12. The Diving Response

Question 1

Sinus arrhythmia

Answer 1

Increased HR in inspiration

Decreased HR in expiration

Question 2

Vagal tone in Sinus arrhythmia is reduced because of:

Answer 2

Vagal neuropathy

Stress

Reduced physical fitness

Age

Question 3

Breath-hold diving (competitive apnoea)

Answer 3

Reflex to block ventilation

Reduced PaO2

Reduced arterial pH

Arterial chemoreceptor stimulation

Question 4

Arterial chemoreceptors: stimulation and ventilatory response

Answer 4

aortic and carotid bodies

Respond to low PaO2 and arterial pH

Increase ventilation

Cardiovascular effects

Question 5

Trigeminal Reflexes which block respiration

Answer 5

Cold shower

Dry drownings

Question 6

Laryngeal Reflexes which block respiration

Answer 6

Intubations

Dentist chair deaths

Cot deaths

Question 7

When there is no increase in ventilation possible e.g. during diving

Answer 7

Trigeminal reflex

Bradycardia

Vasoconstriction

Reduced cardiac work

Question 8

The diving response can be used to break which heart arrhythmia?

Answer 8

SVT

Question 9

When increase in ventilation possible e.g. on resurfacing

Answer 9

Increased HR

Vasodilation

improved circulation

Question 10

Answer 10

A = laryngeal stimulation

B = Chemoreflex alone

C = Diving response (both laryngeal stimulation and chemoreflex stimulation)