Ch. 21 Blood Vessels
21-1 Distinguish among the types of blood vessels based on their structure and function.
-arteries - carry blood away from heart, they branch into the arterioles. Thick walls and higher blood pressure. Constricted artery has a small, round lumen. More elastic -arterioles - smallest branches of arteries that enter the organs and lead to capillary beds, diameter is adjustable -capillaries - smallest blood vessels with thin walls, location of exchange between blood and interstitial fluid -venules - smallest branches of veins that collect blood from capillaries -veins - return blood to heart, contain less smooth muscle than arteries. Less muscle, have valves. Large irregular lumen - there needs to be a pressure gradient in order for the blood here to flow from: arteries - arterioles - capillaries - venules - veins
21-4 Identify the principal blood vessels and functions of the special circulation to the brain, heart, and lungs
Brain -cerebrovascular accident (CVA) - stroke, blockage or rupture in a cerebral artery, stops blood flow Anterior cerebral artery - supplies frontal lobes, parts of the brain that control logical thought, personality, and voluntary movement especially in legs Middle cerebral artery - supplies portion of frontal lobe and lateral surface of temporal and parietal lobes, including primary motor and sensory areas of the face, throat, and hand and arm Posterior Cerebral artery - supplies temporal and occipital lobes Heart -through coronary arteries - heart attack - blockage of coronary blood flow Lungs -pulmonary arteries (deoxygenated) and pulmonary (oxygenated) veins - carries oxygenated blood to the heart from the lungs and vice versus
explain how the activities of the cardiac, vasomotor, and respiratory centers are coordinated to control blood flow through the tissues
Cardiovascular regulation: when certain cells become active, circulation to that region must increase, cardiovascular regulation ensures that blood flow occur: at an appropriate time, in the right area, without changing blood pressure and blood flow to vital organs -vasomotion: contraction and relaxation cycle of precapillary sphincters, causes blood flow in capillary beds to constantly change routes. Vasodilators are factors that promote dilation of precapillary sphincters, increasing blood flow (i.e Low O2 or high CO2 levels, chemicals released by inflammation, histamine, both immediate localized adjustments) -Baroreceptors reflexes (stretch receptors): in walls of carotid sinuses (maintain blood flow to brain, aortic sinuses (monitor start of systemic circuit), right atrium (monitors end of systemic circuit) -Natriuretic peptides: atrial natriuretic peptide (ANP) produced by cells in right atrium. Brain natriuretic peptide (BNP) produced by ventricular muscle cells. Respond to excessive diastolic stretching, reduce blood volume and blood pressure by several means
explain the cardiovascular system's homeostatic response to exercise and hemorrhaging.
Exercise: increases muscular contraction, increase venous return, atrial stretching, increase cardiac output Light Exercise: extension vasodilation occurs - increases circulation Heavy exercise: activates sympathetic NS, cardiac output increases to max, restricts blood flow to nonessential organs, redirects blood flow to skeletal muscles, lungs, and heart, blood supply to brain is unaffected Hemorrhaging - entire CV system adjusts to maintain blood pressure and restore blood volume
21-5 Describe the pulmonary and systemic circuits of the cardiovascular system.
Three general functional patterns 1) peripheral artery and vein distribution is the same on right and left, except near heart 2) the same vessel may have different names in different locations 3) tissues and organs usually have multiple arteries and veins pulmonary - heart to lungs systemic - heart to body oxygenated
explain how and where fluid and dissolved materials enter and leave the cardiovascular system.
Venous pressure - determines the amount of blood arriving at right atrium each minute (venous return), low pressure and low resistance in venous system Return of blood to heart is assisted by: skeletal muscular compression of veins. Skeletal muscle pump: muscles squeeze veins, force blood back to heart, valves prevent backflow. Respiratory pump: thoracic cavity expands during inhalation, decreasing venous pressure in the chest Capillary exchange: exchange between the capillaries and the interstitial fluid, diffusion (filtration: movement out of capillaries, reabsorption: movement back into capillaries) Diffusion Routes: 1) water, ions, and small molecules - between endothelial cells or pores 2) some ions (Na+, K+, Ca2+, Cl-) - through channels 3) large, water soluble compounds - through fenestrated capillaries 4) lipids and lipid soluble materials such as O2 - through plasma membranes 5) plasma proteins cross endothelium of sinusoids
21-9 Discuss the effects of aging on the cardiovascular system, and give examples of interactions between the cardiovascular system and other organ systems.
age affects blood heart and blood vessels age related changes in blood: decreased hematocrit, peripheral blockage by blood clot (thrombus), pooling of blood in legs due to venous valve deterioration age related changes in heart: reduced max cardiac output, changes in nodal and conducting cells, reduced elasticity of cardiac skeleton, progressive atherosclerosis, replacement of damaged cardiac muscle cells by scar tissue age related changes in blood vessels: arteries become less elastic pressure change can cause aneurysm, calcium deposits on vessel walls can cause stroke or infarction, lipid deposits in tunica media and calcium salts can form atherosclerotic plaques, thrombi can form at atherosclerotic plaques
21-7 Identify the major arteries and veins of the systemic circuit.
arteries -carry blood from left ventricle into ascending aorta -coronary arteries: branch from aortic sinus aorta: ascending aorta: rises from left ventricles, curves to form aortic arch, turns downward to become descending aorta branches of aortic arch -deliver blood to head, neck, shoulders, and upper limbs 1) brachiocephalic trunk (right subclavian artery, right common carotid artery), left common carotid artery, left subclavian artery -subclavian arteries: supply blood to arms, chest wall, shoulders, back and CNS Major ones: vertebral, right subclavian, brachiocephalic trunk, aortic arch, ascending aorta, brachial, celiac trunk, radial, ulnar, external illiac, palmer arches, right common carotid, left common carotid, left subclavian, axillary, pulmonary trunk, descending aorta, diaphragm, renal, superior mesenteric, gonadal, inferior mesenteric, common illac, internal illac, deep femoral, femoral, descending genicular, dorsalis pedis, plantar arch, fibular, anterior tibial, posterior tibial, popliteal
21-6 Identify the major arteries and veins of the pulmonary circuit.
arteries -carry deoxygenated blood -pulmonary trunk: branches into left and right pulmonary arteries -pulmonary arteries: branch into pulmonary arterioles -pulmonary arterioles: branch into capillary networks that surround alveoli Veins -carry oxygenated blood -capillary networks around alveoli: join to form venules -venules: join to form four pulmonary veins -pulmonary veins: empty into left atrium Major ones: pulmonary arteries, pulmonary capillaries, pulmonary veins, ascending/descending aorta, superior/inferior vena cava,
21-8 Identify the differences between fetal and adult circulation patterns, and describe the changes in the patterns of blood flow that occur at birth.
before birth - fetal lungs are collapsed, O2 is provided by placental circulation fetal pulmonary circulation bypasses: foramen ovale (interatrial opening): covered by valve-like flap, directs blood from right to left atrium. Ductus arteriosus: short vessel, connects pulmonary trunk to aorta Cardiovascular changes at birth: newborn breathes air and lungs expand: pulmonary vessels expand , reduced resistance increases blood flow, rising O2 causes ductus arteriosus constriction, rising left atrium pressure closes foramen ovale. Pulmonary circulation provides O2
21-3 Describe the control mechanisms that regulate blood flow and pressure in tissues
tissue perfusion - blood flow though the tissue, carries O2 and nutrients to tissues and organs, carries CO2 and wastes away -when blood pressure rises, CV centers: decrease cardiac output, cause peripheral vasodilation -when blood pressure falls, CV centers: increase cardiac output, cause peripheral vasoconstriction -bainbridge reflex - increased venous return - stretches of the wall of the right atrium - increased cardiac output
21-2 Describe the factors that influence blood pressure
total capillary blood flow is determined by pressure and resistance in the cardiovascular system. -Pressure (P) - generated by the heart to overcome resistance -Pressure Gradient (*triangle*P) - the difference in pressure from one end of a vessel to the other -Flow (F) - is proportional to the pressure gradient divided by resistance F= (Pressure gradient)/resistance -blood pressure - pressure that the blood exerts on the vessel's wall, normal arterial blood pressure = 120/80 -hypertension: abnormally high blood pressure, greater than 140/90 -Hypotension: abnormally low blood pressure -systolic pressure: peak arterial pressure during ventricular systole -diastolic pressure: minimum arterial pressure at end of ventricular diastole -Pulse pressure: difference between systolic and diastolic pressure -Mean arterial pressure (MAP): diastolic pressure + one third pulse pressure
