Blood Vessels

1. Arteries – thick muscular walls, under high pressure, carry OXYGENATED BLOOD away from the heart (except for…) 2. Veins – thinner walls, valves present to prevent backflow, carry DEOXYGENATED BLOOD to the heart (except for…) 3. Capillaries - smallest, single layer, nutrients and wastes diffuse here.

Blood Vessel Construction Three Tissue Layers: 1.Tunica interna (intima) – thin endothelium 2.Tunica media – smooth muscle 3.Tunica externa (adventitia) – connective tissue

(Externa)

Blood vessel circulatory order from heart: Arteries Arterioles Capillaries Venules Veins

Venous Blood Flow Since there is no (pressure) force from the heart, movement of venous blood is by: 1.Skeletal muscle contractions 2.Breathing movements 3. Vasoconstrictions of veins *What happens if good valves go bad?

Varicose Veins What causes varicose veins? Bad valves allowing backflow, creating a pooling of blood (bulging) inside vein. Factors that can increase your risk: family history being overweight not exercising enough smoking standing or sitting for long periods of time Women are more likely than men to develop varicose veins.

Capillaries Simple Squamous lining Semi-permeable membrane Filtration Osmosis Diffusion Capillary density depends on tissue needs. Precapillary sphincter muscles regulate flow

Pie graph shows the percentage of the blood in a given location of the circulatory system. Most blood is found in veins at any one time. “Blood reservoirs.”

Atherosclerosis Treatments Angioplasty - balloon inserted into artery and inflated at plaque site. Smashes plaque against wall restoring flow. Stents – metal mesh inserted with an angioplastic technique. Keeps artery open. VideoVideo – Stents Atherosclerosis Video Heart Attack Aortic Stenosis Fix

Pulmonary Circulation Systemic Circulation