1.2 + 1.3 Regulation of the heart

Question 1

What is the sympathetic nervous system?

Answer 1

part of ANS and can activate increase in heart rate
increase cardiac impulse given out by cardiac conduction system

Question 2

What is the parasympathetic nervous system?

Answer 2

part of ANS and can activate decrease in heart rate
decrease cardiac impulses given by cardiac conduction system

Question 3

What are chemoreceptors?

Answer 3

detect change in CO₂ / lactic acid / blood acidity

Question 4

What are baroreceptors?

Answer 4

detect change in blood pressure

Question 5

What are proprioreceptors?

Answer 5

detect change in muscle movement

Question 6

What is adrenaline?

Answer 6

stress hormone released by sympathetic nerves and cardiac nerve during exercise causing increase in heart rate

Question 7

What is vascular shunting?

Answer 7

redistribution of blood flow

Question 8

Why is redistribution of blood flow important?

Answer 8

• increase supply of oxygen to working muscles
• remove waste products from muscles, e.g. CO₂ + lactic acid
• ensure more blood goes to skin during exercise to regulate body temp and get rid of heat through radiation, evaporation + sweating
• direct more blood to heart as muscle requires more oxygen during exercise

Question 9

Describe the process of vascular shunting

Answer 9

chemoreceptors detect increase in CO₂ + lactic acid
chemoreceptors stimulate vasomotor centre (medulla oblongata)
vasomotor signals for redistribution of blood
sends impulse to pre capillary sphincters which adjust blood flow (vasodilation / vasoconstriction)

Question 10

What is the vasomotor centre and where is it located?

Answer 10

Regulates blood pressure by signalling redistribution of blood
Located in medulla oblongata of brain

Question 11

What is the pulmonary circulation?

Answer 11

deoxygenated blood from heart to lungs and oxygenated blood back to heart

Question 12

What is the systemic circulation?

Answer 12

oxygenated blood to the body from heart and then return of deoxygenated blood from body to heart

Question 13

Why is the heart described as myogenic?

Answer 13

it is capable of generating its own impulses

Question 14

Describe the heart conduction system

Answer 14

Sino atrial node receives nerve impulses from brain
sends electrical impulse across atria causes atrial systole - forcing blood into ventricle
Atrioventricular node gather all impulse for 0.1 seconds to allow atria to contract fully
impulses sent down septum to bundle of HIS and into Purkinje fibres causing ventricle to contract, pushing blood up and out of vessels

Question 15

Why does blood flow to the brain remain the same during rest and maximum effort?

Answer 15

vital role in decision making and functions of body so ensuring it has constant supply of blood flow and oxygen is vital

Question 16

What is neural control?

Answer 16

Chemoreceptors detect chemical balance in body / increase in body acidity
cardiac control centre sends impulses to the SA node via accelerator nerve
stimulate SA node to release an electrical impulse which passes across atria causing them to contract
impulse reaches atrioventricular node where its delayed before passing down to bundle of his and purkinje fibres to apex of heart where released casuing ventricles to contract

Question 17

What is hormonal control?

Answer 17

release of adrenaline in blood stream from adrenal glands as part of sympathetic nervous system causes SA node to be stimulate and HR increases
Adrenaline can also cause vasoconstriction of blood vessels
can lead to vascular shunting
anticipatory rise caused by adrenaline

Question 18

What is intrinsic control?

Answer 18

Increase in temperature / contractility
heart rate increases to pump more blood towards skin so heat lost via radiation

Question 19

How do chemoreceptors increase heart rate?

Answer 19

detect changes
impulse sent to medulla oblongata in brain and sympathetic nervous system activated
impulses sent to SA node in order for contraction to increase
lead to increase in heart rate and supply of oxygen for body

Question 20

How do baroreceptors decrease heart rate?

Answer 20

detect changes by detecting stretch of arterial wall
increase in arterial pressure will result in baroreceptors sending message to medulla oblongate in brain
parasympathetic system activated
impulses sent to SA node for contractions to decrease

Question 21

What happens to baroreceptors during exercise?

Answer 21

set point increases, so heart rate doesn’t slow down

Question 22

How do proprioceptors increase heart rate?

Answer 22

located in muscles, joints, tendons
detect increase in muscle movement
impulse sent to medulla oblongata and sympathetic nervous system activated
impulse sent to SA node and heart rate increased