Physiology Flashcards
To which receptor does dobutamine bind
Sympathomimetic both alpha and beta agonist but mainly beta 1
ECG features of hypokalaemia
U waves
Small or absent T waves
Prolonged PR interval
ST depression
long QT interval
Which which cells is histamine released in the stomach to cause secretion of acid
Enterochromaffin cells
Stomach cells and secretions
Parietal cells - HCL, Ca, Ma, Mg, Intrinsic factor
Chief cells - Pepsinogen
Surface mucosal cells - mucus and bicarbonate
I hat is thr maximal site of sodium absorption on the GI tract
Jejunum
Pancreatic secretions
Enzymes - Acinar cells
Water - Ductal Cells
Factors affecting renin sections
Stimulating - hypotension, hyponatraemia, sympathetic stimulation, catecholamines, erect posture
Reducing - beta blockers, NSAIDs
Side effects of neostigmine
Sweating, bradycardia, salivation
Occurs due to activation of the muscsrinic receptors of the autonomic nervous system
What effects does storing blood have on handling oxygen
Stored blood has less 2,3 DPG and therefore a higher affinity for oxygen. This reduces its ability to release it in metabolic tissue
Oxygen and the Bohr effect
What causes secretion of adrenaline from the adrenal medulla
Acetylcholine from the pregangkionic sympathetic fibres of the splanchnic nerves
Cause chromaffin cells release contents via exocytosis
Where is CCK released from
I cells of the duodenum
From which amino acid are catecholamines produced
Tyrosine
What is the greatest stimulus for gastric acid production
Histamine
Cardiovascular changes in pregnancy
Decreased SVR
Increased plasma volume
Increased red cell volume
Increased heart rate
Ventricular distension
Raised BP
Capillary bed dilatation
Where is most dietary iron absorbed
Proximal small bowel (duodenum and jejunum) by divalent transports (as Fe2+) and bound as ferritin
Which drug increases gastric emptying post vagotomy
Erythromycin
Metocloprimide effects mediated by the vagus
What is the primary substrate for bile acids
Cholesterol- primary bile salts are choleys and chenodeoxycholate
What does noradrenaline primarily bind to
Alpha 1
Alpha 1& 2 vasoconstriction
Beta 1 increased cardiac contractual ITU and HR
Beta 2 vasodilatation
Delta 1 renal and spleen vasodilatation
Delta 2 inhibits release of noradrenaline
Adrenaline affects on the heart
Cardiac affects mediated by beta 1 receptors.
Coronary arteries which have beta 2 receptors are unaffected
Half life of albumin
20days
Action of CCK
Increases pancreatic enzyme release, increases pancreatic bicarbonate release, gallbladder contraction, inhibits gastric emptying
Area of GI tract with highest levels of potassium
Rectum
The rectum has the potential to generate secretions rich in potassium. This is the rationale behind administration of resins for hyperkalaemia and the development of hypokalaemia in patients with villous adenoma of the rectum.
Factors affecting renin
Stimulating
Factors stimulating renin secretion
• Hypotension causing reduced renal perfusion
• Hyponatraemia
• Sympathetic nerve stimulation
• Catecholamines
• Erect posture
Factors reducing renin secretion
• Drugs: beta-blockers, NSAIDs
Protein C
It is linked to the action of factor V and VIll, not factor II.
Protein C and S are natural anticoagulant proteins. Protein C is synthesised in the liver and protein S is synthesised by the liver, endothelial cells, magakaryocytes and Leydig cells. Their synthesis is a vitamin K dependent process. Protein C and S bind to form a complex that inactivates factor Va and Villa. Resistance to activated protein C is otherwise known as factor V Leiden and confers an increased risk of thromboembolic events.
Increased rates of gastric emptying
Chloramphenicol has no effect on gastric emptying. Ondansetron slows gastric emptying slightly. Metoclopramide increases the rate of gastric emptying but its effe are mediated via the vagus nerve.
Nerve fibres
ow transmission of mechanothermal stimuli is transmitted via C fibres. a fibres transmit information relating to motor proprioception, A B fibres transmit such and pressure and B fires are autonomic fibres.
