Blood Chapter 12

Introduction What is the function of blood? Blood transports substances (nutrients, oxygen, wastes, and hormones) Also maintains homeostasis in the body with hormones Hematophobia = fear of blood

Blood and Blood Cells Blood is a type of connective tissue with two basic components: –1. Cells (red blood cells, white blood cells, and platelets) = 45% –2. Plasma (water, amino acids, proteins, carbohydrates, lipids, vitamins, hormones, electrolytes, and cellular wastes) = 55%

Hematocrit – percentage of cells in a blood sample –Should be 45%, remaining 55% is plasma –Have to centrifuge a blood sample to test this

Three types of cells Red blood cells - erythrocytes White blood cells - leukocytes Platelets - thrombocytes

Red blood cells - erythrocytes Have a biconcave shape RBCC stand for red blood cell count which is the amount of blood cells in a cubic millimeter (5 million per cubic millimeter) They lack nuclei in a mature stage so they will not divide

Hematopoiesis – formation of new blood cells (done in bone marrow) Blood cells live for about 120 days, then are phagocytized by the liver and spleen

Erythropoietin – a hormone that is part of a negative feedback mechanisms that controls the rate of red blood cell formation –Produced in the liver and kidneys (controlled by oxygen levels

Main functions of Red blood cells Transports oxygen throughout body and picks up carbon dioxide Hemoglobin - molecule which combines with oxygen to transport it within the blood Iron is critical to the creating of hemoglobin

Oxygen levels in blood Oxyhemoglobin – blood has plenty of oxygen, appears bright red Deoxyhemoglobin – blood is not carrying much oxygen, appears "bluish red"

Red blood cell production requires: –Iron –Vitamin B12 –Folic Acid Anemia = too few red blood cells

White blood cells – leukocytes General function - defend the body against disease-causing agents (microorganisms) Five different types in two groups: – 1. Granulocytes (granular cytoplasm): Neutrophils, Eosinophils, Basophils –2. Agranulocytes (lacking granular cytoplasm): Monocytes, Lymphocytes

1. Neutrophils Very active in phagocyting bacteria Are present in large amount in the pus of wounds Most common make up 60% of WBC

2. Eosinophils Attack parasites Control allergic reaction 2% WBC

3. Basophils Produces Heparin (prevents blood clots) and Histamines (causes inflammatory reaction) Less then 1% WBC

4. Monocytes Precursors of macrophages Phagocytes Make up 6% of WBCs

5. Lymphocytes Main constituents of the immune system which is a defense against the attack of pathogenic micro-organisms such as viruses, bacteria, fungi and protista Yield antibodies and arrange them on their membrane Make up 30% of WBCs White blood cell interactive

Platelets – Thrombocytes Help initiate formation of blood clots, They close breaks in damaged blood vessels

Blood Plasma The liquid portion of the blood –92% water –transports nutrients, gases, vitamins, maintains fluid and electrolyte balance, and pH –Four types of proteins in plasma

Albumin Origin: Liver Function: Helps maintain osmotic pressure and blood volume (blood pressure)

Alpha Globulin Origin: Liver Function: Transport lipids and fat – soluble vitamins

Beta Globulin Origin: Liver Function: Transport lipids and fat – soluble vitamins

Gamma Globulin Origin: Lymphatic tissue Function: Constitute a type of antibody for immunity

Fibrinogen Origin: Liver Function: Largest molecules of plasma proteins; important for blood clotting. Major event in blood clotting is the change of fibrogen into fibrin

Hemostasis The process of stopping bleeding Coagulation causes the formation of a blood clot 3 Key Events

1. Blood Vessel Spasm (vasoconstriction) Damaged or broken vessels stimulate muscle tissue in the walls of the blood vessels to contract This slows or stops blood flow, lasts for several minutes. Also, platelets release serotonin, a vasoconstrictor which maintains the muscle spasm even longer.

2. Platelet plug formation Platelets stick to surfaces of damaged blood vessels and to each other to form a "plug"

3. Blood coagulation Most effective, forms a blood clot (hematoma). Injury causes an increase in the release of coagulants. Main event - conversion of fibrinogen into long protein threads called fibrin.

Tissue damage cause the prodction of prothrombin activator (calcium ions must be present) Prothrombin get converted to thrombin Thrombin acts as an enzyme to cause change of fibrinogen to fibrin, which traps platelets and blood cells to form a hematoma

Thrombus - a blood clot abnormally forming in a vessel

Embolus - when the clot moves and becomes lodged in another place

Blood Groups and Transfusions Blood types are controlled by three alleles: –A, B, & O A & B are codominant; O is recessive This makes the genetics of blood very interesting

Antigens and Anitbodies Agglutination is the clumping of red blood cells following a transfusion reaction It is due to a reaction between red blood cell surface molecules called antigens and protein antibodies carried in plasma The type of antigens deternmines what blood type a person is

Blood transfusions Blood that has antibodies on it that is not recognized by the body will be attacked by your immune system O is the Universal Donor because a person with this type of blood does not have antigens on the surface of the blood cells This will not cause an immune reaction in the patient.

AB is the universal Acceptor because this person will not have an immune reaction to A, B, AB, or O

Rh Blood group A person can either be Rh+ (have Rh surface antigens) or Rh- (do not have Rh surface antigens) –Positive is the dominant genotype

Problem: When a fetus is Rh+ and the mother is Rh-, this can cause the mother's immune system to attack the fetus. Called Erythroblastosis fetalis Doctors can prevent this reaction by giving the woman an injection that will suppress her immune reaction.