Unit 14.5.2 - Control Of Heart Rate

Front 1

Chemoreceptors are found in the wall of the _ _ (the _ that serve the _). They are sensitive to changes in the pH of the blood that result from changes in _ _ _.

In solution, carbon dioxide forms an _ and therefore _ pH.

Back 1

carotid arteries / arteries / brain). / carbon dioxide concentration.

acid / lowers

Front 2

The process of control by chemoreceptors works as follows: (1/4)

When the blood has a _ than normal concentration of _ _, its pH is lowered.

The chemoreceptors in the wall of the _ _ and the _ detect this and increase the frequency of _ _ to the centre in the medulla oblongata that _ heart rate.

Back 2

higher / carbon dioxide

carotid arteries / aorta / nervous impulses / increases

Front 3

The process of control by chemoreceptors works as follows: (2/4)

This centre increases the frequency of impulses via the _ _ _ to the sinoatrial node. This, in turn, increases the rate of production of _ _ by the _ _ and therefore _ _ _.

Back 3

sympathetic nervous system / electrical waves / sinoatrial node / increases heart rate.

Front 4

The process of control by chemoreceptors works as follows: (3/4)

The increased _ _ that this causes leads to more _ _ being _ by the lungs and so the _ _ _ of the blood returns to normal.

Back 4

blood flow / carbon dioxide / removed / carbon dioxide concentration

Front 5

The process of control by chemoreceptors works as follows: (4/4)

As a consequence the pH of the blood _ to _ and the chemoreceptors in the wall of the carotid arteries and aorta _ the frequency of nerve impulses to the _ _.

The _ _ reduces the frequency of impulses to the sinoatrial node, which therefore leads to a _ in the _ _.

Back 5

rises / normal / reduce / medulla oblongata.

medulla oblongata / reduction / heart rate.

Front 6

Pressure receptors occur within the walls of the _ _ and the _. They operate as follows: (1/2)

When blood pressure is higher than normal, _ _ transmit more nervous impulses to the centre in the _ _ that _ heart rate. This centre sends impulses via the _ _ _ to the _ _ of the heart, which leads to a _ in the rate at which the heart beats.

Back 6

carotid arteries / aorta.

pressure receptors / medulla oblongata / decreases / parasympathetic nervous system / sinoatrial node / decrease

Front 7

Pressure receptors occur within the walls of the _ _ and the _. They operate as follows: (2/2)

When blood pressure is lower than normal, pressure receptors transmit more _ _ to the _ in the medulla oblongata that _ heart rate. This _ sends impulses via the _ _ _ to the sinoatrial node, which _ the rate at which the heart beats.

Back 7

carotid arteries / aorta.

nervous impulses / centre / increases / centre / sympathetic nervous system / increases