Summary Neuro Made Easy: High-Yield Disorders You Must Know

PROPERTY OF TAHEYA ASAD DO NOT COPY

TOPIC




L/2
Nervous System Disorders
The Nervous System - Overview:
• Macro Structures:
• Brain
• Spinal Cord
• Peripheral Nerves
• Sense Organs
o Eyes
o Ears
o Tongue
o Olfactory bulbs
o Skin
• Functions:
• Detection of stimuli
(external/internal)
• Response to stimuli
• Coordinates activity of other organs
& systems

Organisation of the Nervous System:
Central Nervous System (the “CPU” &
“Motherboard”)
§ Brain
§ Spinal Cord
- when examining it, there is white matter and gray
matter
- White matter is due to abundance of myelinated
axons
-Gray matter is due to scarcity of myelinated axons

Peripheral Nervous System (the “Cables”)
§ Cranial Nerves & Spinal Nerves
§ Communication between CNS & rest of
body

Neuron- Structural Features

I. Receptive field: dendrites
o Stimulated by inputs

II. Cell Body (Soma)
o Responds to graded potentials

III. Efferent projections (Axon)
o Conducts nerve impulses to target
o Myelinated and unmyelinated

IV. Efferent projection (Myelin sheath)

V. Efferent Projection (Nodes of Ranvier)

,PROPERTY OF TAHEYA ASAD DO NOT COPY

VI. Synaptic terminals (axon terminals)

Supporting cells (Neuroglia)
– outnumber neurons
– structural and mechanical support
– roles in maintaining homeostasis and myelination
– immune response via phagocytosis

• Neuroglia of the Central Nervous System (CNS):
o Astrocytes
• Nutrient bridge between neuron & capillaries
• Guide migrating young neurons
• Synapse formation
• Mop up excess K+ ions + neurotransmitters
o Microglia
• Long thorny processes
• Monitors neuron health
• Senses damaged neurons
• Migrates to damaged neuron
• Phagocytoses microbes & debris (immune cells are denied access to CNS)
o Oligodendrocytes
• Myelin formation in CNS
o Ependymal Cells
• Lines central cavities of brain + spinal chord
• Blood-brain barrier
• Beating cilia circulates cerebrospinal fluid

• Neuroglia of the Peripheral Nervous System (PNS):
o Schwann Cells
• Myelin Formation – wrap around axon
• Regeneration of damaged neurons
o Satellite cells
• § Surround neuron bodies
• § Structure, nutritional support & protection.

,PROPERTY OF TAHEYA ASAD DO NOT COPY


Gray Matter and White Matter
• Grey Matter
o Made up of Neuron bodies (Soma)
o Imbedded in Neuroglial cells
o Eg:
§ § Cortex of Brain
§ § Centre of Spinal Chord
§ § Ganglia/nuclei
• White Matter
o Neuron fibres (axons & dendrites
o White due to myelin
o Eg:
§ § Peripheral Nerves & Plexuses
§ Central fibre tracts




Ganglia
• = Collections of neuron cell bodies in PNS
o Afferent Spinal Nerves:
§ § Cell bodies of sensory neurons
§ § ‘Dorsal root ganglion’
o Efferent Spinal Nerves:
§ § Cell bodies of autonomic nerve fibres
§ § ‘Sympathetic trunk ganglion’

In Central Nervous System:
§ § Called: Basal Nuclei / Nuclei

, PROPERTY OF TAHEYA ASAD DO NOT COPY
o Important for BOTH Motor & Autonomic Nervous Systems




Spinal Nerves:
• Dermatomes - Innervation of the Skin: