Ch. 13 Vascular System

I.General Purpose of the Vascular System: * The exchange of materials between blood and tissues

II.Arteries A. Function: to carry blood from the heart to capillaries (to the body) --Heart, Artery, Arterioles, capillaries B. Structure: 3 layers of tissues. Strong because regulates blood pressure and blood flow.

III.Veins A. Function: carry blood from body back to the heart --Body, Capillaries, venule, vein, heart B. Structure: same 3 layers, but not as thick or strong. Inner lining folds to form valve to prevent backflow of blood.

IV.Anastomoses: A. Structure: connection of fibers between vessels B. Function: connects artery to artery, and vein to vein. Ensure blood will get to capillaries and return to the heart.

V.Capillaries A. Structure: is one cell thick (very thin) B. Function: (in exchange) provide site for exchange of materials between blood and tissue fluid.

VI.Pathways of Circulation: A. Pulmonary: where right side of heart pumps blood to the lungs where oxygen and CO2 exchange occurs. B. Systemic: left side of heart pumps blood to aorta, then to body C. Hepatic Portal: part of systemic. Where blood goes thru the liver before returning to the heart.

D.Fetal: 1. Placenta and umbilical: The placenta transports between mother and baby. The umbilical cord is what runs the blood from baby, to placenta, to mother and from mother to placenta to baby. 2. Ductus venosus: empties into inferior vena cava. Disappears after birth. 3. Foramen Ovale: opening in the heart that allows blood from the right atrium to go straight to the left atrium. Bypasses the fetal lungs. 4. Ductus arteriosus: vessels that diverts blood in pulmonary artery to aorta then to body. Bypass the fetal lungs.

VII. Blood Pressure: The body maintains the blood pressure by regulating the amount of blood flow and heart rate. Vessels are made of elastic tissue. The thickness of blood and hormones also regulates.

VIII. Regulation of blood pressure A. Intrinsic Mechanisms: “within” the body. 1. The heart and how forcefully it pumps 2. the kidneys and their filtration. B. Nervous Mechanisms 1. medulla and nervous system and peripheral resistance. ( the constriction of the vessels.

As we age, the artery walls weaken. Cholesterol deposits inside the walls. Blood pressure increases. The valves may start not working as well, and the blood flow slows down.