Nervous System

 

Nervous System Anatomy and Physiology

Anatomy

1. Overview: Nervous system controls body via electrical/chemical signals, split into Central Nervous System (CNS) and Peripheral Nervous System (PNS).
2. CNS - Brain: In skull, includes:
   • Cerebrum (thinking, sensing, moving; two hemispheres).
   • Cerebellum (back, balance, coordination).
   • Brainstem (medulla oblongata, pons, midbrain; vital functions like breathing).
3. Cerebral Cortex: Cerebrum’s surface, four lobes:
   • Frontal (reasoning, movement).
   • Parietal (sensation).
   • Temporal (hearing, memory).
   • Occipital (vision).
4. CNS - Spinal Cord: In vertebral column, relays brain-body signals, 31 spinal nerve pairs.
5. PNS: Nerves outside CNS:
   • 12 cranial nerves (e.g., I Olfactory - smell, II Optic - vision).
   • Spinal nerves (from spinal cord).
6. PNS Divisions:
   • Somatic (voluntary movement).
   • Autonomic (involuntary, e.g., heart rate):
     • Sympathetic (fight or flight).
     • Parasympathetic (rest and digest).
7. Neurons: Nerve cells:
   • Cell body (nucleus).
   • Dendrites (receive signals).
   • Axon (sends signals, myelin-wrapped for speed).
8. Glial Cells: Support neurons (e.g., astrocytes - nourish, Schwann cells - myelin in PNS, oligodendrocytes - myelin in CNS).

Physiology

9. Function: Senses stimuli (receptors), processes (CNS), responds (effectors like muscles/glands).
10. Signal Transmission:
    • Resting potential (-70mV, inside negative).
    • Action potential (sodium in, depolarizes, signal travels).
    • Synapses (neurotransmitters like acetylcholine bridge to next cell).
11. Reflex Arcs: Fast responses (e.g., knee jerk), sensory-to-motor via spinal cord, skips brain.
12. Sympathetic Role: Speeds heart, dilates pupils (stress response).
13. Parasympathetic Role: Slows heart, aids digestion (calm state).

Memory Aids

14. Cranial Nerves (12): “On Old Olympus’ Towering Top, A Finn And German Viewed Some Hops”:
    • I Olfactory, II Optic, III Oculomotor, IV Trochlear, V Trigeminal, VI Abducens, VII Facial, VIII Auditory (Vestibulocochlear), IX Glossopharyngeal, X Vagus, XI Spinal Accessory, XII Hypoglossal.
15. Brain Lobes: “Frontal, Parietal, Temporal, Occipital” (FPTO, say “Fop-toe”).
16. Autonomic: “Sympathetic = Stress, Parasympathetic = Peace” (S vs. P).

Questions

Multiple-Choice: 17. What part of the brain controls balance? - A) Cerebrum B) Cerebellum C) Brainstem D) Temporal lobe
Answer: B) Cerebellum 18. Which cranial nerve is for vision? - A) I Olfactory B) II Optic C) III Oculomotor D) V Trigeminal
Answer: B) II Optic

Short-Answer: 19. Name the four lobes of the cerebral cortex.
Answer: Frontal, Parietal, Temporal, Occipital. 20. What’s the role of myelin in neurons?
Answer: Speeds up signal transmission by insulating axons.

Long-Answer: 21. Explain how a reflex arc works, including its components.
Answer: A reflex arc is a fast response bypassing the brain. A stimulus (e.g., heat) activates a sensory receptor, sending a signal via a sensory neuron to the spinal cord. An interneuron connects to a motor neuron, which triggers an effector (e.g., muscle) to respond (e.g., pull hand away), all in milliseconds.

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How to Use This

• Study: Hit each point like a checklist, linking anatomy (structure) to physiology (function).
• Memorize: Use the mnemonics to nail cranial nerves and lobes.
• Test: Practice the questions to lock it in.

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