Lecture 11 - Challenges to normal respiration

Question 1

How much oxygen do we need at rest

Answer 1

4.8L/kg/min

200 ml/min

Question 2

Effect on alveolar O2 at altitude

Answer 2

oxygen constant at 21%
atmospheric pressure at sea level - 100
PO2 - 21 pKa
Inspired O2 at alveolar level is less
inspired O2 alveolar level is less - 6.3 kPa
Partial pressure of inspired O2 = 0.21 (Patm - 6.3)kPa

Question 3

Alveolar gas equation

Answer 3

PAO2 = [FiO2 x (Patm - PH2o] -(PACO2/R)

13.3 kPa

Question 4

What does hyperventilation and respiratory alkalosis result in?

Answer 4

increased DPG and cause better unloading of oxygen
right shift
Polycythaemia - slow to develop
bicarbonate excretion from CSF and kidneys
Diuresis and hyponatraemia
Acetazolamide

Question 5

Acute mountain sickness

Answer 5

Headache
nausea
loss of apetite
difficult sleeping/exercising
amnesia/dizziness

Question 6

What does sever mountain sickness result in

Answer 6

Cheyne stokes respiration - is an abnormal pattern of breathing characterized by progressively deeper and sometimes faster breathing, followed by a gradual decrease that results in a temporary stop in breathing called an apnea.

cerebral and pulmonary oedema

Question 7

What happens to pressure with an increase in altitude

Answer 7

pressure decreases

Question 8

What stays the same and what changes

Answer 8

Fraction concentration of oxygen stays the same but partial pressure of inspired oxygen changes

Question 9

What does acclimatisation involve

Answer 9

sever physiological changes to help reduce hypoxia

Question 10

Why is deep sea diving possible when snorkelling below 1.6 metres is impossible?

Answer 10

at greater depth, helium-oxygen used
2% O2 sufficient
enables removal of N2
tissue solubility bends
high density at pressure
increased work of breathing
nitrogen narcosis above 40 m

Question 11

Decompression sickness

Answer 11

a condition that results when too rapid decompression causes nitrogen bubbles to form in the tissues of the body.
call it the bends ), and can cause pain in the muscles and joints, cramp, numbness, nausea, and paralysis.

Question 12

Dive reflex

Answer 12

In mammals, overrides homeostatic responses
causes a brain -heart connection as all blood supply directed towards limbs
- causes vasoconstriction
-02 conserved to heart, lungs and brain
reflex vagal bradycardia
suppressed ventilation drive

Question 13

What happens to atmospheric pressure under water

Answer 13

increases. Partial pressure of inspired Oxygen also increases

Question 14

When is deep diving possible?

Answer 14

if lower FiO2 is used to keep PiO2 normal.