physiology

Question 1

Classses of hypovolemic shock

Answer 1

Blood loss ml <750ml 750-1500ml 1500-2000ml >2000ml
Blood loss % <15% 15-30% 30-40% >40%
Pulse rate <100 >100 >120 >140
Blood pressure Normal NormalDecreased Decreased
Respiratory rate 14-20 20-30 30-40 >35
Urine output >30ml 20-30ml 5-15ml <5ml
Symptoms Normal Anxious Confused Lethargic

Question 2

anaphylactic shock treatment

Answer 2

Adrenaline Hydrocortisone Chlorpheniramine
< 6 months 150 mcg 25 mg 250 mcg/kg
6 months - 6 years 150 mcg 50 mg 2.5 mg
6-12 years 300 mcg 100 mg 5 mg
Adult and child 12 years 500 mcg (0.5ml 1 in 1,000) 200 mg 10 mg

Question 3

nerve fibers transmission A B C

Answer 3

Slow transmission of mechanothermal stimuli is transmitted via C fibres.
A γ fibres transmit information relating to motor proprioception, A β fibres transmit touch and pressure and B fibres are autonomic fibres.
Peripheral nociceptors are innervated by either small myelinated fibres (A-delta) fibres or by unmyelinated C fibres.
The A gamma fibres register high intensity mechanical stimuli. The C fibres usually register high intensity mechanothermal stimuli.

Question 4

Phases of gastric acid secretion

Answer 4

1. Cephalic phase (smell / taste of food)
   30% acid produced
   Vagal cholinergic stimulation causing secretion of HCL and gastrin release from G cells
2. Gastric phase (distension of stomach )
   60% acid produced
   Stomach distension/low H+/peptides causes Gastrin release
3. Intestinal phase (food in duodenum)
   10% acid produced
   High acidity/distension/hypertonic solutions in the duodenum inhibits gastric acid secretion via enterogastrones (CCK, secretin) and neural reflexes.

Question 5

gastric hormons

Answer 5

Gastrin
G cells in antrum of the stomach
Distension of stomach, extrinsic nerves
Inhibited by: low antral pH, somatostatin
Increase HCL, pepsinogen and IF secretion, increases gastric motility, trophic effect on gastric mucosa
CCK
I cells in upper small intestine
Partially digested proteins and triglycerides
Increases secretion of enzyme-rich fluid from pancreas, contraction of gallbladder and relaxation of sphincter of Oddi, decreases gastric emptying, trophic effect on pancreatic acinar cells, induces satiety
Secretin
S cells in upper small intestine
Acidic chyme, fatty acids
Increases secretion of bicarbonate-rich fluid from pancreas and hepatic duct cells, decreases gastric acid secretion, trophic effect on pancreatic acinar cells
VIP
Small intestine, pancreas
Neural
Stimulates secretion by pancreas and intestines, inhibits acid and pepsinogen secretion
Somatostatin
D cells in the pancreas and stomach
Fat, bile salts and glucose in the intestinal lumen
Decreases acid and pepsin secretion, decreases gastrin secretion, decreases pancreatic enzyme secretion, decreases insulin and glucagon secretion
inhibits trophic effects of gastrin, stimulates gastric mucous production

Question 6

Cause of low magnesium

Answer 6

Diuretics
Total parenteral nutrition
Diarrhoea
Alcohol
Hypokalaemia, hypocalcaemia

Question 7

causes and features of low magnesium

Answer 7

Diuretics
Total parenteral nutrition
Diarrhoea
Alcohol
Hypokalaemia, hypocalcaemia

Features
Paraesthesia
Tetany
Seizures
Arrhythmias
Decreased PTH secretion → hypocalcaemia
ECG features similar to those of hypokalaemia
Exacerbates digoxin toxicity

Question 8

ST segment

Answer 8

Represents period which the entire ventricle is depolarized and roughly corresponds to the plateau phase of the ventricular action potential

Question 9

Fluid compartment physiology

Answer 9

intracellular 28 L 60-65%
Extracellular 14 L 35-40%
Plasma 3 L 5%
Interstitial 10 L 24%
Transcellular 1 L 3%

Question 10

SIADH causes

Answer 10

malignancy
especially small cell lung cancer
also: pancreas, prostate

Neurological
stroke
subarachnoid haemorrhage
subdural haemorrhage
meningitis/encephalitis/abscess

Infections
tuberculosis
pneumonia

Drugs
sulfonylureas
SSRIs, tricyclics
carbamazepine
vincristine
cyclophosphamide

Other causes
positive end-expiratory pressure (PEEP)
porphyrias

Question 11

CSF circulation

Answer 11

Lateral ventricles (via foramen of Munro)
2. 3rd ventricle
3. Cerebral aqueduct (aqueduct of Sylvius)
4. 4th ventricle
5. Subarachnoid space (via foramina of Magendie and Luschka)
6. Reabsorbed into the venous system via arachnoid granulations into superior sagittal sinus

Question 12

pancreas secretion

Answer 12

The cephalic and gastric phases (neuronal and physical) are less important in regulating the pancreatic secretions. The effect of digested material in the small bowel stimulates CCK release and ACh which stimulate acinar and ductal cells. Of these CCK is the most potent stimulus. In the case of the ductal cells these are potently stimulated by secretin which is released by the S cells of the duodenum. This results in an increase in bicarbonate.

Question 13

secretion of different stomach cell type

Answer 13

Parietal cells: secrete HCl, Ca, Na, Mg and intrinsic factor
Chief cells: secrete pepsinogen
Surface mucosal cells: secrete mucus and bicarbonate

Question 14

mg

Answer 14

Magnesium and calcium interact at a cellular level also and as a result decreased magnesium will tend to affect the permeability of cellular membranes to calcium, resulting in hyperexcitability.

Question 15

jvp

Question 16

hypokalemia due to vomiting

Answer 16

Hypokalaemia may occur in vomiting, usually as a result of renal wasting of potassium, not because of potassium loss in vomit.

Question 17

diuretics types and actions

Answer 17

Site of action Diuretic Carrier or channel inhibited Percentage of filtered sodium excreted
Ascending limb of loop of Henle Frusemide Na+/K+ 2Cl - carrier Up to 25%
Distal tubule and connecting segment Thiazides Na+Cl- carrier Between 3 and 5%
Cortical collecting tubule Spironolactone Na+/K+ ATP ase pump Between 1 and 2%

Question 18

leptin actions

Answer 18

Leptin stimulates the release of melanocyte-stimulating hormone (MSH) and corticotrophin-releasing hormone (CRH). Low levels of leptin stimulates the release of neuropeptide Y (NPY)

Question 19

leptin actions

Answer 19

Leptin stimulates the release of melanocyte-stimulating hormone (MSH) and corticotrophin-releasing hormone (CRH). Low levels of leptin stimulates the release of neuropeptide Y (NPY)

Question 20

causes of hyperuricemia

Answer 20

‘Can’t leap’

C iclosporin
A lcohol
N icotinic acid
T hiazides

L oop diuretics
E thambutol
A spirin
P yrazinamide

Question 21

drug that cuases hyperkalemia

Answer 21

ACE inhibitors, angiotensin 2 receptor blockers, spironolactone, ciclosporin, heparin**( inhbition of aldostrone secretion)

Question 22

ileostomy water loss and jobran

Answer 22

In some individuals a colectomy or similar procedure results in formation of an end or loop ileostomy. Ileostomies typically lose between 500 and 1000ml over a 24 hour period and patients with high output ileostomies can rapidly become dehydrated. Ileostomy effluent typically contains 126mmol/L of sodium and 22mmol/L of potassium. Knowledge of this fluid composition should guide fluid prescribing in replacing losses.

Question 23

acidosis and uric acid

Answer 23

Decreased tubular secretion of urate occurs in patients with acidosis (eg, diabetic ketoacidosis, ethanol or salicylate intoxication, starvation ketosis)

Question 24

hypercalcemia urgent findings and treatment

Answer 24

Calcium > 3.5 mmol/l
Reduced consciousness
Severe abdominal pain
Pre renal failure

Airway Breathing Circulation
Intravenous fluid resuscitation with 3-6L of 0.9% Normal saline in 24 hours
Concurrent administration of calcitonin will also help lower calcium levels
Medical therapy (usually if Corrected calcium >3.0mmol/l)

Question 25

Normal Gap Acidosis: HARDUP

Answer 25

H - Hyperalimentation/hyperventilation A - Acetazolamide R - Renal tubular acidosis D - Diarrhoea U - Ureteral diversion P - Pancreatic fistula/parenteral saline

Question 26

Raised anion gap

Answer 26

Lactate: shock, hypoxia Ketones: diabetic ketoacidosis, alcohol Urate: renal failure Acid poisoning: salicylates, methanol

Question 27

refeeding syndrome

Answer 27

High risk for re-feeding problems If one or more of the following: BMI < 16 kg/m2 Unintentional weight loss >15% over 3-6 months Little nutritional intake > 10 days Hypokalaemia, Hypophosphataemia or hypomagnesaemia prior to feeding (unless high) If two or more of the following: BMI < 18.5 kg/m2 Unintentional weight loss > 10% over 3-6 months Little nutritional intake > 5 days History of: alcohol abuse, drug therapy including insulin, chemotherapy, diuretics and antacids

Question 28

refeeding prescription

Answer 28

Prescription Start at up to 10 kcal/kg/day increasing to full needs over 4-7 days Start immediately before and during feeding: oral thiamine 200-300mg/day, vitamin B co strong 1 tds and supplements Give K+ (2-4 mmol/kg/day), phosphate (0.3-0.6 mmol/kg/day), magnesium (0.2-0.4 mmol/kg/day)

Question 29

hypokalemia and j and delta wave

Answer 29

U waves Small or absent T waves (occasionally inversion) Prolonged PR interval ST depression Long QT interval J waves are seen in hypothermia whilst delta waves are associated with Wolff Parkinson White syndrome.

Question 30

if someone needs blood

Answer 30

Up to 4 units of SAG M Blood may be administered. Thereafter whole blood is preferred. After 8 units, clotting factors and platelets should be considered.

Question 31

ypokalemc acidosis and alkalosis

Answer 31

Hypokalaemia with alkalosis Vomiting Diuretics Cushing's syndrome Conn's syndrome (primary hyperaldosteronism) Hypokalaemia with acidosis Diarrhoea Renal tubular acidosis Acetazolamide Partially treated diabetic ketoacidosis

Question 32

gamma-irradiated blood products

Answer 32

patients at risk of transfusion associated GVHD

Question 33

auses of increased anion acidosis: MUDPILES

Answer 33

M - Methanol U - Uraemia D - DKA/AKA P - Paraldehyde/phenformin I - Iron/INH L - Lactic acidosis E - Ethylene glycol S - Salicylates

Question 33

most important urinary buffer

Answer 33

phosphate

Question 34

cardiac inotropes and vice versa

Answer 34

Glucagon and theophylline are also positive inotropes (although not commonly used for this purpose). In contrast sodium thiopentone causes marked myocardial depression.

Question 35

septicemia with blood products

Answer 35

Platelets are stored at room temperature and must be used soon after collection. This places them at increased risk of culturing gram positive organisms. Iatrogenic infection with gram negative organisms is more likely with packed red cells as these are stored at 4 degrees. Infections with blood products of this nature are both rare.

Question 36

stress respond (after surgery) decreased in which hormones

Answer 36

Insulin Testosterone Oestrogen

Question 37

main IL after surgery

Answer 37

IL-6 main cytokine associated with surgery. Peak 12 to 24 h after surgery and increase by the degree of tissue damage Other effects of cytokines include fever, granulocytosis, haemostasis, tissue damage limitation and promotion of healing.