Blood

functions of blood

• transportation: O2, CO2, metabolic wastes, nutrients, heat & hormones

• regulation: pH, body temp., water content of cells

• protection: from disease and blood loss

physical blood characteristics

• more viscous than water

• temp. 100.4°F

• pH 7.4

• blood volume: 5-6 L in males, 4-5 L in females

• 8% of total body weight

blood components

• 55% plasma, 45% formed elements

• hematocrit: percentage of total blood volume occupied by RBCs. 55% plasma, 45% cells, 99% RBCs, < 1% WBCs & platelets

blood plasma

• over 90% water

• albumin

• globulins

• fibrinogen

• 2% other substances

formed elements

• red blood cells (erythrocytes)

• white blood cells (leukocytes)

  • granular leukocytes: neutrophils, eosinophils, basophil

  • agranular leukocytes: lymphocytes (T cells, B cells), monocytes

• platelets: blood clotting

hematopoiesis

• formation of blood cells

• in embryo: occurs in yolk sac, liver, spleen, thymus, lymph nodes & red bone marrow

• in adult: occurs only in red marrow of flat bones like sternum, ribs, skull & pelvis and ends of long bones

red blood cells (RBC)

primarily made of water and hemoglobin

hemoglobin components

• globin protein: 4 polypeptide chains

• 2 alpha chains

• 2 beta chains

RBC life span

120 days

erythropoiesis steps

1. stem cells in bone marrow are altered

2. after absorption, kidneys secrete erythropoietin (EPO)

3. myeloid differentiated via transcriptions and translations to erythrocyte

neutrophils

combat inflammation and infection via phagocytosis

eosinophils

• combat the effects of histamine in allergic reactions

• phagocytize antigen-antibody complexes

• combat parasitic worms

basophils

develop into mast cells releasing heparin, histamine, and serotonin in allergic reactions intensifying inflammatory response

b lymphocytes

produce antibodies in response to foreign substances called antigens

t lymphocytes

destroy foreign invaders directly

complete blood count

• screens for anemia and infection

• total rbc, wbc, platelet counts

thrombopoietin

stimulates myeloid stem cells to produce platelets

myeloid stem cells

develop into megakaryocyte-colony-forming cells that develop into megakaryoblasts

megakaryoblasts

transform into megakaryocytes which fragment

platelet

• aka thrombocyte

• a fragment enclosed by a piece of cell membrane

agglutinogens

• aka antigens

• A and B determine blood types

agglutinins

• aka antibodies

• react with agglutinogens that are foreign to the individual

• designated as a and b

type A

RBCs with surface antigen A and anti-B antibodies

type B

RBCs with surface antigen B and anti-A antibodies

type AB

RBCs with surface antigen A and B, neither anti-A nor anti-B antibodies

type O

RBCs with neither antigens A nor B and both anti-A and anti-B antibodies

universal recipient

• type AB

• only true if cross match the blood for other antigens

universal donor

type O