Week 1
What blood type is the universal donor?
O- Negative: They lack A, B, and Rh antigens
What does a FEV1/FVC ratio below 80% indicate?
FEV = Forced expiratory volume
FVC = Forced vital capacity
A FEV1/FVC ratio below 80% indicates potential obstructive lung defect, suggesting air is not leaving the lungs as quickly as it should.
What are the three trunks of the aorta?
Brachiocephalic trunk. Left common carotid artery. Left subclavian artery.
What is the difference between a primary follicle and a secondary follicle in a lymph node?
A primary follicle contains inactive B-cells, while a secondary follicle has a germinal centre, showing that B-cells are activated and actively producing antibodies.
True/False: Uncoating is a step that occurs in bacterial infections.
False: Uncoating is a viral process where the virus releases its genetic material, and bacteria don’t do this because they are already complete cells.
A woman with blood type Rh− is pregnant with her second child. Her first child was Rh+, and she did not receive preventative treatment. Why is the second foetus at risk of haemolytic disease of the newborn (HDN)?
The mother has developed anti-D antibodies that can cross the placenta. Exposure to Rh+ blood during the first pregnancy 'sensitises' the Rh- mother, leading to the production IgG anti-D antibodies that attack Rh+ foetal cells in subsequent pregnancies.
True or False: In large vessels, the tunica externa (Adventitia) contains vasa vasorum and nervi vasorum
True: Vessel wall is too thick for nutrients to diffuse from the lumen, and the outer layers need independent oxygen supply, waste removal and nerve control of muscle contraction.
During the cardiac cycle, when do S1 and S2 occur?
Isovolumetric contraction and Isovolumetric relaxation.
After acetylcholine binds to nicotinic receptors at the neuromuscular junction, what exact ion movement triggers the muscle action potential?
Na⁺ influx into the muscle cell, which depolarises the sarcolemma and initiates the muscle action potential.
What is the correct order of cell stages during spermatogenesis?
Spermatogonium → Primary spermatocyte → Secondary spermatocyte → Spermatid → Spermatozoa
During the process of haemostasis, which substance is responsible for stabilising the initial platelet adhesion to exposed collagen in a damaged vessel wall?
Von Willebrand factor - This glycoprotein acts as a bridge between subendothelial collagen and the platelets, stablising adhesion and initiating activation.
The urea and citric acid cycles are metabolically linked, forming a pathway sometimes called the Krebs cycle. Which molecule, produced during the urea cycle, directly enters the TCA cycle to replenish its intermediates?
Fumarate: Cleavage of argininosuccinate yields arginine (which continues in the urea cycle) and fumarate. Fumarate is an intermediate of the TCA cycle, therefore linking the two pathways.
During the conversion of VLDL to LDL, which enzyme is primarily responsible for the further modification of intermediate-density lipoproteins (IDL) in the liver?
Hepatic lipase: Processes remaining triglycerides in IDL to transform it into the cholesterol-rich LDL particle.
Why is more fluid filtered out of capillaries than reabsorbed, and what happens to the excess?
Hydrostatic pressure slightly exceeds oncotic pressure overall, more fluid leaves than returns, and the excess is taken up by the lymphatic system.
Where does fertilisation most commonly occur in the female reproductive tract?
Ampulla
During the third step of haemostasis, coagulation, what is the role of the enzyme thrombin?
Converts soluble fibrinogen into insoluble fibrin strands. Thrombin acts as a catalyst in the final common pathway to create the fibrin mesh that traps blood cells.
If you are treated with a medication that stimulates beta-2 adrenergic receptors. What would be the expected effect on the muscular arteries supplying the skeletal muscles?
Vasodilation, mediated by smooth muscle relaxation. Beta-2 adrenergic receptor stimulation leads to smooth muscle relaxation and subsequent vasodilation, which would increase blood flow to the skeletal muscle.
A patient is diagnosed with Familial Hypercholesterolaemia (FH). Genetic testing reveals that the LDL receptors are being synthesised but are degraded shortly after reaching the endosome, failing to return to the plasma membrane. This describes a defect in which process?
Receptor recycling: Effective clearance of LDL requires that receptors be reused multiple times, failure to recycle leads to functional deficiency of receptors on the cell surface.
Explain why a cancer in the abdomen can present as a swollen left supraclavicular (Virchow’s) node, including the exact lymphatic pathway involved.
Lymph from the abdomen drains into the intestinal trunk → thoracic duct → left venous angle, so cancer cells travel this route and become trapped in the last node before entering the bloodstream (Virchow’s node), causing it to enlarge.
How does exogenous testosterone lead to decreased spermatogenesis despite high circulating testosterone levels?
Injected testosterone creates strong negative feedback, which lowers GnRH, LH, and FSH. This reduces Leydig cell activity (less local testosterone production) and Sertoli cell support (less ABP). As a result, testosterone levels inside the seminiferous tubules drop, so spermatogenesis cannot be maintained, even though blood testosterone is high.
According to the haematopoiesis lineage diagram, which precursor cell is the immediate stage before a mature erythrocyte enters the bloodstream as a fully functional cell?
Reticulocyte: Circulate 1-2 days before maturing into erythrocytes
Glutamate plays a huge role in nitrogen metabolism because it is one of the few amino acids that can undergo oxidative deamination. What is the enzyme responsible for this reaction, and what are its key products?
Glutamate dehydrogenase: produces alpha-ketoglutarate, NADH, and free ammonia. This enzyme removes the amino group from glutamate as free ammonia while also oxidising the carbon skeleton, producing TCA cycle intermediate alpha-ketoglutarate and reducing power in the form of NADH.
In cardiac contractile cells, what is the relationship between the plateau phase and the absolute refractory period, what causes it, and how long does it last?
In contractile cells, the absolute refractory period is when no new action potential can occur, and it is connected with the plateau phase because during this phase, Ca²⁺ enters the cell while K⁺ leaves, keeping the cell depolarised and preventing it from resetting. This means the refractory period lasts approximately 200 ms and prevents the heart from contracting again too quickly.
What happens to baroreceptor firing when blood pressure drops, and what is the immediate effect on the body?
Baroreceptor firing decreases, which causes increased sympathetic output, leading to increased heart rate and constricting of blood vessels, therefore increasing blood pressure.
At what exact stages are oocytes arrested during oogenesis, and what event allows each arrest to be completed?
Primary oocytes are arrested in Prophase I until puberty, and secondary oocytes are arrested in Metaphase II until fertilisation, which allows meiosis II to complete.