Lecture 15

Question 1

Cells Types of the Alveoli:

Answer 1

Type I alveolar cells
Type II alveolar cells (septal cells)
Alveolar dust cells

Question 2

Type I alveolar cells:

Answer 2

simple squamous cells where gas exchange occurs

Question 3

Type II alveolar cells (septal cells):

Answer 3

free surface has microvilli

secrete alveolar fluid containing surfactant

Question 4

Alveolar dust cells:

Answer 4

wandering macrophages remove debris

Question 5

Alveolar-Capillary Membrane:

Answer 5

Respiratory membrane = 1/2 micron thick
Exchange of gas from alveoli to blood
4 Layers of membrane to cross
Vast surface area = handball court

Question 6

4 Layers of membrane to cross:

Answer 6

1. alveolar epithelial wall of type I cells
2. alveolar epithelial basement membrane
3. capillary basement membrane
4. endothelial cells of capillary

Question 7

Breathing or Pulmonary Ventilation:

Answer 7

• Air moves into lungs when pressure inside lungs is less than atmospheric pressure
• Air moves out of the lungs when pressure inside lungs is greater than atmospheric pressure

Question 8

Boyle’s Law:

Answer 8

• As the size of closed container decreases, pressure inside is increased
• The molecules have less wall area to strike so the pressure on each inch of area increases.

Question 9

Quiet Inspiration:

Answer 9

• Diaphragm moves 1 cm & ribs lifted by muscles

- Intrathoracic pressure falls and 2-3 liters inhaled

Question 10

Quiet Expiration:

Answer 10

1. Passive process with no muscle action
2. Elastic recoil & surface tension in alveoli pulls inward
3. Alveolar pressure increases & air is pushed out

Question 11

Labored Breathing:

Answer 11

Forced expiration and inspiration

Question 12

Forced expiration:

Answer 12

abdominal mm force diaphragm up

internal intercostals depress ribs

Question 13

Forced inspiration:

Answer 13

sternocleidomastoid, scalenes & pectoralis minor lift chest upwards as you gasp for air

Question 14

Summary of Breathing:

Answer 14

1. Alveolar pressure decreases & air rushes in

2. Alveolar pressure increases & air rushes out

Question 15

Alveolar Surface Tension:

Answer 15

Thin layer of fluid in alveoli causes inwardly directed force
-water molecules strongly attach to each other

Question 16

Pneumothorax:

Answer 16

Injuries to the chest wall that let air enter the intrapleural space

Question 17

Pleural cavities are

Answer 17

sealed cavities not open to the outside

Question 18

Compliance of the Lungs:

Answer 18

1. Ease with which lungs & chest wall expand depends upon elasticity of lungs & surface tension
   2, Some diseases reduce compliance ex. TB and paralysis

Question 19

Airway Resistance:

Answer 19

1. Resistance to airflow depends upon airway size
   -increase size of chest:
   airways increase in diameter
   -contract smooth muscles in airways:
   decreases in diameter