Lecture 10 2/2/24 Flashcards
What are the characteristics of systemic circulation?
-“greater” circulatory system
-supplies more areas
-greater pressure and resistance
-oxygenated blood enters heart via pulmonary veins and leaves via aorta
What are the characteristics of pulmonary circulation?
-“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
What are the roles of pulmonary circulation?
-accept all blood pumped from right ventricle
-perfuse alveolar capillaries
-participate in gas exchange
What are the characteristics of bronchial circulation?
-branch of systemic circulation
-involves bronchoesophageal and bronchial arteries
-provides nutritional supply to lungs/resp. tissue
-does not participate in pulmonary gas exchange
What are the characteristics of coronary circulation?
-coronary arteries arise from aorta
-thebesian veins drain the myocardium
-supplies heart muscle with blood/oxygen
How do the arteries differ throughout the pulmonary system?
-main pulmonary arteries near bronchi are elastic
-smaller arteries near bronchioles and alveolar ducts are muscular
What are the characteristics of pulmonary capillaries?
-dense, mesh-like network
-not all are perfused at rest
What are the characteristics of pulmonary veins?
-thin-walled
-carry oxygenated blood
-distend to provide reservoir of blood for left ventricle
-can accommodate sudden increases in volume
What are the characteristics of absolute intravascular pressure?
-pressure inside of the vessel as compared to atmospheric pressure
-combination of hydraulic pressure and hydrostatic pressure
-typical “blood pressure”
What is driving pressure?
-difference between two pressures inside a blood vessel
-responsible for blood flow
-primarily hydrostatic pressure
What is transmural pressure?
difference in pressure across the vessel wall
What are the two mechanisms that lead to increased transmural pressure and vessel dilation?
-blood volume increases, causing pressure within vessel to increase
-lung inflates, causing pressure outside vessel to go down
What percent of systemic pressure is seen in the pulmonary system?
10%
What are the characteristics of pulmonary vascular resistance?
-low at rest
-pressure spread over a large thin sheet of pulmonary capillaries
What happens during exercise that changes pulmonary vascular resistance?
-cardiac input increases
-blood flow through pulmonary vasculature increases
-pulmonary blood vessels dilate
How can changes in blood vessel usage decrease pulmonary vascular resistance?
-recruitment of more vessels
-distension of vessels
What can lead to dilation of pulmonary blood vessels besides exercise?
-release of nitric oxide from endothelium, which relaxes smooth muscle
-passive dilation due to increased intravascular pressure
Why is hydrostatic pressure and perfusion less important in quadrupeds compared to bipeds?
most of the lung tissue in quadrupeds is dorsal to the heart/pulmonary artery
What is the goal of hypoxic vasoconstriction?
shunt blood away from alveoli that do not have appropriate oxygenation
What can cause pulmonary hypertension?
-chronic hypoxia
-increased blood flow from right heart
-obstructions
-chronic increases in pulmonary venous pressure
What are the clinical signs associated with pulmonary hypertension?
-syncope
-exercise intolerance
-resp. distress
-cyanosis
What changes occur within the heart due to pulmonary hypertension?
-hypertrophied right ventricle
-flattened interventricular septum
-pulmonary artery enlargement
