gas concentration regulation

Question 1

Cellular respiration occurs in cells to…

Answer 1

provide energy for its function

Question 2

Cells rely on…

Answer 2

continuous supply of oxygen and removal of carbon dioxide

Question 3

what is the respiratory system responsible for?

Answer 3

Respiratory system responsible for taking in oxygen and excreting carbon dioxide from the body

Question 4

movement of oxygen from lungs

Answer 4

Circulatory system carries oxygen from the lungs → cells; also takes away carbon dioxide and delivers to lungs → excretion

Question 5

what cause air to move in and out of the lungs?

Answer 5

Diaphragm and intercostal muscles

Question 6

what is the diaphragm stimulated by?

Answer 6

stimulated by impulses from phrenic nerve

Question 7

what is the intercostal muscles stimulated by?

Answer 7

stimulated by intercostal nerves

Question 8

what controls the nerve impulses for muscle contraction?

Answer 8

• are controlled by a respiratory centre in the medulla oblongata
  
  • 2 regions: one controls expiration; one controls inspiration
  • To coordinate breathing, messages need to pass back and forth between the neurons in these two regions

Question 9

chemicals affecting breathing

Answer 9

• Conc. of O2 and CO2 affect breathing rate and depth
• Conc. of CO2 in the blood plasma affects the conc. of hydrogen ions (H+)
• When CO2 dissolves in water → forms carbonic acid, which breaks down readily to form H+ and bicarbonate ions

Question 10

two types of chemoreceptors

Answer 10

peripheral and central

Question 11

peripheral chemoreceptors

Answer 11

• Groups of cells within the walls of the aorta and carotid arteries
• Sensitive to changes in the conc. of O2, CO2, and H+ in blood plasma
• Known as aortic or carotid bodies

Question 12

central chemoreceptors

Answer 12

• Located in the medulla oblongata
• Sensitive to changes in the conc. of CO2 in the blood and H+ in the CSF
• When stimulated, send a nerve impulse to the area of the respiratory center that regulates breathing

Question 13

Oxygen concentration decrease

Answer 13

• As O2 is consumed by cells, it’s conc. in the blood begins to fall
• If conc. falls below normal while other factors are constant, breathing rate increasesNeeds to be significantly low levels to have a major stimulatory effect

Question 14

oxygen concentration increase

Answer 14

• Large decrease in O2 conc. stimulates the peripheral chemoreceptors → nerve impulses are transmitted to respiratory centre
• Nerve impulses stimulate the transmission of messages → diaphragm and intercostal muscles → breathing rate and depth increases

Question 15

Carbon dioxide concentration increase

Answer 15

• Small increases in the conc. of CO2 can cause a marked increase in the rate and depth of breathing
• Any increase in CO2 in the plasma is associated with the conc. of H+
• Increase in conc. of both chemicals in blood à stimulates central and peripheral chemoreceptorsChemoreceptors located in medulla oblongata are most sensitive to changes
• Nerve impulses → respiratory centre (medulla) → increase in breathing rate and depth
• Increase in breathing rate that occurs following an increase in CO2 conc. = produced by stimulation of aortic and carotid bodies

Question 16

Major factor in the regulation of breathing rate

Answer 16

Carbon dioxide concentration

Question 17

increase in hydrogen ion concentration

Answer 17

• As H+ conc. of blood increases, the pH decreases (more acidic)
• Decrease in pH directly stimulates chemoreceptors in the aortic and carotid bodies →transmits impulses to the respiratory centre → increase in breathing rate and depth

Question 18

gas conc: stimulus

Answer 18

increase of H+ and CO2 (decrease of pH)

Question 19

gas conc: receptors

Answer 19

central chemoreceptors in respiratory store, peripheral chemoreceptors of aortic and carotid bodies

Question 20

gas conc: modulator

Answer 20

respiratory centre in medulla vis nerve impulses

Question 21

gas conc: effectors

Answer 21

diaphragm, intercostal muscles

Question 22

gas conc: responses

Answer 22

increase of stimulation of respiratory muscles (diaphragm and intercostals) causes an increase in breathing rate and depth

Question 23

gas conc: feedback

Answer 23

decrease in CO2 and H+

Question 24

voluntary control of breathing

Answer 24

• Voluntary control comes via connections from the cerebral cortex to descending tracts in the SC
  
  • Bypasses the respiratory centre in the medulla oblongata
  • Protective device enabling us to prevent irritating gases and water from entering the lungs

Question 25

what does build up of CO2 do?

Answer 25

stimulates the inspiratory centre to send impulses to inspiratory muscles

Question 26

Hyperventilation

Answer 26

extremely rapid and deep breathing; results in dizziness and fainting due to loss of CO2 from blood

Question 27

what can stimulate hyperventilation?

Answer 27

Can be stimulated by severe pain or emotional stress

Question 28

how to treat hyperventilation?

Answer 28

Usually corrects itself (reduction in CO2 means that the chemoreceptors are not stimulated, reducing rate and depth of breathing until CO2 returns to normal)

Question 29

exercise and breathing

Answer 29

Contracting muscles cells require large amounts of oxygen → produce large amounts of carbon dioxide
- Rate and depth of breathing increases (take in more oxygen, remove more carbon dioxide)
- Increase in H+ ions also!