5.5.9(controlling heart rate)

Describe what kind of muscle the heart muscle is

• Myogenic

State what part of the brain the heartbeat is controlled by

• It is controlled by the medulla oblongata

Name the 2 parts of the medulla oblongata

• The acceleratory centre

• The inhibitor centre

Name and describe the 2 receptors used in cardio regulation

• Baroreceptors monitor blood pressure

• Chemoreceptors monitor changes in CO2 and O2 and measure PH in the blood

Describe how the sympathetic nervous system is involved in cardioregulation

• It controls the increase in heart rate

• by sending electrical impulses down accelerans nerve

Describe how the parasympathetic nervous system is involved in cardio reguilation

• It controls the decrease of heart rate

• By sending electrical impulses down the vagus nerve

Describe how an increase in CO2 concentration affects heart rate

• An increased CO2 concentration in blood is detected by chemoreceptors.

• They send a signal to the medulla oblongata which then coordinates a response

• Electrical impulses are sent down the sympathetic nervous system to the SAN

• noradrenaline causes the SAN to be stimulated

• This causes an increase in the number og waves of excitation generated by the SAN which causes an increase in heart rate

Describe how a decrease in CO2 concentration affects heart rate

• A decreased CO2 concentration in blood is detected by chemoreceptors.

• They send a signal to the medulla oblongata which then coordinates a response

• Electrical impulses are sent down the parasympathetic nervous system to the SAN

• acetylcholine causes the SAN to be stimulated

• This causes an decrease in the number of waves of excitation generated by the SAN which causes a decrease in heart rate