SSEH2260 Final Exam

What is the cardiac cycle?

The orderly flow of blood throughout the heart.

What does diastole refer to in the cardiac cycle?

Passive ventricular filling during relaxation.

What happens during systole?

AV valves close, semilunar valves open, and ventricles eject blood.

What does Q represent in cardiovascular physiology?

Cardiac output, the amount of blood pumped by the heart in L/min.

What is the formula for calculating cardiac output (Q)?

Q = HR x SV.

What is the approximate resting cardiac output for an average individual?

Around 5 L/min.

How much can cardiac output increase during exercise for sedentary individuals?

20-22 L/min.

What can cardiac output increase to in trained athletes during exercise?

35-40 L/min.

What is stroke volume (SV)?

The amount of blood ejected with each contraction of the left ventricle.

How is stroke volume calculated?

SV = EDV - ESV.

What does preload determine in relation to stroke volume?

It influences the volume of blood in the ventricles at the end of diastole.

How much can stroke volume increase during exercise?

By up to 1.8 times compared to resting levels.

What are the normal ranges of stroke volume for untrained and trained individuals?

Untrained: 70-110 mL; Trained: 100-180 mL.

How do athletes achieve a higher cardiac output?

enhanced stroke volume.

What is the Frank-Starling law?

Increased ventricular filling during diastole increases stroke volume.

What effect does exercise have on ventricular contractility?

It can increase ventricular contraction based on given preload.

What is the positive inotropic effect?

An increase in contractility of the heart.

What factors can cause inotropic effects?

Autonomic nervous system activity, hormones, and changes in ion concentrations.

What is end diastolic volume (EDV)?

The total amount of blood filling the left ventricle.

What affects end diastolic volume?

Filling time, cardiac output, blood volume, and skeletal muscle activity.

What is preload directly proportional to?

End diastolic volume.

How does the Frank-Starling curve represent stroke volume and EDV?

It shows the relationship between stroke volume (y) and EDV/preload (x).

What is the end systolic volume?

The amount of blood left in the ventricle after contraction.

What factors affect end systolic volume?

Ventricular preload, contractility, and afterload.

What does the Fick Principle describe?

Maximal oxygen consumption (VO2 max) reflects the body's ability to transport and utilise oxygen.

What is the formula for VO2 in relation to cardiac output?

VO2 = (Q x a-vO2diff) / 100.

What is the VO2 at rest for an untrained individual?

Around 300 mL.

What is the VO2 at maximal exercise for an endurance athlete?

Around 5570 mL.

How does VO2 change for untrained individuals during exercise?

Increases by approximately 10 times.

What is the relationship between heart rate and workload during exercise?

Heart rate increases directly in proportion to workload.

What is the formula for determining maximum heart rate?

220 - age.

How is heart rate at submaximal exercise affected by training?

It is lower after training, despite similar cardiac outputs.

What causes the increase in heart rate during exercise?

Increased sympathetic tone and decreased parasympathetic tone.

What causes the heart rate to increase initially (up to ~120 bpm) during exercise?

There is a decrease in parasympathetic activity.

What is the heart's internal rhythm regulated by?

The SA node.

How does the cardiovascular control centre function?

It receives input from receptors and sends corrective signals via the nervous system and hormones.

What does cardiovascular drift refer to?

The increase in heart rate as stroke volume gradually decreases during prolonged exercise.

In what situation is less blood supplied to the working muscles?

During exercise in heat, as blood is redirected to the skin for cooling.

What happens to the blood vessels during sweating?

They vasodilate to increase blood flow to the skin.

What prevents backflow in the venous system?

Valves in the veins.

What is the normal range for systolic blood pressure in adults?

110-120 mmHg.

What is classified as hypotension?

Systolic blood pressure less than 100 mmHg and diastolic less than 60 mmHg.

What is the function of baroreceptors?

They are sensitive to blood pressure changes and provide input to the cardiovascular control centre.

What happens during a drop in blood pressure?

The autonomic nervous system modifies its activity to compensate.

What is the Mean Arterial Pressure (MAP)?

The average force exerted by the blood against arterial walls during the cardiac cycle.

What is classified as hypertension?

Systolic blood pressure of 140 mmHg or higher and diastolic of 90 mmHg or higher.

How does regular aerobic exercise affect blood pressure?

Reduces blood pressure by approximately 6-10 mmHg.

What initially happens to systolic blood pressure during the first minutes of exercise?

There is an increase in systolic blood pressure.

What is the Rate Pressure Product (RPP)?

An indirect index of myocardial oxygen consumption, calculated as RPP = SBP x HR.

What is the average blood flow distribution to the liver and kidneys?

Approximately 50%.

How do arterioles regulate blood flow?

By constricting or dilating.

What role do local metabolites play in blood flow regulation?

They can cause vasodilation or vasoconstriction based on tissue needs.

What is the primary avenue of heat loss during exercise?

Evaporation.

What increases the effectiveness of evaporation for heat loss?

Lower relative humidity and higher surface area exposed to air.

What impacts heat acclimatisation after several days in a hot environment?

Increased plasma volume, decreased resting core temperature, and increased sweat rate.

What is a critical strategy for minimising the effects of heat during exercise?

Fluid replacement strategies, like drinking before and during exercise.

What causes cardiovascular drift during prolonged exercise?

Increased heart rate to compensate for decreased stroke volume.

How does the countercurrent flow mechanism help with blood return?

Increased heart rate enhances pulsatility, assisting venous return.

What happens to the blood supply to non-active areas during exercise?

It is restricted, and blood is redirected to active muscles.

What is the significance of thermal receptors in the skin?

They activate the hypothalamus to regulate temperature by stimulating heat loss mechanisms.

What can severe heat stress during exercise lead to?

Reduced exercise performance and premature fatigue.

What adaptations occur due to regular exercise in terms of heat tolerance?

Increased plasma volume and decreased resting core temperature.

What may happen if too much sweating occurs?

Plasma loss can lead to increased blood viscosity and cardiovascular drift.

What should be consumed post-exercise to support recovery?

1.5 times the sweat loss, hydration, and electrolyte replacement.