Systemic vs Pulmonary Circulation - Anatomy and Physiology
- How do pulmonary arterioles respond to low alveolar O2, compared with most systemic arterioles?
- Pulmonary arterioles constrict, diverting blood to better-ventilated alveoli; most systemic arterioles dilate in hypoxia.
- Which vessels carry oxygenated blood into the heart?
- The pulmonary veins, which return blood from the lungs to the left atrium.
- Why must the outputs of the right and left ventricles be equal over time?
- The pulmonary and systemic circuits are connected in series, so blood would pool in one circuit if outputs differed.
- The left ventricle fails and cannot pump out all the blood it receives. In which circuit does blood back up first?
- The pulmonary circuit. Rising pulmonary venous and capillary pressure leads to pulmonary congestion and edema.
- Trace the pulmonary circuit from the right ventricle back to the heart.
- Right ventricle, pulmonary trunk, pulmonary arteries, pulmonary capillaries, pulmonary veins, left atrium.
- What is a typical systolic pressure in the pulmonary artery, compared with the aorta?
- About 25 mmHg, compared with about 120 mmHg in the aorta.
- Which circulation supplies oxygenated blood to the lung tissue itself?
- The bronchial circulation, a branch of the systemic circuit arising from the aorta.
- What kind of blood do the pulmonary arteries carry?
- Deoxygenated blood, from the right ventricle to the lungs; they are named arteries because they carry blood away from the heart.
- Where does most venous blood from the heart wall drain?
- Into the coronary sinus, which empties into the right atrium.
- A clot breaks loose from a deep vein in the leg. In which capillary bed is it most likely to lodge first?
- In the lungs, causing a pulmonary embolism. Venous blood passes through the right heart into the pulmonary arteries.
- Why is the left ventricular wall much thicker than the right?
- It must generate much higher pressure to push blood through the high-resistance systemic circuit.