Hemodynamics

Question 1

the study of the movement of blood throughout the circulatory system along with the regulatory mechanisms and driving forces involved

it studies the factors that govern blood flow

Answer 1

hemodynamics

Question 2

Two major divisions of the circulatory system

Answer 2

Pulmonary- delivers blood to the lungs

Systemic (Peripheral) - delivers blood to all other organs and tissues

Question 3

Arteries transport blood under ___________ pressure to tissues
Arterioles are ______________ valves that regulate local blood flow

Answer 3

high; control

Question 4

Veins serve as a major _____________ of blood

Answer 4

reservoir

Question 5

Arteries are very muscular and hence are not very ________________. As a result increases in arterial pressure (AP) causes only small increases in arterial ________

Answer 5

distensible; diameter

Question 6

Veins are highly _____________. As a result, small increases in venous pressure cause large increases in venous diameter`

Answer 6

distensible

Question 7

The adult circulatory system contains __________ liters of blood, 64% of which is in the systemic ___________-

Answer 7

5; veins

Question 8

What makes blood flow ?

Answer 8

Blood moves through vessels because the force that drives blood flow is greater than the resistance to flow

Question 9

Blood moves through vessels because the force that drives blood flow is greater than the __________________ to blood flow

Answer 9

resistance

Question 10

The force that drives blood flow is the _____________ gradient between two points in a vessel

Answer 10

pressure

Blood will flow from the point where pressure is higher toward the point where pressure is lower

Question 11

Resistance to blood flow is determined by ………..

Answer 11

the diameter and length of the vessel and by blood viscosity,

Question 12

From a pharmacological viewpoint, the most important determinant of resistance is:

Answer 12

vessel diameter; the larger the vessel, the smaller the resistance

Question 13

When vessels dilate, ____________ declines, causing blood flow to ____________

Answer 13

resistance; increase

Question 14

When vessels constrict, ___________ rises, causing blood flow to ____________–

Answer 14

resistance; decline

Question 15

To maintain adequate flow when resistance rises, ______________ must rise as well

Answer 15

blood pressure

Question 16

In addition to the small pressure head in the venules, three mechanisms help ensure venous return to the heart:

Answer 16

1) negative pressure in the right atrium sucks blood toward the heart
2) constriction of veins increases venous pressure and thereby drives blood toward the heart
3) contraction of skeletal muscles, in conjunction with one-way venous valves, pumps blood toward the heart

Question 17

Every minute the heart pumps the equivalent of all the blood in the body. TRUE OR FALSE

Answer 17

TRUE

cardiac output is about 5 L/minute in the average adult

Question 18

CO=

Answer 18

HR X SV

Question 19

Heart rate is increased by the sympathetic branch of the autonomic nervous system acting through ____________________ receptors in the SA node

Answer 19

beta 1 adrenergic receptors

Question 20

Heart rate is decreased by the parasympathetic branch acting through _________________ in the SA node. These impulses reach the heart via the ____________ nerve

Answer 20

muscarinic; vagus

Question 21

What are the 3 factors stroke volume is determined by ?

Answer 21

Contractility, Preload, Afterload

Question 22

defined as the amount of tension (stretch) applied to a muscle before contraction

Answer 22

preload

Question 23

defined as the load against which a muscle exerts its force

Answer 23

afterload

Question 24

for the heart, _______________ is the Arterial pressure that the left ventricle must overcome to eject blood

Answer 24

afterload

Question 25

the force with which the ventricles contract

Answer 25

myocardial contractility

Question 26

Cardiac afterload is determined primarily by peripheral resistance, which in turn is determined by the degree of ____________ in arterioles

Answer 26

constriction

Question 27

_________________ law states that the force of ventricular contraction is proportional to myocardial fiber length. Because of this relationship, when more blood enters the heart, more is pumped out. As a result the healthy heart is able to precisely match output with venous return.

Answer 27

Starling’s

basically states that the stroke volume of the heart increases in response to an increase in the volume of blood in the ventricles, before contraction, when all other factors remain constant

Question 28

this is the force that returns blood to the heart

Answer 28

systemic filling pressure

Question 29

_____________ is the primary determinant of stroke volume

Answer 29

venous return

Question 30

_________ volume and venous ___________ can both be altered with drugs

Answer 30

Blood; tone

This can effect the systemic filling pressure and hence the stroke volume and hence the Cardiac output

Question 31

The most important determinant of venous return is _____________ filling pressure, which can be raised by _____________________

Answer 31

systemic; constricting veins and increasing blood volume

Question 32

Because cardiac muscle operates under Starling’s law, the right and left ventricles always pump exactly the same amount of blood (assuming the heart is healthy). Hence, balance between the ______________ and ____________ circulations is maintained.

Answer 32

pulmonary; systemic

Question 33

Arterial pressure is regulated by the _____________, the RAAS, the __________, and natriuretic peptides

Answer 33

Autonomic nervous system; kidneys

Question 34

The ANS regulates arterial pressure through 2 things

Answer 34

1) tonic control of heart rate and peripheral resistance

2) through the baroreceptor reflex

Question 35

The __________________ reflex is useful only for short term control of AP. When pressure remains elevated or lowered, the system resets to the new pressure within 1-2 days, and hence ceases to respond

Answer 35

baroreceptor

Question 36

Drugs that lower AP trigger the ____________________ reflex, and thereby _________ tachycardia. Hence, the _______________ reflex can temporarily negate efforts to lower AP with drugs.

Answer 36

baroreceptor; reflex; baroreceptor

Question 37

The RAAS supports AP by causing

Answer 37

1) constriction of arterioles and veins
2) retention of water by the kidneys

vasoconstriction is mediated by angiotensin II; water retention is mediated in part by aldosterone

Question 38

The _______ provide long term control of blood pressure by regulating ______________ volume

Answer 38

kidneys; blood

Question 39

Postural (orthostatic) hypotension is caused by decreased ___________return secondary to pooling of blood in veins, which can occur when we assume an ____________ posture.

Answer 39

venous; erect

Question 40

Drugs that ____ veins intensify and prolong ________________. As with other drugs that reduce AP, venodilators trigger the ______________ reflex and can thereby cause reflex tachycardia

Answer 40

dilate; postural hypotension; baroceptor

Question 41

Natriuretic peptides defend the cardiovascular system from _________________ overload- primarily by reducing blood volume and promoting ____________

Answer 41

volume; vasodilation