Blood

Blood is a liquid connective tissue that transports various substances to body cells & helps to maintain homeostasis.

Nutrients from digestive tract to body cells

Oxygen from lungs to body cells Wastes from cells to respiratory and

excretory systems Hormones to target tissues Body temperature control – distributes

heat

Blood/Blood Cells

Volume Varies with body

size – usually between 4-6 liters

Solid portion – RBS, WBC, & platelets – Fig. 11-1

Liquid portion – plasma (55% of blood volume)

RBC’s – Erythrocytes - Fig. 11-2

Characteristics Biconcave disks; shape provides increased SA

& places cell membrane close to internal parts Contain hemoglobin – oxygen carrying protein Mature RBC’s lack nucleus, but contain

enzymes needed for energy releasing processes

Approx. 4-6 million/mm3

RBC’s (cont.)

Destruction of RBC’s (last about 120 days) Fragile & as they age they are damaged while

moving through capillaries Damaged cells are phagocytized by

macrophages in the liver & spleen Hb molecules are decomposed & the Fe they

contain is conserved

Macrophage engulfing two RBC’s

RBC’s (cont.) RBC production and its control (hematopoiesis)

During fetal development RBC’s are formed in yolk sac, liver & spleen; later produced by red bone marrow

Number remains relatively stable Rate of RBC production is controlled by a negative

feedback mechanism Kidney & liver tissues experience oxygen deficiency Tissues release erythropoietin Erythropoietin travels to red bone marrow stimulating

an increase in RBC production As RBC numbers increase the oxygen carrying capacity

of the blood rises Oxygen concentration in kidney & liver increase and the

release of erythropoietin decreases

WBC’s leukocytes – Table 11-1, Fig. 11-4 – Function to control disease conditions Types of WBC’s

Granulocytes – granules present in cytoplasm; include neutrophiles (phagocytize), eosinophi9ls, (defense against parasites), & basophils (inflammatory response)

Agranulocytes – monocytes & lymphocytes (humoral and cellular immune response)

Approx. 5,000 – 10,000/mm3; however the number of WBC’s may change as a result of infections, emotional disturbances or excessive loss of body fluids

Functions of WBC’s WBC’s may be stimulated by the

presence of chemicals (histamine) released by damaged cells & many move toward these chemicals

http://www.youtube.com/watch?v=y3bOgdvV-_M (body’s response to an allergen)

Neutrophils & monocytes phagocytize foreign particles

http://www.youtube.com/watch?v=7VQU28itVVw&feature=related (phagocytosis – fig. 11-5)

Functions of WBC’s Eosinophils kill parasites & help control

inflammation & allergic reactions Basophils release heparine – inhibits

blood clotting Lymphocytes produce antibodies that act

against specific foreign substances http://www.dnatube.com/video/194/Specif

ic-Adaptive-immunity-humoral-and-cell-mediated (immune response)

Platelets - thrombocytes

Fragments of giant cells that become detached & enter circulation

Help close breaks in blood vessels, Fig. 11-6

Approx. 130,000 – 360,000/mm3

Hemostasis – stoppage of bleeding http://www.youtube.com/watch?v=--bZUe

b83uU&feature=related (blood clotting)

Be familiar with the steps of blood clotting shown in the above link

Blood Clot

Blood Plasma

Liquid port of the blood that is composed of H2O and a mixture of organic & inorganic substances. It transports nutrients & gases, regulates fluid and electrolyte balance and helps maintain a stable pH.

Blood Types – blood can be typed on the basis of antigens displayed on the cell membranes of RBC’s

Antigens & antibodies Fig. 11-7 RBC membranes may contain antigens

(agglutinogens) and blood plasma may contain antibodies (agglutinins)

Blood typing involves identifying the antigens present on the red cell membranes

ABO Blood Groups

Type A blood Type A antigen; type B antibody

Type B blood Type B antigen; type A antibody

Type AB blood Type A & B antigens; no antibodies

Type O blood No antigens; A & B antibodies

ABO Blood Groups Adverse transfusion reactions are

avoided by preventing the mixing of blood that contain the antigen with plasma that contains the corresponding antibody

Adverse reactions involve agglutination (clumping) of the RBC’s

For example – if RBC’s with antigen A are added to blood containing antibody A….. The antibodies react with the antigens of the RBC’s and cause them to clump together

Agglutination

Rh Blood Group

Rh antigens are present in the RBC membranes of Rh+ blood; they are absent in Rh- blood

No antibodies are present in RH+ blood (do not develop spontaneously)

Mixing Rh+ RBC’s with plasma that contains anti-Rh antibodies results in agglutination of the + cells

Erythroblastosis fetalis – Fig. 11-8

Rh- woman becomes pregnant with her first Rh+ child

Pregnancy is uneventful, but at time of birth some Rh+ cells enter maternal circulation through damaged placental tissues

Maternal tissues produce anti-Rh antibodies Second Rh+ child is conceived Anti-Rh antibodies from the maternal

circulation pass through the placental membranes & enter the fetal blood

Fetal blood agglutinates because of reaction with the anti-Rh antibodies