Blood

Blood Blood transports substances and maintains homeostasis in the body Blood is a type of CONNECTIVE TISSUE It has two basic components CELLS – the hematocrit  (rbc, wbc, platelets)  = 45% Plasma (water, proteins, amino acids..etc)  = 55%

Plasma The liquid portion of blood is 92% water Also contains nutrients, gases, vitamins (etc) and plasma proteins

Types red blood cells (erythrocytes) white blood cells (leukocytes) platelets (thrombocytes)

Red Blood Cells Biconcave discs 5 million per cubic millimeter Lack nuclei Liver & Spleen – where macrophages phagocytize or destroy damaged RBCs Average life span of a RBC is about 120 days

Functions Transports oxygen, picks up carbon dioxide HEMOGLOBIN - molecule that combines with O2 IRON is critical to synthesize hemoglobin

Elements Critical to RBC formation Folic Acid Vitamin B12 Iron Too few RBC = anemia Hormone – erythropoietin controls the rate of RBC formation. The kidneys and liver release this hormone in response to prolonged oxygen deficiency. Within a few days newly formed RBCs appear circulating through the blood.

WBC’s - General function is to protect the body against disease (develop in red bone marrow and live for about 12 hours) Granulocytes (granular cytoplasm) Neutrophils, Eosinophils, Basophils Agranulocytes (lacking granular cytoplasm) Monocytes, Lymphocytes (can also form in the organs of the lymphatic system)

Neutrophil Active phagocytes 60% of WBC Present in the pus of wounds

Basophil Produces Heparin and Histamines Important in Inflammatory Reaction 1% WBC

Eosinophil Mainly attack parasites 2% WBC

Monocyte Become macro-phages

Lymphocyte Defense against invaders Yield Antibodies 30% WBC

Functions Protect against infection either by Phagocytosis or Produce proteins (antibodies) that destroy or disable foreign particles

Antibody immune response

Platelets Blood clots and vessel repair

Plasma Proteins Albumins – help to maintain blood pressure Globulins (alpha, beta, gamma) – transport lipids and antibodies for immunity Fibrinogen – important for blood clotting

Hemostasis The process of stopping bleeding Involves the coagulation and clotting of the blood to seal the site of damage

Events in Hemostasis 1. Blood Vessel Spasm Seratonin = vasoconstrictor 2.  Platelet plug formation platelets adhere to the collagen underlying the lining of blood vessels 3.   Blood coagulation conversion of fibrinogen to fibrin COAGULATION  -  the thickening of blood to form a clot  (hematoma)

THROMBUS – blood clot (abnormal) EMBOLUS – when the clot moves to another place.

Blood Groups and Transfusions Antigens and antibodies (Rh blood factor) ABO blood groups erythroblastosis fetalis