ESA1/ESA2 revision Flashcards
What effect does the hormone insulin have on the enzyme phosphofructokinase in liver?
Increase in activity
CORRECT. PFK is the rate limiting enzyme in glycolysis. Think of Insulin as the “hormone of plenty” and glucagon opposing the effects of insulin. If you have just had a meal then you would want to promote the utilisation of glucose to bring plasma glucose back down.
A 16 year old girl presents to her GP with anorexia and symptoms of anaemia, night blindness and xeropthalmia (dry eyes). The GP suspects that the girl may be suffering from Vitamin A deficiency.
Damage to which cells is likely inhibit vitamin A storage?
stellate cells of the liver
A 79 year old man with a 40-pack-year history of smoking and COPD presents to his GP complaining of lethargy and breathlessness. On examination he has a raised jugular venous pressure, pitting oedema in both legs and hepatomegaly which is smooth and tender to touch. His cardiac output is 3.8L/min, heart rate 108 beats per minute and his end diastolic volume is 90ml.
What is the most likely diagnosis?
Right Sided Heart Failure with Reduced Ejection Fraction
CORRECT – The patient has symptoms of right sided heart failure like lethargy and breathlessness. The patient also has signs that indicate right sided heart failure. Right sided heart failure leads to congestion of the venous system. This congestion leads to a decrease in the venous drainage of the hepatic portal circulation (leading to hepatomegaly) and a decrease in the venous drainage of the systemic circulation (leading to pitting oedema). The accumulation of blood in the right atrium also leads to a raised jugular venous pressure. As the patient has no signs of left sided heart failure (e.g pulmonary oedema, paroxysmal nocturnal dyspnoea and orthopnoea), it appears that the patient is suffering from right sided heart failure. The man has a cardiac output of 3.8L/min and a heart rate of 108 beats per minute. Therefore, his stroke volume is (3,800ml min / 108) is 35.2ml. As his end diastolic volume is 90ml, his ejection fraction is ((32.5 / 90) x 100) 39.1%, meaning that they have a reduced ejection fraction (any ejection fraction below 40% indicates a reduced ejection fraction). Therefore, the patient is suffering from right sided heart failure with a reduced ejection fraction. The patient has COPD and in long term hypoxia the pulmonary circulation vasoconstricts. This increases the afterload on the right ventricle only. The right ventricle is much weaker than its left counterpart and so is less able to adapt to an increase in afterload. Therefore, as the afterload increases, the right ventricle fails. This is one of the few causes of isolated right sided heart failure. Most right sided heart failure occurs as a result of left sided heart failure.
A cell biologist looking at an electron microscope image of skeletal muscle notes the presence of I-bands?
Which label in the image below indicates this feature?
d
A medical student reads about Hilton’s Law in an Anatomy textbook.
What does this law state?
CORRECT – This is the perfect definition of Hilton’s Law. If the nerve supply to the muscles that move a joint is known, then the nerve supply to the joint capsule itself is also known.
In the table below, which option would be most consistent with Grave’s disease?
H
CORRECT. Grave’s disease is an autoimmune disease resulting from the production of thyroid stimulating immunoglobulins (TSIs). These stimulate the thyroid gland to secrete thyroid hormone (T3 and T4) resulting in an increase in the plasma levels of these hormones. TSH secretion from the anterior pituitary gland would be decreased due to the negative feedback exerted by increased T3 and T4 but the decrease inTSH has no effect on thyroid hormone release by the thyroid gland because TSI is outside the normal negative feedback pathway. Grave’s disease usually presents with goitre.
A 2 month old baby boy is repeatedly breathless, tires easily and is failing to thrive. A paediatric cardiologist performs an echocardiogram and diagnoses atrioventricular septal defect (AVSD), a congenital heart defect resulting from abnormal development of the endocardial cushions (precursors to heart valves and septa).
From which cell type are these precursors derived from?
CORRECT – The endocardial cushions are formed from neural crest cells. These cells migrate to the area from outside of the developing heart. This migration is vulnerable to becoming disrupted as the foetus develops, and it is a failure in this migration that can lead to congenital heart defects. Other causes include genetic factors and exposure of the foetus to chemicals, drugs or infectious agents. This complexity of development helps explain why congenital heart defects are the most common form of birth defects, with an incidence rate of 1%.
A medical student has developed a flu like illness three weeks after completing her elective in Kenya. She has a fever, generalised aches and a headache. The infectious disease doctor is concerned that the patient may have Malaria and so requests a blood test.
Which blood test is most useful in diagnosing Malaria?
blood film
