Blood & Blood Diseases

blood, plasma, RBCs, WBCs, platelets, hematopoiesis, hemoglobin, and anemias

Plasma

liquid portion of blood; contains water, proteins, nutrients, hormones, wastes, electrolytes

RBCs (erythrocytes)

carry oxygen using hemoglobin; made in bone marrow

WBCs (leukocytes)

immune cells that fight infection; include granulocytes and agranulocytes

platelets

cell fragments that help stop bleeding by forming plugs and promoting vascoconstriction

formed elements

RBCs, WBCs, and platelets

hemotocrit

percentage of blood volume made of cells (~45% cells, 55% plasma)

hemocytoblast

stem cell that gives rise to all blood cells

colony stimulating factors

chemicals that direct hemocytoblasts to become specific blood cells

function of RBCs

transport oxygen and carbon dioxide

RBC shape

biconcave disc; increases surface area for gas exchange

hemoglobin

protein in RBCs that binds oxygen and CO2

oxyhemoglobin

hemoglobin + oxygen; bright red

deoxyhemoglobin

hemoglobin without oxygen; dull red

carbaminohemoglobin

hemoglobin + CO2

why RBCs lack nucleus & mitochondria

maximizes space for hemoglobin; mitochondria would use oxygen

hematopoiesis

formation of all blood cells in bone marrow

erythropoiesis

formation of red blood cells

erythropoietin (EPO)

hormone from kidneys/liver that stimulates RBC production

RBC lifespan

about 120 days

where old RBCs are destroyed

spleen and liver by macrophages

hemoglobin breakdown products

globin → amino acids; heme → iron + biliverdin

iron recycling

iron binds transferrin → reused in bone marrow; excess stored as ferritin

biliverdin → bilirubin

converted in liver; excreted in bile

RBC count

number of RBCs per cubic millimeter of blood

erythrocytosis

increased RBC count; caused by lung disease, dehydration, high altitude

anemia

low RBC count or low hemoglobin

pernicious anemia

vitamin B12 deficiency due to lack of intrinsic factor; macrocytic cells

iron deficiency anemia

low iron → small RBCs with low hemoglobin

nutrients needed for RBC production

vitamin B12, folic acid, iron

intrinsic factor

stomach secretion needed for vitamin B12 absorption

neutrophils - granulocytes

MC WBC; segmented nucleus; first responders; phagocytize bacteria/viruses

Basophils - granulocytes

release histamine (inflammation) and heparin (anticoagulant)

eosinophils - granulocytes

fight parasites; moderate allergic reactions

monocytes - agranulocytes

kidney-shaped nucleus; become macrophages; phagocytize debris and bacteria

lymphocytes

same size as RBC; large nucleus; include T cells and B cells; immune support

platelets

cell fragments that help stop bleeding by forming plugs and promoting vasoconstriction