NEET PG Physiology Flashcards

24 sample cards from the Physiology deck

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

1. Write the Henderson-Hasselbalch equation for the bicarbonate buffer system and the normal arterial values.

   pH = 6.1 + log10([HCO3-]/(0.03 x PCO2)). Normal arterial pH 7.35-7.45, HCO3- ~24 mEq/L, PCO2 ~40 mmHg.

2. How do the kidneys regulate acid-base balance?

   By reabsorbing filtered HCO3- (mainly in the proximal tubule via H+ secretion and carbonic anhydrase) and generating new HCO3- through excretion of H+ buffered as titratable acid (phosphate) and ammonium (NH4+) in the collecting duct.

3. Classify the four primary acid-base disorders by pH, HCO3-, and PCO2.

   Metabolic acidosis: low pH, low HCO3-. Metabolic alkalosis: high pH, high HCO3-. Respiratory acidosis: low pH, high PCO2. Respiratory alkalosis: high pH, low PCO2 (each with appropriate compensation).

4. List the major GI secretions with their key components and functions.

   Saliva (amylase, lubrication); gastric juice (HCl from parietal cells, pepsinogen from chief cells, intrinsic factor); pancreatic juice (bicarbonate plus amylase, lipase, trypsinogen); bile (bile salts, emulsify fat); intestinal/brush-border enzymes (final digestion).

5. Name the four phases/patterns controlling GI motility and the main slow-wave pacemaker.

   Gastric phases of secretion are cephalic, gastric, and intestinal; the migrating motor complex (MMC) clears the gut between meals. Slow waves originate from the interstitial cells of Cajal, the GI pacemaker.

6. Match these GI hormones to their main actions: gastrin, secretin, CCK.

   Gastrin (G cells): stimulates gastric acid secretion and growth. Secretin (S cells): stimulates pancreatic/biliary bicarbonate, inhibits acid. CCK (I cells): stimulates pancreatic enzyme secretion and gallbladder contraction, slows gastric emptying.

7. Describe the hypothalamo-pituitary-thyroid axis and its feedback control.

   Hypothalamic TRH stimulates anterior pituitary TSH, which stimulates thyroid release of T3/T4; T3/T4 exert negative feedback on both the pituitary (TSH) and hypothalamus (TRH).

8. Which hormones are secreted by the posterior pituitary, where are they made, and what do they do?

   ADH (vasopressin) and oxytocin are synthesized in the hypothalamic supraoptic and paraventricular nuclei and stored/released from the posterior pituitary; ADH conserves water and constricts vessels, oxytocin causes uterine contraction and milk ejection.

9. Compare the actions of thyroid hormone, cortisol, and insulin on metabolism.

   Thyroid hormone increases basal metabolic rate and overall metabolism; cortisol is catabolic, raising blood glucose via gluconeogenesis and protein/fat breakdown; insulin is anabolic, lowering blood glucose by promoting glucose uptake, glycogenesis, and lipogenesis.

10. Name the three zones of the adrenal cortex and their principal hormone products.

    Zona glomerulosa -> mineralocorticoids (aldosterone); zona fasciculata -> glucocorticoids (cortisol); zona reticularis -> androgens (DHEA). The adrenal medulla secretes catecholamines (epinephrine/norepinephrine).

11. Distinguish the dorsal column-medial lemniscus pathway from the spinothalamic tract.

    Dorsal column-medial lemniscus carries fine touch, vibration, and proprioception, decussating in the medulla. The spinothalamic (anterolateral) tract carries pain and temperature, decussating within 1-2 segments in the spinal cord.

12. Where does the corticospinal (pyramidal) tract decussate, and what does a lesion above versus below it produce?

    About 85-90% of fibers decussate at the pyramidal decussation in the lower medulla (lateral corticospinal tract). Lesions cause contralateral upper motor neuron weakness (spasticity, hyperreflexia, Babinski sign).

13. Compare upper motor neuron and lower motor neuron lesion signs.

    Upper motor neuron lesion: spasticity, hyperreflexia, positive Babinski, no significant atrophy, no fasciculations. Lower motor neuron lesion: flaccid paralysis, hyporeflexia, marked atrophy, and fasciculations.

14. Describe the stretch (myotatic) reflex and identify it as mono- or polysynaptic.

    Muscle stretch activates Ia afferents from muscle spindles, which synapse directly on alpha motor neurons causing the same muscle to contract; it is a monosynaptic reflex (e.g., knee-jerk).

15. What are the main functions of the cerebellum and the typical signs of cerebellar dysfunction?

    The cerebellum coordinates movement, balance, and motor learning; lesions cause ipsilateral ataxia, intention tremor, dysmetria, dysdiadochokinesia, nystagmus, and hypotonia.

16. Outline the direct and indirect pathways of the basal ganglia and their net effect on movement.

    Direct pathway (via D1 receptors) disinhibits the thalamus and facilitates movement; indirect pathway (via D2 receptors) inhibits the thalamus and suppresses movement. Dopamine from the substantia nigra promotes movement by activating the direct and inhibiting the indirect pathway.

17. Contrast the parasympathetic and sympathetic divisions of the autonomic nervous system by outflow and ganglion location.

    Sympathetic: thoracolumbar (T1-L2/3) outflow with short preganglionic and long postganglionic fibers (ganglia near the cord). Parasympathetic: craniosacral outflow (CN III, VII, IX, X and S2-S4) with long preganglionic and short postganglionic fibers (ganglia near/in target organs).

18. Identify the neurotransmitters and receptors at autonomic ganglia and effector organs.

    All preganglionic fibers release ACh acting on nicotinic receptors. Parasympathetic postganglionic fibers release ACh on muscarinic receptors; sympathetic postganglionic fibers release norepinephrine on adrenergic receptors (except sweat glands, which use ACh).

19. Explain the focusing of light in the eye and which structure provides most refractive power.

    Light is refracted by the cornea (which provides about two-thirds of total refractive power) and fine-focused by the lens, which changes shape during accommodation; the image is focused on the retina (fovea for sharpest vision).

20. What are rods and cones, and which photopigment is found in rods?

    Rods provide high-sensitivity, low-resolution, monochromatic (scotopic/night) vision and contain rhodopsin; cones provide high-resolution color (photopic) vision via three opsins (red, green, blue) and are concentrated at the fovea.

21. Describe how the cochlea performs frequency discrimination (place theory).

    The basilar membrane is tonotopically organized: high-frequency sounds maximally vibrate the stiff, narrow base near the oval window, while low-frequency sounds vibrate the wider, floppier apex; hair cells at the point of maximal displacement signal that frequency.

22. How do the semicircular canals and otolith organs sense head movement?

    The three semicircular canals detect angular (rotational) acceleration via endolymph movement bending the cupula; the otolith organs (utricle and saccule) detect linear acceleration and head position relative to gravity via otoliths on the macula.

23. List the EEG rhythms with their frequency ranges and associated states.

    Beta (>13 Hz, alert/active thinking), alpha (8-13 Hz, awake relaxed eyes closed), theta (4-7 Hz, drowsiness/light sleep/children), and delta (<4 Hz, deep slow-wave sleep).

24. Compare REM and non-REM (slow-wave) sleep.

    NREM (slow-wave) sleep shows delta EEG, reduced muscle tone, and is restorative. REM sleep shows a low-voltage fast (desynchronized, awake-like) EEG, rapid eye movements, vivid dreaming, and skeletal muscle atonia (paradoxical sleep).

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