Homeostasis - Chapter 6

Question 1

Where is the respiratory centre located?

Answer 1

the medulla oblongata

Question 2

Two types of chemoreceptors

Answer 2

peripheral and central

Question 3

Peripheral chemoreceptors

Answer 3

• within the walls of the aorta and carotid arteries.
• sensitive to changes in concentration of oxygen, carbon dioxide and hydrogen ions in blood plasma.
• known as aortic and carotid bodies

Question 4

Central chemoreceptors

Answer 4

• in medulla oblongata
• sensitive to changes of carbon dioxide in the blood and hydrogen ions in the cerebrospinal fluid

Question 5

Oxygen concentration

Answer 5

a large decrease in O2 concentration stimulates the peripheral chemoreceptors, and nerve impulses are transmitted to the respiratory centre. these impulses stimulate the transmission of messages to the diaphragm and intercostal muscles to increase breathing rate and depth.

Question 6

Carbon dioxide concentration

Answer 6

• any increase in CO2 results in an associated increase in hydrogen ion concentration.
• central and peripheral chemoreceptors are stimulated, transmitting nerve impulses to respiratory centre to increase rate and depth of breathing
• response takes several minutes - immediate increase in breathing rate is produced by the stimulation of aortic and carotid bodies stimulated by increase in hydrogen ion concentration.

Question 7

Hydrogen ion concentration

Answer 7

• as hydrogen ion concentration in the blood increases, pH decreases
• a decrease in pH stimulates chemoreceptors in aortic and carotid bodies, which then transmit impulses to respiratory centre, resulting in an increase in rate and depth of breathing.

Question 8

Voluntary control of breathing

Answer 8

• voluntary control comes via connections from the cerebral cortex to descending tracts in the spinal cord
• is a protective device as it enables us to prevent irritating gases and water from entering the lungs.