2 Blood Vessels Three Types Arteries: carry blood away from the heart Thick walled, smaller vessels are called arteriolesVeins: carry blood towards the heartThin walled, smaller vessels are called venulesContains valvesCapillaries: connect the arteries to the veinsSmallest of the blood vesselsRBC’s travel single file through capillariesBranch like system to increase surface area for diffusionSite of gas exchange
4 Arterial System Transports blood under pressure. Blood moves in a pulse-like wave.Contraction & relaxation of arteriolesis the major determinant of theoverall blood pressure.
5 Venous SystemThinner walls, larger diameters & less muscle than arteries.Contains 70% of total blood volume.Most veins work against gravity.Valves allow one-way flow.Contraction of skeletal musclespushes blood toward heart.
6 Pathways of Blood Pulmonary Circuit Systemic Circuit Right side of heart.Low-pressure system.Takes deoxygenated blood to thelungs and back to the heartSystemic CircuitLeft side of heart.High-pressure system.Takes oxygenated blood to the body and returns deoxygenated blood back to the heart
8 Pulmonary Circuit Right atrium receives oxygen-poor blood from: Superior vena cava.Inferior vena cava.Blood flows through thetricuspid valve or theright atrioventricular (AV)valve to the right ventricle.Blood frombodyBlood frombody
9 Pulmonary CircuitBlood flows through the pulmonary semi-lunar valve & enters the pulmonary trunk, which divides into the left & right pulmonary arteries.Divides into capillaries where external gas exchange(respiration system) occurs.Oxygenated blood enters the left & right pulmonary veins,returning blood to theleft atrium.
10 Systemic CircuitBlood flows through the left AV-valve or bicuspid (mitral) valve to the left ventricle.Left ventricular walls are two times thicker than in the right ventricle.Blood travels through theaortic semi-lunar valveto the aorta.
11 Systemic CircuitAorta branches into smaller systemic arteries, which branch into arterioles & then capillaries.Internal gas exchange occurs.Capillaries rejoin as venules & then veins.Deoxygenated blood returns to the right atrium via the superior & inferior vena cava.
12 Coronary Circulation Delivers oxygenated blood to the heart muscle. Consists of the left & right coronary artery.