What is Circulation?• All living things must capture materials fromtheir environment that enables them to carry onlife processes.• Single celled organisms “capture” materialsfrom their environment through diffusion.• In larger organisms, these “materials” not onlyhave to be captured, but also circulated to allcells in the organism.
Human Circulatory Functions• Transport oxygen gas(hemoglobin).• Transport carbondioxide gas.• Transport foodmolecules (lipids,carbos, amino acids).• Transport hormones.• Maintain bodytemperature.• Works with immunesystem to help fightdisease.
Blood• In 1628, William Harveydemonstrated that bloodtravels in one direction and ina “closed circuit.”• Blood is pumped out of theheart to all parts of the body to“drop off” materials and “pickup” waste products.• Blood is a “liquid tissue” thatconsists of different parts.
Blood Pressure• When ventricles contract,blood is forced into thearteries.• Pressure.• When ventricles relax,pressure decreases.• How is blood pressuremeasured?
Blood Pressure• 120/80 mmHg What does this mean?• Numerator gives pressure in artery when heartis squeezed (systolic).• Denominator gives pressure in artery whenheart is relaxed (diastolic).• With age, arteries become less elastic (lessflexible) and pressure builds up.
Blood Chemistry• With a blood sample, many things can bestudied about the blood.• A “CBC” or complete blood count cancount the red and white blood cells,platelets, and amount of plasma to look forirregularities.
Cholesterol• Cholesterol is needed by the body formaking cells and hormones.• Two types: HDL and LDL• LDL “bad cholesterol” cannot be removedfrom the body. Builds up on artery walls.• HDL “good cholesterol” can be carried tothe liver and removed from the body.• A “cardiac risk profile” measures theamount of cholesterol in the blood.
Diseases of the Heart• “Cardiovascular disease.” Diseases of theheart and blood vessels.• Leading cause of death in the U.S.• Plaque.• Atherosclerosis (blocked arteries).• Results in hypertension (high bloodpressure), strokes, or heart attacks.