Chapter 18- Blood

branch of science that studies the blood, blood-forming tissues and blood disorders

-nutritive & excretory function -respiratory function -transport of hormones and enzymes -regulation of water & acid-base balance -regulation of body temp -restricts fluid loss (clotting) -blood has white blood cells= protect against disease

• Blood is a type of connective tissue, the matrix is the plasma and this dissolves and suspends various substances, cells, and cell fragments • Maintains a temperature of 38°C • Denser and about 5 x more viscous than water • pH of 7.35 – 7.45 (average of 7.4) • Adult volume: male – 5-6L female 4-5L; about 8% of body weight in kg • Regulated by several hormones (e.g., aldosterone, ADH)

1)Superficial veins – easier to locate 2)Vein walls are thinner and easier to penetrate than comparable sized arteries 3) Blood pressure lower in venous system, puncture seals quickly

-plasma (55% of whole blood) -buffy coat: leukocytes and platelets (<1% of whole blood) -erythrocytes (formed elements) (45% of whole blood)

-albumins (60%) major contributors to osmotic pressure of plasma; transport lipids, steroid hormones -globulins (36%) trasnport ions, hormones, lipids; immunity function -fibrinogens (4%) essential component of clotting system; can be converted to insoluble fibrin

-a precursor for fibrin -soluble plasma protein fibrin -insoluble protein -forms clots

-plasma proteins 7% -other solutes 1% -water 92%

• erythrocytes (majority RBC) • thrombocytes (platelets) • leukocytes (WBC) ALL MADE IN RED BONE MARROW

-hematocytoblast (HSC) -myeloid cell (erythropoietin, hormone from kidneys) -progenator cell -blast cells -proerythroblast (EPO) -erythroblast (last stage with nucleus) -reticulocyte (no nucleus, found in patient with regnerative anemia) -erythrocyte (RBC)

1) Pick up oxygen from lungs and deliver it to tissues 2) Pick up carbon dioxide from tissues and unload it in the lungs

1) Large surface area allows for rapid exchange of oxygen as cells pass through capillaries of the lungs or peripheral tissue. 2) Allows RBCs to temporarily form stacks that smooth their flow through narrow blood vessels. 3) The strong and flexible plasma membrane allows them to deform without rupturing as they squeeze through narrow capillaries

No nucleus, ribosomes, or mitochondria means no repair. RBCs have a finite life span of about 120 days

female 42% (range: 37 -47); male 46% (range: 40-54) * Testosterone stimulates RBC production whereas estrogen does not * Also, loss of blood during menstruation impact Hct in females

• Reduction in the oxygen-carrying capacity of the RBCs • Significant decrease in hematocrit is present • Many types of anemia: decrease in absolute number of RBCs (increased loss –hemorrhagic/hemolytic or decreased production) or insufficient hemoglobin (or iron or vitamin B12)

• Increase in hematocrit is present (>65%) • Abnormal increase in RBC production (absolute polycythemia) or due to dehydration (relative polycythemia) • Blood becomes too viscous, harder for heart to pump, increases blood pressure and increase risk for stroke or heart attack

-gives blood its red colour -Hb is a protein with 4 identical chains -Each chain is made up of a polypeptide chain called a globin, a chemical group called a heme, which contains and iron molecule that can bind to an oxygen molecule -1 RBC can carry 1 billion O2 molecules

1) Reduction in cell size 2) Increase in cell number 3) Synthesis of hemoglobin (erythroblast stage) 4) Loss of the nucleus and other organelles (reticulocyte & mature RBC)

-gastroferrin (stomach) -transferrin (blood)

ferritin (in liver)

hypoxemia, sensed by liver and kidneys, secretion of erythropoietin, stimulation of red bone marrow, accelerated erythropoiesis, increased RBC count, increased O2 production

Old RBCs are broken down by macrophages in the spleen, liver, or bone marrow, with hemoglobin splitting into heme and globin. Heme is processed into iron and biliverdin (green pigment), which converts to bilirubin (yellow pigment) and is eventually excreted as urobilin (yellow in urine) or stercobilin (brown in feces)

Agglutination occurs when plasma antibodies bind to antigens on RBCs, forming antibody-antigen complexes. We have antibodies for antigens not present on our own RBCs but not for our own antigens.

The RBCs: surface antigen A In plasma: Anti-B antibodies