L15-Cardiovascular-respiratory interactions and reflexes

Question 1

What are the two different types of interactions that occur between respiration and heart rate?

Answer 1

Mechanical - Inspiration increases venous return which increases HR by starlings law.
Neural- Inspiration increases HR, sinus arrhythmia

Question 2

What is the central neural respiratory effect on HR?

Answer 2

When central neural inspiratory neurones fire they exert inhibitory influence on vagal activity to the heart which increases HR

Question 3

What effects do pulmonary stretch receptors have on the heart?

Answer 3

Pulmonary stretch receptors send signals to the NTS that further inhibits the vagal activity so this increases HR.

Question 4

What is expected to happen to HR when respiration increases e.g. in exercise?

Answer 4

Heart rate increases

Question 5

What are the reflex effects of hypoxia on the heart?

Answer 5

Chemoreceptors increase the ventilation rate during hypoxia causes increased HR due to the effects explained above

Question 6

What happens to the heart during hypoxia if respiration cannot increase?

Answer 6

It is primarily a cardiovascular reflex to conserve O2

HR decreases and systemic vasoconstriction

Question 7

What is an example of a patient that is hypoxic but cannot increase their respiration rate and what causes their symptoms?

Answer 7

A Blue Bloater
they are hypoxic so appear blue
They have pulmonary vasoconstriction so are likely to get pulmonary oedema

Question 8

What is an example of a patient that is hypoix and can increase their respiration rate and what causes their symptoms

Answer 8

This can occur in a hypoxic environment such as at altitude.
The symptoms are a pink puffer
The increased respiration causes increased HR
This is because effects of increased resp overcome effects of chemoreceptors