Respiratory Unit Lesson 3: Gas Exchange

Question 1

What is the exchange of gases in the lungs?

Answer 1

External Respiration

Question 2

What is the exchange of gases in the tissues?

Answer 2

Internal Respiration

Question 3

Where does External Respiration occur?

Answer 3

In the lungs at the alveoli

Question 4

How many alveoli exist in the lungs and how many capillaries do they contain?

Answer 4

300 million alveoli and 280 billion capillaries

Question 5

What does large surface area on each alveolus allow for?

Answer 5

High degree of vascularization

Question 6

What are the conditions like at the alveoli?

Answer 6

Cooler and more basic than in tissues, leading to a greater affinity for O2 and a lower affinity for CO2

Question 7

What happens when air is inhaled into the lungs? be specific with the details. (external respiration)

Answer 7

At the alveoli, O2 diffuses across the pulmonary capillaries due to the low Po2 in the blood, the lower temperature, and the higher pH. Most of the O2 binds to the heme portion of hemoglobin (Hb) (in red blood cells), creating the carrier protein oxyhemoglobin (HbO2). The blood then transports the O2 away from the lungs and back to the heart

Question 8

explain the process of exhaling air. explain how the CO2 is carried in the blood(name the chemicals) (external respiration)

Answer 8

Blood returning from the tissues carries a larger [CO2]. Most of the CO2 is carried as bicarbonate ions (HCO3-) in the blood and exists in equilibrium with carbonic acid (H2CO3).

The lower the Pco2 outside the bloodstream, plus the lower the temperature and higher pH causes the CO2 to move across the pulmonary capillaries and into the lungs where it is exhaled

Question 9

How is the release of CO2 travelling as bicarbonate sped up?

Answer 9

The blood enzyme carbonic anhydrase catalyzes the conversion of carbonic acid to CO2 and H2O

Question 10

Where does internal respiration occur?

Answer 10

In the body’s tissues, between the systemic capillaries and tissue fluid

Question 11

note:

Answer 11

molecules tend to move from high concentration to low concentration

Question 12

how can the pressure that gas produces be subdivided into

Answer 12

partial pressures(ex. Pgas, PN2, PO2, etc.)

Question 13

Why does H+ combine with heme?

Answer 13

To form reduced hemoglobin (HHb) to prevent blood pH from growing too low

Question 14

composition of air(name the chemicals)

Answer 14

nitrogen gas(~78%), oxygen gas(~21%), and 1% other gases

Question 15

describe the conditions in the lungs

Answer 15

it is cooler and more basic than that of the tissues

Question 16

explain the process of internal respiration with oxygen gas. include details

Answer 16

oxygen is first carried in the blood as HbO2 and has a higher PO2 relative to the tissues(the O2 in the tissues is used up in cellular respiration, creating CO2 as a byproduct). HbO2 releases its O2 and CO2 is removed from the tissues

Question 17

explain the process of internal respiration with CO2

Answer 17

the waste product CO2 diffuses from its high PCO2 in the tissues to the low PCO2 in the bloodstream. about 10 percent of CO2 combines with hemoglobin to form carbaminohemoglobin(HbCO2). since now there is a high concentration of CO2 in the blood, carbonic anhydrase moves the remaining CO2 to combine with H2O to form carbonic acid(H2CO3)