Blood Ch 17 Flashcards
Components of blood
Erythrocytes
Plasma
Buffy coat
Buffy coat
Thin white layer between the etythrocytes and the plasma
Made up of Leukocytes and platelets
Hematocrit
% of BRC in the blood, +/- 47 in men and 42 in women
Functions
Distribution
Regulation
Protection
Distribution functions include
Delivering O2 from the lungs and nutrients from the GI tract
Transporting metabolic waste products from cells to elimination sites
Transporting hormones from endocrine glandes to their target cells
Regulation functions include
Maintaining body temp
Maintaining normal pH reservoir for alkaline reserve
Maintaining adequate fluid volume, prevent blood loss into tissue spaces
Protection functions include
Preventing blood loss by clotting
Preventing infection, WBC defend against invaders
Blood Plasma
Straw colored sticky fluid, 90% water and 10% is made of dissolved solutes including nutrients, gasses, hormones, wastes and products of cell activities. Proteins and electrolytes are the most numerous of the solutes.
Albumin
60% of the plasma. Major blood protein contributes to plasma osmotic pressure (helps keep water in blood stream) Acts as a carrier to shuttle molecules through the blood and is an important buffer.
Formed elements unusual features
Erythrocytes, leukocytes and platelets:
2 of the 3 are not true cells
Most only survive in the blood stream for a few days
Most do not undergo mitosis
Erythrocytes
RBC, small biconcave cells.
No nucleus or organelles
“bags” of hemoglobin
major factor contributing to blood viscosity
Characteristic that contribute to RBC O2 carrying capacity
Huge surface area
Low water content, 97% hemoglobin
Do not consume any O2 they carry
Hemoglobin
Protein that makes RBC red, binds easily to O2
Made of heme pigment bound to a protein globin.
4 heme groups (2 beta 2 alpha) each containing one iron atom in the center
Each hemoglobin molecute can carry 4 oxygen
20% of CO2 combines with hemoglobing
Erythrocyte production
A mitotic and live only 100-120 days
produced in red bone marrow
100 billion new cells are produced daily
Hemocytoblasts
Hematopoietic stem cells from which all blood cells rise.
Erythropoietin (EPO)
Produced mainly in the kidneys and also in the liver
Glycoprotien hormone that stimulates RBC production in response to hypoxic kidney cells (Hypoxia-induced factor HIF)
RBC recycling
after 100-120 days RBC lose their flexibility and they are engulfed by macrophages in the spleen liver and bone marrow. The iron is stored as ferrin in the liver and the hemoglobing is broken down and recycled
Bilirubin
The balance of the heme group is degraded to bilirubin and the yellow pigment is secreted from the liver as bile.
Anemia
The bloods oxygen carrying capacity is too low to support normal metabolism.
Leukocytes
WBC: The only formed elements that are complete cells.
Move out of the blood into the tissues “leaping across’ (diapedesis)
Neurophils
Most numerous WBC and are 2x bigger than RBC
Bacteria slayers (and some fungi)
multilobed nucleus,
Eosinophils
Lead the counter attack against parasitic worms, flat worms and round works. Also have roles in allergies and asthma.
Basophils
Least numerous blood cells. Contain histamine which is an inflammatory chemical that acts as a vasodilator and attracts other WBC to the site.
Lymphocytes
2nd most numerous WBC and are closelt related to the lymphoid tissues where they play a crucial role in immunity
B cell lymphocytes: give rise to plasma cells
T cell lymphocytes: act directly on virus infected or tumor cells.
Monocytes
Leave circulation and become macrophages in the bodies tissues. Defense against viruses and some bacterial parasites.
Leukopoiesis
Production of WBC is stimulated by chemical messengers and rise from hemocytoblasts as well.
Platelets
Not cells but actually cytoplasmic fragments of the large megakaryocyte cells.
Essential for the clotting process
Thrombopoietin
Regulates the formation of platelets
Hemostasis
.Events that stop bleeding
- vascular spasm
- platelet plug formation
- coagulation
Platelet plug formation
As a rule platelets do not stick to each other or smooth endothelium. When the vessel is damaged the platelets adhere to the exposed underlying collagen.
Coagulation
blood clotting reinforces the platelet plug with fibrin threads.
Intrinsic pathways
- called intrinsic because the factors needed for clotting are present in the blood
- Triggered by negatively charged surfaces such as platelets. collagen or glass.
- Slower because it has many intermediate steps
Extrinsic pathways
- Called extrinsic because the tissue factor it requires is outside the blood
- Triggered by exposing blood to a factor found in the tissue under the damaged epithelium. (TF tissue factor)
- Fastest because is bypasses several steps of the intrinsic pathway.it can form a clot in 15 sec.
Clot retraction
Fybrinolysis
Platelets contain contractile proteins and release platelet derived growth factor to stimulate the vessel to rebuild. Plasmin the clot buster ia a fibrin-digesting enzyme
Factors limiting clot growth
- swift removal of clotting factors
- inhibition of activated clotting factors
Antithrombin III : a protein present in plasma that quickly inactivates any thrombin not found in fibrin
Heprin: a natural anticoagulant contained in basophil and mast cell granules, also found on the surface of epithelial cells.
Hemostasis disorders
Thromboemebolic disorders: undesirable clot formation
Bleeding disorders: prevent normal clot formation
DIC: characteristics of both types
Thrombus
A clot that develops and persists in an unbroken blood vessel
Embolus
Thronbus breaks free of the vessel wall and floats freely through the blood stream (embolism when it obstructs a vessel)
Anticoagulant drugs
ASA: blocks plateles aggregation
Heprin
Warfran
Diabigatran: direct inhibitor of thrombin
Antigen
ANything the body preceves as foreign and that generatesan immune responce
Blood types
O=Universal donor A & B antigens
AB=Universal recipient No antigens
A=Anti-B
B=Anti-A
