Physiology Mock Flashcards
Which of the following mechanisms best accounts for the release of adrenaline?
Release from the adrenal medulla in response to increased angiotensin 1 levels
Release from the zona fasiculata from the adrenal gland in response to increased sympathetic discharge
Release from the adrenal medulla in response to increased noradrenaline levels
Release from the adrenal medulla in response to sympathetic stimulation from the splanchnic nerves
None of the above
D
The adrenal gland releases adrenaline in response to increased sympathetic discharge from preganglionic sympathetic fibres of the splanchnic nerves. These cause the chromafin cells of the medulla to release adrenaline (which is preformed) by exocytosis.
A 73 year old lady is admitted for a laparoscopic cholecystectomy. During her pre-operative assessment it is noted that she is receiving furosemide for the treatment of hypertension. Where is the site of action of this diuretic?
Proximal convoluted tubule Descending limb of the loop of Henle Ascending limb of the loop of Henle Distal convoluted tubule Collecting ducts
C
Action of furosemide = ascending limb of the loop of Henle
Furosemide and bumetanide are loop diuretics that act by inhibiting the Na-K-Cl cotransporter in the thick ascending limb of the loop of Henle, reducing the absorption of NaCl.
A 34 year old lady develops septic shock and features of the systemic inflammatory response syndrome as a complication of cholangitis. Which of the following is not a typical feature of this condition?
Body temperature less than 36o C or greater than 38oC Respiratory rate >20 Lactate <4 mmol/L High levels of tumour necrosis factor α WCC >12,000 mm3
C
Septic shock will typically result in end organ hypoperfusion and as a result lactate levels will often be high. In the surviving sepsis campaign it is suggested that elevated lactate levels are an independent indicator for vasopressor support in patient with sepsis. The WCC may be paradoxically low in severe sepsis, although it is most often elevated.
Which main group of receptors does dobutamine bind to?
α-1 α-2 ß-1 ß-2 D-12
C
Dobutamine is a sympathomimetic with both alpha- and beta-agonist properties; it displays a considerable selectivity for beta1-cardiac receptors.
What is the substrate of renin?
Aldosterone Angiotensinogen Angiotensin converting enzyme Angiotensin I Angiotensin II
B
Renin hydrolyses angiotensinogen to form angiotensin I.
Which of the following statements is true of glucagon?
Glucagon is produced in response to hyperglycaemia
Released by beta cells
Inhibits gluconeogenesis
Produced in response to an increase of amino acids
Composed of 2 alpha polypeptide chains linked by hydrogen bonds
D
Glucagon is a protein comprised of a single polypeptide chain.
Produced by alpha cells of pancreatic islets of Langerhans in response to hypoglycaemia and amino acids.
It increases plasma glucose and ketones.
A 52 year old man develops septic shock following a Hartmans procedure for perforated diverticular disease. He is started on an adrenaline infusion. Which of the following is least likely to occur?
Peripheral vasoconstriction Coronary artery vasospasm Gluconeogenesis Lipolysis Tachycardia
B
It’s cardiac effects are mediated via β 1 receptors. The coronary arteries which have β 2 receptors are unaffected.
Which of the following statements relating to alveolar ventilation is untrue?
Anatomical dead space is measured by helium dilution
Physiological dead space is increased in PE
Alveolar ventilation is defined as the volume of fresh air entering the alveoli per minute
Anatomical dead space is increased by adrenaline
Type 2 pneumocytes in the alveoli secrete surfactant
A
Anatomical dead space is measured by Fowlers method.
A patient inhales 100% oxygen to empty the conducting zone gases of nitrogen and then exhales through a mouthpiece which analyses the nitrogen concentration at the mouth. Initially the exhaled gases contain no nitrogen as this is dead space gas; the nitrogen concentration will increase as the alveolar gases are exhaled. Nitrogen which is measured following the breath of 100% oxygen must then have come only from gas exchanging areas of the lung and not dead space.
A 74 year old male with colon cancer sustains an iatrogenic splenic injury during surgery. He is bleeding profusely. What is the most appropriate course of action?
Infusion of human prothrombin complex Infusion of packed red cells Infusion of blood from the cell saver salvaged during surgery Infusion of factor VIII concentrate Infusion of gelofusine
B
The cell saver is inappropriate because the cells will be contaminated with malignant cells and faecal matter from the open bowel.
What is the most likely electrolyte abnormality in a patient with diarrhoea and a soft mass felt on digital rectal examination?
Hyperkalaemia Hypokalaemia Hyponatraemia Hypernatraemia Hypocalcaemia
B
Large villous adenomas of the rectum may have marked secretory activity and result in the development of hypokalaemia as rectal secretions are rich in potassium.
A 25 year old man is undergoing respiratory spirometry. He takes a maximal inspiration and maximally exhales. Which of the following measurements will best illustrate this process?
Functional residual capacity Vital capacity Inspiratory capacity Maximum voluntary ventilation Tidal volume
B
The maximum voluntary ventilation is the maximal ventilation over the course of 1 minute.
A 25 year old man is undergoing respiratory spirometry. He takes a maximal inspiration and maximally exhales. Which of the following measurements will best illustrate this process?
Functional residual capacity Vital capacity Inspiratory capacity Maximum voluntary ventilation Tidal volume
B
The maximum voluntary ventilation is the maximal ventilation over the course of 1 minute.
The oxygen-haemoglobin dissociation curve is shifted to the left in:
With decreased 2,3-DPG in transfused red cells Respiratory acidosis Sudden move to high altitude Pyrexia Haemolytic anaemia
A S shaped curve The curve is shifted to the left when there is a decreased oxygen requirement by the tissue. This includes: 1. Hypothermia 2. Alkalosis 3. Reduced levels of DPG:
DPG is found in erythrocytes and is reduced in non exercising muscles, i.e. when there is reduced glycolysis.
- Polycythaemia
Which of the following does not decrease the functional residual capacity?
Obesity8% Pulmonary fibrosis8% Muscle relaxants21% Laparoscopic surgery7% Upright position56%
I
E
ncreased FRC:
Erect position Emphysema Asthma
Decreased FRC:
Pulmonary fibrosis
Laparoscopic surgery
Obesity
Abdominal swelling
Muscle relaxants
When the patient is upright the diaphragm and abdominal organs put less pressure on the lung bases, allowing for an increase in the functional residual capacity (FRC). Other causes of increased FRC include:
Emphysema Asthma
In addition to those listed above, causes of reduced FRC include:
Abdominal swelling Pulmonary oedema Reduced muscle tone of the diaphragm Age
Which of the following statements relating to cerebrospinal fluid is untrue?
The choroid plexus is only present in the lateral ventricles
Total CSF volume is 100-150ml
CSF pressure is usually 10-15mmHg
The cerebral aqueduct connects the third and fourth ventricles
The foramen of Luschka are paired and lie laterally in the fourth ventricle
A
The choroid plexus lies in all ventricles.
