山东大学：《医学生理学 Medical Physiology》课程教学资源（PPT课件讲稿，人体生理学 Human Physiology）Chapter 4 Cardiovascular Physiology section 3 Blood Vessels

Section Physiology ofthe Blood Vessels

Section 3 Physiology of the Blood Vessels

Artery Vein Tunica intima (endothelial cells Valve elastin Tunica media (smooth muscle Tr Tunica externa (loose fibrous connective tissue) Serosa (epithelial cells)

I. Physiologica Classification of blood essels

I. Physiological Classification of Blood Vessels

Aorta Artery Arteriole Sphincter Capillary Venule ena cava ○ ○ Inner diamter 4mm 30μm35 8um 20pm 5mm 3 2mm Imm 20 30J lpm2μm0.5mm 1.5mm Endothelium Elastic fiber Smooth muscle Collagenous fiber 劬时能Q爆胁 Comparision of the inner diameter, wall thickness and components between different blood vessels

Metarteriole (forming arteriovenous shunt Precapillary sphincter Arteriole Capillaries Artery Vein Blood flow Blood Heart and Circu

Windkessel Vessel --- Aorta and big arteries Contain a large amount of elastic tissue besides the smooth muscle Transiently store blood during systole, and then shrink to produce onward blood flow during diastole 120 60 LVP aft Atrium Ventricle Diastole TIME (s) Function of the windkessel vessel

Windkessel Vessel --- Aorta and big arteries. ➢ Contain a large amount of elastic tissue besides the smooth muscle. ➢ Transiently store blood during systole, and then shrink to produce onward blood flow during diastole

Windkessel effect Convert the sharp pressure fluctuations in ie ventricle(0 to 120 mmHg) into much smale pressure fluctuations in the arteries(80 to 120 mmhG, Convert the intermittent ventricular ejection into continuous blood blood in the vessels 120 Ventricle LVP Function of the windkessel vessel A TIME(s)

➢ Windkessel effect. ➢ Convert the sharp pressure fluctuations in the left ventricle (0 to 120 mmHg) into much smaller pressure fluctuations in the arteries (80 to 120 mmHg). ➢ Convert the intermittent ventricular ejection into continuous blood blood in the vessels

2. Distribution Vessel-middle arter Rich in smooth muscle, systole or diastole under some physical and chemical factors Together with resistance vessels. match the blood flow to different organs with their requirements

2. Distribution Vessel – Middle arteries ➢ Rich in smooth muscle, systole or diastole under some physical and chemical factors. ➢ Together with resistance vessels, match the blood flow to different organs with their requirements

Distribution of Cardiac Out 25L Cardiac output min 25 L/min 100% 3-5% 4-5%2-4%0.5-1%3-4% 80-85% -20 L/min utricle Heavy work Rest Rest Left ventricle 0.75L/ 100% 20-25%4-5% o°o 15-20% Cardiac output 5 L/

Distribution of Cardiac Output

3. Precapillary Resistance Vessels Small arteries and aster Less elastic than the larger Arteries arteries Have a thicker layer of Metarterioles act as a Precapillary bypass channel and sphincters regulate flow into smooth muscle Arteriole capillary beds Venule smooth Capillaries Provide the greatest resistance to blood flow through the arterial system Sm venule since they have narrow lumina Arteriovenous bypass Precapillary sphincters

3. Precapillary Resistance Vessels – Small arteries and arterioles ➢ Less elastic than the larger arteries ➢ Have a thicker layer of smooth muscle. ➢ Provide the greatest resistance to blood flow through the arterial system ➢ since they have narrow lumina