Blood Flashcards
What are the four main constituents of blood?
Erythrocytes (5 billion), leukocytes, platelets, plasma
What does plasma contain?
proteins
Where are plasma proteins produced?
In the liver (except for antibodies)
What are the three types of plasma proteins?
- Albumins: transport substances poorly soluble in plasma; nonspecific
- Globulins: different subtypes may transport specific substances, or are factors in blood clotting, or help regulate salt balance
- Fibrinogen: key factor in blood clotting
What is the main function of erythrocytes?
To carry O2
What is the main molecule inside erythrocytes?
hemoglobin
Where does O2 bind within this molecule?
On an Fe atom
What is the color of hemoglobin bound to O2? How about without O2?
Reddish with, bluish without
What is the function of carbonic anhydrase? What contains this enzyme?
enzyme that catalyzes CO2 + H2O H+ + HCO3− (bicarbonate ion)
contained by erythrocytes.
Why do erythrocytes have a short life span?
Lack of nucleus and organelles, squeezing through capillaries causes damage to plasma membrane that they cannot repair.
Where are old, fragile erythrocytes removed?
spleen
Where does erythropoiesis occur?
Bone marrow of sternum, ribs, pelvis, and upper end of limb bones
What do the kidneys secrete that affects erythropoiesis? Is the secretion in response to low or high O2 level in the blood?
Erythropoietin, controlled by negative homeostatic feedback loop, in response to decreased O2 levels in blood detected by kidneys.
What is antigen? How does it relate to the ABO and Rh factor blood types?
Large molecule (usually protein, glycoprotein, or glycolipid on cell surface) that triggers immune response in the body.
What happens during a transfusion reaction?
Antigens from opposing blood types attack each other, the red blood cells from the donor agglutinate, usually rupture and cause blockages in capillaries.
What is the main function of leukocytes? Where are they produced?
Mobile units of the body’s immune system, produced in bone marrow
What are the two groups of leukocytes?
- Polymorphonuclear granulocytes
a. Nuclei segmented into several lobes of different shapes
b. Presence of membrane-enclosed granules filled with stored chemicals that can be released by exocytosis - Mononuclear agranulocytes
What are the five subtypes of leukocytes?
- Neutrophils
- Eosinophils
- Basophils
- Monocytes
- lymphocytes
What are megakaryocytes?
Very large cell in bone marrow that sheds off platelets (cell fragments)
What hormone stimulates megakaryocyte production and activity?
thrombopoietin
What do platelets consist of?
Cytoplasm of megakaryocyte, some organelles and enzymes, actin and myosin
What is hemostasis?
The arrest of bleeding from a broken blood vessel
What are the three steps of hemostasis?
- Vascular spasm
- Formation of platelet plug
- Blood coagulation
How does vascular spasm occur?
injury to blood vessel triggers release of a paracrine from endothelial lining that causes vasoconstriction. the inner endothelial surface becomes sticking and opposing ends adhere to each other.
Exposure of what protein in the blood vessel to plasma leads to platelet plug formation?
von Willebrand factor
What do actin and myosin in platelets do?
contract to tighten plug
What is the ultimate step in formation of a blood clot? How does this form a clot?
conversion of fibrinogen (plasma protein produced in liver) to fibrin
What is clot retraction?
platelets trapped in clot retract, pulling edges of damaged vessel closer together.
What is the difference between the intrinsic and extrinsic clot pathways?
intrinsic: triggered at exposure of blood to damaged blood vessel
extrinsic: triggered at exposure of blood to factors in damaged tissue outside of blood vessel
What does activated plasmin do?
slowly dissolves fibrin mesh over time (dissolves clot)
