HR
289
Q

The aspects of sympathetic control on AR cells are considered:

A

positive chronotropic agens

290
Q

Describe the effects of Ach binding to muscarinic receptors to control AR cells:

A
  • decrease in probability of opening F-type channels
  • Increase in probability of opening of K+ channels
  • Hyperpolarization of membrane
  • Increase in time to threshold
  • Decrease in HR
291
Q

The aspects of parasympathetic control on AR cells are considered:

A

negative chronotropic agents

292
Q

Agents that function to increase HR:

Agents that function to decrease HR:

A
  1. positive chronotropic agents
  2. negative chronotropic agents
293
Q

Facilitated diffusion rate of ion= (equation)

A 
                  Probability of opening of channels
294
Q

________ we need to be able to change the HR based on the needs of the body

A

teleologically

295
Q

SA node spontaneous rate =
Normal resting HR=

Meaning the heart is under ______ NS control

A

100bpm
80bpm

parasympathetic

296
Q

Contractile Cell Depolarization Events:

Phase 4=

Caused by:

A

resting membrane potential- sodium channels reset gate and are ready for next AP

297
Q

Contractile Cell Depolarization Events:

Phase 0=

Caused by:

A

spike of depolarization- due to sodium entry through fast voltage gated sodium channel- activation/inactivation gates are open here

298
Q

Contractile Cell Depolarization Events:

Phase 1=

Caused by:

A

Partial repolarization- fast gated sodium channels close,

299
Q

Contractile Cell Depolarization Events:

Phase 2=

Caused by:

A

plateau- transient potassium channels close and L-type calcium channels open

300
Q

Contractile Cell Depolarization Events:

Phase 3:

Caused by:

A

Repolarization- L-type calcium channels close, slow K+ channels open

301
Q

Unlike AR cells, contractile cells have:

A

resting membrane potential

302
Q

Plateau phase is unique to:

A

contractile cells (does NOT) occur in NS or skeletal system

303
Q

During this phase of contractile cell AP, the number of positive charges entering the cell is equal to the number of positive charges exiting the cell:

A

plateau phase

304
Q

Atrial cell contraction corresponds to what wave on an ECG?

A

P-wave

305
Q

Ventricular depolarization corresponds to what wave on an ECG?

A

QRS complex

306
Q

Ventricular repolarization corresponds to what wave on an ECG?

A

T-wave

307
Q

The ____ cells have the AP with the pacemaker potential, while the _____ cells have the AP with the plateau

A

AR cells; contractile cells

308
Q

What are located in the membrane of T-tubules in contractile cells?

A

DHP L-type calcium channels

309
Q

What stimulates the DHP L-type calcium channels to open?

A

Stimulated to open when AP reaches them

310
Q

What are the two ways to reduce cytosolic calcium following contractile cell contraction?

A
  1. calcium ATPase in SR membrane (primary active uniporter)
  2. secondary antiporter in PM (sodium in, calcium out)
311
Q

Excitation contraction coupling in cardiac muscle:

Excitation (depolarization of the plasma membrane) leads to:

A

Opening of plasma membrane L-type Calcium channels in T-tubules

312
Q

Excitation contraction coupling in cardiac muscle:

Following the opening of plasma membrane L-type channels in t-tubules, what occurs?

A

flow of calcium into the cytosol from the ECF (10%)

313
Q

Excitation contraction coupling in cardiac muscle:

After calcium flows into the cell from the cytosol, what occurs?

A

calcium binds to calcium ryanodine receptors on the outer membrane of the SR

314
Q

Excitation contraction coupling in cardiac muscle:

After calcium binds to the ryanodine receptors of the SR, what occurs?

A

Flow of calcium out of the SR and into the cytosol (90%)

315
Q

When calcium from outside the cell causes calcium from inside the SR to be released into the cytosol, this is known as:

A

calcium-induced-calcium release

316
Q

Excitation contraction coupling in cardiac muscle:

Once the bulk of calcium (90%) flows into the cytosol from the SR with the addition of the other 10% of calcium from the ECF this ultimately causes:

A

Increase in cytosolic calcium concentration, cross-bridge cycling and contraction

317
Q

In both skeletal muscle and cardiac muscle contraction, _____ is required.

A

calcium

318
Q

In both skeletal and cardiac muscle contraction, ______ begins once calcium binds to troponin

A

cross-bridge cycling

319
Q

In both skeletal and cardiac muscle contraction, a _____ pumps calcium back into the _____.

A

primary active uniporter; SR

320
Q

A difference between cardiac and skeletal muscle contraction is that in addition to the primary active uniporter, cardiac muscle uses a _____ in the membrane to pump calcium into the _____.

A

secondary active antiporter; ECF

321
Q

In skeletal muscle, all the calcium from contraction comes form the _____ while in cardiac muscle, some calcium comes from ______ and the rest comes from _____

A

SR; ECF and SR

322
Q

In skeletal muscle, the AP is very quick and over before the contractile event even begins which allows for:

A

summation and tetanus to occur

323
Q

What aspect of cardiac muscle contractile events causes the AP to be longer?

A

plateau phase

324
Q

In cardiac muscle contraction, the contractile event occurs simultaneously with the:

A

Electrical activity in the cell

325
Q

In cardiac muscle contraction, by the time the muscle has returned to its resting state, the ____ is already over

Because of this, _____ and ____ cannot occur

A

contractile event

summation and tetanus

326
Q

What is the mechanistic explanation of cardiac muscles inability to go into summation and tetanus?

A

Because the duration of the absolute and relative refractory periods is so long that by the time you can actually generate another AP, the muscle has relaxed

327
Q

What is the teleological explanation of cardiac muscles inability to go into summation and tetanus?

A

We do not want our heart to go into summation and tetanus, we want our heart to contract and relax in between beats so we can fill the heart with blood and pump it out to the body

328
Q

Where does the electrical signal for skeletal muscle contraction come from? What stimulates contractile cells to contract?

A

somatic motor neurons; AP from the AR cells

329
Q

In skeletal muscle, contraction response to a single AP is:

A

All or none

330
Q

Graded potential is the opposite of:

A

all or none- it may happen differently every time

331
Q

Because skeletal muscle contractile response to a single AP is all or none, the calcium released saturates _____ and contraction strength is _____.

A

troponin; maximal

332
Q

In cardiac muscle, contractile response to a single AP is:

A

graded

333
Q

In “resting” state, AP-induced sarcoplasmic release of calcium in cardiac cells does NOT:

A

saturate troponin sites

334
Q

The strength of contraction in cardiac muscle is dependent on:

A

the concentration of calcium inside the cell

335
Q

The amount of intracellular calcium is adjusted to:

A

change or increase the strength of contraction

336
Q

Substances that alter the force of contraction of cardiocytes by changing the cytosolic calcium concentration are termed:

A

inotropic agents

337
Q

Inotropic agents change the _____ of the heart

A

contractility

338
Q

Positive inotropic agents _____ the force of contraction
Negative inotropic agents _____ the force of contraction

A

Increase; decrease

339
Q

Inotropic agents work via:

A

voltage gated calcium channels

340
Q

Under sympathetic influence, describe what happens to heart contraction?

A

More forceful contraction and shorter duration of contraction

341
Q

When epinephrine and norepinephrine bind to _______ which are GPCRs, these activate ________.

A

Beta-1 adrenergic receptors; CAMP

342
Q

When Epinephrine and NE bind to beta-1 adrenergic receptors causing activation of CAMP, this results in what two things:

A
  1. phosphorylation of voltage-gated calcium channels
  2. phosphorylation of phospholambin
343
Q

When CAMP causes the phosphorylation of voltage-gated calcium channels, this causes the voltage gated calcium channels to ______ resulting in ______.

A

stay open longer resulting in increased calcium entry from ECF

344
Q

Because phosphorylation of the voltage gated calcium channels allows them to stay open longer and bring more calcium into the cell from the ECF, This leads to what 3 things?

A
  1. Increased calcium stores in SR
  2. Increased calcium release from SR
  3. More forceful contraction
345
Q

CAMP phosphorylating phospholamban increased the activity of ______ in the SR

A

calcium ATPase

346
Q

The increased activity of the calcium ATPase in the SR (caused by phosphorylation via camp on phospholamban) leads to :

A
  1. increased calcium stores in the SR
  2. faster calcium removal from cytosol
347
Q

The chain events of phosphorylation of phospholamban that ultimately increase the calcium ATPase activity which increases calcium stores in the SR and causes calcium to be removed faster from cytosol more quickly leads to:

A
  1. increased calcium release from SR leading to a more forceful contraction
  2. Shortens Ca-troponin binding time leading to a shorter duration of contraction
348
Q

Ultimately under sympathetic influence on contractile cells, you get:

A
  1. more forceful contraction
  2. quicker duration of contraction
349
Q

Pressure Aria < Pressure Veins
Pressure Atria > Pressure Ventricles
Pressure Ventricles < Pressure Arteries

A

Between Beats

350
Q

Describe the atria and ventricles between beats:

A

completely relaxed (in diastole)

351
Q

Between beats, the the pressure of the atria is less than the pressure in the veins, therefore:

A

blood will flow into the atria

352
Q

Between beats, the pressure of the atria is greater than the pressure in the ventricles, therefore:

A

AV valves are open so blood is flowing into the ventricles

353
Q

Between beats, the pressure of the ventricles is less than the pressure in the arteries, therefore:

A

The semilunar valves are shut

354
Q

Between beats, the blood returning to the right atrium is from the:

Between beats, the blood returning to the left atrium is from the:

A

systemic circulation

pulmonary circulation

355
Q

Between beats is the period of _______, meaning:

A

Period of Passive Filling- 80% of blood for contraction is loaded into the ventricles at this time

356
Q

Pressure of atria is elevated
Pressure atria> Pressure veins
Pressure atria> Pressure ventricles
Pressure ventricles < Pressure arteries

A

Atrial systole

357
Q

During atrial systole:

  1. The pressure of the atria is greater than the pressure of the veins, therefore:
  2. The pressure of the atria is greater than the pressure of the ventricles, therefore:
  3. The pressure of the ventricles is less than the pressure of the arteries, therefore:
A
  1. potential backflow into the veins may occur
  2. AV valves are open
  3. Semilunar valves are shut
358
Q

As the atria contracts, blood will travel into the:

A

ventricles

359
Q

Atrial systole is a period of ______ meaning ______.

A

Period of active filling; 20% of blood for contraction is loaded into the ventricles at this time

360
Q

Pressure of atria decreased
Pressure of ventricles increased
Pressure atria < Pressure veins
Pressure atria < pressure ventricles
Pressure ventricles < pressure arteries

A

Atrial diastole/early ventricular systole

361
Q

In atrial diastole/early ventricular systole:

  1. The pressure of the atria is decreased because:
  2. The pressure of the ventricles is increased because:
  3. The pressure of the A < Pressure of veins therefore:
  4. The pressure of the atria < pressure of the ventricles therefore:
  5. The pressure of the ventricles <the pressure of the arteries:
A
  1. the atria are relaxed
  2. the ventricles contract
  3. blood will start flowing back into the atria
  4. AV valves will shut
  5. Semi lunar valves are shut
362
Q

We’ve filled the bag with blood and now closed all entrances and exits and then we start to squeeze causing a rapid rise in pressure in ventricles:

What stage of the cardiac cycle does this describe?

A

Atrial diastole/ early ventricular systole

363
Q

During atrial diastole/early ventricular systole is the period of ____ meaning that:

A

period of isovolumetric contraction; pressure in ventricles rises rapidly

364
Q

Pressure atria< pressure veins
Pressure atria < pressure ventricles
Pressure ventricles > pressure arteries

A

Late ventricular systole

365
Q

In late late ventricular systole:

  1. The pressure of the atria is less than the pressure of the veins, therefore:
  2. The pressure of the atria is less than the pressure in the ventricles, therefore:
  3. The pressure in the ventricles is greater than the pressure in the arteries, therefore:
A
  1. blood will be flowing into the atria
  2. The AV valves are shut
  3. Semilunar valves are open and blood will be ejected into the arteries
366
Q

During late ventricular systole is the ________ meaning ______.

A

Ejection phase; equal volume of blood ejected into both circulations

367
Q

In the ejection phase where is the blood ejected into?

A

aorta on the left side and pulmonary trunk on the right side

368
Q

Pressure of ventricles is decreased
Pressure atria < pressure veins
Pressure atria < pressure ventricles
Pressure ventricles < pressure arteries

A

early ventricular diastole

369
Q

During early ventricular diastole:

  1. Pressure of ventricles is decreased because:
  2. Pressure of atria is less than the pressure of the veins, therefore:
  3. Pressure of atria is less than the pressure of the ventricles, therefore:
  4. Pressures of the ventricles is less than the pressure of the arteries, therefore:
A
  1. because ventricles are relaxing
  2. so blood will be flowing into atria
  3. AV valves will be shut
  4. Semilunar valves are shut
370
Q

So we have emptied this bag of atleast half of its volume, closed both entrances and exits, and have allowed it to relax

This describes what stage of the cardiac cycle?

A

early ventricular diastole

371
Q

During early ventricular diastole is the period of _____ meaning:

A

Period of isovolumetric relaxation meaning the pressure of the ventricles falls rapidly

372
Q

Pressure atria< pressure veins
Pressure atria> pressure ventricles
Pressure ventricles < pressure arteries

A

Late ventricular diastole

373
Q

During late ventricular diastole:

  1. The pressure pressure of the atria is greater than the pressure of the ventricles, therefore:
  2. The pressure in the ventricles is less than the pressure in the arteries, therefore:
A
  1. AV valves are open- we start to fill the ventricles again
  2. Semilunar valves are shut
374
Q

During late ventricular diastole, the period of ______ begins.

A

Period of passing filling (again)

375
Q

Volume of blood in the ventricle before it contracts (at the end of ventricular diastole)

A

end diastolic volume

376
Q

EDV=

A

end diastolic volume

377
Q

The average EDV=

A

135 ml

378
Q

The volume of blood that is in the ventricle at the end of ventricular systole (the minimum amount of blood after contraction)

A

end systolic volume (ESV)

379
Q

ESV=

A

end systolic volume

380
Q

What is the average ESV?

A

65ml

381
Q

Volume of blood ejected per beat:

A

stroke volume

382
Q

Stroke volume (SV) =

(equation)

A

EDV- ESV

383
Q

An average stroke volume is around:

A

70ml/beat

384
Q

Fraction of EDV ejected per beat:

A

ejection fraction

385
Q

Equation for ejection fraction:

A

SV/ EDV

386
Q

The average ejection fraction is _____ at rest

A

52%

387
Q

Heart sounds are due to:

A

valve closures

388
Q

What causes the 1st heart sound?

A

Closure of AV valves

389
Q

What causes the 2nd heart sound?

A

closure of semilunar valves

390
Q

Abnormal heart sounds due to valve dysfunction:

A

heart murmurs

391
Q

Heart murmur caused by failure of valves to open completely:

A

stenosis

Lub-shhh-dub

392
Q

Heart murmur caused by failure of valves to close properly:

A

Insufficiency or prolapse

Lub-dub-shhh

393
Q

Compare pressure changes in pulmonary circulation to the pressure changes in systemic circulation:

A

Pressure changes in pulmonary circulation are much smaller

394
Q

The amount of blood pumped out of each ventricle in one minute:

A

cardiac output

395
Q

Equation for cardiac output:

A

CO= HR x SV

396
Q

Normal resting CO= 70bpm x 70 ml/beat=

A

5L per minute

397
Q

During intense exercise, CO can:

A

elevate (30-35 L/min)

398
Q

CO is regulated to match:

A

demands of tissues

399
Q

What factors can increase CO?

A
  • physical activity
  • metabolic status
  • drugs
400
Q

What factors can decrease CO?

A
  • blood loss
  • heart disease
401
Q

How can we control CO?

A

by changing HR and SV

402
Q

Factors that increase HR

A

positive chronotropic agents

403
Q

Factors that decrease HR

A

negative chronotropic agents

404
Q

HR is mainly controlled by:

A

input from the nervous system

405
Q

_____ increases the heart rate (AR and contractile cells)

____ decreases heart rate (AR cells only)

A

SNS; PNS

406
Q

If we want to affect the heart rate we want to change the function of ____ cells, NOT ____ cells

A

AR cells; contractile cells

407
Q

In order to increase heart rate we need to (2):

A
  1. Increase speed at which APs are generated by SA node
  2. Increase speed at which those APs travel through the conduction system
408
Q

Factor that increases the speed at which the action potential moves through the myocardium:

What NTs might do this?

A

positive dromotropic agent

Epinephrine & NE

409
Q

Factor that reduces the speed at which the AP moves through the myocardium:

What NTs might do this?

A

negative dromotropic agent

Acetylcholine

410
Q

Equation for stroke volume (SV)

A

SV= EDV-ESV

411
Q

SV is altered by:

A
  1. change in preload (EDV)
  2. change in afterload (BP)
  3. change in contractility (force of contraction)
412
Q

At rest, cardiac muscle sits at a length that is:

A

less than optimum

413
Q

___EDV: ___ stretch of myocardium: moves cardiocyte length toward ____: ____SV

A

Increase; increased; optimum; increased

414
Q

Starling Law of the heart states:

A

Increased EDV leads to Increased SV

415
Q

Anything that increased EDV increases what two things?

A

force of contraction and stroke volume

416
Q

Stroke volume is an index of:

A

force of contraction

417
Q

EDV is an index of:

A

resting fiber length

418
Q

EDV is ____ to venous return (VR)

A

directly related to

419
Q

Rate at which blood is returned to the heart from veins

A

VR

420
Q

High compliance, flaccid vessels that can hold up to 60% of the total blood volume:

A

veins

421
Q

Can expand to hold more blood with out a change in pressure:

A

veins

422
Q

The change in pressure to return blood to the heart from the capillaries is:

A

very small

423
Q

_____ facilitates blood movement back to the heart (venous return)

A

one-way valves

424
Q

Factors that increase VR that are dependent on one-way valves in veins:

A
  1. increase in skeletal muscle pump
  2. increase in thoracic pump
  3. increase in venoconstriction via sympathetic NS
425
Q

The increase in venoconstriction via the sympathetic nervous system increasing venous return is due to what receptors?

A

alpha-1 adrenergic receptors

426
Q

What is one factors that increases VR that is NOT dependent on one way valves in veins:

A

Extremely high HR (tachycardia) because this causes a drop in EDV which leads to a drop in CO leading to a lower stroke volume

427
Q

increasing thoracic pressure against a closed glottis, used during defecation reflex:

A

valsalva maneuver

428
Q

Valsalvas maneuver functions to ____ venous return because it crease a large increase in thoracic pressure, which ____ VR, ____ EDV, ____SV, ___ CO

A

decrease all of them

429
Q

How is HR related to SV?

A

indirectly related

430
Q

How is CO related to HR (at a NORMAL HR)

A

directly related

431
Q

_____ has a greater affect on CO than ____ under normal conditions

A

HR; SV

432
Q

When you increase HR, you increase CO, however past _____ increasing HR will lead to a decrease in CO and this is because:

A

200bpm; you do not have enough time to fill the ventricles with blood before they beat, reducing EDV and SV and CO

433
Q

The pressure that the ventricles must overcome to force open the aortic and pulmonary valves

A

afterload

434
Q

Anything that increases systemic or pulmonary arterial pressure can _____ the afterload

A

increase (hypertension)

435
Q

Increase in afterload causes a ____ In SV

A

decrease

436
Q

_____ is not a major factor in healthy subjects

A

afterload

437
Q

Peak pressure in ventricle:

A

systolic BP

438
Q

Pressure at which the semilunar valves open and minimum pressure in aorta=

A

diastolic BP

439
Q

At 130/90 what pressure is needed to open the semilunar valves?

A

90

440
Q

If the heart has to work harder to open the valves (increased BP for example), the heart will _____ and this will lead to ____.

A

grow; left ventricular hypertrophy

441
Q

Anything that increases the afterload on the heart will lead to a ____ in SV

A

reduction

442
Q

The ability of the heart to contract at any given resting fiber length

A

Contractility

443
Q

The ventricles are never completely empty of blood (ejection fraction), so a more forceful contraction will:

A

expel more blood with each pump

444
Q

Contractility is varied by controlling the amount of ____ that enters the contractile cell via _____ gated channels

A

Ca++; L type voltage gated Ca++ channels

445
Q

Because the amount of calcium that enters the cell via the L-type voltage gated ca++ channels determines the contractility of the muscle, this is considered a _____ contration

A

graded

446
Q

What effects does a positive inotropic agent have on contractility and ejection fraction

A

Increase in contractility and increase in ejection fraction

447
Q

Give examples of positive inotropic agents:

A

Sympathetic stimulation and epinephrine

448
Q

What effects does a negative inotropic agent have on contractility and ejection fraction?

A

Decrease in contractility and decrease in ejection fraction

449
Q

Give examples of negative inotropic agents:

A

beta 1 blockers and Ca++ Channel blockers

450
Q

Adrenergic effects on cardiac muscle contractility: (2)

A
  1. increase force
  2. increase speed
451
Q

Adrenergic effects on cardiac muscle contractility:

The SNS releases Epi and NE which bind to:

A

Beta1 adrenergic receptors

452
Q

Adrenergic effects on cardiac muscle contractility:

When Epi and NE bind to beta1 adrenergric receptors in the contractile cell membrane, this activates:

A

The inactive CAMP dependent protein kinase

453
Q

Adrenergic effects on cardiac muscle contractility:

When the CAMP-dependent protein kinase becomes activated, what effects are seen in the contractile cell? (3)

A
  1. VG L-type calcium channel gets phosphorylated
  2. Myosin heads get phosphorylated
  3. Calcium ATPase activity in SR membrane is increased (indirect through phospholambin)
454
Q

Adrenergic effects on cardiac muscle contractility:

Further explain the effects of the VG L-type calcium channel after it is phosphorylated:

A

This increases the FDR (the rate that calcium ions come into the cell- bc the probability that the channel is open)

The increased FDR results in more calcium release form SR which leads to a greater calcium spike, more troponin bound to calcium and therefore a MORE FORCEFUL CONTRACTION

455
Q

Adrenergic effects on cardiac muscle contractility:

Further explain what happens when the myosin heads get phosphorylated by CAMP-dependent protein kinase?

A

When myosin heads get phosphorylated, this will cause the heads to cycle faster which will GENERATE TENSION MORE QUICKLY

456
Q

Adrenergic effects on cardiac muscle contractility:

What aspect of the SNS affects on contractile cells is considered “contractility effect”

A

Voltage gated calcium channels getting phosphorylated causing a more forceful contraction

457
Q

Adrenergic effects on cardiac muscle contractility:

Further explain what happens to the activity of the calcium ATPase

A

This occurs indirectly through phosolambin- When the calcium ATPase gets phosphorylated, its activity increases therefore the rate of calcium removal from the cytosol is increased so the cell can relax faster

458
Q

Under the effects of SNS on contractile cells:

  1. The overall amount of tension will go up. Why?
  2. Speed of tension development will be quicker. Why?
  3. Muscle will relax more quickly. Why?
A
  1. Due to increased amount of calcium from SR (contractility effect)
  2. Because of myosin heads getting phosphorylated
  3. Because of increased calcium ATPase activity
459
Q

Startlings law of the heart states that:

A

Anything that increases EDV will increase SV

460
Q

Sympathetic motor neurons and epinephrine through B1 receptors act on ______ to do _____

A

Atria and ventricles to increase BOTH HR and SV

461
Q

Parasympathetic neurons releases Ach that will bind to muscarinic receptors on the ____ that will only effect ____.

A

atria; HR

462
Q

Describe parasympathetics motor neurons effect on stroke volume:

A

No effect on SV

463
Q

At rest, the amount of ______> ______ so we know at rest our heart is overall under _____ influence.

A

Ach> NE; parasympathetic

464
Q

Receptors on the atria are for the influence of ______, while the receptors on the ventricles are for _______.

A

HR; SV

465
Q

Cardiac output is a function of _____ & _____.

A

SV and HR

466
Q

What is the functional unit of cardiac muscle? What is the functional unit of skeletal muscle?

A

Sarcomeres

467
Q

Since sarcomeres are the functional unit of both cardiac skeletal muscle; they both have _____ relationship

A

length/tension

468
Q

What does having a length/tension relationship mean?

A

Means that there is a resting fiber length where you will have optimum tension

469
Q

What happens if you move away from the resting fiber length?

A

You decrease the tension the muscle can generate

470
Q

The stimulus for cardiac muscle is _____; while the stimulus for skeletal muscle is _____.

A

Intrinsic; extrinsic

471
Q

Describe the calcium release in skeletal muscle:

A

100% SR

472
Q

Describe the calcium release in cardiac muscle:

A

90% SR, 10% ECF

473
Q

Contractile response to a single action potential:

A

muscle twitch

474
Q

Describe the muscle twitch in cardiac muscle:

A

graded

475
Q

What is the preferred drug of choice for dysrhythmia?

A

Beta-blockers

476
Q

Describe the effects of each on CO:

  1. Increasing Sympathetic activity
  2. Increasing parasympathetic activity
  3. Increasing movement
  4. Decreasing HR
  5. Increasing resting sarcomere length
  6. Increasing BP`
A
  1. Increase CO
  2. Decrease CO
  3. Increase CO
  4. Decrease CO
  5. Increase CO
  6. Decrease CO
477
Q

Explain why increasing movement would increase CO:

A

Due to skeletal muscle pump, which increases venous return, that will increase EDV and therefore increase SV

478
Q

Explain why increasing resting sarcomere length would increase CO. What would happen if we decreased it?

A

Cardiac muscle sits at a less than optimum length, so by increasing resting sarcomere length, we are getting closer to optimum.

If we decreased it because we are already at a less than optimum length, this would move it further away from optimum.

479
Q

Explain why decreasing BP would increase CO:

A

Because BP is the afterload on the heart. Anything that will decrease the load that the heart has to contract against will increase SV

Physiology (10 decks)

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