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List and describe the various functions of blood related to its roles in transportation,
protection and regulation.
- transport of gasses such as O2 and CO2
- transport of nutrients, electrolytes, metabolic wastes
- transportation of heat
- provides mechanism for clotting and inflammation
- provides antibodies (immunity)
-regulates fluid balance, electrolyte balance, pH of body fluids, body temperature, blood flow (perfusion)
Describe the components of blood and their relative proportions in a sample of blood:
plasma, formed elements (RBCs, platelets, WBCs).
Plasma - complex matrix w/in blood composed mostly of water (92%);
- Many substances dissolve in it, such as nutrients, electrolytes, gases, nitrogenous waste, hormones and enzymes forms a colloid with plasma proteins in blood
- makes up 55% of blood volume top layer in tube of blood
Formed elements - variety of cells types w/in blood
form suspension w/ water in blood makes up 45% of blood volume
- majority of formed elements are RBC's (99%); bottom-layer in tube of blood, remaining 1% is WBCs and platelets --middle-layer in tube of blood
Define the term: hematocrit and describe how it is measured.
- percent volume of RBCs in the blood
- Measured through CBC test
Identify the various formed elements of the blood in a peripheral blood smear.
- erythrocytes (RBCs)
- thrombocytes (platelets)
- leukocytes (WBCs)
Describe the composition of blood plasma
- contains dissolved substances and plasma proteins (albumins (60%), globulins (36%), fibrinogen(4%))
Describe the functions of the three major classes of plasma proteins.
Albumins (60%) - responsible for colloid osmotic pressure; blood viscosity; contributes to protein buffer
Globulins (46%) - transports electrolytes
Fibrinogen (4%) - major component for blood clots
Describe the general steps involved in hemopoiesis - the production of blood cells
1) Blood production begins in yolk sac of embryo with pluripotent stem cell
2) specific hormone signals stem cell which type of blood cell it could become
3) Liver takes over
4) After birth, spleen also responsible for blood cell production
5) Thymus helps w/ maturation of T-lymphocytes
- Occurs in red bone marrow, with some in lymphatic organs
Describe the steps in the process of erythropoiesis - the production of erythrocytes (RBCs), and describe the relationship between anemia, RBC count, and RBC production.
1) Pluripotent stem cells is signaled by EPO from liver to become RBC
2) Matures into erythroblast
3) Erythroblast becomes reticulocyte, which becomes erythrocyte
- High retic count during anemia shows normal bone marrow RBC production
- Low retic count during anemia shows abnormal bone marrow RBC production
- High retic count when patient is not anemic could show sign of bone cancer
Define the term: hypoxemia
- insufficient oxygen in the blood
- Signals kidneys to release EPO to signal stem cells to become RBCs
Describe the basic structure of hemoglobin and identify the element that provides a binding site for O₂.
- protein (peptide chains) containing alpha and beta chain (2 of each)
- W/in each chain is a hem group (non-protein) with Fe²+ ion in middle
Element of binding site for O₂:
- Fe²+ is binding site for oxygen -- potential for 4 oxygens per molecule of hemoglobin
State the normal values for hematocrit, hemoglobin concentration and RBC count in males and females and provide at least three reasons for the differences between males and females.
- Hematocrit - 45 - 50%
- Hemoglobin - 1/3 amount hematocrit
- RBC count - most abundant type of blood cell
Difference b/t males and females:
- body mass
- Men have more lean body mass - lean body mass requires more blood flow
- testosterone stimulates RBC mass
Describe the life cycle of an RBC and summarize the breakdown products of hemoglobin
1) Iron, amino acids, folic acid and Vitamin B absorbed through small intestine from diet
2) Nutrients deliver to red bone marrow which stimulates EPO
3) RBC produced
4) RBCs break down
5) Spleen and liver break down RBCs
6) Fragments of RBCs eaten up via phagocytosis
7) Hemoglobin molecule is broken down
- Globin is hydrolized into free amino acids
- Heme is broken down into bilirubin, broken down into bile and excreted w/in feces
- Iron is stored and/or reused, b/c necessary for RBC production
Define the terms anemia and polycythemia and list causes and treatments for each.
Anemia - insufficient amount of RBC
- Treatment: transfusion, iron therapy
Polycythemia - high RBC count
- Causes: chronic hypoxemia
- Treatments: therapeutic phlebotomy
Describe the three classifications of anemia and list examples within each category
1) Insufficient production of RBC in kidneys or in bone marrow
- kidney disease not producing enough EPO
- bone marrow - due to inadequate diet
2) Loss of blood - trauma, GI bleeding, menstrual cycle
3) Premature RBC destruction - hemolysis
Describe the pathology, genetics and pathophysiology associated with Sickle-cell disease.
- abnormal hemoglobin - 1 amino-acid mutation on beta chain changing shape of hemoglobin
- Fine if oxygen is available. Low oxygen in body, hemoglobin changes shape, causing red blood cells to change shape and look like a sickle
- Blood vessels get plugged w/ sickled red blood cells which would block blood passages
Explain the process by which hemolytic disease of the newborn (HDN) can develop in an Rh+ fetus of an Rh- mother.
- Mother who is Rh- (any negative blood type) and father is Rh+ (any positive blood type) give the baby Rh+ blood type, so mom and baby have different Rh types
- During pregnancy some of the baby's blood is brought into mother's body, so mother develops Rh+ antibodies
- Next time she's pregnant with Rh+ baby, some antibodies can cross placenta and attack baby's blood cells -- baby is born with HDN
Define the terms leukopenia and leukocytosis.
Explain causes and treatments for each
Leukopenia - low WBC count
- Causes: environmental toxins, severe viral infections
- Treatment: removal of offending agent, pharmacologic stimulation of bone marrow
Leukocytosis - high WBC count
- Causes: infection, physiologic stress, leukemia
- Treatment: treat underlying cause
Explain the use of the WBC differential in diagnosing the cause of illness
The counts of WBC types help determine the type of illness (i.e. high lymphocytes = viral infection)
Describe the sequence of events involved in hemostasis - the cessation of bleeding for a small damaged blood vessel
1) Vascular spasm - vasoconstriction of blood vessel stops RBCs from leaving wound
2) Platelet plug - plugs the wound to stop blood from flowing
3) Coagulation - create mesh of threads of collagen fibers and platelets that trap platelets and RBC and harden (forms scab)
Explain why hemostasis is an example of a positive feedback mechanism
- As clotting starts, thrombin continues to produce itself, allowing fibrogen to convert to fibrin, helping with the clotting
- This is broken by fibrinolytic system
Define the terms thrombosis and embolism
Thrombosis - clot in deep vein
Embolism - clot in an artery
Define thrombocytopenia and thrombocytosis. List symptoms and treatments for each.
Thrombocytopenia - abnormally low platelet count
- Causes - bone marrow disease
- Treatments - platelet transfusion
Thrombocytosis - elevated platelet count
- Causes - physiologic stress
- Treatment - treat underlying cause
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