Why is the Circulatory System Important? 1. Transport of oxygen and carbon dioxide (why are these gases important?) 2.Transport nutrients and wastes. Sugars, nucleotides, amino acids, lipids from the diet. 3.Transport of hormones and vitamins. 4. Thermoregulation through Dilation and constriction of small arteries in the skin. 5. Immunity (fight disease, infection)

“Red Blood Cells” 45% (Erythrocytes)

Erythrocytes are “bi-concave” Hemoglobin makes up 90% of protein in erythrocytes. Each hemoglobin molecule can carry four oxygens. R T X 100%

Leukocytes

Phagocytosis by Neutrophil

Diapedesis If a tissue is injured, Mast Cells release histamine. The histamine causes blood capillaries to become more permeable, and signals neutrophils to move out of the blood and into the surrounding tissues.

Lymphocytes Release Antibodies

Erythropoietin and Blood Doping Erythropoietin: Treatment following chemotherapy Blood Doping in Athletics

Hemostasis: platelet plug formation Break in vessel wall Blood escaping through break Blood vessel spasm – constricts and Reduces blood loss Platelets adhere to each other and exposed collagen Platelet Plug helps control blood loss.

Blood Coagulation 1.Damaged Tissue (and rough edges of damaged blood vessels) cause the release of tissue thromboplastin 2.This initiates a long series of events that require Calcium ion and the formation of an enzyme called thrombin (produced by platelets). 3.Thrombin catalyzes the conversion of fibrinogen to fibrin. The fibrin forms long threads that stick to the edges of blood vessels and trap red blood cells.