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  • Overview
  • Cellular neurophysiology
  • Synapses and transmitters
  • Neuroanatomy
  • Reflexes and autonomic system
  • Worked micro‑examples
  • Pitfalls
  • Practice prompts
  • References

Anatomy and Physiology - Nervous System

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Type: Study
Divisions: B, C
Participants: Up to 2
Approx. Time: 50 minutes
Allowed Resources: Binders/notes allowed per rules; non‑programmable calculator as permitted.

Overview

Neuroanatomy and neurophysiology integrate cellular excitability with systems‑level organization. Common question styles include action potential mechanics, synaptic integration, tract/lobe functions, and autonomics.

Cellular neurophysiology

  • Resting potential: set by ion gradients (Na⁺/K⁺ ATPase, K⁺ leak); Goldman/Hodgkin–Katz conceptually.
  • Action potential: threshold → rapid Na⁺ influx (depolarization) → Na⁺ inactivation + K⁺ efflux (repolarization) → after‑hyperpolarization; absolute vs relative refractory periods.
  • Conduction: myelination enables saltatory conduction at nodes of Ranvier; velocity increases with axon diameter and myelin thickness.

Synapses and transmitters

  • Chemical synapses: presynaptic Ca²⁺ influx → vesicle fusion → neurotransmitter release; postsynaptic receptors (ionotropic vs metabotropic) generate EPSPs/IPSPs.
  • Major transmitters (scope): glutamate (excitatory), GABA (inhibitory), acetylcholine (neuromuscular junction, autonomics), monoamines (dopamine, norepinephrine, serotonin) with modulatory roles.
  • Summation: temporal and spatial integration at axon hillock; inhibitory shunting reduces EPSP effectiveness.

Neuroanatomy

  • CNS regions: cerebrum (lobes), diencephalon (thalamus/hypothalamus), brainstem (midbrain/pons/medulla), cerebellum, spinal cord.
  • Lobes and functions: frontal (motor, executive), parietal (somatosensory, spatial), temporal (auditory, memory), occipital (vision). Broca (expressive) vs Wernicke (receptive) language areas.
  • Tracts: corticospinal (motor), dorsal column–medial lemniscus (fine touch/proprioception), spinothalamic (pain/temperature). Decussation points are test favorites.

Reflexes and autonomic system

  • Reflex arc: receptor → afferent → integration → efferent → effector; stretch reflex (monosynaptic) vs withdrawal (polysynaptic).
  • Autonomic: sympathetic (thoracolumbar; fight‑or‑flight) vs parasympathetic (craniosacral; rest‑and‑digest); receptor pharmacology (nicotinic vs muscarinic; adrenergic α/β) at survey depth.

Worked micro‑examples

  1. Lesion localization
  • Loss of pain/temp on contralateral body with ipsilateral facial deficits suggests brainstem lesion; dorsal column loss ipsilateral below lesion suggests spinal cord hemisection.
  1. Synaptic integration
  • Two subthreshold EPSPs summate temporally to reach threshold; concurrent IPSP near soma can prevent spiking (shunting inhibition).
  1. Conduction velocity
  • Demyelination reduces membrane resistance, increasing capacitance per unit length → slowed conduction and conduction block in long fibers.

Pitfalls

  • Confusing sensory tract decussation locations; mixing Broca vs Wernicke aphasia features.
  • Assuming all inhibitory synapses are GABAergic in the periphery (glycine in spinal cord also inhibitory).
  • Ignoring passive cable properties when reasoning about synaptic integration.

Practice prompts

  • Trace dorsal column vs spinothalamic pathways and mark decussation sites.
  • Predict effects of a left MCA stroke on language and motor/sensory deficits.
  • Explain how myelination changes conduction speed and metabolic cost.

References

  • SciOly Wiki – Anatomy & Physiology (Nervous system)
  • OpenStax Anatomy & Physiology (Nervous tissue; CNS/PNS)