Topic 6—A: Stimuli and Responses- 5. Control of heart rate

Question 1

What two different systems is the nervous system split into?

Answer 1

1. The central nervous system.
2. Peripheral nervous system.

Question 2

What is the central nervous system made up of?

Answer 2

• It is made up of the brain and spinal cord

Question 3

What is the peripheral nervous system made up of?

Answer 3

• It is made up of the neurones that connect the central nervous system to the rest of the body

Question 4

What are the two different systems in the peripheral nervous system?

Answer 4

1. Somatic.
2. Autonomic.

Question 5

What is the somatic nervous system?

Answer 5

• It controls conscious activities
  Example- running, playing video games

Question 6

What is the autonomic nervous system?

Answer 6

• Controls unconscious activities
  Example- digestion

Question 7

What is the autonomic nervous system split into?

Answer 7

1. Sympathetic nervous system.
2. Parasympathetic nervous system.

Question 8

Sympathetic nervous system

Answer 8

• ‘fight or flight’ system
• Gets the body ready for action

Question 9

Parasympathetic nervous system

Answer 9

• ‘rest and digest’ system
• Calms the body down

Question 10

What is cardiac (heart) muscle?

Answer 10

Myogenic

Question 11

Definition of myogenic

Answer 11

• It can contract and relax without receiving signals from nerves
• Pattern of contractions controls the regular heartbeat

Question 12

Control of heart beat

Answer 12

• process starts in the sinoatrial node which is a small mass of tissue in the wall of the right atrium
• SAN initiates a wave of excitation that spreads across the atria making them contract (systole)
• there is a layer of non-conductive tissue that prevents the impulse spreading to the ventricles
• Instead, these waves of electrical activity are transferred from the SAN to the Atrio ventricular node (AVN)
• the AVN initiates a second nervous impulse that spreads down the bundle of his and then around the purkinje fires at the base of the ventricles
• This makes the ventricles contract (systole)

Question 13

Sympathetic

Answer 13

• Accelerates heart
• Stimulates glucose release by liver
• Relaxes bronchi
• Heart rate quickens

Question 14

Parasympathetic

Answer 14

• Inhibits heart
• Construct bronchi
• constrict bladder
• slows down heart rate

Question 15

Medulla oblongata

Answer 15

• region of brain with a centre to increase and a centre to decrease heart rate

Question 16

Pressure receptors

Answer 16

• They are called Baroreceptors
• They are located in aorta and carotid arteries
• The stimulated by high/low blood pressure

Question 17

Chemical receptors

Answer 17

• They are called chemo receptors
• they are located in the aorta carotid arteries and in the Medulla
• they detect changes in pH

Question 18

What happens when electrical impulses from receptors are sent to the medulla along sensory neurones?

Answer 18

• the Medulla processes the information and sends impulses to the SAN along sympathetic or parasympathetic neurones

Question 19

High blood pressure

Answer 19

• baroreceptors detect high blood pressure
• Stimulates baroreceptors to increase the frequency of electrical impulses to the centre of the medulla
• heart rate decreases as the Medulla increases frequency of impulses along the parasympathetic nervous system
• when the impulse reaches the end of the para-sympathetic nervous system acetyl choline diffuses across the synapse to the SAN by binding to receptors which decreases the frequency of electrical impulses
• This lowers the heart rate

Question 20

Low blood pressure

Answer 20

• Baro receptors detect low blood pressure
• Stimulates baro receptors to increase the frequency of electrical impulses to the centre of the Medulla
• heart rate increases as the medulla increases the frequency of impulses along the sympathetic nervous system
• when the impulse reaches the end of the sympathetic nervous system, nor adrenaline diffuses across the synapse to the SAN which increases the frequency of electrical impulses
• This increases heart rate

Question 21

High blood pH level

Answer 21

• Chemo receptors detect chemical changes in the blood
• stimulates chemoreceptors to increase the frequency of electrical impulses to the centre of the medulla.
• Heart rate decreases as the medulla increases the frequency of impulses along the parasympathetic nervous system.
• When the impulse reaches the end of the parasympathetic nervous system, acetylene choline diffuses across the synapse to the SAN by binding to receptors which decreases the frequency of electrical impulses
• This lowers the heart rate

Question 22

Low blood ph levels

Answer 22

• Chemoreceptors detect chemical changes in the blood
• Stimulates chemoreceptors to increase the frequency of electrical impulses to the centre of the medulla
• Heart rate increases as the medulla increases the frequency of impulses along the sympathetic nervous system
• When the impulse reaches the end of the sympathetic nervous system, nor adrenaline diffuses across the synapse to the SAN which increases