Respiration and Breathing 3 Flashcards Preview

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Flashcards in Respiration and Breathing 3 Deck (27):
1

What does gravity influence

Ventilation and perfusion

2

Why is local matching of ventilation and perfusion important

To optimise gas exchange in lungs

3

Why is there better airflow at the base of the lungs

Due to pressure gradients

4

What is perfusion

Blood supply

5

What happens when there is no ventilation and good perfusion

Blood passing through the lung without coming into contact with alveolar air (right to left shunt)

6

What happens when there is good ventilation but no perfusion

Anatomically an increase in dead space or ventilated alveoli are not perfused

7

What mechanisms are in place to prevent alveolar ventilation rate matching perfusion rate

Achieved by modulation of blood flow.

8

What happens during hypoxia

When there is low PO2 vasoconstriction occurs. Blood is directed away from poorly ventilated areas. The response is very non-linear.

9

What happens during ventilation

The delivery of oxygen and removal of carbon dioxide.

10

Describe what happens to blood before perfusion

Blood from ventricle. Has high levels of CO2 and low levels of O2

11

How are alveoli adapted for gas exchange

Fluid lining of pulmonary surfactant which reduces pressure. Surrounded by a single cell capillary. Have a very small interstitial space (0.5 um)

12

What is transfer of oxygen influenced by

Diffusion across red blood cell membrane. Combination with haemoglobin.

13

What does combination of oxygen with haemoglobin do

Increases affinity and increases O2 capacity of blood.

14

Why is haemoglobin vital

Removes O2 so maintains conc gradient

15

What is the equation for oxygen and haemobglobin

O2 + Hb -> HbO2

16

Describe the Haemoglobin-O2 dissociation curve

% haemoglobin saturation (0-100)

PO2 of blood (mm Hg)

ml O2 per 100ml in blood (0-20)

17

Describe haemoglobin binding with oxygen

4 binding sites. Co-operation between sites so more sites bound easier it is to bind to another O2. Affinity depends on amount of O2 already bound

18

Describe the Bohr Shift

In the presence of CO2 there is a change in the haemoglobin bidning of O2. An increase in PCO2 helps haemoglobin to release O2 where metabolsim is taking place

19

Which factors result in the Bohr shift and so the release of O2 from haemoglobin

Increase PCO2 (metabolsim). Increase in conc H+ (metabolsim). Increase in temperature (muscles contract). Increase in BPG (hypoxia).

20

What is the PO2 in body tissue

Less than or equal to 40 mm Hg

21

What is the PO2 of oxygen in the alveoli

100 mm Hg

22

What is the PCO2 in the body

Greater than or equal to 46

23

What is the PCO2 in the alveolus

40 mm Hg

24

How is carbon dioxide carried in the blood

Chemical comination in plasma

CO2 + H2O -> H2CO3 -> H+ + HCO3(-) 

25

How much CO2 is carried in the plamsa

70%

26

How much CO2 is bound to Hb

30%

27

What is the name of the compound formed when CO2 bonds to Hb

carbamino compounds