Midterm 1 Flashcards
what is the average blood volume? How much of it is erythrocytes, neutrophils, and platelets?
5 L
- erythrocytes (hematocrit) ~ 40%
- WBCs (leukocytes) < 5% -> neutrophils make up 50-70% of WBCs
- thrombocytes (platelets) < 1%
what electrolytes are present in plasma and why are they important?
- Na+ (APs)
- K+ (APs)
- Ca2+ (muscle contraction)
- Mg2+ (bound to ATP)
- H+ (regulate pH -> 7.35-7.45)
- HCO3- (regulate pH)
what is plasma made of?
- 92% water (electrolytes, nutrients)
- 7% proteins
what nutrients are present in plasma?
- glucose
- lipids
- cholesterol
- vitamins
- FFAs
what proteins are present in plasma?
- albumin (transports FFAs)
- globulin
- fibrinogen (clotting)
what gases are present in plasma?
- CO2
- O2
- N2
what are the approximate cellular constituent numbers and how much of the blood volume do they take up?
- RBCs: 5 mil/uL
- WBCs: 7000/uL
- platelets: 250000/uL
40-45% blood volume
how much of each cell is produced daily through hematopoiesis?
75% cells produced:
- leukocytes (lifespan is from hours-days)
20-25% cells produced:
- erythrocytes (lifespan is from 90-120 days)
- produced in bone marrow
what are the cytokines that regulate hematopoiesis?
- colony stimulating factors - leukocytes
- erythropoeitin (EPO) - erythrocytes
- thrombopoeitin (TPO) - platelets
what does Hb production require?
- iron
- B12
- folic acid
what is the structure of Hb and how does it work?
has 4 globin subunits
- each subunit has a heme group containing Fe to which oxygen binds
Hb binds 4 oxygen molecules
- binding is co-operative (binding of one oxygen molecule facilitates binding of another)
what does the oxygen dissociation curve represent?
- good saturation/binding in lungs (loading)
- poor saturation/binding in capillaries (unloading)
sigmoidal relationship
what factors influence hematocrit?
- lower in females (increased by testosterone)
- higher at altitude
- higher in athletes
what pathophysiological term would you use to describe a hematocrit of 80%?
polycythemia
what factors regulate hematocrit?
- oxygen (via EPO)
- nutritional status
- menstruation/hemorrhage
- hormones
- vit B12 complex
- folic acid
what is anemia and what are the different types?
insufficient Hb
- hypochromic (low Hb in RBCs, Fe deficiency)
- megaloblastic (pernicious (low B12) and non-pernicious (low folic acid)) -> increased size of RBCs
- hemolytic (fragile RBCs ex. sickle cell anemia)
- aplastic (low RBC production ex. from chemotherapy radiation damage)
what is hyperbilirubinaemia?
when you cannot excrete bilirubin (byproduct of old RBCs) and it builds up in the blood
- causes jaundice
- can be reversed through urinary excretion
what is the normal state of cells without clotting?
endothelial cell lining intact generate prostacyclin which promotes vasodilation (and thus blood flow) and inhibits platelet activation (and thus clotting) by keeping them soluble
how does clotting occur after endothelial cell lining is damaged?
- injury to endothelial cells reduces prostacyclin (platelets no longer soluble); collagen is exposed and binds and activates platelets
- following this activation, platelet factors such as 5-HT, ADP and thromboxane A2 are released
- factors attract more platelets causing them to aggregate and form a platelet plug
- during this temporary hemostasis, coagulation cascade is triggered: factors I-XIII activate which convert prothrombin to thrombin, thrombin converts fibrinogen to fibrin, ultimately clotting and reinforcing the platelet plug
what are PMNs?
- neutrophils
- eosinophils
- basophils
what is the function of neutrophils?
neutralize foreign substances
what is the function of eosinophils?
destroy invading parasites and cells
what do basophils form and what is their function?
- form mast cells (can enter tissues and trigger histamine release; where injury occurs causes vasodilation)
- mediate allergic response and inflammation
what do monocytes differentiate into?
macrophages
- “big eaters” -> ingest invaders