Idiopathic Thrombocytopenia Purpura Flashcards
What portion of the blood = Plasma?
55%
13
What portion of the blood is the Hematocrit?
45%
(about 5 million mm3 + or - 1/2 million)
(14)
What makes up the “Buffy Coat” in a centrifuged vile of blood?
Leukocytes and Platelets
13-14
What is a decreased hematocrit indicative of?
Anemia
(below 4 million)
(14)
What is an increased hematocrit indicative of?
Polycythemia
(above 6 million)
(14)
About how many molecules of hemoglobin does 1 RBC carry?
250 million
14
How many molecules of Oxygen does 1 RBC carry?
About 1 billion
(250 million hemoglobin)
(14)
What hormone is in charge of RBC production?
Erythropoietin
*released from the kidneys then forms new RBCs through the process erythropoiesis in the bone marrow
(example of negative feedback)
(15)
What are 2 examples of non-regulatory factors that affect RBC synthesis (their absence will alter production)?
Iron and Amino Acids for hemoglobin synthesis
Vitamin B12 and Folic Acid for DNA synthesis
(15)
What is Pernicious Anemia caused by?
What is the result?
Caused by malabsorption of vitamin B12
Result = slowing of erythropoiesis produces large RBCs (macrocytes) that are fragile and easily destroyed
(15)
When is the Erythrocyte Sedimentation Rate increased?
Elevated during infection, arthritis, and other inflammatory diseases
*During infections, tissues release “acute phase reactant proteins” which stick to RBCs and allow them to clump together = increase rate that they fall out of solution
(16)
What are the 3 broad groups of plasma proteins?
Albumins (smallest and most common) Globulins Fibrinogen (largest and least common) *all made in liver except y-globulins (from lymphatic tissue) (16)
What does plasma colloidal osmotic pressure do?
Which plasma protein is the main contributor to plasma colloidal osmotic pressure?
Prevents excessive fluid filtration
Albumin = main contributor
(16)
What will a lack of Albumin cause?
Hypoproteinemia
Decr. plasma protein = decr. plasma colloidal osmotic pressure = incr. loss of fluid from capillaries == Edema
(16)
What is the general function of: a-globulin, b-globulin, y-globulin?
a-globulin = carrier proteins and clotting factors
b-globulin = carrier proteins i.e. transferrin, apo-protein B, b1, b2
y-globulin = antibodies
(17)
What is the main precursor to a clot?
Fibrinogen
(fibrinogen = precursor for fibrin; fibrin forms insoluble mesh a.k.a coagulation/clotting)
(17)
What is the term for the ability of blood to maintain its volume?
What are the 3 key mechanisms that make this possible?
Homeostasis 1) vascular constriction 2) platelet plugs 3) clot formation (17)
Describe the vascular constriction step of blood homeostasis
Trauma to vessel wall induces vasoconstriction
- nervous stimulation causes endothelin-1 (vasoconstrictive factor) to release from smaller vessels
- platelets release thromboxane A2 and serotonin = vasoconstriction
(17)
During the platelet plug step of blood homeostasis, what 2 things promote platelet aggregation?
Thromboxane (from tissues) and Thrombin
17
Define homeostasis
Dynamically balanced state of self-regulation
(always changing but always staying the same)
(8)
What are the clinical features of idiopathic thrombocytopenia purpura?
*Disorder of decreased platelet numbers* Easy bleeding w/ increased bleeding time Micro-bleeds at capillaries (purple spots on skin) Easy bruising Nosebleeds (12)
What is specific gravity and what is blood’s specific gravity?
Specific Gravity = measure of the density of a solution relative to water.
Blood’s specific gravity = 1.050 g/ml
(13)
What is the pH of blood?
What is the temperature of blood?
Is blood more or less viscous than water?
pH = 7.4
temp = 98.6 F or 37 degrees C
blood = 3-5 times more viscous than water
(13)
True or False: Erythropoiesis is a fast-acting form of negative feedback?
False;
Erythropoiesis (forming new RBC) is a slow-acting example of negative feedback
(15)
What hormone is secreted to promote vasoconstriction of blood vessels?
Serotonin
18
What conversion initiates the cascade of a clot formation?
Conversion of fibrinogen to fibrin (via prothrombin being converted to thrombin, thanks to prothrombin activator)
(18)
Does the intrinsic pathway or extrinsic pathway of activating prothrombin require Factor IX (Christmas Factor)?
Intrinsic requires Christmas Factor (and needs Factor 8a as a co-factor for amplification)
(19)
Which characteristics occur in the extrinsic pathway of activating prothrombin: Fast or slow, Strong or weak?
Extrinsic = Fast and Weaker than intrinsic
Intrinsic = Slow and Stronger than extrinsic pathway
(19)
Which Factor(s) does the external pathway of activating prothrombin require?
Factor 7 and 3
19
True or False: In the huge cascade of activating Prothrombin (intrinsic and extrinsic pathways), Thrombin acts as an agent of positive feedback?
True
Factors 5 and 8 function as-is, but are greatly improved after being activated by thrombin
(20)
Removal of what molecule will result in stalled clotting reactions?
Calcium
-Calcium Chelation (removal of calcium via oxalates and citrates) used in test-tubes to keep blood from clotting
(20)
What are 3 anti-clotting mechanisms?
1) Endothelial linings - smooth simple squamous cells w/ glycocalyx coating (repels clotting factors)
2) Consumption of clotting factors - thrombin activates antithrombin 3 (which is enhanced by Heparin)
3) Fibrinolysis - done by the protease Plasminogen
(22)
What is the active form of Plasminogen? What activates it?
Plasmin
*activated by tPA (tissue plasminogen activator); released from injured tissue a day after injury
*Plasminogen to Plasmin conversion also done by Tissue Lysosomes
(22)
Which lipid-soluble vitamin is taken to hepatocytes and required for the synthesis of several clotting factors?
Vitamin K
22
What compound acts as a competitive inhibitor for vitamin K sites in hepatocytes, substantially reducing the amount of prothrombin, factors 7,9, and 10?
Coumarin (Dicoumarol) *man-made version = warfarin ***Blood thinners This minimizes dangerous clotting in some patients (22)
What is an abnormal clot that forms in a vessel?
If it freely floats it is called … ?
Thrombus
Freely floating = embolism
(22)
What is the chronic adult form of Idiopathic Thrombocytopenia Purpura due to?
Autoimmunity - antibodies to platelets found in patients
Childhood form is self-limiting; acute
(23)
Why do some patients with idopathic thrombocytopenia purpura recieve a splenectomy?
Platelets are removed from the blood by the Spleen
23
