Cardiovascular system

Question 1

Define stroke volume?

Answer 1

volume of blood pumped from the LV each contraction (70ml approx)

Question 2

What’s is starlings law?

Answer 2

• explains how SV increases during exercise
• increased venous return results in greater diastolic fill
• cardiac muscles are stretched more creating more powerful contraction force
• increases ejection and therefore SV

Question 3

What is heart rate and how do you calculate maximum value?

Answer 3

number of times the heart beats per minute (between 60 and 100bpm)

maximum = 220 - age

Question 4

What is bradycardia?

Answer 4

• slow HR below 60bpm
• caused by regular exercise leading to heart hypertrophy
• results in increased SV and max HR

Question 5

What is cardiac output?

Answer 5

volume of blood ejected from the LV per minute

Question 6

What are the 2 phases of the cardia cycle?

Answer 6

Diastole = where muscles are relaxed

Systole = where cardiac muscles contract

Question 7

What happens during atrial systole?

Answer 7

• atria walls contract
• blood forced through AV valves into ventricles

Question 8

What happens during ventricle systole?

Answer 8

• ventricle walls contract
• pressure of blood opens semilunar valves
• blood ejected into the pulmonary artery, to lungs, aorta then body
• AV valves then shut

Question 9

What happens during diastole?

Answer 9

blood refills the heart chambers, first the atria then ventricles passively fill

Question 10

The heart is myogenic what does that mean?

Answer 10

• creates it’s own electrical impulse from the SA node
• the impulse travels to the AV node, down the bundle of his then purkinje fibres
• this causes the ventricles to contract

Question 11

What are neural factors?

Answer 11

• regulate HR during exercise controlled by CCC
• sympathetic control stimulate HR to beat faster (sending a signal from the CCC down the accelerator nerve)
• parasympathetic control stimulate HR to beat slower (sending a signal from the CCC down the vagus nerve)

Question 12

How do chemoreceptors increase HR during exercise?

Answer 12

• chemoreceptors detect increased CO2 levels in the blood
• this stimulates the CCC to send an impulse
• this impulse travels through the sympathetic system down the accelerator nerve
• this causes the SA node to increase HR

Question 13

How do baroreceptors increase HR during exercise?

Answer 13

• baroreceptors detect increase stretch in blood vessel walls
• this stimulates the CCC to send an impulse through the sympathetic system down accelerator nerve
• this causes the SA node to increase HR

Question 14

How do proprioceptors increase HR during exercise?

Answer 14

• proprioceptors detect an increase in motor activity
• this stimulates the CCC to send an impulse through the sympathetic system down accelerator nerve
• this causes the SA node to increase HR

Question 15

How does adrenaline affect HR?

Answer 15

• released during exercise by cardiac and sympathetic nerves
• stimulates SA node resulting in an increased cardiac output

Question 16

How do intrinsic factors affect stroke volume?

Answer 16

• changes in temperature affect blood viscosity and speed nerve impulse transmission
• venous return also increase stretching cardiac muscle
• this stimulates the SA node to increase SV

Question 17

What is the structure and function of arteries?

Answer 17

• transport oxygenated blood to the muscles
• have thick muscular walls and a small lumen
• have an elastic layer to cope with carrying blood at high pressure

Question 18

What is the structure and function of veins?

Answer 18

• transport deoxygenated blood back to the heart
• they have thin muscle and elastic tissue layers, valves to prevent back flow and a large lumen
• carries blood at a low pressure

Question 19

What is the structure and function of capillaries?

Answer 19

• the site of gaseous exchange
• walls are one cell thick providing a short diffusion pathway
• have a large SA and narrow diameter to slow blood flow down

Question 20

What mechanisms increase venous return during exercise

Answer 20

• valves
• skeletal muscle pump
• respiratory pump
• smooth muscle
• gravity

Question 21

How do skeletal muscle and respiratory muscle pumps work to increase venous return

Answer 21

skeletal muscle = muscular contraction and relaxation presses on nearby veins

respiratory = respiratory muscle relaxation and contraction presses on nearby veins

Question 23

What is the vascular shunt mechanism and what does it control?

Answer 23

• controls redistribution of blood
• during exercise vasodilation occurs in arterioles to muscles increasing blood supply and therefore O2 supply
• vasoconstriction of arterioles to non essential muscles decreasing blood flow

Question 24

What is the structure and function of pre capillary sphincters?

Answer 24

• tiny rings of muscle located at capillary openings
• aid blood redistribution during exercise
• relax around the muscle during exercise to increase blood flow and saturating the muscles with oxygen