Physio Exam 2 Lecture 10: Fluid Balance

Front 1

PHYSIO EXAM 2 LECTURE 10: FLUID BALANCE


How is pressure in the pulmonary artery compared to aortic pressure?

Back 1

Much lower.

8 mmHg vs. 110 mmHg

Front 2

The hydrostatic pressure in pulmonary capillaries about how much?

Back 2

8 mmHg

Left atrium: ~ 3-4mmHg

Pulmonary artery: 8 (diastolic) to 25 mmHg (systolic)

Front 3

O2 affinity drops under the conditions of:

Back 3

1. Increased Temp
2. Increased acidity
3. Elevated partial pressure of CO2.
4. Elevated levels of 2,3 diphosphoglycerate.

Front 4

What is the Bohr effect?

Back 4

Shift in O2-Hb saturation curve with changing pH and CO2.

NOTE: relating to pH and CO2!

Front 5

What is the Haldane effect?

Back 5

Shift in CO2 capacity of blood that happens with changing Hb saturation with O2.

In other words, the changes in O2 blood saturation affects the blood carrying capacity of CO2.

When Hb becomes fully saturated with O2, as in the lungs, the blood tends to release more CO2.`

Front 6

The movement of CO2 from cells to atmosphere:

Back 6

CO2 produced in cell--> interstitial fluid--> crosses tissue capillary walls--> plasma--> RBC--> crosses pulmonary capillary wall--> alveoli--> atmosphere.

Front 7

What is anemic hypoxia?

Back 7

O2 partial pressure is normal but Hb and O2 content are low.

Front 8

Hypoxemia

Back 8

Low content AND partial pressure of O2 in arterial blood (a lung issue).

Front 9

Ischemic hypoxia

Back 9

Poor blood flow

Front 10

Histotoxic hypoxia

Back 10

Poisoned tissues unable to utilize O2.

Front 11

What are some possible causes of hypoxemia?

Back 11

1. Hypoventilation: i.e. barbituate overdose

2. Diffusion impairment (i.e. lung edema).

3. Shunt: venous blood entering the arterial system.

4. Ventilation-perfusion inequality: due to lung's lack of homogeneity. BY FAR THE MOST COMMON.

Front 12

Differences in ventilation and perfusion in different lung regions:

Back 12

Ventilation
Top region: intrapleural pressure more negative. Greater transmural pressure gradient. Alveoli larger, less compliant--> less ventilation

Bottom region: opposite

Perfusion:
Top region:lower intravascular pressures. Less recruitment and distension. Higher resistance--> less blood flow.

Bottom region: Directly opposite.

Therefore, there is greater ventilation and perfusion at the bottom region of lungs.

Front 13

Perfusion and Ventilation at bottom of lung:

Back 13

Much greater for both.

For perfusion, the reasons are:
1. lung distension
2. pulmonary vascular pressure (gravity)
3. alveolar hypoxia

For ventilation:

1. Gravity

Front 14

Effect of V-Q matching on gas exchange:

Back 14

It optimizes gas exchange.

Perfusion of pulmonary capillary blood (CO2) with ventilation of alveolar air (O2).

Front 15

Compare V and Q at bottom and top of lungs using arrows.

Back 15

Bottom Top

Q I V Q I V







.