The human circulatory systemPresentation Transcript
The Human Circulatory System
What is Circulation?• All living things must capture materials from their environment that enables them to carry on life processes.• Single celled organisms “capture” materials from their environment through diffusion.• In larger organisms, these “materials” not only have to be captured, but also circulated to all cells in the organism.
Human Circulatory Functions• Transport oxygen gas • Transport hormones. (hemoglobin). • Maintain body• Transport carbon temperature. dioxide gas. • Works with immune• Transport food system to help fight molecules (lipids, disease. carbos, amino acids).
Blood• In 1628, William Harvey demonstrated that blood travels in one direction and in a “closed circuit.”• Blood is pumped out of the heart to all parts of the body to “drop off” materials and “pick up” waste products.• Blood is a “liquid tissue” that consists of different parts.
Blood Pressure• When ventricles contract, blood is forced into the arteries.• Pressure.• When ventricles relax, pressure decreases.• How is blood pressure measured?
Blood Pressure• 120/80 mmHg What does this mean?• Numerator gives pressure in artery when heart is squeezed (systolic).• Denominator gives pressure in artery when heart is relaxed (diastolic).• With age, arteries become less elastic (less flexible) and pressure builds up.
Blood Chemistry• With a blood sample, many things can be studied about the blood.• A “CBC” or complete blood count can count the red and white blood cells, platelets, and amount of plasma to look for irregularities.
Cholesterol• Cholesterol is needed by the body for making cells and hormones.• Two types: HDL and LDL• LDL “bad cholesterol” cannot be removed from the body. Builds up on artery walls.• HDL “good cholesterol” can be carried to the liver and removed from the body.• A “cardiac risk profile” measures the amount of cholesterol in the blood.
Diseases of the Heart• “Cardiovascular disease.” Diseases of the heart and blood vessels.• Leading cause of death in the U.S.• Plaque.• Atherosclerosis (blocked arteries).• Results in hypertension (high blood pressure), strokes, or heart attacks.
Causes of Cardiovascular Disease• Genetics• Lack of exercise.• Diet high in saturated fats.• Cigarette smoking.