NEET MDS General Physiology Syllabus

What is the formula for cardiac output?

Cardiac Output = Heart Rate × Stroke Volume (normal ~5 L/min).

State the relationship between flow, pressure, and resistance (Ohm's law for hemodynamics).

Blood flow = Pressure difference / Resistance (Q = ΔP/R).

How does vessel radius affect resistance according to Poiseuille's law?

Resistance is inversely proportional to the fourth power of the radius (R ∝ 1/r⁴), so small changes in radius cause large changes in resistance.

What is the formula for mean arterial pressure (MAP)?

MAP ≈ Diastolic pressure + 1/3 (Systolic − Diastolic), i.e., MAP = DBP + 1/3 pulse pressure.

What is the functional unit of the lung where gas exchange occurs?

The alveolus (alveoli), surrounded by pulmonary capillaries forming the respiratory membrane.

What roles do the diaphragm and external intercostals play in breathing?

They are the main muscles of quiet inspiration; their contraction increases thoracic volume, lowering intrapulmonary pressure to draw air in. Quiet expiration is passive.

What is the role of pulmonary surfactant?

Surfactant (produced by type II alveolar cells) reduces alveolar surface tension, preventing alveolar collapse and reducing the work of breathing.

By what process does gas exchange occur across the respiratory membrane?

Simple diffusion down partial pressure gradients: O2 moves from alveoli to blood, CO2 moves from blood to alveoli.

In what three forms is CO2 transported in the blood?

As bicarbonate ions (~70%, the majority), bound to hemoglobin as carbaminohemoglobin (~23%), and dissolved in plasma (~7%).

Where is the primary respiratory control center, and what is the main chemical stimulus for increased ventilation?

The medulla oblongata (with pontine centers); the main stimulus is a rise in arterial CO2 (and resulting fall in pH), detected by central chemoreceptors.

What are the three major parts of the brain and a key function of each?

Cerebrum (higher functions: thought, voluntary movement, sensation); cerebellum (coordination and balance); brainstem (vital autonomic functions like breathing and heart rate).

What are the structural and functional parts of a neuron?

Dendrites (receive signals), cell body/soma (integrates), axon (conducts action potentials), and axon terminals (release neurotransmitters at synapses).

What is saltatory conduction and why is it faster?

In myelinated axons the action potential jumps between nodes of Ranvier (where Na+ channels cluster), greatly speeding conduction compared to continuous conduction in unmyelinated fibers.

What is a sensory receptor, and name the receptor type for pain.

A specialized structure that converts a stimulus into a nerve signal (transduction); pain is detected by nociceptors.

What is the difference between the pyramidal (corticospinal) and extrapyramidal motor systems?

The pyramidal/corticospinal system controls voluntary, precise (especially distal) movements; the extrapyramidal system modulates posture, muscle tone, and involuntary coordination (via basal ganglia and brainstem).

Compare the sympathetic and parasympathetic nervous systems.

Sympathetic = 'fight or flight' (thoracolumbar outflow, mostly noradrenaline, increases heart rate, dilates pupils); parasympathetic = 'rest and digest' (craniosacral outflow, acetylcholine, slows heart, stimulates digestion).

How are hormones classified by chemical structure?

Into peptide/protein hormones, amino-acid-derived (amine) hormones, and steroid hormones (derived from cholesterol).

How do steroid and peptide hormones differ in their mechanism of action?

Steroid hormones (lipid-soluble) cross the membrane and bind intracellular receptors to alter gene transcription; peptide hormones (water-soluble) bind membrane receptors and act via second messengers like cAMP.

What is the relationship between the hypothalamus and the pituitary gland?

The hypothalamus controls the anterior pituitary via releasing/inhibiting hormones through the hypophyseal portal system, and produces ADH and oxytocin that are stored and released by the posterior pituitary.

Name the hormones secreted by the anterior pituitary.

GH, TSH, ACTH, FSH, LH, and prolactin (mnemonic: FLAT PiG).

What hormones does the thyroid gland produce and what are their main effects?

T3 and T4 (raise basal metabolic rate and regulate growth/development) and calcitonin (lowers blood calcium).

What are the three layers of the adrenal cortex and their secretions?

Zona glomerulosa → mineralocorticoids (aldosterone); zona fasciculata → glucocorticoids (cortisol); zona reticularis → androgens. (Adrenal medulla secretes adrenaline/noradrenaline.)

Which pancreatic islet cells secrete insulin and glucagon, and what are their opposing effects?

Beta cells secrete insulin (lowers blood glucose); alpha cells secrete glucagon (raises blood glucose).

Which hormones regulate the female menstrual cycle and the testes?

FSH and LH from the pituitary; in females they regulate estrogen and progesterone (ovaries); in males LH stimulates testosterone (Leydig cells) and FSH supports spermatogenesis (Sertoli cells).

What is the functional unit of the kidney and its two main parts?

The nephron, consisting of the renal corpuscle (glomerulus + Bowman's capsule) and the renal tubule (proximal tubule, loop of Henle, distal tubule, collecting duct).

What are the three basic processes of urine formation?

Glomerular filtration, tubular reabsorption, and tubular secretion.

How do ADH and aldosterone regulate fluid and electrolyte balance?

ADH increases water reabsorption in the collecting ducts (concentrating urine); aldosterone increases Na+ (and water) reabsorption and K+ secretion in the distal tubule/collecting duct.

What are the body's main mechanisms for regulating acid-base balance?

Chemical buffers (e.g., bicarbonate) act immediately, the respiratory system adjusts CO2 within minutes, and the kidneys excrete H+ and reabsorb bicarbonate over hours to days.

List the major regions of the GI tract in order.

Mouth → pharynx → esophagus → stomach → small intestine (duodenum, jejunum, ileum) → large intestine (colon) → rectum → anus.

What is the difference between mechanical and chemical digestion?

Mechanical digestion physically breaks food into smaller pieces (chewing, churning, segmentation); chemical digestion uses enzymes to break molecules into absorbable units.

What digestive secretions do the liver and pancreas contribute?

The liver produces bile (emulsifies fats); the pancreas secretes digestive enzymes (amylase, lipase, proteases) and bicarbonate to neutralize chyme.

Which hormones regulate digestion and what does each do?

Gastrin stimulates gastric acid secretion; secretin stimulates pancreatic bicarbonate; cholecystokinin (CCK) stimulates pancreatic enzymes and gallbladder contraction.

What is the sliding filament theory of muscle contraction?

Muscle shortens when actin (thin) filaments slide over myosin (thick) filaments via cross-bridge cycling; the filaments themselves do not shorten, the sarcomere does.

What is the role of calcium and troponin in skeletal muscle contraction?

Ca2+ released from the sarcoplasmic reticulum binds troponin, moving tropomyosin off actin's binding sites, allowing myosin cross-bridges to form (excitation-contraction coupling).

What are the roles of osteoblasts and osteoclasts in bone remodeling?

Osteoblasts build/deposit new bone matrix; osteoclasts resorb (break down) bone, releasing calcium.

How do parathyroid hormone (PTH) and calcitonin regulate blood calcium?

PTH raises blood calcium (stimulates bone resorption, renal reabsorption, and vitamin D activation); calcitonin lowers blood calcium (inhibits osteoclasts).

Classify synovial joints by movement, giving an example of a hinge and a ball-and-socket joint.

Hinge joint (uniaxial, e.g., elbow or knee) allows flexion/extension; ball-and-socket joint (multiaxial, e.g., shoulder or hip) allows movement in all planes.

What is the pathway of light through the eye to the photoreceptors, and which cells detect color?

Cornea → aqueous humor → pupil → lens → vitreous humor → retina; cones detect color (in bright light) and rods detect dim light/black-and-white.

How is sound transduced into a nerve signal in the ear?

Sound vibrates the tympanic membrane → ossicles (malleus, incus, stapes) → oval window → fluid in the cochlea → bends hair cells of the organ of Corti, generating signals via the auditory (cochlear) nerve.

What are the five basic taste modalities?

Sweet, sour, salty, bitter, and umami (savory).

How is the sense of smell (olfaction) detected?

Odorant molecules bind receptors on olfactory receptor neurons in the nasal epithelium; signals travel via the olfactory nerve (CN I) to the olfactory bulb and brain.

How does the vestibular system maintain equilibrium?

Semicircular canals detect rotational (angular) acceleration, while the utricle and saccule (otolith organs) detect linear acceleration and head position relative to gravity.