Quick Recall Paper 1 Flashcards
Reduced vitamin k to active form
Vitamin K epoxide reductase complex 1
Vitamin K adds
Carboxyl group to glutamic acid residues of factors 2, 4, 9, 10 and protein C
Hemophilia
Factor
8—small unit for intrinsic pathway—hemophilia A
Large unit—von willebrand disease
9—-hemophilia B
Disseminated intravascular coagulation
Results from large amounts of traumatized tissue that releases great quantities of tissue factor
Small numerous clots
Widespread septicemia where endotoxins activate clotting mechanism
Lead to circulatory shock
More bleeding due to many clotting factors being removed from blood
Heparin
> 60 mins or more instantaneously
Lasts for 1.5 - 4 hours
Destroyed by heparinase
Heart lung machine or artificial kidney machine
Inactivates 9, 10, 11, 12, thrombin and platelet
Warfarin/coumarin
Inhibits VKOR c1 Decreases vitamin k availability Coagulation factors become inactive Activity to 50% in 12 hrs and 20% in 24 hrs Returns to normal in 1-3 days
Silicone
Prevents activation of platelets and factor 12
Oxalate
Decrease Ca concentration by forming calcium oxalate
Toxic
Citrate
As Na, K, or NH4
Combines with Ca to form unionized Ca
removed by liver and polymerized to glucose
If liver is damaged, Ca levels may decrease extensively causing tetany
Prothrombin time
Oxalated
Excess calcium and tissue factor
Normal- 12 seconds
INR
International Normalised Ratio
Standardized measurement of prothrombin time.
INR = (PTt/PTn)ISI
Normal - 0.9-1.3
Patients undergoing warfarin therapy - 2-3
Low INR - risk of bleeding
High INR - chance of clotting
ISI
International sensitivity index
Indicates activity of standardized sample
Usually 1-2
PTT/APTT
Partial thromboplastin time
Tests efficacy of intrinsic and common coagulation pathways
Oxalated
+Ca +silica/kaolin
Structures that do not contain lymph vessels
Superficial skin layers Cornea Brain Spinal cord Lens of eye Bones Alveoli of lungs
Functions of lymph
- Return of P, Elect. and H2O to blood, maintaining its viscosity
- Redistribution of body water (compartments)
- Removes bacteria in nodes
- Body defence
- Transports antibiotics
- Fat absorption lacteals
- St. and func. integrity of tissues
- Nutrients and O2 to where blood can’t reach
- Maintains interstitial fluid level
- Concentration of urine in kidney
Lymphadenopathy
Generalised enlargement of lymph glands
Elephantiasis
Enlargement of lower limbs and scrotum due to obstruction of lymph vessels by filaria
Lymphangitis
Inflammation of lymph nodes
Normal blood volume
79mL + 10 mL/kg body wgt
Determination of blood volume
Direct:
Welcker
Biscoff
Indirect: Estimating RBC mass Estimating plasma volume Both ---use dilution principle method
Estimation of RBC mass
Radioactive chromium, iron, phosphorus
Radioactive iron
- Rd. Fe into ferric ammonium citrate
- Injected into donor of group O
- New cells take up iron and appear in 24hrs
- Reaches Max in 21 days
- 70-100mL having Rd. 2500-3000 counts per min per mL injected intravenously to recipient
- samples drawn at 10 min intervals, thrice
- RBC separated, Rd. determined by Geiger Muller counter
Vrbc = Vd * RaD/RaR
Vd - volume of donor cells
RaD - Rd. Of donor cells
RaR - Rd. Of recipient cells
Plasma volume estimation
Dye method
Isotope method
Dye method
Evans blue dye injected Binds to albumin and circulates by 10 mins Samples taken out every 10 mins Cells separated conc. of dye estimated 5% excreted in urine/hr
Vp = amt. Injected - Amt. Excreted/mean conc.
Blood volume = 100*Vp/55
Conditions of decreased blood volume
- Haemorrhage- l.o.whole blood
- Burns- l.o.plasma
- Dehydration- l.o.water
- Myxoedema- less whole blood
- Addison’s- less whole blood
Extrinsic pathway order
3
7
10
5
Intrinsic pathway order
12 11 9 8 10 5
Activation of factor 11 requires
HMW kininogen accelerated by prekallekrein
Ageing disorders
Progeria
Werners syndrome
Sources of embryonic stem cells
Human umbilical cord perivascular cells
Amniotic fluid
Bone marrow
Effect of drugs on protein channels
Tetradotoxin - Na
Tetraethyl ammonium - K
Vermapil - Ca
Local anaesthetics and their action
Procaine
Tetracaine
- act directly on activation Gates of Na making it difficult to open
- Reduce membrane excitability.
- When safety factor is <1 nerve impulse doesn’t propagate
Refractory period of nerve
0.3-1 msec
Adaptation and accommodation
- excitability of never decreases when stimulus of constant strength is applied for a long period
- nerves are less excitable when simulated by slowly rising current strength. Slow rise activates both Na and K simultaneously
Erlanger gasser classification
Aà - mixed - 12-20mm
Abeta - sensory - 5-12mm
Agamma - motor - 3-6mm
Adelta - sensory - 2-5mm
B - preganglionic - 3mm - 0.5-2m/s
C- postganglionic - 0.3-1.3mm - 0.7-2.3m/s
Drugs preventing release of ACh
Botulinum
Prevents fusion of ACh vesicles
Drugs with ACh like action
Methacholine
Carbachol
Nicotine
Causes initial twitching but paralysis due to persistent depolarization
Drugs inhibiting AChesterase
Neostigmine
Physostigmine
Diisopropyl fluorophosphate - nerve gas poison - inhibits for weeks
Drugs blocking ACh receptors
Crurariform drugs
Bungarotoxin
In t tubules voltage is sensed by
Dihydropyridine receptors linked to calcium release channels
