The chief ionic determinant of the resting membrane potential in most neurons is:
A) Na⁺ permeability

B) K⁺ permeability

C) Ca²⁺ permeability

D) Cl⁻ permeability

 

Define equilibrium (Nernst) potential.
 

(True/False) The Na⁺/K⁺ pump directly sets the resting membrane potential.

 

Which transport shows saturation kinetics?
A) Simple diffusion

B) Channel diffusion

C) Facilitated diffusion (carrier)

D) Osmosis

 

Osmolarity vs. tonicity?
 

Increasing extracellular K⁺ will:
A) Hyperpolarize

B) Depolarize

C) No change

D) Make V_rest equal E_Na

 

Osmosis requires:
A) Ion channels

B) ATP

C) Semipermeable membrane + solute gradient

D) Vesicular transport

 

Gibbs–Donnan effect?
 

Absolute refractory period is due to:
A) K⁺ channels open

B) Na⁺ channel inactivation

C) Ca²⁺ influx

D) Na⁺ channel closed (resting)
 

Saltatory conduction—what & why faster?

 

Opening which channel produces an IPSP in many CNS neurons?
A) Na⁺

B) Ca²⁺

C) Cl⁻

D) Nonselective cation

 

(True/False) Myelination increases axonal membrane capacitance.
 

Temporal summation?
 

 

NMJ transmitter removal primarily by:
A) Reuptake

B) Diffusion

C) Acetylcholinesterase

D) Endocytosis

 

A Gs-coupled receptor first activates:
A) Phospholipase C

B) Adenylyl cyclase

C) Guanylyl cyclase

D) Tyrosine kinase
 

Ionic driving force definition?
​

Ca²⁺ for skeletal muscle contraction primarily comes from:
A) ECF

B) SR

C) Mitochondria

D) T-tubule lumen

 

Troponin–tropomyosin role?
 

(True/False) ATP binding to myosin is needed for cross-bridge detachment.
 

Maximal active tension occurs at:
A) Very short

B) Optimal

C) Very long

D) Independent of length

 

Tetanic fusion occurs because:
 

Cardiac refractory period is long due to:
A) Na⁺ window current

B) L-type Ca²⁺ plateau

C) K⁺ inward rectifier

D) Cl⁻ current
 

Smooth muscle contraction is triggered by:
A) Troponin

B) Calmodulin → MLCK

C) Titin

D) DHP receptor alone

 

Isometric vs. isotonic?
 

A motor unit is:
A) One myofibril

B) One motor neuron + all its fibers

C) One sarcomere

D) All muscles in a limb

​

Frank–Starling law:
A) ↑Afterload → ↑SV

B) ↑Preload → ↑SV

C) ↑HR → ↓SV

D) ↑Contractility → ↓SV

 

MAP (approximate) = ?
 

(True/False) Arterioles are the main site of adjustable resistance.

 

Flow sensitivity to radius (Poiseuille):
A) r

B) r²

C) r³

D) r⁴

 

Vascular compliance?
 

High-pressure baroreceptors are in:
A) Carotid sinus & aortic arch

B) Atria

C) Ventricles

D) Pulmonary artery

 

Isovolumetric contraction:
A) All valves open

B) All valves closed

C) AV open only

D) Semilunar open only
 

Pulse pressure = ? Influenced by?
 

Fastest intrinsic pacemaker:
A) AV node

B) Purkinje

C) SA node

D) His bundle

​

Primary driver of ventilation at rest:
A) PaO₂

B) PaCO₂ (via H⁺ in CSF)

C) BP

D) Temp

 

Surfactant: made by? effect?
 

(True/False) End-expiratory intrapleural pressure is positive.
 

At FRC:
A) Lungs recoil inward > chest wall

B) Outward > inward

C) Balanced

D) Both zero
 

Dead space?
 

O₂ content of blood depends most on:
A) Dissolved O₂

B) Hb concentration & saturation

C) Alveolar humidity

D) CO₂

 

Hypoventilation effect on PaCO₂:
A) ↓

B) ↑

C) No change

D) Unpredictable

 

Regional V/Q in upright lung?
 

Surfactant primarily:
A) Decreases compliance

B) Increases collapsing pressure

C) Reduces surface tension

D) Thickens alveolar membrane

 

Ideal GFR marker (freely filtered, not handled):
A) PAH

B) Inulin

C) Creatinine (exact)

D) Glucose

 

Starling forces at the glomerulus determine what?
 

 

(True/False) Most filtered Na⁺ is reabsorbed in the proximal tubule.

​

ADH promotes water reabsorption by inserting:
A) AQP1 in PCT

B) AQP2 in collecting duct

C) NKCC2 in TAL

D) Na⁺/K⁺-ATPase in CD

 

Countercurrent multiplier function?
 

Aldosterone on principal cells:
A) ↓Na⁺ reabsorption

B) ↑Na⁺ reabsorption & ↑K⁺ secretion

C) ↑Cl⁻ secretion

D) ↑HCO₃⁻ reabsorption

 

Afferent arteriole constriction:
A) ↑GFR

B) ↓GFR

C) No effect

D) ↑RPF, ↓GFR

 

Transport maximum (T_m)?
 

Macula densa senses:
A) K⁺

B) NaCl in distal tubule

C) Urea

D) Glucose

 

Principal extracellular buffer:
A) Phosphate

B) Hemoglobin

C) Bicarbonate

D) Proteins

 

Henderson–Hasselbalch (bicarbonate system)?
 

(True/False) Lungs directly change plasma bicarbonate to compensate.
 

Increasing alveolar ventilation generally:
A) Lowers pH

B) Raises PaCO₂

C) Raises pH

D) No effect on pH

 

Osmolarity vs. osmolality?
 

Plasma osmolality is determined mainly by:
A) Proteins

B) Na⁺ and its anions (± glucose, urea)

C) K⁺

D) Ca²⁺

 

Infusing isotonic saline primarily expands:
A) ICF only

B) ECF only

C) Both equally

D) Plasma only

 

Effective osmoles?
 

 

Most important intracellular buffers:
A) Proteins and phosphate

B) Bicarbonate

C) Calcium salts

D) Ammonia
​

GI slow waves originate from:
A) Vagus

B) Skeletal muscle

C) Interstitial cells of Cajal

D) Paneth cells

 

Gastrin actions?
 

(True/False) Pancreatic acinar cells secrete bicarbonate.

 

Secretin is released by acid in duodenum and:
A) ↓Pancreatic HCO₃⁻

B) ↑Pancreatic HCO₃⁻

C) Contracts gallbladder

D) ↑Gastric acid

 

(Short) CCK functions?
 

Most overall nutrient absorption occurs in:
A) Duodenum

B) Jejunum

C) Ileum

D) Colon

 

Migrating motor complex (MMC) occurs during fasting and is triggered by:
A) Gastrin

B) Secretin

C) Motilin

D) VIP

 

ENS plexuses?
 

Bile salts mainly:
A) Digest proteins

B) Form micelles for lipid absorption

C) Buffer gastric acid

D) Increase iron uptake

 

Steroid hormones typically act by:
A) cAMP

B) IP₃/DAG

C) Nuclear receptors altering transcription

D) Ion channels

 

Peptide vs. steroid hormones—storage/transport?
 

(True/False) Posterior pituitary synthesizes ADH/oxytocin.

 

Insulin receptor type:
A) GPCR

B) Ligand-gated channel

C) Receptor tyrosine kinase

D) Nuclear receptor
 

Hormone permissiveness?
 

TRH → TSH → thyroid hormones is an example of:
A) Long-loop feedforward

B) Hypothalamo–pituitary–target axis

C) Ultrashort loop only

D) Paracrine reflex

 

A classic cAMP-mediated hormone is:
A) PTH

B) Aldosterone

C) Thyroxine

D) Insulin

 

Negative feedback example in HPT axis?
 

Receptor up-regulation example:
A) Fewer receptors after high ligand

B) More uterine oxytocin receptors near term

C) Fewer insulin receptors with fasting

D) None

​

Ovulation is triggered by the surge of:
A) FSH

B) LH

C) Prolactin

D) Progesterone

 

Menstrual cycle phases & dominant hormones?
 

(True/False) Sperm acquire motility in the epididymis.

 

Sertoli vs. Leydig primary responses:
A) Sertoli–LH; Leydig–FSH

B) Sertoli–FSH; Leydig–LH

C) Both to FSH

D) Both to LH

 

Capacitation?
 

Basal body temperature rises post-ovulation due to:
A) Estrogen

B) Progesterone

C) LH

D) Inhibin

 

Early maintenance of the corpus luteum is by:
A) FSH

B) Prolactin

C) hCG

D) Oxytocin

 

Oxytocin’s main roles?