5. Control of Heart

central nervous system

brain and spinal chord

peripheral nervous system

neurones that connect the CNS to the rest of the body.

What two systems is the peripheral nervous system split up into?

• Somatic nervous system

• Autonomic nervous system

Somatic nervous system

controls conscious activities

e.g. running, playing video games

Autonomic nervous system

controls unconscious activities, e.g. digestion

What is the autonomic nervous system split into

• Parasympathetic nervous system

• Sympathetic nervous system

Parasympathetic nervous system

• ‘rest and digest’ system that calms the body down

Sympathetic nervous system

• ‘fight or flight’ system that gets the body ready for action.

What type of nervous system is involved in heart rate?

autonomic nervous system

which involves the sympathetic/ parasympathetic nervous system.

myogenic

cardiac muscle can contract and relax without receiving signals from nerves.

where and function of the sinoatrial node

• - wall of the upper right atrium

• pacemaker - it sets the rhythm of the heartbeat by sending out regular waves of electrical activity to the atrial walls.

What stopes the electrical impulses from traveling down directly to the ventricles?

a band of non-conducting collagen tissue.

where and function atrioventricular node

• responsible for passing the electrical impulse on to the bundle of His.

Why is there a slight delay before the AVN reacts?

To allow the blood to flow into the ventricles

bundle of his

A group of muscle fibres responsible for passing the waves of electrical activity between the ventricles to the bottom of the heart.

Purkyne tissue

Carries the waves of electrical impulses to the walls of the right and left ventricles causing them to contract simultaneously, FROM THE BOTTOM UP.

What part of the brain controls the rate of the sinoatrial node?

medulla

baroreceptors

• pressure receptors in the carotid arteries and aorta.

• They’re stimulated by high or low blood pressure.

chemoreceptors

• chemical receptors in the aorta, carotid arteries and medulla.

• It monitors Co2 concentrations/ pH, oxygen levels.

Body response to high blood pressure

1. Baroreceptors detect high blood pressure and sends impulses along sensory neurones to the medulla.

2. Sends impulses along parasympathetic neurone.

3. These secrete acetylcholine which binds to receptors on the SAN.

4. This causes the heart rate to slow down in order to reduce blood pressure back to normal.

Body response to low blood pressure

1. Baroreceptors detect low blood pressure and sends impulses along sensory neurones to the medulla.

2. Sends impulses along sympathetic neurone.

3. These secrete noradrenaline which binds to receptors on the SAN.

4. This causes the heart rate to speed up in order to increase blood pressure back to normal.

Body response to high blood O2, low CO2, high blood pH levels.

1. Chemoreceptors detect chemical changes in the blood and send impulses along the sensory neurones to the medulla.

2. this sends impulses to the parasympathetic neurones,

3. These secrete acetylcholine, which binds the receptors of the SAN.

4. This causes the heart rate to decrease in order to return oxygen levels, CO2 or pH back to normal.

Body response to low blood O2, high CO2, low blood pH levels.

1. Chemoreceptors detect chemical changes in the blood and send impulses along the sensory neurones to the medulla.

2. this sends impulses to the sympathetic neurones,

3. These secrete noradrenaline, which binds the receptors of the SAN.

4. This causes the heart rate to increase in order to return oxygen levels, CO2 or pH back to normal.