11.3 Blood Vessels Pages

Blood Vessels km

Arteries Carry blood away from the heart 3-layers:  Outer connective tissue (elastic)  Middle muscle layer  Inner epithelial layer (endothelium)

Arterioles Arteries branch into arterioles

Controlling blood flow Vasodilation: Increases diameter of blood vessel Increased blood flow to the skin Cooling strategy

Controlling Blood Flow Vasoconstriction Nerves cause smooth muscle to contract Narrowing of blood vessel diameter Restricts blood flow Response to cold

Capillaries No cell is farther than two cells away from a capillary. Blood cells move through them in single file.

Pre-capillary sphincters Relax and increase blood flow during exercise

Venules and veins Return blood to the heart Less elasticity in the walls Less smooth muscles in the walls Valves keep blood flowing in the right direction

Varicose veins Damaged valves in legs

Blood pressure Sphygmomanometer Blood pressure cuff Inflated until blood flow ceases then released Systolic pressure…heart contracts 120 mmHg Diastolic pressure…heart relaxed 80 mm Hg

Hypertension High blood pressure Diet, age, weight, activity level, medication are contributors to high blood pressure

Lymphatic System Circulatory system and immune system Maintains blood volume Destroys foreign invaders

Lymph Proteins from blood  tissue fluid  lymph vessels  veins Contains fluid, germs, dead or damaged cells, fat from lacteals of villi Lymph nodes filter out germs

Spleen and tonsils Spleen filters lymphatic system, reservoir for RBC’s and WBC’s Tonsils filter germs/enlarge

thymus Secretes hormones that help lymphocytes, a type of leuknocyte, develop their ability to recognize and attack foreign invaders