Chapter 9

Question 1

“Provide an overview of the design and function of the circulatory system.

Answer 1

purpose of the cardiovascular system are the following
1) transport O2 to the tissues and removal of waste
2) transport nutrients to the tissues
3) the regulation of body temperature

Question 2

Describe the cardiac cycle and the associated electrical activity recorded via the electro- cardiogram.

Question 3

Discuss the pattern of redistribution of blood flow during exercise.

Answer 3

cardiac out put = HR x SV

the pace marker of the heart is the SA node. Sa node activity is modified by the parasympathetic nervous system (slows HR_ and the sympathetic nervous system ( increase HR)
heart rate increase at the beginning of exercise due to a withdrawal of parasympathetic tone. at higher intensity work rates, the increase in HR is achieved via an increase in sympathetic outflow to the SA node
stroke volume is regulated via 1) end-diastolic volume 2) the muscle pump 3) the respiratory pump

oxygen delivery to exercising skeletal muscle increase due to 1) an increase in Cardiac output 2) residrtution of blood flow from inactive organs to the contracting skeletal muscles

During exercise, blood flow is redistributed to meet the increased metabolic needs of working muscles. “Baroreceptors detect the rise in blood pressure, but during exercise they are reset to allow higher pressures without triggering decreased heart rate.” Sympathetic nervous activity increases, producing vasoconstriction in non-working tissues such as the splanchnic organs and inactive muscles, reducing their blood flow. At the same time, local metabolic factors (e.g., adenosine, nitric oxide, CO₂, H⁺, heat, K⁺) in active muscles cause strong vasodilation, overcoming sympathetic vasoconstriction through functional sympatholysis. As cardiac output increases, the majority of the extra blood flow is directed to the working muscles, while brain and heart blood flow are maintained. This redistribution ensures adequate oxygen delivery and removal of metabolic waste during exercise.

Question 4

Outline the circulatory responses to various types of exercise.

Answer 4

cardiac output increase as a linear function of oxygen uptake during exercise. during exercise in the upright photino, stroke volume reaches a plateau at around 50% vo2 max therefore at work rate about 60 a rise in cardiac output is due to an increase in HR alone

Question 5

Identify the factors that regulate local blood flow during exercise.

Answer 5

regulatory of muscle blood flow during exercise is primary regulated by local factors called auto regulation. auto regulation refers to intrinsic control of blood flow by increase in local metabolites (nitric oxide, prostaglandins, ATP, Adenosine, endothelium derived hyperpolarizatoin factors) . these factors work together to promote vasodilation to increase blood flow in working muscles

Question 6

List and discuss those factors responsible for regulation of stroke volume during exercise.

Answer 6

1) end-diastolic volume ( EDV) –> volume of blood in ventricles at end of diastole
2) average aortic blood pressure ( cardiac after load)
3) strength of ventricular construction (cardiac contractility)

Question 7

Discuss the regulation of cardiac output during exercise.

Answer 7

cardiac output = cardiac rate x stroke volume

see graph for factors that increase and decrease HR and SV

see graphs for summary of cardiovascular response to cerise and a summary of cardiovascular control during exercise

Question 8

arteries

Question 9

arterioles

Question 10

atrioventricular node (AV node)

Question 11

autoregulation

Question 12

capillaries

Question 12

cardiac accelerator nerves

Question 13

cardiac output

Question 14

cardiovascular control center

Question 15

central command

Question 16

diastole

Answer 16

relaxation period

Question 17

diastolic blood pressure

Answer 17

during relaxtion the arterial blood pressure decreases representing diastolic blood pressure

Question 17

double product

Answer 17

double produce = heart rate x systolic blood pressure

he Double Product (DP), also called Rate-Pressure Product (RPP), isn’t a blood pressure measurement itself, but rather a crucial indicator of myocardial workload and oxygen demand by multiplying Systolic Blood Pressure (SBP) by Heart Rate (HR) (SBP x HR). It estimates how hard your heart muscle (myocardium) works, showing how much oxygen it needs, and is used in stress testing and cardiovascular risk assessment, especially with exercise.

Question 18

electrocardiogram (ECG or EKG)

Question 19

heart rate variability

Answer 19

Heart rate variability (HRV) is the variation in time intervals between consecutive heartbeats. High HRV usually occurs when parasympathetic activity is dominant and sympathetic activity is low, indicating good autonomic balance and cardiovascular adaptability.”

Question 20

intercalated discs

Question 21

mixed venous blood

Answer 21

Mixed venous blood is deoxygenated blood from the entire body, collected in the pulmonary artery after the superior and inferior vena cava have combined it,

Question 22

myocardium

Question 22

pulmonary circuit

Question 22

sinoatrial node (SA node)

Question 23

stroke volume

Answer 23

“Stroke volume is the amount of blood ejected by the left ventricle with each heartbeat, typically measured in milliliters per beat.”

Question 24

systole

Question 24

sympatholysis

Question 25

systolic blood pressure

Question 26

vagus nerve

Question 27

veins

Question 28

venules

Question 29

What are the major purposes of the cardiovascular system?

Answer 29

pump blood to the tissues

Question 30

Briefly outline the design of the heart. Why is the heart often called “two pumps in one”?

Answer 30

has pulmonary (lungs) and systemic ( body) circuit

Question 31

Outline the cardiac cycle and the associated electrical activity recorded via the electrocardiogram.

Question 31

Graph the heart rate, stroke volume, and cardiac output response to incremental exercise.

Answer 31

HR - increases until around 50% vo2max then exponential increase SV - increases linearly until plate at around 40 % vo2max cardiac output = HR x SV

Question 32

What factors regulate heart rate during exercise? Stroke volume?

Answer 32

HR - parasympathetic nerves - sympathetic nerves SV - heart contractility strength - artortic pressure (after load) - end diastolic volume

Question 33

How does exercise influence venous return?

Answer 33

1) venoconstriction increase nervous constriction by decreae in vessel diameter and increase in vein pressure 2) pumping action of contracting skeletal muscles --> contracting muscles during exercise cause venous blood to return to heart 3) respiratory pump increases when breathing increases --> inspiration causes venous blood to move as pressure differences have changed in chest

Question 34

What factors determine local blood flow during exercise?

Answer 34

blood flow = change in pressure / resistance resistance = length x viscosity / radius ^4 local factors called auto regulation

Question 35

Graph the changes that occur in heart rate, stroke volume, and cardiac output during prolonged exercise. What happens to these variables if the exercise is performed in a hot/humid environment?

Answer 35

during prolonged exercise HR increases , SV decrease and cardiac output remains the same (cardiac drift) . increase the temperature results in the same graphs just exaggerated

Question 36

Compare heart rate and blood pressure responses to arm and leg work at the same oxygen uptake. What factors might explain the observed differences?

Answer 36

arms have a higher blood pressure and HR than legs this is due to greater sympathetic outflow in the upper limbs since they are closer to the heart increase pressure is due to an increase in vasoconstriction

Question 36

Explain the central command theory of cardiovascular regulation during exercise.

Answer 36

that the initial drive to increase heart rate when exercise starts is due to central common. see graph

Question 37

describe the factors that impact EDV

Answer 37

1) venoconstriction 2) muscle pumps 3) respiratory pump

Question 38

what is cardio vascular drift

Answer 38

“During prolonged exercise, decreased plasma volume from dehydration reduces venous return, which lowers stroke volume. To maintain cardiac output, heart rate increases. Cardiovascular drift is especially pronounced in hot or humid environments.”