Control of Heart Rate

Question 1

How does the heart adapt to supply more oxygen and glucose?

Answer 1

increase in beats per min: heart rate, increase strength of contraction, increase volume of blood pumped per beat: stroke volume

Question 2

What is the cardiovascular centre?

Answer 2

specific region of medulla oblongata that receives sensory input about levels of physical activity, blood CO2 and BP, sends nerve impulses to SAN to alter frequency of excitation waves

Question 3

How does movement of limbs affect heart rate?

Answer 3

detected by stretch receptors in muscles, send impulses to cardiovascular centre, informs more O2 may be needed, increases heart rate

Question 4

How does muscles producing more carbon dioxide affect heart rate?

Answer 4

some of this extra CO2 reacts with water in blood plasma and reduces its pH, change in pH detected by chemoreceptors in carotid arteries, aorta and brain, receptors impulses to CC= increases heart rate

Question 5

How does stopping exercise affect heart rate?

Answer 5

Concentration of CO2 in blood falls, reduces activity of accelerator pathway, heart rate declines

Question 6

How does adrenaline affect heart rate?

Answer 6

secreted in response to stress, shock, anticipation, excitement. Causes increase in heart rate

Question 7

How does blood pressure affect heart rate?

Answer 7

monitored by stretch receptors in walls of carotid sinus (small swelling in artery), if too high signals sent to CC, heart rate reduced

Question 8

What is an artificial pacemaker?

Answer 8

mechanism that delivers electrical impulse to heart muscle

Question 9

How big are modern pacemakers?

Answer 9

4cm long, implanted under skin and fat on chest (sometimes within chest cavity)

Question 10

What is the purpose of pacemakers that deliver impulses to the ventricle walls?

Answer 10

for conditions where the AVN that normalls sends impulse from atria to ventricles isn’t functioning but SAN may still be functioning