L20

Question 1

How does PO2 and PCO2 affect active tissue?

Answer 1

O2 is delivered to active tissue
O2 is used up in tissues
O2 supply must increase
Respiring tissue produce CO2, pCO2 increases, which causes VASODILATION locally around the working tissues, this increases blood flow to tissue

Question 2

What is LUNG PERFUSION?

Answer 2

• O2 is used up in tissues, PO2 decreases in blood
• This will lead to local VASOCONSTRICTION in lungs
• this will lead to lungs shunting and directing bloods into oxygen rich areas within the lungs

Question 3

How is bronchodilation brought about in terms of pCO2?

Answer 3

• CO2 returns from working tissues
• pCO2 increases
• this causes BRONCHODILATION
• more air flow id directed towards area within lung that bring CO2
• more CO2 is removed

Question 4

What changes do central Chemoreceptor in detect and where are they located?

Answer 4

• change in pH
• hypercapnia
  (are not affected by hypoxia)
  medulla

Question 5

What do peripheral chemoreceptors detect and LOCATION?

Answer 5

• Change in pH
• hypercapnia
• hypoxia
  aortic and carotid arteries

Question 6

What stimulus do mechanoRECEPTOR respond to?

Answer 6

• Stretch

Question 7

What type of mechanoreceptor are there and EXPLAIN their function.

Answer 7

• Slowly adapting mechanoreceptor = related to Hering Breuer reflex
• Rapidly adapting mechanoreceptor = related to cough reflex
• C-fibre ending ending = defence mechanism against anything that irritates airways

Question 8

What does the rhythmic centre do?

Answer 8

controls automatic breathing

Question 9

What does pneumataxis and apneustic centres do?

Answer 9

modify firing patterns of the rhythmic centre

Question 10

What does the pneumataxis centre and apneustic

Answer 10

Apneustic centre =
- stimulates INSPIRATION
- stimulating I neurones
Pneumataxis centre = inhibits apneustic centre
- stops inhalation and PROMOTES exhalation