lecture 19

Question 1

what is P50

Answer 1

the pressure at which the blood is 50% saturated with oxygen

Question 2

in what 3 forms is CO2 transported in the blood

Answer 2

dissolved in plasma, around 7%
as bicarbonate, 70%
combined with proteins as carbamino compounds, 23%

Question 3

what converts the CO2 to carbonic acid

Answer 3

carbonic anhydrase

Question 4

what do carbonic acid molecules do in the RBC

Answer 4

immediately dissociate into Hydrogen ions and bicarbonate ions

Question 5

what do H+ ions from carbonic acid do

Answer 5

bind to Hb to make HbH+

Question 6

what do bicarbonate ions from carbonic acid do

Answer 6

move into plasma in exchange for Cl-, this is chloride shift

Question 7

where are the The respiratory rhythmicity centres

Answer 7

they are in the medulla of the brainstem

Question 8

what do the The respiratory rhythmicity centres do

Answer 8

This part makes cycles of relaxation and contraction in the diaphragm, making the pace of ventilation. This can be modified by higher areas of the brain in response to chemical and pressure signals.

Question 9

what are the 4 mechanisms by which respiratory function is regulated

Answer 9

chemoreceptors, baroreceptors, lung stretch receptors, protective reflexes

Question 10

what are the three centres of the rhythmicity centres

Answer 10

Ventral respiratory group, Dorsal respiratory group, Pre-Botzinger complex

Question 11

describe the DRG and their roles

Answer 11

inspiratory neurons, these send signals to the diaphragm and external intercostals to contract to inspire.

Question 12

describe the Pre-botzinger complex and its roles

Answer 12

like the SA node for the heart but this for the lungs, it generates rhythm and generation of respiration.

Question 13

describe the VRG and their roles

Answer 13

inspiratory and expiratory centers, these arent active in quiet breathing. during forced inspiration they send signal to accessory muscles, in forced expiration they send signals to accessory muscles and internal intercostals.

Question 14

where are the central chemoreceptors and what are they sensitive to

Answer 14

they are in the medulla. they are sensitive to PCO2 but not PO2

Question 15

process for central chemoreceptors to activate

Answer 15

CO2 diffuses from cerebral capillaries and into the CSF, the central chemoreceptors then respond to this PH change in the CSF.

Question 16

where are the peripheral receptors and what do they respond to

Answer 16

located in the carotid and aortic bodies, mainly responding to PO2 changes, limited CO2 response, these adapt fast

Question 17

whats the most important thing in determining respiratory activity

Answer 17

the receptors acting on CO2