Chapter 38 - Guyton

Question 1

What is the significance of the large compliance of the pulmonary arteries?

Answer 1

allows the pulmonary arteries to accommodate the stroke volume output of the right ventricle

Question 2

Why would the flow into the left atrium and the left ventricular output be about 1 to 2 per cent greater than the right ventricular output?

Answer 2

Blood also flows to the lungs through small bronchial arteries that originate from the systemic circulation, amounting to about 1 to 2 per cent of the total cardiac output (this blood supplies the lungs).

Question 3

Lymph from the lungs primarily drains through what?

Answer 3

right thoracic lymph duct

Question 4

Normal pulmonary pressures.

Answer 4

Systolic - 25 mmHg
Diastolic - 8 mmHg
Mean - 15 mmHg
Capillary - 7 mmHg

Question 5

When the concentration of oxygen in the alveoli decreases, what occurs, resulting in automatic regulation of pulmonary blood flow distribution?

Answer 5

If some alveoli are poorly ventilated so that their oxygen concentration becomes low, the local vessels constrict. This causes the blood to flow through other areas of the lungs that are better aerated, thus providing an automatic control system for distributing blood flow to the pulmonary areas in proportion to their alveolar oxygen pressures.

Question 6

How do the lungs accommodate increased cardiac output during exercise (increased blood flow)?

Answer 6

by increasing the number of open capillaries; and by distending all the capillaries and increasing the rate of flow through each capillary (pulmonary arterial pressure does not have to rise as much)

Question 7

Left heart failure will likely result in what clinically?

Answer 7

pulmonary edema

Question 8

What is the mechanism for keeping the alveoli “dry” or from collapsing?

Answer 8

negative pressure in the interstitial spaces

Question 9

What is the acute safety factor in the body that prevents pulmonary edema?

Answer 9

pulmonary capillary pressure elevates to compensate left atrial pressure rise (once it rises above 25-30 mmHg death from pulmonary edema can occur within hours)

Question 10

Pleural effusion

Answer 10

collection of large amounts of free fluid in the pleural space

Question 11

What is the potential space?

Answer 11

space between the visceral and parietal pleura; thin layer of fluid (pressure within the space is -7 mmHg to keep the lungs from collapsing)

Question 12

What causes the negative pressure in the pleural space?

Answer 12

pumping of fluid from the space by lymphatics