Lecture 9

Question 1

2 regions of the respiratory system, whah happens in the first region ? (3 things)

Answer 1

upper (until larynx) and lower regions (trachea and rest)

in upper :
- warming air to 37 so that alveoli are not damaged by cold
- adding water vapor -> exhange epithelium doesn’t dry out
- filtering out foreign material

Question 2

what is each alveoli surrounded by ?

Answer 2

elastic fibers, network or capillaries and lymphathic vessels

Question 3

how is the thrachea held open ? how many times can the primary bronchi divide ?

Answer 3

Help open by cartilage rings.

Up to 22 times.

Question 4

at what level of the division does the gas exchange start ?

Answer 4

bronchioles - alveoli

Question 5

cite the layers where alveoli and capillari are in contact for gas exchange

Answer 5

vessel endothelium - fused basement membrane - surfactant - alveolar space

Question 6

what is the mucus made of ? how can it move ?

Answer 6

saline + mucins

mucins are glycoproteins (protein core and carbohydrate side chains)

moves thanks to water and ciliated cells

Question 7

how is saline generated ? one disease ?

Answer 7

Cl- brought from ECF to epithelial cell, then Cl- and Na+ go into the lumen -> concentration gradient and water follows to go to lumen (osmosis)

cystic fibrosis : malfunction of CFTR channel, the one that brings Cl- to lumen -> solid mucus

Question 8

what acts as the “pump” in the respiratory system ?

Answer 8

diaphragm and thoracic cage (because most lung tissue is thin epithelium)

Question 9

approximately how much pleural fluid ?

Answer 9

25-30 mL

Question 10

how do we assess pulmonary function ?

Answer 10

how much air the person moves during quiet breathing and then with max effort

using a spirometer (inverted bell suspended in water)

Question 11

what is the dead space ?

Answer 11

air that does not reach the alveoli and remains in conducting airways (no gas exchange)

about 150 mL

Question 12

what is the difference between hyperpnea and hyperventilation ?

Answer 12

both are an increased respiratory rate / volume but :
- hyperpnea : increased metabolism (exercise)
- hyperventilation : no increased metabolism

Question 13

list the 5 lung volumes that we look at in tests

Answer 13

1) dead space : volume of airways without gas exchange
2) residual volume : volume after max exhalation
3) exspiratory reserve volume : forcefully exhaled after end of normal respiration
4) tidal volume : normal respiration
5) inspiratory reserve volume : additional volume we can maximally inspire above tidal volume

Question 14

how do we find the partial pressure of a gas in dry air ? and in humid air ? what changes at high altitude ?

Answer 14

Pgas = Patm * gas%

in humid : we substract water vapor pressure
Pgas = (Patm - PH2O) * gas%

At high altitude, the O2% doesn NOT change, but PO2 changes because Patm changes

Question 15

partial pressure of oxygen in : dry air, alveoli, capillaries, venos blood

Answer 15

all in mm Hg

160
100
40
40

Question 16

PO2 and PCO2 when alveolar ventilation increases and decreases

Answer 16

hyperventilation : PO2 increases, PCO2 decreases (what divers do)

hypoventilation : PO2 decreases, PCO2 increases

Question 17

how does the perfusion / ventilation match work ?

Answer 17

if underventilated alveoli, the blood passing there does not get oxygenated -> arterioles constrict to divert blood to better ventilated alveoli

Question 18

what are hypoxia and hypercapnia ?

Answer 18

hypoxia = too little oxygen on blood

hypercapnia = too much CO2 in blood

Question 19

how is the carbon dioxide transported in blood ? (three aspects)

Answer 19

1) 7% remains dissolved in plasma

2) 23% binds to hemoglobin in red blood cell

3) 70% in converted to bicarbonate (via carbonic acid) in red blood cell, bicarbonate enters the plasma in exchange of Cl-. At the lungs, it’s pulled back into RBC and converted to CO2.