Respiratory physiology

Question 1

what is carbaminohemoglobin?

Answer 1

is when CO2 chemically combines with hemoglobin in RBCs for transport to the lungs (where the reaction is then reversed)

this is the 2nd most common transport mechanism for CO2 from peripheral tissues

Question 2

Most CO2 that enter RBCs is converted to what with the help of what enzyme?

Answer 2

converted to carbonic acid with carbonic anhydrase

Question 3

What does the carbonic acid “become” in RBCs?

Answer 3

rapidly dissociates into a hydrogen ion and a bicarbonate ion

Question 4

What is the most common form in which CO2 is transported in the blood?

Answer 4

after CO2 conversion to carbonic acid,

then subsequent dissociation to a hydrogen ion and bicarbonate ion,

the hydrogen ion remains in the RBC (is buffered by hemoglobin),

and the bicarbonate ion exits the RBC and travels in the plasma

within the lungs, the above reaction is reversed allowing expiration of CO2

Question 5

What are the 2 main CO2 transport mechanisms?

Answer 5

1st - becomes carbonic acid in RBCs, dissociates & travels as separate hydrogen ion (in RBC) and bicarbonate ion (in plasma)

2nd - becomes carbaminohemoglobin in RBCs

both reactions are reversed in the lungs

Question 6

What is the 3rd mechanism of CO2 transport?
(smallest percentage takes this route)

Answer 6

simply dissolved in plasma (7%)

Question 7

Is intrapleural and intrapulmonic pressure negative or positive on inspiration?

Answer 7

intrapleural becomes more neg.
intrapulmonic becomes neg.

Question 8

Is intrapleural and intrapulmonic pressure negative or positive on exspiration?

Answer 8

intrapleural remains neg.
intrapulmonic becomes pos.

Question 9

define eupnea

Answer 9

normal, “quiet” breathing

Question 10

what resp. reflex center is responsible for setting breathing rate?

Answer 10

medullary rhythmicity area

Question 11

What is the Hering-Breuer reflex?

Answer 11

a reflex triggered to prevent the over-inflation of the lung.

Pulmonary stretch receptors respond to excessive stretching of the lung during large inspirations and send afferent impulsesvia the vagus nerve to inhibit the inspiratory center.

Question 12

What is the Bohr effect?

Answer 12

explains how carbon dioxide and hydrogen ions influence haemoglobin’s oxygen affinity

so

The rate of O2 unloading is increased in metabolically active tissues due to increased acidity.

Question 13

What is PaCO2

Answer 13

Partial pressure of carbon dioxide in arterial blood: This measures the amount of carbon dioxide in your blood and how well carbon dioxide can move out of your body.

Question 14

what is the haldane effect

Answer 14

oxygenation of blood in the lungs displaces carbon dioxide from hemoglobin, increasing the removal of carbon dioxide.

Consequently, oxygenated blood has a reduced affinity for carbon dioxide.

Question 15

renal compensation is absent in what grade of resp. acidosis?

Answer 15

acute respiratory acidosis

and thus, renal compensation is present in chronic resp. acidosis

Question 16

Acute hypoventilation causes

Answer 16

respiratory acidosis.

Question 17

Hyperventilation causes

Answer 17

respiratory alkalosis.

Question 18

What is positive cooperativity

Answer 18

This means that when deoxyhemoglobin binds a single oxygen, it causes the other heme groups to become much more likely to bind other oxygen molecules.

Question 19

What does it mean when the O2 - Hb curve shifts to the right?

Answer 19

it means there is reduced hemoglobin oxygen affinity

(this occurs in tissues e.g. in muscles during exercise)

Question 19

What does it mean when the O2 - Hb curve shifts to the left?

Answer 19

it means there is increased hemoglobin oxygen affinity

(this occurs in the lungs)

Question 20

What 3 factors are associated with reduced O2-Hb affinity?

Answer 20

increase in CO2
decrease in pH
increase in DPG/BPG

Question 21

What 3 factors are associated with increased O2-Hb affinity?

Answer 21

decrease in CO2
increase in pH
decrease in DPG/BPG