Lecture 10 2/2/24

Question 1

What are the characteristics of systemic circulation?

Answer 1

-“greater” circulatory system
-supplies more areas
-greater pressure and resistance
-oxygenated blood enters heart via pulmonary veins and leaves via aorta

Question 2

What are the characteristics of pulmonary circulation?

Answer 2

-“lesser” circulatory system
-deoxygenated blood enters right atrium via vena cavae
-exits via main pulmonary artery to go to lungs
-blood only flows through pulmonary system before returning to heart

Question 3

What are the roles of pulmonary circulation?

Answer 3

-accept all blood pumped from right ventricle
-perfuse alveolar capillaries
-participate in gas exchange

Question 4

What are the characteristics of bronchial circulation?

Answer 4

-branch of systemic circulation
-involves bronchoesophageal and bronchial arteries
-provides nutritional supply to lungs/resp. tissue
-does not participate in pulmonary gas exchange

Question 5

What are the characteristics of coronary circulation?

Answer 5

-coronary arteries arise from aorta
-thebesian veins drain the myocardium
-supplies heart muscle with blood/oxygen

Question 6

How do the arteries differ throughout the pulmonary system?

Answer 6

-main pulmonary arteries near bronchi are elastic
-smaller arteries near bronchioles and alveolar ducts are muscular

Question 7

What are the characteristics of pulmonary capillaries?

Answer 7

-dense, mesh-like network
-not all are perfused at rest

Question 8

What are the characteristics of pulmonary veins?

Answer 8

-thin-walled
-carry oxygenated blood
-distend to provide reservoir of blood for left ventricle
-can accommodate sudden increases in volume

Question 9

What are the characteristics of absolute intravascular pressure?

Answer 9

-pressure inside of the vessel as compared to atmospheric pressure
-combination of hydraulic pressure and hydrostatic pressure
-typical “blood pressure”

Question 10

What is driving pressure?

Answer 10

-difference between two pressures inside a blood vessel
-responsible for blood flow
-primarily hydrostatic pressure

Question 11

What is transmural pressure?

Answer 11

difference in pressure across the vessel wall

Question 12

What are the two mechanisms that lead to increased transmural pressure and vessel dilation?

Answer 12

-blood volume increases, causing pressure within vessel to increase
-lung inflates, causing pressure outside vessel to go down

Question 13

What percent of systemic pressure is seen in the pulmonary system?

Answer 13

10%

Question 14

What are the characteristics of pulmonary vascular resistance?

Answer 14

-low at rest
-pressure spread over a large thin sheet of pulmonary capillaries

Question 15

What happens during exercise that changes pulmonary vascular resistance?

Answer 15

-cardiac input increases
-blood flow through pulmonary vasculature increases
-pulmonary blood vessels dilate

Question 16

How can changes in blood vessel usage decrease pulmonary vascular resistance?

Answer 16

-recruitment of more vessels
-distension of vessels

Question 17

What can lead to dilation of pulmonary blood vessels besides exercise?

Answer 17

-release of nitric oxide from endothelium, which relaxes smooth muscle
-passive dilation due to increased intravascular pressure

Question 18

Why is hydrostatic pressure and perfusion less important in quadrupeds compared to bipeds?

Answer 18

most of the lung tissue in quadrupeds is dorsal to the heart/pulmonary artery

Question 19

What is the goal of hypoxic vasoconstriction?

Answer 19

shunt blood away from alveoli that do not have appropriate oxygenation

Question 20

What can cause pulmonary hypertension?

Answer 20

-chronic hypoxia
-increased blood flow from right heart
-obstructions
-chronic increases in pulmonary venous pressure

Question 21

What are the clinical signs associated with pulmonary hypertension?

Answer 21

-syncope
-exercise intolerance
-resp. distress
-cyanosis

Question 22

What changes occur within the heart due to pulmonary hypertension?

Answer 22

-hypertrophied right ventricle
-flattened interventricular septum
-pulmonary artery enlargement