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Physiology > Exam #2 (Ch 4 & 5) > Flashcards

Exam #2 (Ch 4 & 5) Flashcards

1
Q

Pulmonary circulation is a low/high pressure system

A

Low Pressure System

Right heart, pulmonary arteries, veins & capillaries & pulmonary system

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2
Q

Systemic circulation is a low/high pressure system

A

High Pressure System

Left heart, and rest of body arterial circulation

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3
Q

In order to create a flow one needs

A

A pressure gradient

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4
Q

Deliver blood and nutrients to tissues
Takes waste away from tissue
Assist in regulating blood pressure

A

Blood Vessels

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5
Q

Blood Vessels

A

Deliver blood and nutrients to tissues
Takes waste away from tissue
Assist in regulating blood pressure

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6
Q

Where do arteries conduct blood?

A

Arteries conduct blood away from the heart

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7
Q

Are arteries high or low pressure?

A

High pressure

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8
Q

What is the largest artery?

A

Aorta

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9
Q

What are characteristic of the walls of the arteries?

A

Elastic tissue
Smooth muscle
Connective tissue

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10
Q

What is stressed volume?

A

The blood that is in the arteries is under high pressure so it is called stressed volume

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11
Q

The blood that is in the arteries is under high pressure so it is called

A

Stressed Volume

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12
Q

The smallest branches of the arteries

A

Arterioles

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13
Q

The site of highest resistance to blood flow

A

Arterioles. Their walls are made up of smooth muscle.

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14
Q

The smooth muscle of the arterioles are tonically active or inactive?

A

Tonically active (always contracted)

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15
Q

The sympathetic fibers that innervate the smooth muscles of the arterioles

A

Alpha 1: found on the arterioles near skin & splanchnic organs. Cause contraction or vasoconstriction
Beta 2: Less common & cause relaxation or vasodilation when activated. Found in skeletal muscle cells

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16
Q

These sympathetic fibers of the smooth muscles of the arterioles are found near skin & splanchnic organs. Cause contraction or vasoconstriction.

A

Alpha 1

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17
Q

These sympathetic fibers of the smooth muscles of the arterioles are found in skeletal muscle cells. They are less common. Cause relaxation or vasodilation when activated

A

Beta 2

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18
Q

Capillaries

A

Thin-walled allowing for effective diffusion

Lined w/ a single layer of endothelial cells again allowing for exchange of nutrients, water, and gases

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19
Q

The Selective Perfusion of Capillaries is determined by

A

The degree of dilation or constriction of the arterioles & precapillary sphincters. The degree of dilation or constriction controlled by sympathetic innervation of vascular smooth muscles & by vasoactive metabolites produced in the tissues

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20
Q

Veins

A

Thin-walled
Modest amount of elastic tissue
Very large capacitance. Contains the largest proportion of blood in the cardiovascular system (most blood volume is found in veins)
Considered unstressed volume
Have valves to prevent retrograde or back flow
Innervated by sympathetic fibers. An increase in sympathetic activity = constriction = reduces their capacitance & therefore reduces the unstressed volume

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21
Q

The blood in the veins is also called

A

Unstressed volume

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22
Q

Purpose of valves in veins

A

Prevent retrograde or back flow

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23
Q

Increase in sympathetic activity on veins

A

Increase in sympathetic activity = constriction = reduces their capacitance & therefore reduces the unstressed volume

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24
Q

Formed from merged capillaries (low pressure)

A

Venules

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25
Q

Velocity of blood flow

A 
V = Q/A
Rate of displacement of blood per unit time
V = Velocity of blood flow (cm/sec)
Q = Flow (mL/sec)
A = Cross-sectional area (cm^2)
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26
Q

Variables Impacting Blood Flow Velocity

A

It is directly proportional to blood flow & inversely proportional to cross-sectional area

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27
Q

Where is blood flow high & where is it low?

A

Blood flow is higher in the aorta (small cross sectional area) than the sum of all the capillaries (large cross sectional area)

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28
Q

How do we want blood flow velocity to be in areas of exchange?

A

Lower velocity allows for optimal exchange

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29
Q

Blood Flow is determined by

A

Pressure gradient

Resistance

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30
Q

Equation for Blood Flow

A

Q = ∆P/R

Q = Flow (mL/min)
∆P = Pressure difference (mmHg)
R = Resistance (mmHg/mL/min)
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31
Q

Blood flow is directly proportional to ____ & inversely proportional to _____

A

Magnitude of blood flow is directly proportional to pressure gradient and inversely proportional to resistance

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32
Q

The major mechanism for changing blood flow in the cardiovascular system is by

A

Changing the resistance of blood vessels. Occurs primarily at the level of the arterioles due to smooth muscle contraction.

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33
Q

Total Peripheral Resistance (TPR)

A

Resistance of the entire systemic vasculature. Aka Systemic Vascular Resistance (SVR)
R = ∆P/Q

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34
Q

Resistance to Blood Flow is dependent on

A

Vessel diameter/radius & blood viscosity. Also based on parallel or series arrangement of blood vessels

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35
Q

Poiseuille Equation

A

R = 8µl / πr^4

R = Resistance
µ = viscosity of blood
l = length of blood vessel
r = radius
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36
Q

According to the poiseuille equation resistance is proportional to

A

Directly proportional to viscosity, length, and inversely proportional to the radius raised to the 4th power (r^4)

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37
Q

Series Resistance of Blood Flow

A

Within a given organ
Within the organ or blood flows from the major artery to smaller arteries, to arterioles, to capillaries, to venules, to veins
As resistors are added, total resistance increases
Total resistance of a system arranged in series is equal to the sum of the individual resistances

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38
Q

Parallel Resistance of Blood Flow

A

Found among the various major arteries branching off the aorta
As resistors are added, total resistance decreases
Total resistance in a parallel arrangement is less than any of the individual resistances
1/Rtot = 1/R1 + 1/R2
This arrangement ensures pressure is not loss through the system

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39
Q

What is the purpose of parallel resistance of blood flow?

A

It ensures pressure is not loss through the system

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40
Q

Laminar blood flow

A

Straight. Ideally, blood flow in the cardiovascular system is laminar. Shows a parabolic profile of velocity within a blood vessel.
Velocity of flow at the vessel wall is zero, and maximal at the center

41
Q

Turbulent blood flow

A

Disrupted flow. Stream mixes radially & axially. Found at the valves or at the site of a blood clot, or in vessels of high velocity. More energy (pressure) is required to drive turbulent blood flow than laminar blood flow. Often accompanied by audible vibrations called heart sounds or murmurs

42
Q

This type of blood flow is often accompanied by audible vibrations called heart sounds or murmurs

A

Turbulent flow

43
Q

What is Reynold’s number?

A

It predicts whether flow will be laminar or turbulent

44
Q

An increase is Reynold’s number means

A

Greater tendency for turbulence

45
Q

If Reynold’s number is less than 2000 then

A

Blood flow is likely laminar

46
Q

If Reynold’s number is greater than 2000 then

A

Blood flow is likely turbulent

47
Q

If Reynold’s number is greater than 3000 then

A

Blood flow is always turbulent

48
Q

What factors increase Reynold’s number?

A

A decrease in blood viscosity (ex: decrease in hematocrit, anemia), also increase cardio output
An increase in blood velocity (ex: narrowing of blood vessel; thrombi)

49
Q

What is compliance or capacitance?

A

Describes the distensibility of blood vessels

Inversely related to elastance

50
Q

Formula for compliance

A

C = V / P

C = compliance
V = volume (mL)
P = pressure (mmHg)
51
Q

What happens to the amount of pressure in the systemic circuit as blood flows through it?

A

Pressure decreases progressively through the systemic circulation due to increased resistance

52
Q

Blood pressure is highest in

A

The Aorta

53
Q

Blood pressure is lowest in

A

The Vena Cava

54
Q

The largest vein in the body?

A

IVC

55
Q

Diastolic Pressure

A

Pressure in the artery during ventricular diastole/relaxation
It is the lowest arterial pressure measured during a cardiac cycle

56
Q

Systolic Pressure

A

Arterial pressure measured during ventricular systole/contraction
Highest arterial pressure measured during a cardiac cycle

57
Q

Pulse Pressure

A

Difference between systolic and diastolic pressure. Co-relates to stroke volume

58
Q

Mean Arterial Pressure (MAP)

A

Average pressure in a complete cardiac cycle. MAP = diastolic pressure + 1/3 pulse pressure

59
Q

This type of pressure fluctuates during the cycle and is pulsatile

A

Arterial Pressure

60
Q

This type of pressure is very low due to high compliance

A

Venous Pressure

61
Q

Atrial Pressure

A

lower than venous pressure

62
Q

Dicrotic notch or incisura

A

The “blip” in the arterial pressure curve. Produced when the aortic valve closes

63
Q

What produces the “blip” in the arterial pressure curve?

A

When the aortic valve closes. It is called the Dicrotic notch or incisura

64
Q

Arteriosclerosis

A

Is a pathology that will alter the arterial pressure curve. It is due to plaque deposits in the arterial walls which decreases diameter/radius. It stiffens walls making them more rigid & less compliant

65
Q

Impact of Arteriosclerosis on Arterial Pressure Curve

A

Systolic pressure, pulse pressure, & mean pressure will be increased

66
Q

Impact of Aortic Stenosis on Arterial Pressure Curve

A

Occurs when the aortic valve is stenosed (hardened) due to calcification
Stroke volume is decreased b/c less blood enters the aorta on each beat. Systolic, pulse, & mean pressure will be decreased

67
Q

Aortic regurgitation

A

Due to incompetent valve causing retrograde flow

68
Q

The pacemaker of the heart

A

SA (Sinoatrial) Node. the AP originates from SA node

69
Q

Why is the SA node the pacemaker of the heart?

A

B/c it has the highest intrinsic firing rate in the heart

70
Q

Normal heart rate

A

60-100 bmp

71
Q

Sequence of myocardium activation

A

SA node -> AV node -> Bundle of His (common bundle) -> Right/Left Bundle Branches -> Purkinje Fibers

72
Q

Latent Pacemakers take over when

A

SA node firing rate decreases
SA node stops completely or is removed
If the intrinsic rate of firing of a latent pacemakers should become faster than that of the SA node, then it assumes the pacemaker role
Blocked conduction from SA node to conducting pathways

73
Q

Excitability

A

The ability of cardiac cells to initiate an action potential in response to an inward, depolarizing current. Reflects the recovery of channels that carry the inward current for the upstroke of the action potential

74
Q

Refractory Period

A

The time during which another action potential cannot be elicited

75
Q

Absolute Refractory Period

A

Period during which another action potential can be initiated, regardless of how much inward current is supplied. Begins with upstroke of the AP and ends after the plateau. Cell has repolarized to about -50 mV

76
Q

Effective Refractory Period

A

Period during which a generated action potential cannot be conducted
Slightly longer than the Absolute Refractory Period
The Na+ channels begin to recover whereby they become available to carry inward current
Inward current is not enough to conduct to the next site

77
Q

Relative Refractory Period

A

Period during which an action potential can be elicited, but more than usual current is required. Immediately after the ARP when repolarization is almost complete

78
Q

Chronotropic Effects

A

Effects of the ANS on heart rate (HR) via SA node

79
Q

Positive Chronotropic vs Negative Chronotropic Effects

A

Positive increases HR, Negative decreases HR

80
Q

Chronotropic Effectors determine the heart rate by controlling

A

The rate of phase 4. The smaller the phase 4, the faster the heart rate. Mechanism of Action for both, you change the flux of sodium. To increase HR you increase the influx of sodium. To decrease HR you decrease the influx of sodium

81
Q

Positive chronotropic effects sympathetic nervous system via

A

Beta 1

82
Q

Negative chronotropic effects parasympathetic nervous system via

A

M2

83
Q

Dromotropic Effects

A

Effects of the ANS on conduction velocity via AV node

84
Q

Positive vs Negative dromotropic effects

A

Positive leads to an increase in conduction velocity via AV node. Negative leads to a decrease in conduction velocity via AV node

85
Q

Sympathetic receptor for positive dromotropic effects

A

B1

86
Q

Parasympathetic receptor for negative dromotropic effects

A

M2

87
Q

What is a heart block?

A

AP not being conducted from atria to ventricle

88
Q

A measurement of tiny potential differences on the surface of the body that reflect the electrical activity of the heart

A

Electrocardiogram (ECG or EKG)

89
Q

P Wave

A

Represents depolarization of the atria. Duration of the wave correlates with conduction time through the atria. Atrial repolarization is not seen on a normal ECG, b/c it is “buried” in the QRS complex

90
Q

PR interval

A

From beginning of P wave to the beginning of Q wave (initial depolarization of the ventricle). Correlates w/ conduction time through the AV node. It represents ventricular filling

91
Q

QRS complex

A

Represent depolarization of the ventricles

Conduction thru the ventricle is similar to the atria b/c of high conduction velocity of the His-purkinje system

92
Q

T wave

A

Represents repolarization of the ventricles. Ventricular relaxation or diastole

93
Q

QT interval

A

Interval from beginning of Q wave to end of the T wave. Represents the entire period of depolarization & repolarization of the ventricles. Contraction & relaxation

94
Q

ST segment

A

From end of S wave to the beginning of the T wave. Represents ventricular repolarization

95
Q

Gap junctions allow are heart muscle to behave as

A

A syncytium or a unit

96
Q

Inotropism

A

The intrinsic ability of myocardial cells to develop force at a given muscle cell length

97
Q

The amount of calcium released by the sarcoplasmic reticulum is dependent on

A
  1. The size of the inward calcium current

2. The amount of calcium that was previously stored in the SR

98
Q

Positive Ionotropic Effects

A

Increase in contractility
Use Beta 1 as receptors
Increase Rate of Relaxation

Physiology (13 decks)

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