Pulmonary/Respiratory

Question 1

Function of the lungs

Answer 1

• gas exchange (alveolus)
• regulation of H+ concentration
• partial or complete removal of neurotransmitters and paracrine agents from the blood stream (endothelial cells of pulmonary capillaries)
• production and secretion of substances into the blood (histamine and angiotensin II)
• acts as a sieve that traps and dissolves small blood clots

Question 2

pulmonary circulation

Answer 2

-role is to deliver deoxygenated blood to the pulmonary capillaries and alveoli gas exchange
-high compliance, low resistance system
alveolar hypoxia results in pulmonary vasoconstriction to shunt blood from poorly ventilated area of lungs
-carries deoxygenated blood from right ventricle to pulmonary trunk, to pulmonary arteries
-after gas exchange, reoxygenated blood will enter the pulmonary veins and drain into left atrium
-as it travels through aorta to right atrium start of bronchial circulation

Question 3

Bronchial circulation

Answer 3

• role to deliver O2 & nutrients to the lung tissues
• high pressure, high resistance systemic vessels
• originates from branches off of aorta
• supplies supporting tissue, connective tissue
• after supplying the supporting tissues, bronchial venous blood drains directly into the pulmonary veins, diluting the oxygenated blood that has just passed through
• hypoxia in this system results in vasodilation

Question 4

Gas exchange

Answer 4

• O2 absorption and CO2 excretion occurs in alveolus
• gases diffuse across the membrane of alveolus and the pulmonary capillaries through a thin fluid layer containing, surfactant plasma and connective tissue
• O2 diffuses from alveoli to blood and carried to tissues
• CO2 is produced in cells/tissues during metabolism

Question 5

CO2 movement: tissues to blood stream

Answer 5

-10% of CO2 that diffuses from the tissues into capillaries dissolves in plasma
-30% reacts with Hb within RBcs to become Hb-CO2
-60% converted to bicarbonated within the RBC
-

Question 6

Haldane effect

Answer 6

• the lower the Hb saturation with O2, the greater the blood carry capacity for CO2

Question 7

Bohr effect

Answer 7

-as more CO2 enters the blood stream, more )2 is released from Hb

Question 8

Carbonic anhydrase

Answer 8

the Co2 that enters the RBS is converted to carbonic acid with this enzyme
-then converted to bicarbonate

Question 9

Chloride shift

Answer 9

-once HCO3 is formed, it moves out of RBC into plasma exchange for Cl-

Question 10

Reduced hemoglobin (HHb)

Answer 10

• the H+ ion bind to Hb and become this

- plays role in preventing acidosis

Question 11

CO2 movement: blood stream to alveolus

Answer 11

• CO2 dissolved in the plasma diffuses into the alveoli (across concentration gradient)
• as Co2 leaves the blood, Co2 concentration in blood decreases, triggers more CO2 to be released from hemoglobin and diffuse into the blood
• H+ becomes available as HbH releases H+
• the H+ will be donated to plasma HCO3 forming H2CO2 eventually H2o + CO2

Question 12

O2 movement: alveoli to blood stream

Answer 12

• O2 is brought to the lungs then into the systemic vessels (via left heart pump)
• high concentrations of O2 in the alveoli and low concentrations in the blood allows the O2 to diffuse out of alveoli and into blood stream
• O2 is relatively insoluble in the blood
• the rest must be carried by Hb(98.5 %)
• oxygen molecules bind to heme groups in Hb, 4 heme groups for one oxygen
• the hemoglobin changes shape increasing the uptake and binding oxygen to empty hemes

Question 13

percent hemoglobin saturation

Answer 13

%Hb saturation= (amount of O2 on Hb)/(max possible amount) X 100

Question 14

hemoglobin saturation is determined by:

Answer 14

(i) blood Po2 (partial pressure of O2 in blood)
(ii) amount of hemoglobin in each L of blood
- the rate at which oxygen combine with Hb increases rapidly as PO2 increases from 10-60mmHg

Question 15

maximal saturation of Hb

Answer 15

• as low as 60mmHg

Question 16

Other factors that influence saturation Hb with oxygen

Answer 16

(1) 2,3-bisphosphoglycerate (BPG) concentrations
(2) temperature
(3) [H+]/acidity

Question 17

2,3-bisphosphoglycerate (BPG) concentrations

Answer 17

• BPG is produced by the erythrocytes, as a result of anaerobic glycolysis and increases low oxygen situations
• increasing BPG will decrease affinity of Hb for oxygen= increasing the ability to offload oxygen to tissues

Question 18

Temperature

Answer 18

• blood temp drops, affinity for Hb for oxygen increases (oxygen bound tighter to hemoglobin)
• as temp increases affinity decreases
• increases temperature can occur as result of metabolism
• decreasing affinity of oxygen to Hb during exercise means that oxygen will more readily dissociate from Hb and enter the tissues more completely and rapidly

Question 19

(3) [H+]/acidity

Answer 19

• as acidity increases, affinity for Hb oxygen decreases
• the more active a tissue is, the greater PCO2, [H+], and temperature, all decrease affinity for oxygen for Hb and the greater release of oxygen into the tissues

Question 20

O2 movement: blood stream to cells/tissues

Answer 20

• plasma O2 concentrations will be higher than peripheral tissue concentrations so easy diffusion from blood into the tissues
• initially, dissolved oxygen will diffuse out of blood into the tissues than oxygen bound to Hb
• ~75%of Hb still saturated with O2 as blood leaves the capillaries, this is reserve O2
• during exercise, O2 consumption by tissues/cells increases