ventilation and gas transport

Question 1

the total volume of blood is divided into 4 volumes. what are they?

Answer 1

tidal volume (TV): volume of air inspired and expired during regular breathing NOT NECESSARILY AT REST
inspiratory reserve volume (IRV): volume of air that can be inspired after a tidal inspiration
expiratory reserve volume (ERV): volume of air that can be expired after a tidal expiration
residual volume (RV): volume of air that cannot be emptied from the lungs.

Question 2

the combination of the 4 volumes that make up the total volume of air form capacities. what are these capacities?

Answer 2

total lung capacity: TLC=RV+IRV+ERV+TV
functional residual capacity: FRC=RV+ERV
inspiration capacity: IC=TV+IRV
vital capacity: VC=TV+IRV+ERV or VC=TLC-RV

Question 3

what is the most influential factor that contribute to the variation of the total volume of lung? and what are other factors?

Answer 3

height is the most influential one. others: age, genetic, disease…

Question 4

what is dead space?

Answer 4

part of the airways that do NOT participate in gas exchange

Question 5

what are the different dead spaces (Vd)?

Answer 5

3 dead spaces:
anatomical dead space: entirety of the conducting airways and the upper respiratory tract (oral/nasal, pharynx and larynx)
alveolar dead space: respiratory tissue unable to participate in gas exchange usually due to an absent or inadequate blood flow
physiological dead space: anatomical+alveolar dead space

Question 6

what does pulmonary ventilation mean (Ve)? how do you calculate it?

Answer 6

amount of air moving in and out of the lungs per minute.

Ve=TV x breathing frequency (Rf)

Question 7

what is the alveolar ventilation (Valv)and how do you calculate it?

Answer 7

it is the amount of air per minute reaching the gas exchange surface. Valv= (VT-Vd)xRf

Question 8

what is poiseuille’s law?

Answer 8

airway resistance= 8nl/pi(r)^4

n: viscosity of a fluid
l: length of a tube
r: radius of the tube

Question 9

what is fick’s law of diffusion and its formula?

Answer 9

molecule diffuse from regions of high concentration to low concentration at a rate proportional to the concentration gradient (P1-P2)
V(Gas)=(A/T)xDx(P1-P2)
A: exchange surface area
T: thickness of the exchange surface 
D: diffusibility of the gas

Question 10

what is Henry’s law’s formula?

Answer 10

Cd(gas)= alpha(gas)xP(gas)
alpha: solubility of gas
P: partial pressure

Question 11

what is the barometric pressure at sea level?

Answer 11

Pb=101.3kPa=760mmHg

Question 12

how do you calculate the partial pressure of a gas (P(gas)) within a mixture?

Answer 12

P(gas)=Pbxfraction

Question 13

what is called the process that modifies the air that travels through the upper airway to optimise gas exchange and to protect the lung tissue? and what does this process consist of?

Answer 13

respiratory conditioning consists of
warming of the air to a physiological temperature, then humidification to a PH2O of 6.3 kPa (100% saturation), then slowing down of the air, mixture of the newly inspired air with the air already in the lungs.

Question 14

from what does haemoglobin consists of?

Answer 14

4 Hb monomers formed of 2 parts:

haem: F2^(2+) int he middle of a tetrapyrrole porphyrin ring that can bind to one molecule of oxygen. when O binds to the ring is modifies.
global: protein chain

Question 15

what is an allosteric protein? give an example of an allosteric protein

Answer 15

an allosteric protein is a protein that undergoes conformation changes when a compound binds to it. example: haem

Question 16

what is the process of cooperativity?

Answer 16

the fact that O2 can bind more easily to those monomers the more they’re saturated because when O2 bind to one of the monomers than it undergoes conformational changes into a more relaxed state.

Question 17

what does the oxygen dissociation curve show?

Answer 17

it shows that Hb is very efficient at loading oxygen in the lungs and very efficient at unloading oxygen at respiring tissues.

Question 18

what factors could influence the oxygen dissociation curve and how do these affect it?

Answer 18

decrease in temperature, alkalosis, hypocapnia, and decrease in 2,3-DPG –> leftward shift/increased affinity
increase in temperature, acidosis, hypercapnia, 2,3-DPG
–> rightward shift ==> BOHR EFFECT

Question 19

some disease may affect the oxygen dissociation curve? give example of diseases and how do these diseases affect the oxygen dissociation curve?

Answer 19

polycythaemia increases RBCs –> stretches the ODC upwards (no change in HbO2 saturation but O2 content increases)
anaemia decreases RBCs –> stretches the ODC downwards (no change in HbO2 saturation but O2 content decreases)

Question 20

why is it better to refer to deoxygenated blood as mixed venous?

Answer 20

the deoxygenated blood has 75% of the oxygen that arterial blood has.

Question 21

where does oxygen pass from during oxygenation?

Answer 21

alveolar space pulmonary epithelial cells, interstitial space, vascular endothelial cells, plasma, RBCs, to binding to Hb that are not fully saturated.

Question 22

some of the CO2 binds to haemoglobin BUT NOT haem. it binds to the amino group. How is then called the haemoglobin?

Answer 22

carbaminohaemoglobin