Blood and Immunity

Red blood cells (and what it needs)

Live about 120 days, 30 trillion, replace about 1% a day

Needs:

• iron

• B12

• Erythropoietin → from kidney, released if blood O2 is low

Anemia (what it is and the diff types)

Low oxygen carrying capacity → fatigue

Iron deficiency anemia

• low iron, low Hb

• Small cells, low Hct

Pernicious anemia

• Low B12

• Low RBC count

Polycythemia (what it is and the diff types)

High RBC count or high hematocrit

Primary → tumour that causes high RBC production

Secondary → high EPO causes high RBC production

Relative → dehydration so reduced plasma so high hct

Types of white blood cells

Neutrophils → phagocytes, most common

Monocytes → macrophages

Eosinophils → allergy response

Basophils → histamine

Lymphocytes → T cells and B cells

Platelets

Cell fragments needed for clotting

• lifespan 5-9 days

• 5000-10000/ megakaryocyte

Blood clotting processes

Vascular spasm → vasoconstriction to reduce blood loss

Platelet plug

Coagulation

Platelet plug

Exposure to collagen (charged surface) activates platelets

• activates other platelets to increase plug size

• Surrounding healthy tissues inhibit platelets

Coagulation

Formation of fibrin threads

Clotting requires

• clotting factors, platelets, calcium, vit K

• Vit K needed for the formation of several factors

Positive feedback loops

• two pathways → intrinsic and extrinsic

Extrinsic vs intrinsic pathway for coagulation

Extrinsic → needs external factor

• initiated first → small amount of fibrin

Intrinsic → slower, more fibrin

• triggered through positive feedback → produces high volume of fibrin