Lecture 17 cont'd

Question 1

Which pulmonary disorder has destroyed elastic fibers and high lung compliance but low lung elastance.

What type of pulmonary disorder is it?

Answer 1

Emphysema

Obstructive pulmonary disorder

Question 2

Which pulmonary disorder is characterized by the accumulation of fibrous connective tissue?

Answer 2

Pulmonary Fibrosis

Question 3

Which pulmonary disorder has a feeling of shortness of breath and unpleasant or labored breathing?

What type of pulmonary disorder is it?

Answer 3

Asthma

Obstructive pulmonary disorder

Question 4

What is Eupnea?
What is Dyspnea?
What is Apnea?

Answer 4

• Normal quiet breathing
• Difficulty breathing
• Cessation of breathing

Question 5

What does HYPERVENTILATION cause? What does it lead to?

Answer 5

Causes low blood CO2 (hypocapnia) which leads to rise in blood pH and results in respiratory alkalosis

Question 6

What does HYPOVENTILATION cause? What does it lead to?

Answer 6

Causes high blood CO2 (hypercapnia) which leads to drop in blood pH and results in respiratory acidosis

Question 7

What is ventilation?

Answer 7

The bulk flow of air into and out of the lungs

Question 8

What does dalton’s law state?

Answer 8

The total pressure of a gas mixture is the sum of partial pressures of each gas in mixture

Question 9

What are some factors that decrease gas exchange in the lungs?

Answer 9

1. Inadequate oxygen in the alveoli (decrease in alveolar P O2 means less O2 is available to enter blood
2. Problems with diffusion of gases between alveoli and capillaries
3. Impaired blood flow (aka PERFUSION) to the alveoli

Question 10

What are two things that can lead to inadequate oxygen in the alveoli?

Answer 10

1. Decreased oxygen intake due to increase in altitude
   (think ppl climbing mount everest)
2. Hypoventilation

Question 11

What are some pathological changes affecting diffusion of gases between alveoli and capillaries?

Answer 11

1. Emphysema (decrease in amt of alveolar surface area)
2. Fibrotic lung diseases (increase in amount of alveolar surface area)
3. Pulmonary edema (increase in diffusion distance between alveoli and blood

Question 12

O2 that enters pulmonary capillaries first dissolves in ______ and then enters ____ blood cells where it binds to ________

Answer 12

Plasma, Red, Hemoglobin

Question 13

(slide 61) Where does loading and unloading of Hemoglobin (Hb) occur?

Answer 13

Loading in the lungs
Unloading in tissues

Question 14

True or False: each Hb has 4 globin polypeptide chains and 4 heme groups that bind to O2

Answer 14

TRUE

Question 15

High plasma O2 (P O2) favors _____ and low P O2 favors _____

Answer 15

Loading
Unloading

Question 16

How are Hb levels in anemia? In polycythemia?

Answer 16

• Below normal levels
• Higher than normal levels

Question 17

What is carboxyhemoglobin?

Why does this make carbon monoxide deadly?

Answer 17

• Heme combined with carbon monoxide
• Heme’s bond with carbon monoxide is 210x stronger than O2 bonds, so they will be more likely to bond with CO than O2

Question 18

What is the percentage of oxyhemoglobin saturation of blood in systemic arteries?

What about venous blood?

Answer 18

97-98%

75%

Question 19

What is the consequence of decreased affinity of hemoglobin?

Answer 19

More unloading of O2 to tissues

Question 20

What is the Bohr Effect?

Answer 20

Affinity of hemoglobin for O2 decreases when pH decreases/ temperature or CO2 levels increase

Question 21

What are 3 ways in whic CO2 is transported?

Answer 21

1. 7% of CO2 is dissolved in plasma
2. 23% is in RBC bound to Hb
3. 70% is transported as bicarbonate ions in plasma

Question 22

What is the chloride shift?

Answer 22

HCO3- diffuses out of RBC into plasma in exchange for CL-

Question 23

GAS TRANSPORT IN BLOOD:

What are the first three steps?

Answer 23

1. CO2 diffuses out of cells into systemic capillaries
2. Only 7% of CO2 remains dissolved in plasma
3. Nearly a fourth of CO2 enters RBCs and binds to hemoglobin, forming carbaminohemoglobin

Question 24

GAS TRANSPORT IN BLOOD:

What is step 4 and what is the name of the enzyme that catalyzes this reaction?

Answer 24

4. 70% of the CO2 load enters RBCs and is first converted to carbonic acid, then dissociates into bicarbonate and H+. Hemoglobin buffers H+

Carbonic anhydrase

Question 25

GAS TRANSPORT IN BLOOD:

What are steps 5 and 6?

Answer 25

5. HCO3- (bicarbonate) enters the plasma in exchange for Cl- (chloride shift)
6. At the lungs, dissolved CO2 diffuses out of the plasma and enters alveoli

Question 26

GAS TRANSPORT IN BLOOD:

What is step 7?

Answer 26

By the law of mass action, CO2 unbinds from hemoglobin and diffuses out of the RBC and then out of the plasma into the alveoli

Question 27

GAS TRANSPORT IN BLOOD:

What is the final step?

Answer 27

The carbonic acid reaction reverses, pulling HCO3- back into the RBC and converting it back to CO2. The CO2 then diffuses out of the RBC and then out of the plasma into the alveoli.

Question 28

Where is automatic breathing generated? Where specifically?

What is it influenced by?

Answer 28

In the brainstem, specifically the respiratory centers in the medulla oblongata and pons

Influenced by activity of chemoreceptors that monitor blood (P CO2, P O2, pH)

Question 29

Where are central chemoreceptors found?

Where are peripheral chemoreceptors found?

Answer 29

• In medulla oblongata
• In aorta (aortic bodies) and carotid arteries (carotid bodies)

Question 30

Which chemoreceptor is most crucial in ventilation and why?

Answer 30

P CO2 is most crucial because of its effects on blood pH (combines with H2O forming carbonic acid which dissociates quickly and results in increased levels of H+