The Circulatory System

purpose of circulatory system

• circulate necessary materials to all cells

  • ex. oxygen, hormones, nutrients

• remove waste products of cell metabolism

• regulate body temperature

composition of blood

55% plasma, 45% formed elements

plasma

liquid portion of blood that includes:

• water: dissolves materials and ions and allows blood contents to flow

• plasma proteins: antibodies for defense against bacteria and viruses

• solutes: ions and minerals needed elsewhere and also to maintain balance of substances

formed elements

red blood cells, white blood cells, platelets

red blood cells

• aka erythrocytes

• transport oxygen and nutrients

• transport carbon dioxide and other wastes outside of cells and body

white blood cells

• aka leucocytes

• fight against infectious agents

platelets

• not cells, but made of blood cells and platelets

• help heal wounds, repair blood vessels, and prevent blood clotting

blood vessels

superhighway for blood

types of blood vessels

arteries, arterioles, veins, venules, capillaries

arteries and arterioles

• carry blood away from heart

• have thick muscle layer to control blood flow and allow them to withstand high pressures

veins and venules

• carry blood towards heart

• thinner muscle layer and stretch more

  • cannot carry high pressures

what do veins have to prevent blood backflow

one way valves

capillary

• connect arterioles and venules

• thin, permeable walls

  • narrowest blood vessels

what is gas exchange and where does it occur

• diffusion of oxygen into cells and carbon dioxide out

• in capillaries