Respiratory Physiology

Question 1

how does gas move

Answer 1

gas movement through the conducting airways occurs by convection. Gas exchange across the blood gas barrier in the alveolous occurs by diffusion

Question 2

Rate of oxygen transfer hamelgobin calculation

Answer 2

Dt = Kt x S x (1/t)
Rate of Oxygen transfers to hemoglobin
Rate at which oxygen travels through liquid krogh oxygen permeation coefficient
Mean Barrier Thickness

Question 3

Oyxgen is transported in tow forms in blood

Answer 3

Oyxgen is transported in tow forms in blood
O2 bound to hemoglobin enlabes O2 offloading to tissues
Plasma Soluble O2 (less soluble than CO2)

Question 4

what is oxygen content

Answer 4

Oxygen Content is determined by amount of Hb and O2 in blood

Question 5

Saturation percentage

Answer 5

oxygen saturation is the portion of oxygen
Oxyhemoglobin / O2 carrying capacity of Hb
saturation stays the same when Hb content

Question 6

what is P50

Answer 6

P50 value PO2 required for half maximal Hb saturation

Question 7

V in the graph for Hb saturation

Answer 7

Steep phase of curve favours offloading of arterial oxygen to tissues. greater HBO2 dissociation for small changes in tissue PO2

Question 8

A in the graph for Hb saturation

Answer 8

Arterial Plateau phase ensures maximal HbO2 saturation even if alveolar PO2 is below the normal oxygen tension

Question 9

Left Shift for graph for HB saturation

Answer 9

Left Shift - increases HBO2 affinity and reduces O2 offloading to tissues

Question 10

Right shift for graph for Hb Saturation

Answer 10

Right shift - decrease HB02 affinity and raised O2 offloading to tissues and may be induced stressors such as acidosis fever and hypoxia

Question 11

Haemoglobin

Answer 11

Heterotetramer composed of 2a and 2b subunits
oxygen reversibly binds to Fe3+ ions in the centre of the heme ring
CO2 Ph AND 23 bpg alter this affinity by interacting with charged amino groups between a and b subunits
contains 4 iron binding HEME doamins

Question 12

Bohr effect

Answer 12

Bohr effect is when pH alters the ability of oxygen to bind to hemoglobin

Question 13

what does amino binds to

Answer 13

amino terminus of hemoglobin a subunit binds to the carboxy terminal histidine in b subunit this stabilises Hb structure

Question 14

How is the interaction sensitive

Answer 14

this interaction is pH and O2 sensitive requires H+ and 2O2 released
Acidosis decrease pH favours the a b subunit interaction and reduces the binding of O2 to heme

Question 15

Increase blood pCO2 releases O2 from Hb in two ways

Answer 15

production of carbonic acid
carbamate reaction at N terminal amino groups on Hb a subunit

Question 16

Porduction of carbonic acid and carbamte reaction causes

Answer 16

Porduction of carbonic acid and carbamte reaction causes acid stabilisation of a b Hb subunit interaction Low Hb affinity for O2

Question 17

three ways to CO2 transported in blood

Answer 17

CO2 is transported in three forms in blood by
Plasma Soluble CO2
Bicarbonate Ion
Carbamino Hemoglobin

Question 18

Carbon dioxide dissociation curve

Answer 18

Hypoxia is higher than venous and lowest is alveolar
Deoxygenation of blood improves carriage of CO2

Question 19

step one CO2 Release from Tissue

Answer 19

CO2 dissolves into plasma & red cellalong partial pressure gradient

Question 20

step two CO2 Release from Tissue

Answer 20

Low tissue O2 favours CO2 carriageby blood (HALDANE EFFECT

Question 21

step three CO2 Release from Tissue

Answer 21

Carbamate reaction reducesHbO2 affinity (BOHR EFFECT)

Question 22

step four CO2 Release from Tissue

Answer 22

Carbonic Anhydrase reactiongenerates carbonic acid whichprotonates. HCO3- leaves cell andmaintains inward CO2 gradient

Question 23

step five CO2 Release from Tissue

Answer 23

Increased red cell [H+] reducesHbO2 affinity by promoting ab Hbsubunit interaction (BOHR EFFECT)

Question 24

CO2 release from red cell step one

Answer 24

O2 dissolves into plasma & red cellalong partial pressure gradient

Question 25

CO2 release from red cell step two

Answer 25

High affinity of Hb for O2 reversesHb carbamation and protonation raisingavailabiity of high affinity Hb (BOHR EFFECT)

Question 26

CO2 release from red cell step three

Answer 26

CO2 diffuses into alveolus alongpressure gradient. High PO2 decreasesCO2 affinity for Hb (HALDANE EFFECT)

Question 27

CO2 release from red cell step four

Answer 27

Movement of CO2 out of red cell increases HCO3- uptake (Cl- moves out)

Question 28

CO2 release from red cell step five

Answer 28

Proton release from Hb and [HCO3-] drive carbonic anhydrase reaction in reverse, maintaining outward CO2 gradient and lowering plasma bicarbonate

Question 29

high altitude adaptation

Answer 29

conserve pAO2:
increasing breathing frequency - paCO2 decreases
high carbohydrate , RQ = 1
Climb when barometric pressure (Krogh)

Question 30

poor ventilation and large blood flow

Answer 30

poor ventilation and large blood flow
need to reduce perfusion hypoxia constricts pulmonary arterioles

Question 31

Good ventilation and poor blood flow

Answer 31

Good ventilation and poor blood flow
need to reduce ventilation - low CO2 constricts bronchioles

Question 32

What is hypoxia

Answer 32

Hypoxia - constricts pulmonary arteries to increase pulmonary transit time of blood
Re directs blood flow to well ventilated areas of lung

Question 33

what does CO2 do

Answer 33

Low CO2 - consitrcts bronchioles to area of vascular obstruction and re directs air flow in lungs away from obstruction