Blood supply

Question 1

Two types of blood circulation

Answer 1

Bronchial/ Nutritional
-arises from systemic circulation
-Bronchial capillaries
- to smooth muscle of airwyas. lung tissue
Pulmonary:
-Arises from right ventricle
-supplies capillaries surrounding the alveoli
-pulmonary arteries
-Unique system
-Returns oxygenated blood to the left atrium

Question 2

What is gas exchange proportional to?

When is it fastest?

Answer 2

Between alveoli and tissues
Proportional to
-the PP gradient
-gas solubility
-Surface area
Inversely proportional to:
-thickness of membrane 

Fastest over short distances

Question 3

What does gas exchange involve?

Concentration gradients and partial pressures of the alveoli and tissues

Answer 3

Partial pressure in alveoli= partial pressure in systemic arterial blood
Partial pressure in pulmonary artery=partial pressure in tissue
02: From alveoli to tissues
C02: from pulmonary artery to alveoli

Question 4

Disease in gas exchange

Answer 4

Emphysema:
-destroys the alveoli therefore decreasing SA
Fibrosis:
-Increases thickness of the alveoli due to XS tissue
Pulmonary edema:
-Increases intersistial fluid and therefore diffusion pathway
Asthma:
-Bronchioles contract which increases resistance

Question 5

Ventilation and perfusion in the lungs

Answer 5

Optimum when ventilation in the alveoli is equal to the perfusion in the pulmonary capillaries

When mismatched then Pco2 will increase and P02 will decrease.
Blood vessels surrounding these alveoli will have reduced gas exchange.
The capillaries surrounding the affected alveoli will contract reducing the blood flow in these areas.

Question 6

Alveolar dead space

Shunt

Answer 6

A.D.S: When alveoli ventilate but do not have perfusion

Shunt: movement Is the movement of blood from the right side to the left without passing by the lungs

Question 7

Distribution of blood flow in the lungs

Answer 7

Depends on alveolar pressure and hydrostatic arterial pressure.
It decreases from the base to the apex.
Base: Arterial pressure> alveolar pressure so low vascular resistance
Apex: Alveolar pressure> arterial pressure so high vascular resistance

Question 8

What are the values for Alveolar, arterial and venous pressure of the O2 and C02?
Definition of alveolar and arterial

Answer 8

PA02=100 mmhg -13.3 Kpa
PACO2=40 mmhg-5.3 Kpa
paO2=100 mmhg-13.3 Kpa
PaCO2=40 mmhg-5.3 Kpa
Pv02=40 mmhg- 5.3 Kpa
PvC02= 46 mmhg- 6.2 Kpa
alveolar: partial pressure of the alveolar air
arterial: partial pressure of the arterial blood

Question 9

Ratios V:Q

Answer 9

Ideal= 1.0
V> Q= >1.0
V

Question 10

Where does the majority of V:Q mismatch occur

Answer 10

At the apex of the lungs

Question 11

What is FEF

Answer 11

The flow over the middle of the FVC so 25% to 75%
Corresponds to the FEV1
Changes are more striking