INI CET Pre-Clinical Sciences Flashcards

24 sample cards from the Pre-Clinical Sciences deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. Define ejection fraction and give the normal value.

   Ejection fraction = (Stroke volume / End-diastolic volume) x 100; normal is about 55-70%.

2. What is the mean arterial pressure (MAP) and how is it estimated?

   MAP is the average arterial pressure during a cardiac cycle; MAP = diastolic pressure + 1/3 (pulse pressure) = DBP + 1/3(SBP - DBP).

3. Define tidal volume, vital capacity, and residual volume.

   Tidal volume: air moved per normal breath (~500 mL); Vital capacity: maximum air expired after maximum inspiration (IRV+TV+ERV, ~4.5 L); Residual volume: air left in lungs after maximal expiration (~1.2 L).

4. What is the oxygen-haemoglobin dissociation curve, and name three factors that shift it to the right.

   It plots % Hb saturation against PO2 (sigmoid). A right shift (decreased O2 affinity) is caused by increased CO2, increased H+ (low pH), increased temperature, and increased 2,3-BPG (Bohr effect).

5. What are the three forms in which CO2 is transported in the blood and their approximate proportions?

   As bicarbonate (~70%), bound to haemoglobin as carbamino compounds (~23%), and dissolved in plasma (~7%).

6. What is the normal glomerular filtration rate (GFR) and which substance is the gold standard to measure it?

   Normal GFR is about 125 mL/min; inulin clearance is the gold standard because it is freely filtered and neither reabsorbed nor secreted.

7. What is the counter-current multiplier system in the kidney and where does it operate?

   It is the mechanism in the loop of Henle (and vasa recta as exchanger) that generates and maintains the hyperosmotic medullary interstitial gradient, enabling production of concentrated urine.

8. How does antidiuretic hormone (ADH/vasopressin) act on the kidney?

   It increases water permeability of the collecting duct by inserting aquaporin-2 channels, promoting water reabsorption and concentrated urine.

9. Which hormones are released from the anterior pituitary?

   GH, TSH, ACTH, FSH, LH, and prolactin (the anterior pituitary also can be remembered as releasing the FLAT PiG hormones).

10. What is the mechanism of action of insulin on glucose uptake?

    Insulin binds its receptor tyrosine kinase, triggering translocation of GLUT4 transporters to the cell membrane in muscle and adipose tissue, increasing glucose uptake.

11. Compare the actions of glucagon and insulin on blood glucose.

    Insulin lowers blood glucose (promotes glycogenesis, glycolysis, lipogenesis, glucose uptake); glucagon raises blood glucose (promotes glycogenolysis and gluconeogenesis).

12. Describe the hormonal control of the menstrual cycle's ovulation.

    Rising oestrogen from the dominant follicle exerts positive feedback on the hypothalamus/pituitary, causing an LH surge (~day 14) that triggers ovulation.

13. What is the role of the corpus luteum and which hormone does it mainly secrete?

    The corpus luteum forms from the ruptured follicle and mainly secretes progesterone (and some oestrogen) to maintain the endometrium; it regresses if no pregnancy occurs.

14. Name the photoreceptors of the retina and their respective functions.

    Rods (high sensitivity, scotopic/night vision, no colour) and cones (colour and high-acuity photopic/day vision).

15. What is the function of the semicircular canals versus the otolith organs (utricle and saccule)?

    Semicircular canals detect angular (rotational) acceleration; the utricle and saccule (maculae) detect linear acceleration and head position relative to gravity.

16. What are the four levels of protein structure?

    Primary (amino acid sequence), secondary (alpha-helix/beta-pleated sheet via H-bonds), tertiary (3D folding of a polypeptide), and quaternary (assembly of multiple subunits).

17. What is the Michaelis-Menten constant (Km) and what does it indicate about an enzyme?

    Km is the substrate concentration at which the reaction rate is half of Vmax; a low Km indicates high affinity of the enzyme for its substrate.

18. How does a competitive inhibitor affect Km and Vmax?

    A competitive inhibitor increases the apparent Km (lower affinity) but leaves Vmax unchanged (can be overcome by increasing substrate).

19. What is the net ATP yield from the complete aerobic oxidation of one glucose molecule?

    About 30-32 ATP (classically taught as 36-38 ATP) via glycolysis, the citric acid cycle, and oxidative phosphorylation.

20. Which is the rate-limiting enzyme of glycolysis, and which one of gluconeogenesis?

    Phosphofructokinase-1 (PFK-1) is rate-limiting for glycolysis; fructose-1,6-bisphosphatase is a key regulatory enzyme of gluconeogenesis.

21. What is the rate-limiting enzyme of cholesterol synthesis and which drug class inhibits it?

    HMG-CoA reductase; inhibited by statins.

22. State the central dogma of molecular biology.

    Genetic information flows from DNA to RNA (transcription) to protein (translation); DNA can also be replicated, and reverse transcription (RNA to DNA) occurs in some viruses.

23. What pattern of inheritance is shown by a trait that affects only males and is passed from carrier mothers, with no male-to-male transmission?

    X-linked recessive inheritance (e.g., haemophilia A, Duchenne muscular dystrophy).

24. Which vitamin deficiency causes scurvy and what is the underlying biochemical defect?

    Vitamin C (ascorbic acid) deficiency; impaired hydroxylation of proline and lysine residues leads to defective collagen synthesis.

What this deck covers

Pre-Clinical Sciences flashcards FAQ