CV3 Flashcards
(23 cards)
Blood makes up approximately how much of our body weight? Of that weight how much is in the form of formed elements?
6-8%, 80-85 mL/kg of total body weight
45% is formed elements
55% is fluid or plasma
What is the hematocrit and what is its impact on function? What are normal ranges for the hematocrit?
Hematocrit (Hct): ratio of the volume of formed elements to total blood volume. Hematocrit levels can indirectly tell you how much of your blood is made up of RBCs which carry O2.
Normal Ranges:
Females: 36-46%
Males: 41-53%
Distinguish serum from plasma.
Serum: lacks blood cells and clotting factors
Plasma: straw colored liquid component of blood that remains after cellular components have been removed.
contains water, electrolytes, hormones, enzymes, antibodies, proteins, clotting factors, etc.
Describe the major groups of molecules that can be found in the blood
Enzymes Hormones Ions Inorganic molecules Hematology: hematocrit, hemoglobin, RBC, WBC
Describe 2 major functions of albumin. What is unique about gamma globulin.
Transports hormones (lipid soluble/nonpolar), free fatty acids, drugs (affects half life) and bilirubin Responsible for creating colloid osmotic pressure Gamma globulins are where you find antibodies that function in immunity
What is fibrinogen and how is it linked to blood clotting?
Fibrinogen is a plasma protein that is synthesized by the liver. It is converted into fibrin which acts to bind platelets together to form clots
What is the process of blood cell formation called? Where does blood formation take place? What is the role of pluripotent hematopoietic stem cells? What is a myeloid stem cell?
- Hematopoiesis
- Takes place in the marrow of all bones in children
- Pluripotent hematopoietic stem cells: undifferentiated cells that can mature into adult blood cells
- Myeloid stem cell: immature cells that mature into erythrocytes, neutrophils, monocytes, eosinophils, basophils and megakaryocytes (which turn into platelets)
What hormone regulates the development of RBCs? Where does it come from and what regulates its production and release?
- Erythropoietin regulates development of RBCs
- It is produced in the kidney and controlled by O2 availability
- There are cells in the kidney that sense the amount of O2 in blood
Explain the ABO blood typing scheme in terms of 1) antigens present/absent, 2) antibodies present/absent and 3) donor/recipient limitations.
Type A: RBCs have -A antigen -Anti-B antibody -Donate to A and AB -Receive from A and O Type B: RBCs have -B antigen -Anti-A antibody -Donate to B and AB -Receive from B and O Type AB: RBCs have -A and B antigen -No antibodies -Donate to AB -Receive from ALL types Type O: RBCs have -No antigens -Anti-A and B antibodies -Donate to ALL types -Receive from O
Explain the Rh factor.
The Rhesus Factor: certain type of protein found on the outside of blood cells
Rh Positive: RBCs express the protein; protein seen as self (85% of population)
Rh Negative: RBCs do not express protein; protein seen as foreign
Describe the role of platelets.
Platelets participate in clot formation by getting “tied” together by fibrin to form mesh over injured area limiting blood loss
Smallest formed element in blood
What is thrombocytopenia?
Deficiency of platelets
What is another name for white blood cells? Identify 2 sub groups of WBC.
Leukocytes
- Granulocytes
- Agranulocytes
What is a granulocyte and what white blood cells are included in this group.
Subgroup of Leukocytes (WBCs) that has granules in the cytoplasm
- Neutrophils
- Eosinophils
- Basophils
What agranulocytes and what white blood cells are included in this group.
Subgroup of Leukocytes (WBCs) that lacks granules in the cytoplasm
- Lymphocytes
- Monocytes
Describe the specific functions of neutrophils and lymphocytes.
Neutrophils:
-Called into the site of injury to clean the area,
-They are phagocytic, consume microbes and foreign particles associated with infections
-They are critical to the 5 constructs of inflammation
-Needed for muscle repair
Lymphocytes:
-Antibody producing cells
-Include natural killer cells, T cells and B cells
-Function of T and B cells is to recognize “non-self” antigens and eliminate “non-self” tissue
What are monocytes?
Agranular Leukocytes produced in bone marrow
- Phagocytic “vacuum cleaner”
- Maturate into macrophages after entering body tissue
Define hemostasis. Why is the prevention of blood loss of homeostatic significance?
Hemostasis: the prevention of blood loss by clot formation
- Blood delivers oxygen throughout our body which is needed to function. We need to maintain our blood volume to maintain homeostasis. When blood loss occurs, we are thrown out of homeostasis so the body will work to stop the blood loss, depending on the amount of blood loss
What is the default state of hemostasis? What helps to maintain this default state?
Prevention of clot formation is default state of hemostasis
Factors that help maintain default state:
- Physical separation of blood/platelets from collagen and other clot activators located in vessel wall
- Release of clot suppressing molecules from cells of endothelial layer of blood vessels including Prostacyclin PGI2, NO (nitric oxide) which favors vasodilation and inhibits platelet aggregation
- Production of clot degrading molecules: Antithrombin III
What is the key step in initiating the formation of a clot?
Injury/damage to the endothelium
What role do platelets play in the clotting process? What molecules are released by platelets that help to cause clot formation to continue? Why is this a positive feedback mechanism?
-Platelets bind resulting in “platelet plug”
- Molecules released by platelets
- ADP: makes platelets “sticky”
- Serotonin: vasoconstriction
- Thromboxane A: creates “sticky” platelets and vasoconstriction
- It is a positive feedback loop because activated platelets continue to recruit more platelets to injury site to form “platelet plug”
Describe the “legs” of Virchow’s triangle. Why would a PT need to understand the “legs” of Virchow’s triangle? What situations might suggest increased risk for clot formation?
- Stasis of blood flow: slowing of blood movement
- Endothelial injury: cut, puncture, etc.
- Hypercoagulability: increased clot formation
- A PT would need to understand the “legs” of Virchow’s triangle so we know if our patients have comorbidities that fall under these categories that they are at a higher risk for clot formation so we can observe for symptoms
- Situations that might suggest increased risk for clot formation
- Atrial fibrillation (stasis of blood flow)
- Post surgical procedure (endothelial injury)
- Patients with cancer (hypercoagulability)
- Old birth control pills + cigarette smoking (hypercoagulability)
What is a thrombus? What is an embolus? What is a DVT? A PE?
- Thrombus: blood clot connected to vessel wall that impedes blood flow
- Embolus: blood clot that is being carried through bloodstream and can get caught in a smaller vessel causing an embolism
- Deep vein thrombosis (DVT): blood clot in deep vein, usually in legs
- Pulmonary embolism (PE): clot that has moved into a pulmonary artery and occluded it
