+ Importance of Blood

+ Functions Transports oxygen and nutrients to cells. Carries away metabolic wastes and secretions (including hormones). Stabilizes internal pH. Serves as a highway for white blood cells. Helps stabilize body temperature in mammals.

+ What is blood made of? Plasma- a straw colored liquid that serves as a transport medium for blood cells and platelets. Red Blood Cells- aka Erythrocytes- concave disks that transport oxygen to cells and carry away carbon dioxide. White Blood Cells- aka Leukocytes-made in the bone marrow-they engulf dead cells and anything foreign to the body (bacteria). Platelets-cell fragments that initiate blood clotting.

+ Plasma 92% Water 8% proteins, ions, nutrients… Accounts for 50-60% of blood volume. Transports lipids and vitamins through the body. Gives blood the “liquid” texture. Acts as a solvent- sugars, lipids, amino acids, vitamins, oxygen, carbon dioxide and nitrogen are all dissolved into plasma.

+ Red Blood Cells Transport oxygen to cells. Carries carbon dioxide away from cells Do not have a nucleus. Live for about 120 days. Phagocytes remove old blood cells.

Why are Red Blood Cells red? Red blood cells are made up of a protein pigment called hemoglobin. Hemoglobin contains iron which binds to oxygen. Hemoglobin helps RBCs to carry oxygen.

+ White Blood Cells Made in the bone marrow and usually clump together in lymph nodes and the spleen. They continue to divide in the lymph nodes until needed. There are 5 types of WBCs- neutrophils, eosinophils, basophils, monocytes, and lymphocytes Neutrophils and monocytes act as phagocytes to destroy foreign invaders. Lymphocytes are more specialized.

+ Platelets Cell fragments wrapped in plasma membrane. Last about 5-9 days Hundreds of thousands are constantly in the blood stream. Release substances that cause clotting- a necessary part of the blood.