Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
14 Cards in this Set
- Front
- Back
|
What are the characteristics of the RBC? |
carries O2 around the body no nucleus, no organelles - cannot respond to environment all enzymes/contents last for life of RBC from production biconcave and deformable to fit in small capilaries Hb loads O2 at high O2 tension (lungs), release at low O2 tension (tissues) |
|
|
What are the requirements of RBCs? |
ENERGY (ATP) - to keep volume(Na/K ATPase)/shape/flexibility. Get from EMP (anaerobic glycolysis) (4ATP, 2lactate, 2NADH) NADH - reduce Fe3+ to Fe2+ (would bind to O2 ->Hi, convert Methaem(Hi) to Haem (Hb) - methaemaglobin reductase) NADPH - recycle oxidised glutathione (GS-SG) -> GSH. cleans up reactive oxygen species (give up H+) (get from Hexose monophosphate shunt) 2,3 Bisphosphoglycerate - modulate O2 affinity (get from Rapoport-leubering shunt) |
|
|
What can occur if the EMP (Ebden Myerhoff pathway) goes wrong? |
Decrease in NA/K ATPase -RBC swell -> stomatocytes (Na + H2O leaks in) -Haemolysis Decrease in NADH - loss of reducing capacity of methaem. reductase -Hi generation, cant carry O2 -> Heinz body form |
|
|
What can occur if the HMS (hexose monophosphate shunt) goes wrong? |
-cell succumbs to oxidant stress -accumulation of peroxides and ROS -denaturation of Hb -> Heinz bodies -Peroxidation of membrane lipids ->weaken membrane -> INTRAVASCULAR haemolysis |
|
|
What are the 6 causes of Normocytic Normochromic anaemia? |
Haemolysis Lack of production Acute loss of blood failure of production lack of nutrients required for production insufficient Bone Marrow |
|
|
What tests should you perform on a NN anaemia? |
RETIC COUNT - if increased know BM is producing more RBC if normal BM ASPIRATE -if normal = kidney disease -if high = myeloma, MF, MDS If abnormal due to haemolysis -intrinsic defect -extrinsic defect |
|
|
What tests allow for evaluation of the degree of haemolysis? |
Hb, retic, Bilirubin, LDH, Haptoglobin |
|
|
Discuss Hereditary Spherocytosis |
-1 in 5000, mostly Auto dominant (homo not compatible with life) -deficiency of SPECTRIN (most common) 4.1, ankyrin -defect btwn linkage of spectrin and phospholipid bilayer -MORE VERTICAL -episodic congenital (from birth) Haemolytic anaemia -see spherocytosis -jaundice, splenomegally, gallstones, aplastic crisis, folate deficiency Pathophysiology - EVH Test - Eosin-5-Malemide flow cytometry **E5MA DECREASED** |
|
|
Discuss Hereditary Eliptocytosis |
-1 in 1000 (5x HS) auto dom (NO SE asian) both homo and hetero, range of severity -4 classes (common, w infintile polik(negro<1yr), w sphero, w stomato(SE asian, recessive)) -common defect - spectrin but also 4.1 -MORE LATERAL -see eliptocytes |
|
|
Discuss Hereditary Pyropoikilocytosis (HPP) |
-Auto recessive, mod-severe -defective spectrin synthesis and dimerisation -microspherocytes, micropolikocytes, heat sensitive RBC -splenectomy of benefit |
|
|
Discuss Hereditary Stomatocytosis (Hst) |
-Auto dom, variable haemolysis -incompletely resolved by splenectomy |
|
|
Discuss Hereditary Xerocytosis (Hx) |
-Auto dom, mild/compensated haemolysis -irregularly contracted cells -excessive leakage of K+ (therefore less H20, increase MCHC) NO BENEFIT OF SPLENECTOMY |
|
|
Discuss disorders of the Ebden Myerhoff pathway |
Decreased ATP -> loss of E dependent processes (eg Na/K ATPase) -> CNSHA (congential non sphero HA) auto recessive, Hb60 (if infection very bad!) may relieve with splenectomy G6PD Deficiency -X linked recessive (140 mutations known) -involved in converting G6P, also reduces NADP->NADPH (reduces glutathione-> oxidative damage) deficency classed (1 worst, 5 not clin relevant) - common in W Africa, Mediterranean, middle east, SE Asia -dif isoforms (most common G6PD-b, A-/+ African. -=disease/+=normal, Med - Mediterranean) GSH def (2ndary) -> aggregation of CSK protiens, perioxidation membrane lipids (loss of deformability), oxidation globin (Heinz bodies) chronic haemolysis - EVH in crisis - IVH *RETICS and WBC have 5x G6PD enzyme amount therefore give FALSE NEGATIVE for G6PD deficiency assay |
|
|
Discuss the 4 acquired haemolytic disorders |
Immune mediated Warm AIHA - due to IgG Ab, reacts at 37: DAT pos IAT. see spherocytes. can occur 2ndary to autoimmune disorders, lymphoprolif disorders, drug induced (BP drug) chemicals/drugs/toxins Oxidative haemolysis -> heinz bodies salazopyrin, sulpha drugs, antimalarials potassium chlorate, napthalene snake/spider bites infection common malaria, other intracellular parasites, clostridium perfringes (gas gangrene IVH) physical damage Physical damage + MAHAs (microangiopathicHAs) HUS, TTP, DIC, HELLP, Mechanical Physical trauma (burns, repeat shock) |
