Week 7

Question 1

cohesion

Answer 1

attractive forces between substances that are alike i

Question 2

adhesion

Answer 2

attractive forces between unlike substances

Question 3

what forces are responsible for surface tension?

Answer 3

Cohesive forces

Question 4

Surface tension -

Answer 4

property of a liquid surface that causes it to behave like an elastic sheet, as the result of cohesive forces

Surface tension acts to reduce the surface area of a body of liquid

γ = F/L

Question 5

When two bubbles collide, air always flows from the ___ to the ___ and why

Answer 5

When two bubbles collide, air always flows from the smaller to the larger, because the pressure in the small bubble, is larger than that of in the bigger bubble.

Question 6

pressure inside the bubble must be ___ than the outside pressure to ___

Answer 6

The pressure inside the bubble must be higher than the outside pressure to stop the
surface tension from collapsing the bubble

Question 7

Air moves from ___ to ___ P

Answer 7

Air moves from high to low P

Question 8

surfactant -

Answer 8

substance that, when added to a liquid, reduces the liquid’s surface tension

Question 9

Capillarity -

Answer 9

distortion of a liquid surface due to adhesive forces between the surface of the liquid and an adjacent solid surface. This can result in the liquid being pulled up or down a narrow tube.

Question 10

important functions of lungs (4):

Answer 10

1. They interact with blood by exchanging carbon dioxide for oxygen.
2. They maintain the blood pH.
3. They are involved in heat exchange and fluid balance in the body.
4. They are a key element in voice production.

Question 11

how much air do we typically breathe in?

Answer 11

We typically breathe in ≈6 L/min of air

Question 12

since air is ≈20.9 % oxygen, we inhale how much oxygen/min?

Answer 12

~1.2 L oxygen/min

Question 13

breathing rates:

Answer 13

typically
- 12/min for men
- 20/min for women
- 60/min for infants

Question 14

Alveoli are typically stable at

Answer 14

approximately ¼ of their maximum size

Question 15

Functions of surfactant:

Answer 15

• provide alveolus stability
• lower the force needed to be supplied by the diaphragm to inflate the alveoli

Question 16

How are lungs expanded and contracted by the motion of structures surrounding them?

Answer 16

1. The diaphragm moves downward to lengthen the chest cavity during inspiration.
2. The ribs are elevated by the neck muscles to increase the front-to-back diameter of the
   chest cavity and are lowered by the abdominal recti to decrease it.

Question 17

Processes in breathing:

Answer 17

Lungs before inspiration: atmospheric P

=> Lower atmospheric P in pleural sac => attractive force from the visceral to the parietal pleura and the outward force of the
outer lung wall cause each lung to expand

=> Lung V increases (1. attraction of the visceral and parietal pleurae increases as they are separated further and 2. this separation causes P_lung− P_pleura (ΔΡ) to decrease even more)

=> Both of the forces in the direction of lung expansion increase and overcome the springiness of the lungs that favors lung contraction

=> the lung expands => pressure in the lungs and alveoli decreases and air flows from the mouth and nose into the lungs

Question 18

volume of the lungs depends on

Answer 18

transpulmonary pressure (difference in pressure in the alveoli and that around the lung in the pleural sac, which is called the intrapleural pressure.)

Question 19

VC - Vital capacity:

Answer 19

important measure of how well the lungs are functioning

VC = Inspiratory Capacity (Inspiratory Reserve V + Tidal V) + Expiratory Reserve V

Question 20

With advancing age, what happens to the total lung capacity and vital capacity?

Answer 20

With advancing age, the total lung capacity does not change, but the vital capacity decreases.

Question 21

Airway resistance -

Answer 21

ratio of pressure difference to volume rate of airflow (units of P per unit flow rate, ex: Pas/L)