1meqr03

Royal Free and University College Medical School Phase 1, Year 1: resit 2003 Copyright 2003 Royal Free and University College Medical School Modified Essay Question paper 3 hours are allowed for this paper. You should attempt all 20 questions, answering each one on the page for that question

if you need more space, continue on the reverse of the page for that question only. Pages will be separated and given to different people to mark.

You are provided with a sheet of bar-code labels. Place one label in the space marked

on the computer-readable card and one label on the page for each question except questions 3 and 14 these questions are answered on the computer-readable card.

For questions 3 and 14 you must transfer your answers to the appropriate numbered

lines of the mark-sense (computer-readable) card that is provided. For this type of card there is only one correct answer (A P) on each line, and if you enter more than one answer on a line you will score zero for that line. Some answers may be used more than once and some may not be used at all

You should read through all parts of each question before you begin to answer it the

number of marks for each part question is shown. Most questions are linked to clinical scenarios. Information about the patient is shown

at the top of each question; this may differ from one question to another, as additional information is relevant to the question being asked. Some questions do not refer to any specific patient.

This question paper must not be removed from the examination room.

Place your bar-code label here

Question 1

Malcolm Elks is a 50-year old man. He comes to A&E complaining of severe chest pain. He tells the nurse that over recent months he has experienced a similar pain when exercising. However, on this occasion the onset was not linked to exercise and has persisted for several hours. What is the most important mechanism controlling coronary vascular resistance: local, nervous or hormonal? (1 mark) Left ventricular coronary blood flow occurs mainly in which part of the cardiac cycle, and why ?

(3 marks) How is the regulation of coronary blood flow impaired in coronary heart disease?

(2 marks) If the SA and AV nodes are supplied by the right coronary artery, what possible effects will a disease leading to impaired blood flow through this artery have on the heart beat?

(2 marks) As the left coronary artery supplies the majority of the left ventricle what effect will a disease limiting blood flow through this vessel have on myocardial oxygen supply and what condition will develop?

(2 marks) What is the possible outcome if the condition is not treated?

(1 mark) Give the three important groups of drugs used to treat angina.

(1 mark each) Give 3 main ways in which anti-anginal drugs improve myocardial blood flow and reduce myocardial oxygen consumption?

(1 mark each)

Year 1 MEQ resit 2003 1


Question 2

Malcolm Elks is 167 cm tall and weighs 87 kg. What is his Body Mass Index: BMI = weight (kg) / height2 (m)

(1 mark) Would you classify him as being of desirable weight, overweight or obese?

(1 mark) Mr Elks has a total daily energy expenditure of about 12 MJ /day and a BMR of 8.4 MJ / day. What is his physical activity level (PAL)?

(2 marks) How much weight would you expect him to lose per week if he reduced his food intake from 12 MJ /day to 10 MJ /day ? (assume that the loss will be only adipose tissue, which is 15% water, 5% protein and 80% triacylglycerol protein yields 17 kJ /g and triacylglycerol 37)

(4 marks) Mr Elks GP recommends him to take more exercise and suggests that he walks moderately gently (3.5 km /h, a PAR of 3.0) for two hours each day. What will be his additional energy expenditure per day?

(3 marks) Assuming that he maintains a food intake of 12 MJ /day, how much adipose tissue would he lose per week at this level of increased activity?

(4 marks)


Question 3

Answer this question on lines 1 8 of the computer-readable card. There is only one correct answer for each line. Some answers may not be used at all and some may be used more than once. An angiogram of Malcolm Elks heart reveals narrowing of the coronary arteries and cardiac enlargement

Diagram 1

A B C D E

Diagram 2

F

G

H I

J

K

F

G

H I

J

K

Referring to the labels in the diagrams above, answer the following questions: (2 marks each)

1. In diagram 1, which area of the heart (A E) is normally supplied by the left coronary artery?

2. In diagram 2, which area of the heart (F K) is normally supplied by the right coronary artery?

3. Identify the left coronary artery (A K)

4. Identify the branch of the right coronary artery to the sinuatrial node (A K)

5. Identify the posterior interventricular artery (A K)

6. Identify the circumflex artery (A K)

The next two questions do not refer to the letters in the diagrams 7. In which intercostal space should you palpate the apex beat of a normal heart:

(2 marks) (A) 4th (B) 5th (C) 6th (D) 7th

8. In which intercostal space would you auscultat

(A) 5th left (B) 5th right (C) 2nd left (D) 2nd right

Year 1 MEQ resit 2003 e the aortic valve: (2 marks)

3

Place your bar-code label here Question 4

During his daily walk Mr Elks finds that he is very breathless. He mentions his to his GP, who asks you to examine his respiratory system. Describe how you would undertake this examination

(6 marks for communications skills, 8 marks for clinical skills) Describe how you would measure his peak expiratory flow rate (PEFR).

(6 marks).


Place your bar-code label Question 5 here

The table shows Respiratory Function data collected from 3 men attending an out-patient clinic at the Whittington Hospital. The normal values (1 standard deviation) for healthy subjects matched for age and body size are also shown below each patient.

PEFR litres min-1 FEV1 litres FVC litres Patient A 650 2.6 3.1 control 670 60 4.5 0.5 5.3 0.6 Patient B 230 1.7 4.1 control 560 60 3.5 0.5 4.5 0.6 Patient C 530 3.2 3.8 control 520 50 3.1 0.4 3.9 0.5

From the respiratory function data given, mark the following statements true or false:

(1 mark each)

TRUE FALSE Patient B is normal Patient C is normal Patient A has an obstructive defect Patient B has an obstructive defect Patient C has an obstructive defect Patient A has a restrictive defect Patient C has a restrictive defect

From abnormalities you have identified, mark the following statements true or false:

(1 mark each)

TRUE FALSE Patient A might have bronchitis Patient A might have fibrosis of the lungs Patient B might have fibrosis of the lungs Patient B might have asthma Patient C might have emphysema Patient C might have fibrosis of the lungs

Which patient(s) would you expect to derive benefit from inhalation of a bronchodilator drug such as salbutamol (tick one only)

(2 marks)

Patient A Patient B Patient C Patients A & B Patients A & C Patients B & C



Mr Elks currently smokes 20 cigarettes a day. He started smoking at the age of 11. Rates of smoking amongst adolescents in the UK remain a public health concern. Outline a range of factors that may influence young peoples smoking behaviour?

(5 marks) Describe what health promotion strategies can be implemented to reduce rates of smoking amongst adolescents

(10 marks) What agencies outside of the NHS have an important role to play in reducing adolescent smoking

(5 marks)



Question 7

Mr Elks has been persuaded that he should give up smoking, but finds it extremely difficult. He finds a report of the following trial of nicotine patches on the web: A randomised double blind study was conducted in order to investigate smoking cessation rates for people given nicotine patches versus those given placebo patches. Five hundred smokers were recruited to the trial 260 of who were randomly allocated to receive nicotine patches and 240 of who were allocated to receive placebo patches. At one-year follow-up 130 people in the nicotine patches group and 60 in the placebo patches group had successfully given up smoking according to reports from doctor-patient interviews. The data was analysed on an intention to treat basis. Explain what is meant by, and the importance of, the study being: a) Double blind

(4 marks) b) Analysed on an intention to treat basis

(4 marks) Calculate and explain the number needed to treat (NNT)

(12 marks)



Mr Elks plasma cholesterol was 8.5 mmol /L, compared with a desirable range of < 5 mmol /L, and he was placed on a low-fat, cholesterol-free diet Cholesterol is carried by plasma lipoproteins. Describe briefly the functions of the three main types of plasma lipoprotein: Very low density lipoprotein (VLDL)

(3 marks) Low density lipoprotein (LDL)

(3 marks) High density lipoprotein (HDL)

(3 marks)

After 3 months on the diet, Mr Elks plasma cholesterol was still 8.5 mmol /L. How is it possible for him to continue to have high plasma cholesterol after adhering to a cholesterol-free diet for 3 months?

(3 marks) Why would administering an HMG CoA reductase inhibitor lead to a fall in plasma LDL concentration?

(3 marks)



Question 9

This question does not refer specifically to any particular patient. Outline the potential areas of conflict between doctors and pregnant women

(20 marks)



Aminata Shah is a 45 year old stockbroker who suffers from gastric discomfort due to dyspepsia. She takes an antacid, drug A, for this condition. Some months later she complains of intermittent, upper abdominal pain and is referred by her GP to the outpatients department. Endoscopy shows the presence of a gastric ulcer. (A) Give an example of drug A and state its mechanism of action

(4 marks) Does drug A cause any drug interactions ?

(2 marks) (B) What major drugs can be used for the treatment of gastric ulcers and what are their mechanisms of action?

(10 marks)



Question 11

Aminata Shah is a 45 year old stockbroker who suffers from gastric discomfort due to dyspepsia and is subsequently found to have a gastric ulcer.

Name the gastric cells that produce hydrochloric acid? (1 mark)

In which anatomical part and histological layer of the stomach are they to be found?

(2 marks) List 3 functions of gastric HCl in a healthy subject

(3 marks) With the aid of a diagram, explain the cellular processes by which gastric HCl is produced and secreted. In your answer describe the role of carbonic anhydrase and explain the term alkaline tide of acid secretion.

(8 marks)



Aminata Shah is a 45 year old stockbroker who suffers from gastric discomfort due to dyspepsia and is subsequently found to have a gastric ulcer.

Describe the role of efferent nerves in the control of gastric acid secretion. (4 marks)

Explain why habitual aspirin ingestion may lead to peptic ulceration.

(2 marks) What processes normally serve to reduce gastric HCl secretion in order to prevent gastric pH from reaching dangerously low levels?

(3 marks) How are the gastric and duodenal mucosal lining normally protected from damage by secreted HCl?

(3 marks) Give two reasons why patients with peptic or duodenal ulceration are often anaemic.

(2 marks)



Question 13

Aminata Shah is a 45 year old stockbroker who suffers from gastric discomfort due to dyspepsia and is subsequently found to have a gastric ulcer. One of the drugs she was prescribed acts as an irreversible enzyme inhibitor. Explain what is meant by the term irreversible enzyme inhibitor?

(4 marks) Describe an experiment to determine whether a given compound is a reversible or irreversible inhibitor you can assume that there is a simple way of measuring the product of the enzyme reaction you are studying.

(6 marks) What is the advantage to the patient of taking a compound that acts as an irreversible inhibitor of a target enzyme, rather than a reversible inhibitor?

(3 marks) What is a possible disadvantage of using an irreversible inhibitor as a drug?

(3 marks) If a drug is an irreversible inhibitor of an enzyme, why does the patient have to continue to take it?

(4 marks)



Question 15

Peter Choo is a medical student who acquired an intestinal infection while on elective. He became dehydrated as a result of severe vomiting and diarrhoea. His rate of urine production decreased and urine became excessively hypertonic with a darker colour than normal. Explain what is meant by the term hypertonicity. (2 marks) State the normal range of values for plasma and urine osmolality.

(2 marks) What regions of the nephron are involved in the production of hypertonic urine?

(2 marks) Briefly describe the tubular processes in the nephron involved in the production of hypertonic urine.

(5 marks) What is the approximate normal body water content of a healthy 70 kg male.

(2 marks) Approximately what percentage of total body water is:

(1 mark each)

Plasma

Intracellular fluid

Extracellular fluid

Describe briefly how you would determine Peter Choos plasma volume

(4 marks)



Peter Choo is a medical student who acquired an intestinal infection while on elective. He became dehydrated as a result of severe vomiting and diarrhoea. His rate of urine production decreased and urine became excessively hypertonic with a darker colour than normal. Which hormone is particularly important in minimising Peters excretion of water? State where it is released, what physiological stimuli cause it to be released, and what major renal actions it has.

(6 marks) Describe in outline the mechanism of action (at the molecular level) of fast acting (peptide) hormones

(10 marks)



Martina Swift was told by her optician at a routine eye test that she should see her doctor as she had raised intra-ocular pressure. Her GP prescribed the -adrenoceptor antagonist timolol as eye drops. Two days later she returned to the surgery complaining of great shortness of breath.

Explain how timolol caused this problem? (8 marks)

The GP subsequently prescribed pilocarpine eye drops. Describe what effects this would have in the eye and indicate the mechanisms involved.

(6 marks) Tropicamide, a muscarinic receptor antagonist, is used to aid examination of the eye. State briefly why it is useful and why it may be dangerous.

(6 marks)



Question 18

This question does not concern a particular patient Draw the oxygen dissociation curves for haemoglobin and myoglobin in the box below. You must label the axes

(6 marks)

myoglobin haemoglobin

Explain briefly how the structures of haemoglobin and myoglobin account for the difference in the curves you have drawn.

(6 marks) After even moderate exercise (eg climbing a flight of stairs), there is a considerable increase in the plasma concentration of lactate, resulting in lowering of plasma pH. What is the effect of this fall in plasma pH on oxygen binding to haemoglobin?

(4 marks)



This question does not concern a particular patient Explain briefly what is meant by each of the following terms:

(2 marks each) mRNA tRNA DNA replication Transcription Translation Ribosome Polysome A number of antibiotics act to inhibit bacterial protein synthesis but have little or no effect on human protein synthesis. What differences between bacterial and human protein synthesis explain this?

(6 marks)



Question 20

A newborn girl developed a severe pneumococcal infection (Streptococcus pneumoniae) at 8 weeks of age. She was investigated and found to have low levels of IgG, increased neutrophils and reduced levels of lymphocytes in her blood. On further examination it was found that no cells with surface antibodies were present in her blood stream. Describe what kind of immunodeficiency is consistent with the clinical and laboratory findings

(2 marks) Where are the lymphocytes which are deficient in this patient made in a healthy baby?

(2 marks) Why did the baby have IgG but not IgM in her blood stream?

(2 marks) Describe the basic structure of an antibody molecule

(5 marks) What forces contribute to the interaction between specific antibody and its antigen

(5 marks)


For questions 3 and 14 you must transfer your ansQuestion 1Answer this question on lines 1 8 of the comput

controlPatient B is normalPatient AQuestion 13This question does not concern a particular patientThis question does not concern a particular patient

1meqr03

Documents

myocardial blood flow

impaired blood flow

left coronary artery

mark mr elks

coronary heart disease

right coronary artery

number of marks

coronary vascular resistance