RESPIRATORY SYSTEM: Breathing Mechanisms

Question 1

Air moves from a ____pressure to a ______pressure

Answer 1

high to low

Question 2

Describe inhalation

Answer 2

Requires ATP

• brain realizes there is to much CO2, sends message to intercostal muscles and diaphragm to contract
• ribs move up and out, diaphragm flattens
• lungs expand, creating move space for air
• Patm>Pthor resulting in air rushing in to fill space

Question 3

Describe exhalation

Answer 3

Passive process (no ATP)

• Alveoli get to stretched and stretch receptors tell brain to stop inhaling
• brain tells muscles to relax causing ribs to move down and in, and diaphragm to go back to dome shape
• lung space decreases–> pressure increases
• Pthor>Patm resulting in air rushing out

Question 4

How is the brain involved with inhalation?

Answer 4

• Brains respiratory centre chemoreceptors detect CO2 and H+ levels
• As ph drops (H+ increases), and CO2 increases the message is sent to the ribs & diaphragm to contract
• There are chemoreceptors in the carotid arteries and aortic bodies as well the sense change in CO2 and H+ (and O2) which send message to the brain to as well
• stimulates inhalation to decrease H+ levels

Question 5

As H+ increases CO2 _____

Answer 5

Increases

Question 6

How is the brain involved with exhalation?

Answer 6

Alveoli has stretch receptors that send impulse to brain to STOP inhalation and start exhalation

• exhalation is caused by the relation of the diaphragm and intercostal muscle
• as diaphragm relaxes, thoracic volume decreases and lung pressure increases pushing the air out

Question 7

What is respiration?

Answer 7

a set of processes involved with the conduction of oxygen to the tissues and the removal of CO2

Question 8

4 aspects of respiration

Answer 8

breathing 
external respiration (at lungs)
internal respiration (at tissues)
Cellular respiration (mitochondria turning O2& glucose into CO2 H2O and ATP)

Question 9

What is external respiration?

Answer 9

Happens at lungs
involves the diffusion of O2 into pulmonary capillaries and the diffusion of CO2 and water into the alveoli to be exhaled

Question 10

Describe the diffusion in External respiration

Answer 10

• there is a lot of CO2 returning to the lungs and not a lot in the alveoli so the CO2 moves from high to low (down the concentration gradient) into the alveoli to be breathed out
• there is a lot of O2 in the fresh air in the alveoli, and not a lot in the deO2 blood in the lungs, the O2 moves from high to low (down the concentration gradient) and into the blood

Question 11

Conditions of the blood at the alveoli

Answer 11

pH=7.4 (basic)
37 degrees
low pressure (negative)
Hemoglobin has low affinity for CO2 and high affinity for O2
when leaving the lungs 99% of hemoglobin turns to oxyhemoglobin which is transported into systemic tissues
O2 + Hb –> HbO2

Question 12

What is internal respiration?

Answer 12

• happens at tissues (capillary-tissue fluid exchange)
• Diffusion of O2 into the tissue cells and the diffusion of –CO2 and H2O out of the system tissue into capillaries
• CO2 is then sent to heart & lungs to be removed via external respiration

Question 13

Conditions of the blood at the tissues?

Answer 13

pH of 7.3 (slightly acidic)
38 degrees
high pressure

Question 14

Describe the diffusion in internal respiration?

Answer 14

-hemoglobin lets go of O2 under certain conditions and binds to CO2
-O2 then diffuses into extracellular space along with H2O that is forced from plasma due to BP (arteriole end)
-water is then drawn back in due to Osmotic pressure and CO2 enter the blood (venule end)
-

Question 15

What are the 3 ways CO2 can be transported?

Answer 15

Dissolved gas in Blood plasma
Carbaminohemoglobin (HbCO2)
Bicarbonate Ion (HCO3)

Question 16

What happens now that hemoglobin loves CO2 (internal respiration)

Answer 16

• they join to form carbaminohemoglobin
• CO2 also joins with H2O to form bicarbonate Ion (carbonic anhydrase catalyses this reaction)
• this results in an excess hydrogen ion that hemoglobin joins with to form reduced hemoglobin (HHb) so homeostasis is not askew (acts as a buffer)

Question 17

External respiration (when blood returns to lungs)

Answer 17

the conditions change again and essentially the whole process repeats but in reverse

• hemoglobin dumps CO2 and H+ and has affinity for O2 again
• after process repeats all that is left is H2O and CO2
• CO2 diffuse into alveolar space

Question 18

what happens to the water in the lungs (external respiration)

Answer 18

It is either:
exhaled into air
enters alveoli for moisture
remains in blood plasma