A&P

• Hemodynamics is the means by which blood flow is altered and distributed and by which blood pressure is regulated.
• The histology of blood vessels and anatomy of the primary routes of arterial and venous systems are surveyed in this chapter.
• Structure and function of blood vessels are discussed in this chapter.
• Angiogenesis is the growth of new blood vessels and is an important process in the fetus and in postnatal processes.
• Malignant tumors secrete proteins called tumor angiogenesis factors (TAFs) that stimulate blood vessel growth to nature the tumor cells.
• Scientists are looking for chemicals that inhibit angiogenesis to stop tumor growth and to prevent the blindness associated with diabetes.
• Blood vessels form a closed system of tubes that carry blood away from the heart, transport it to the tissues of the body, and then return it to the heart.
• Arteries carry blood from the heart to the tissues.
• Arterioles are small arteries that connect to capillaries.
• Capillaries are the site of substance exchange between the blood and body tissues.
• Venules connect capillaries to larger veins.
• Veins convey blood from the tissues back to the heart.
• Vaso vasorum are small blood vessels that supply blood to the cells of the walls of the arteries and veins.
• The wall of an artery consists of three major layers: Tunica interna (intima) with simple squamous epithelium known as endothelium, basement membrane, and internal elastic lamina; Tunica media with circular smooth muscle & elastic fibers; Tunica externa with elastic & collagen fibers.
• Obstructive shock is due to obstruction of blood flow.
• The pulse is a pressure wave, consisting of the alternate expansion and recoil of an elastic artery after each systole of the left ventricle.
• Cardiogenic shock is due to poor heart function.
• Pulse pressure is the difference between systolic and diastolic pressure, normally about 40 mm Hg, and provides information about the condition of the arteries.
• Vascular shock is due to inappropriate vasodilation.
• Local changes in response to physical changes, such as warming and decrease in vascular stretching, promote vasodilation.
• Local factors cause changes in each capillary bed, which is important for tissues that have major increases in activity such as the brain, cardiac, and skeletal muscle.
• Homeostatic responses to shock include activation of the renin-angiotensin-aldosterone system, secretion of ADH, activation of the sympathetic division of the ANS, and release of local vasodilators.
• Systemic vessels dilate in response to low levels of O2.
• The normal blood pressure of a young adult male is 120/80 mm Hg (8-10 mm Hg less in a young adult female).
• Shock is an inadequate cardiac output that results in failure of the cardiovascular system to deliver adequate amounts of oxygen and nutrients to meet the metabolic needs of body cells.
• Hypovolemic shock is due to decreased blood volume.
• In shock, cells are forced to switch to anaerobic respiration, lactic acid builds up, cells and tissues become damaged and die.
• Pulmonary vessels constrict in response to low levels of O2.
• Vasoactive substances released from cells alter vessel diameter, including K+, H+, lactic acid, and nitric oxide.
• Arteries carry blood away from the heart to the tissues.
• The functional properties of arteries are elasticity and contractility.
• Elasticity in arteries allows them to accept blood under great pressure from the contraction of the ventricles and to send it on through the system.
• Contractility in arteries allows them to increase or decrease lumen size and to limit bleeding from wounds.
• Vascular smooth muscle is innervated by sympathetic nervous system and an increase in stimulation causes muscle contraction or vasoconstriction.
• The renin-angiotensin-aldosterone system decreases blood pressure or decreases blood flow to kidney, resulting in the formation of angiotensin II, causing systemic vasoconstriction, and causing the release of aldosterone for H2O and Na+ reabsorption.
• The ability of a tissue to automatically adjust its own blood flow to match its metabolic demand for supply of O2 and nutrients and removal of wastes is called autoregulation.
• Baroreceptor reflexes maintain normal blood pressure in the brain (aortic reflex) and general systemic blood pressure (aortic reflex).
• Autoregulation is a process that occurs in the cardiovascular system, the nervous system, and the renal system.
• Sympathetic stimulation can speed up the heart, while parasympathetic stimulation can slow it down.
• • Autoregulation is a process that occurs in the cardiovascular system, the nervous system, and the renal system.