Physiology Exam 4 - Cardiac Output and Blood Pressure

Question 1

What are the heart rhythm and contraction controlled by?

Answer 1

cardiac centers in the medulla oblongata

Question 2

What does the cardioacceleratory center do?

Answer 2

sends sympathetic innervation via the cardiac nerves and increases heart rate and contraction strength

Question 3

What does the cardioinhibitory center do?

Answer 3

sends parasympathetic innervation via the vagus nerves and slows the heart rate

Question 4

Cardiac output (CO)

Answer 4

the amount of blood ejected by each ventricle in 1 min (L/min)

Question 5

What is the equation for cardiac output?

Answer 5

CO = heart rate x stroke volume

Question 6

What is the normal cardiac output at rest?

Answer 6

4 to 6 L/min

Question 7

How does vigorous exercise change cardiac output?

Answer 7

it increases to 21 L/min all the way up to more than 40 L/min

Question 8

Stroke volume

Answer 8

the volume of blood each ventricle ejects during contraction

Question 9

What variables govern stroke volume?

Answer 9

• preload
• contractility
• afterload

Question 10

What is the equation for stroke volume?

Answer 10

SV = EDV - ESV

Question 11

What happens when a person experiences hemorrhage (blood loss) and the SV declines to maintain CO?

Answer 11

The heart rate increases

Question 12

Cardiac reserve

Answer 12

the difference between a person’s maximum and resting CO (increases with fitness and decreases with disease)

Question 13

Positive chronotropic agents

Answer 13

factors that raise the heart rate (see list in slides)

Question 14

Negative chronotropic agents

Answer 14

factors that lower the heart rate (see list in slides)

Question 15

Positive ionotropic agents

Answer 15

increase the force of muscle contraction of the heart (see list in slides)

Question 16

Negative ionotropic agents

Answer 16

weaken the force of muscle contraction and slow the heart (see list in slides)

Question 17

Pulse

Answer 17

surge of pressure produced by heart beat that can be felt by palpating a superficial artery (measured in beats per minute)

Question 18

What is the normal heart rate of infants?

Answer 18

120 bpm or more

Question 19

What is the normal heart rate of young adult males?

Answer 19

65 to 75 bpm

Question 20

What is the normal heart rate of young adult females?

Answer 20

70 to 78 bpm (higher than males because of hormones)

Question 21

Tachycardia

Answer 21

resting adult heart rate above 100 bpm

Question 22

Why are the two most common causes of tachycardia?

Answer 22

• stress, anxiety, drugs, heart disease, or fever
• loss of blood or damage to myocardium

Question 23

Bradycardia

Answer 23

resting adult heart rate of less than 60 bpm

Question 24

What are causes of bradycardia?

Answer 24

• low body temperature and endurance-trained athletes
• experienced during sleep (lower metabolic demands)

Question 25

What symptoms can bradycardia cause?

Answer 25

fainting, lightheadedness, and headache

Question 26

Preload

Answer 26

the amount of tension in ventricular myocardium immediately before it begins to contract - increased preload causes increased force of contraction - the stroke volume increases as the EDV increases

Question 27

Frank-Starling law

Answer 27

- cardiac hemodynamics as it relates to cardiomyocyte stretch and contractility - SV will increase as the left ventricular volume increases due to the myocyte stretch causing a more forceful systolic contraction

Question 28

Contractility

Answer 28

how hard the myocardium contracts for a given preload

Question 29

Ejection fraction

Answer 29

percentage of blood leaving the heart each time it contracts

Question 30

What is the equation for ejection fraction?

Answer 30

EF = SV/EDV (expressed as a percentage)

Question 31

What is the average ejection fraction at rest?

Answer 31

50% to 75%

Question 32

Afterload

Answer 32

sum of all forces opposing ejection of blood from ventricles; the largest part of afterload is blood pressure in the aorta and pulmonary trunk (opposes the opening of semilunar valves)

Question 33

What does hypertension do?

Answer 33

increases afterload and opposes ventricular ejection

Question 34

What does an increase in arterial pressure do to afterload and stroke volume?

Answer 34

increases afterload and decreases stroke volume

Question 35

Echocardiography

Answer 35

- noninvasive technique that uses ultrasonic waves - can detect abnormal functioning of cardiac valves or contractions of the cardiac walls - can also be used to measure ejection fraction

Question 36

Cardiac angiography

Answer 36

- endovascular procedure where a catheter is inserted through an artery or vein into the heart - a liquid containing radiopaque contrast material is then injected through the catheter during high-speed x-ray videograpth - it is useful for evaluating cardiac function and for identifying narrowed coronary arteries

Question 37

How does the pressure in the pulmonary and systemic circulation vessels differ?

Answer 37

the pressure is higher in the systemic circulation

Question 38

What vessel is the pressure the highest in?

Answer 38

arteries

Question 39

What vessel is the pressure the lowest in?

Answer 39

veins

Question 40

Arteries

Answer 40

elastic tubes with thick walls that contain large quantities of elastic tissue; due to their elasticity, they also act as "pressure reservoirs" for maintaining blood flow through the tissues during diastole

Question 41

Systolic pressure

Answer 41

maximum arterial pressure reached during the peak of ventricular contraction and ejection

Question 42

Diastolic pressure

Answer 42

minimum arterial pressure reached just prior to ventricular ejection

Question 43

Arterial blood pressure

Answer 43

SP/DP (120/80)

Question 44

Pulse pressure

Answer 44

the difference between SP and DP

Question 45

Mean arterial pressure

Answer 45

average pressure driving blood to the tissues over the cardiac cycle

Question 46

What is the formula for mean arterial pressure?

Answer 46

MAP = DP + 1/3PP

Question 47

What is the name of the sounds listened for when measuring blood pressure?

Answer 47

Korotkoff sounds