What does blood distribute?
-O2 and nutrients to cells
-Metabolic wastes to the lungs and kidneys for elimination
-Hormones from endocrine organs to target organs
What does blood regulate?
-Body temp (by absorbing and distributing heat)
-Normal pH (using buffers such as bicarbonate)
-Adequate fluid volume in the circulatory system (salts and blood proteins maintain osmotic pressure)
What does blood protect against?
-Blood loss (plasma proteins and platelets initiate clot formation)
-Infection (antibodies/complement proteins/WBCs defend against foreign invaders)
-Protein globin: 2 alpha and 2 beta chains
-Heme pigment bonded to each globin chain
Blood cell formation (can make all different formed elements/RBCs, WBCs, and platelets)
Where does hematopoiesis occur?
In red bone marrow (girdles and proximal epiphyses of humerous and femur)
Hemocytoblasts (hematopoietic stem cells)
-Gives rise to all formed elements
-Hormones and growth factors push the cell toward a specific pathway of blood cell development
-New blood cells enter blood sinusoids
What are the 4 phases in erythropoiesis development?
1. Ribosome synthesis
2. Hemoglobin accumulation
3. Ejection of the nucleus and formation of reticulocytes
4. Reticulocytes then become mature erythrocytes
-Direct stimulus for erythropoiesis
-Released by the kidneys in response to hypoxia
-Increasing retic count in 1-2 days
Causes of hypoxia:
-Hemorrhage or increased RBC destruction
-Insufficient hemoglobin (iron deficiency)
-Reduced availability of O2 (high altitudes)
-Absent or faulty globin chain in Mediterranean ancestry.
-RBCs are thin, delicate, and deficient in Hgb
-Defective gene codes for abnormal hemoglobin (HbS)
-Causes RBCs to become sickle shaped in low-oxygen situations, clogging small vessels, and causing CP and bone pain.
-More common in African Americans
Contain histamine (an inflammatory chemicle that acts as a vasodilator and attracts other WTCs to inflamed sites.)
Lymphocytes and monocytes (lack visible cytoplasmic granules/Spherical or kidney shaped nuclei)
-Leaves circulation, enters tissue, and differentiates into macrophages.
-Activates lymphocytes to mount an immune response.
-The largest leukocyte
S & S of leukemia
-Death (internal hemmorhage and overwhelming infections)
-Form a temporary plug that seals breaks in blood vessels.
-Small fragments of megakaryocytes
-Formation is regulated by thrombopoietin
Are kept inactive and mobile by NO (nitrous oxide) and prostacyclin from endothelial cells of blood vessels.
What does a vascular spasm trigger?
-Chemicals released by endothelial cells and platelets
-A set of reactions in which blood is transformed from a liquid to a gel (blood clotting)
-Reinforces the platelet plug with fibrin threads
3 Phases of coagulation
1. Prothrombin activator is formed (intrinsic and extrinsic pathways)
2. Prothrombin is converted into thrombin
3. Thrombin catalyzes the joining of fibrinogen to form a fibrin mesh
-Triggered by negatively charged surfaces (activated platelets, collagen, glass)
-Uses factors present within the blood
-Triggered by exposure to tissue factor (TF) or factor III (an extrinsic factor)
-Bypasses several steps of the intrinsic pathway, causing it to be faster
-Clot that develops and persists in an unbroken blood vessel.
-May block circulation, leading to tissue death (MI due to coronary thrombus).
A free floating thrombus in the bloodstream.
-Pulmonary emboli impair the ability of the body to obtain O2
-Cerebral emboli can cause strokes
Disseminated Intravascular Coagulation (DIC)
-Widespread clotting blocks intact blood vessels.
-Severe bleeding occurs because residual blood is unable to clot.
-Most common in pregnancy, septicemia, or incompatible blood transfusions.
What is the most common blood transfusion?
Packed red blood cells (plasma removed)
-Used to restore oxygen carrying capacity