Homeostasis - Regulation of Gases

Question 1

What is the function of the respiratory centre?

Answer 1

The respiratory centre is part of the brain that regulates breathing rate.

Question 2

Where is the respiratory centre located?

Answer 2

Medulla Oblongata

Question 3

Where are four places the respiratory centre receives information from?

Answer 3

1. Chemoreceptors
2. Mechanoreceptors
3. Cerebral cortex
4. Hypothalamus

Question 4

What do these places that receive information allow and do?

Answer 4

Regulates the rate of the depth of breathing.

Question 5

What do mechanoreceptors do?

Answer 5

They will stretch the lungs.

Question 6

What does the intercostal nerve do?

Answer 6

Stimulates the contraction of intercostal muscles.

Question 7

What does the phrenic nerve do?

Answer 7

Stimulates the contraction of the diaphragm.

Question 8

What is the word equation for breathing?

Answer 8

carbon dioxide + water <> carbonic acid <> bicarbonate and hydrogen ions

Question 9

What is the chemical equation for breathing?

Answer 9

CO2 + H2O <> H2CO3 <> HCO3- + H+

Question 10

What are the 3 ways carbon dioxide travels in the blood?

Answer 10

1. Dissolved in blood plasma.
2. Travels via carbominohaemoglobin
3. Reacts with water to be carried as bicarbonate ions.

Question 11

What do chemoreceptors do?

Answer 11

Chemoreceptors recognise changes in the concentration of oxygen, carbon dioxide and hydrogen ions in the blood. They send nerve impulses to the respiratory centre in the medulla oblongata which controls the rate and depth of breathing.

Question 12

What are the two types of chemoreceptors based on their location?

Answer 12

1. Peripheral chemoreceptors
2. Central chemoreceptors

Question 13

What are peripheral chemoreceptors?

Answer 13

Peripheral chemoreceptors are groups of cells within the walls of the aorta and the carotid arteries. These are sensitive to changes in the concentration of oxygen, carbon dioxide and hydrogen ions in the blood plasma.

Question 14

What are peripheral chemoreceptors known as?

Answer 14

Aortic and Carotid bodies.

Question 15

What is the aortic body?

Answer 15

The aortic body is the group of cells within the walls of the aortic arch that are sensitive to changes in the concentration of oxygen and carbon dioxide in the blood and its pH.

Question 16

What is the carotid body?

Answer 16

The carotid body is a group of cells within the walls of the carotid arteries that are sensitive to changes in the concentrations of oxygen and carbon dioxide in the blood and its pH.

Question 17

What central chemoreceptors?

Answer 17

Central chemoreceptors are located in the medulla oblongata. These are sensitive to changes in the concentration of carbon dioxide in the blood and hydrogen ions in the cerebrospinal fluid.

Question 18

What happens when chemoreceptors are stimulated?

Answer 18

They will send a nerve impulse to the area of the respiratory centre that regulates breathing.

Question 19

Why is the concentration of oxygen insignificant in maintaining a regular breathing rhythm?

Answer 19

Oxygen levels have to fall to very low levels to have a major stimulatory effect.

Question 20

Why does the concentration of carbon dioxide play a major role in breathing rhythm?

Answer 20

A small change will stimulate a relatively large increase in the rate of the depth of breathing. The chemoreceptors most sensitive to this change are those in the medulla which respond in a few minutes.

Question 21

How do hydrogen ion concentrations play a role in the breathing rhythm?

Answer 21

The concentration of hydrogen ions increases with the concentration of carbon dioxide. An increase in hydrogen ions is caused by the production of carbonic acid and lactic acid. This is detected by the peripheral chemoreceptors, which send a direct message to the medulla which results in an increased rate and depth of breathing.

Question 22

Why can humans voluntarily control their breathing?

Answer 22

1. Important for speech
2. Protective mechanism

Question 23

Describe how humans voluntarily control their breathing?

Answer 23

This control comes from connections with the cerebral cortex to descending tracts in the spinal cord. Voluntary control will bypass the respiratory centre in the medulla oblongata to send messages directly to the intercostal muscles and the diaphragm.

Question 24

Define hyperventilation

Answer 24

Hyperventilation is extremely rapid and deep breathing that can provide more oxygen than required and a reduction in carbon dioxide in the blood.

Question 25

What happens to chemoreceptors during hyperventilation?

Answer 25

Chemoreceptors will not be stimulated and there will be a reduction in depth and rate of breathing.

Question 26

Why is it dangerous to hyperventilate before swimming?

Answer 26

It is dangerous because the lack of carbon dioxide causes the body to assume that taking a breath is not required and will not register the lack of oxygen.

Question 27

What happens when there is an increase in the concentration of hydrogen ions?

Answer 27

The body’s pH decreases due to an increase in carbon dioxide.

Question 28

Write an SRMERF when the stimulus is an increase in carbon dioxide.

Answer 28

S - Increase in carbon dioxide.
R - Central chemoreceptors in the medulla oblongata.
M - Medulla oblongata.
E - Increases nerve stimulation of the intercostal muscles and diaphragm.
R - Increase in rate and depth of breathing.
F - Decrease in carbon dioxide.

Question 29

Write an SRMERF when the stimulus is an increase in hydrogen ions.

Answer 29

S - Increase in hydrogen ions.
R - Peripheral chemoreceptors in the carotid and aortic bodies.
M - Medulla Oblongata.
E - Increase nerve stimulation of the intercostal muscles and diagram.
R - Increase in rate and depth of breathing.
F - Decrease in hydrogen ions.