Lecture 15 Flashcards Preview

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Flashcards in Lecture 15 Deck (19):
1

Cells Types of the Alveoli:

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

2

Type I alveolar cells:

simple squamous cells where gas exchange occurs

3

Type II alveolar cells (septal cells):

free surface has microvilli
secrete alveolar fluid containing surfactant

4

Alveolar dust cells:

wandering macrophages remove debris

5

Alveolar-Capillary Membrane:

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

6

4 Layers of membrane to cross:

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

7

Breathing or Pulmonary Ventilation:

-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

8

Boyle’s Law:

-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.

9

Quiet Inspiration:

-Diaphragm moves 1 cm & ribs lifted by muscles
-Intrathoracic pressure falls and 2-3 liters inhaled

10

Quiet Expiration:

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

11

Labored Breathing:

Forced expiration and inspiration

12

Forced expiration:

abdominal mm force diaphragm up
internal intercostals depress ribs

13

Forced inspiration:

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

14

Summary of Breathing:

1. Alveolar pressure decreases & air rushes in
2. Alveolar pressure increases & air rushes out

15

Alveolar Surface Tension:

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

16

Pneumothorax:

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

17

Pleural cavities are

sealed cavities not open to the outside

18

Compliance of the Lungs:

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

19

Airway Resistance:

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