resp quick fire

Question 1

what stimulates carotid chemoreceptors?

Answer 1

changes in partial pressure of O2

Question 2

does blood or CSF have better buffering capacity?

Answer 2

Blood.

Question 3

what stimulates medullary chemoreceptors?

Answer 3

changes in CSF pH (H+ conc)

Question 4

what is hypoxic pulmonary vasoconstriction?

what drugs inhibit HPV

Answer 4

hypoxic pulmonary vasoconstriction occus in response to a fall in oxygen tension (below 11-12kPa) in nearby alveoli, directing blood away from poorly ventilated areas of the lung.

Drugs that inhibit HPV:
-all inhalation agents (dose-dependent_
-beta-2 adrenoreceptor agonists, resulting in VQ mismatch

midazolam, ketamine and thio have no effect

Question 5

blood supply pf lungs

Answer 5

The bronchial arteries are branches of the descending aorta (not pulmonary arteries) and supply the bronchi, the lung connective tissue and the visceral pleura.

The bronchial veins communicate with the pulmonary veins and drain into the azygos and hemiazygos veins.

The terminal branches of the pulmonary arteries deliver deoxygenated blood to the alveoli (not oxygenated).

Following oxygenation the blood leaves the alveolar capillaries and drains into the tributaries of the pulmonary veins, which follow the intersegmental connective tissue septa to the lung root, thus there are a total of four (not two).

Question 6

what is mapleson A also known as

Answer 6

magill or lack (coaxial A)

Question 7

what is mapleson D also known as

Answer 7

Bain (co-axial D)

Question 8

what is mapleson E known as

Answer 8

T pieces

Question 9

what is mapleson F also known as

Answer 9

modified jackson Rees

Question 10

what is RQ for:
glucose/carbs
Proteins
Fats
Ethyl alcohol

mixed diet:

Answer 10

glucose/carbs= 1
Proteins=0.9
Fats= 0.7
Ethyl alcohol= 0.67

mixed diet: 0.8

RQ=CO2 produced/ O2 consumed
typically 200ml/min CO2 produced/ 250 ml consumer =RQ of 0.8

The above are because lipids and alcohol require more oxygen than carbs for complete oxidation.

Question 11

what is the effect of volatiles including N2O on hypoxic pulmonary vasoconstriction

Answer 11

volatiles cause vasodilation and inhibit hypoxic pulmonary vasoconstriction thus worsening V/Q mismatch. Volatiles also reduce FRC and can cause atelectasis further impairing gas exchange and contributing to V/Q mismatch.

Sevo and ISO have the mildest HPV inhibiton.
DEs is more pronounced, particularly at high volumes

Question 12

what is hypoxic pulmonary vasoconstriction?

Answer 12

a process where low PO2 in alveoli causes vasoconstriction of blood in neighbouring alveoli to help reduce VQ mismatch

low PO2 in alveoli influences this more than low PO2 in blood