Chapter 17: Mechanisms of Breathing

Question 1

What are the 4 functions of the respiratory system

Answer 1

Gas exchange, regulation of body pH, protection from inhaled pathogens, vocalization

Question 2

External Respiration

Answer 2

1. Ventilation
   2.exchange of O2 and CO2 by lungs and blood
2. transport of O2 and CO2 by blood
3. exchange of gases between lungs and cells

Question 3

Structure of upper respiratory tract

Answer 3

mouth, pharynx, larynx

Question 4

Structure of lower respiratory tract

Answer 4

trachea, bronchi, branches, lungs

Question 5

What is the function of Pleural Fluid

Answer 5

It lowers friction between membranes
holds lungs against the thoracic wall

Question 6

Why are there no muscles in the lungs? How do they expand

Answer 6

Muscles would interfere with gas exchange. So lungs have muscles around the lungs to help expand and contract them

Question 7

Type one alveoli cells

Answer 7

Used in gas exchange. They are large but thin and flat epithelial cells whose basement membrane binds to capillary endothelium. There is also a small amount of fluid present in the remaining area.

Question 8

Type 2 Alveoli cells

Answer 8

These are cuboidal cells that secrete and synthesize surfactants. They also minimize the amount of fluid in alveolar space by transporting solutes and water out of the alveoli air space.

Question 9

What do surfactants do

Answer 9

It mixes with the alveolar fluid to aid the lungs as they expand. They decrease the surface tension of alveolar fluid, and decreases resistance of the lung to stretch

Question 10

Is the blood flow in the pulmonary arteries Low flow or high flow? Low pressure or high pressure? Why?

Answer 10

High flow, Low pressure. Lungs receive the entire cardiac output of the right ventricle causing the high flow. The low pressure is due to the right ventricle not having to pump as forcefully because resistance is low. The low resistance is attributed to the shorter total length of blood vessels.

Question 11

Why do gases diffuse rapidly in the alveolar space?

Answer 11

The distance between alveolar air space and capillary endothelium is short.

Question 12

Is blood flow through the pulmonary trunk greater than, less than, or equal to blood flow through the aorta?

Answer 12

About equal

Question 13

If nitrogen is 78% of atmospheric air, what is the partial pressure of nitrogen (PN2) in a sample of dry air that has an atmospheric pressure of 720 mm Hg? Why?

Answer 13

720 mm Hg * 0.78 = 562 mm Hg
Because the problem states that nitrogen makes up 78% of atmospheric air. To convert this percentage into mmHg you would multiply the sample of dry air(720 mm HG) by the percentage (0.78) of nitrogen.

Side note: I like to think of this in cookies. So if you have a box of an assortment of 720 cookies, and 78% of them are chocolate chip. You would use the calculation above to figure out how many cookies makeup 78% of the box.

Question 14

Does all venous blood leaving the bronchi, pleura, and part of the heart to go through pulmonary circulation?

Answer 14

No, some of it drains directly into the anatomic shunt which is on the left side of the heart.

Question 15

What does Boyles law describe?

Answer 15

It describes the pressure-volume relationships of gas. P1V1=P2V2

Question 16

What does Boyles law state?

Answer 16

if the volume of gas is reduced pressure increases, if the volume of gas is increased, then the pressure decreases.

Question 17

Does pressure in the respiratory system decrease or increase when you breathe out?

Answer 17

It increases to push the air out.

Side note: Think of it like a balloon. When you blow up a balloon you add air making the inside of the balloon bigger aka, increasing its volume. When you let go of the balloon, the balloon gets smaller, decreasing the volume and air gets pushed out.

Question 18

How do you calculate the partial pressure of gas in humid air?

Answer 18

You do the same as in dry air but subtract the water vapor pressure first before multiplying the gas’s contribution

Question 19

What tool is used to test pulmonary function?

Answer 19

Spirometer

Question 20

Tidal volume(V1)

Answer 20

the volume that moves during a respiratory cycle

Question 21

Inspiratory Reserve Volume (IRV)

Answer 21

additional volume above tidal volume

Question 22

Expiratory Reserve Volume (ERV)

Answer 22

exhaled after end of a normal expriation

Question 23

Residual Volume (RV)

Answer 23

The volume of air in the respiratory system after maximum exhalation

Question 24

total lung capacity

Answer 24

vital capacity + the residual volume

Question 25

Inspiratory capacity

Answer 25

tidal volume + inspiratory reserve volume

Question 26

Functional residual capacity

Answer 26

expiratory reserve volume + residual volume

Question 27

For air to move into the alveoli, what must happen

Answer 27

pressure inside the lungs must become lower than atmospheric pressure

Question 28

When your diaphragm contracts, are you inhaling or exhaling

Answer 28

inhaling

Question 29

What is the law of LaPlace

Answer 29

P=2T/r
Pressure inside a bubble formed by a fluid film is a function of the surface tension(T) and the radius of a bubble (r)

Question 30

according to the Law of Laplace if two bubbles have different diameters but are formed by fluids with the same surface tension, would the bigger one or smaller one have a greater inside pressure

Answer 30

The smaller one

Question 31

What does the stimulation of b2-receptors in bronchioles

Answer 31

They respond to epinephrine and cause bronchodilation

Question 32

What is anatomic dead space

Answer 32

place where gases are not exchanged. 150ml

Question 33

What is the total pulmonary ventilation

Answer 33

The volume of air moved in and out of lungs per minute
ventilation rate x tidal volume

Question 34

What is alveolar ventilation?

Answer 34

a more accurate way to measure how much fresh air reaches the alveoli
Ventilation rate x (tidal volume - dead space)

Question 35

Define compliance

Answer 35

the measure of the ease with which the chest wall and lungs expand. Loss of compliance increases the work of breathing

Question 36

Elastance

Answer 36

the ability of a lung to resist stretching or to return to its unstretched state.

Question 37

What air passages of the respiratory system are collapsible

Answer 37

The bronchioles