Central Nervous System Histology Cheat Sheet

Nervous System Structure and Division

Central Nervous System (CNS)

The command center comprising the brain and spinal cord.

Brain

The central organ of the human nervous system.

• Function: processes information from the PNS, initiates responses.

• Structures: includes the cerebrum, cerebellum, and brainstem.

• Lobes: divided into frontal, parietal, occipital, and temporal lobes.

Spinal Cord

A long, thin, tubular bundle of nerves and supporting cells.

• Function: relays messages to and from the brain and body.

• White Matter: contains myelinated ascending and descending nerve fibers.

• Grey Matter: forms the core, shaped like a butterfly, where synapses occur.

Meninges

Protective layers enveloping the CNS.

• Dura Mater: the tough outer layer.

• Arachnoid Mater: the delicate, web-like middle layer.

• Pia Mater: the inner layer closely adhering to the brain and spinal cord.

Peripheral Nervous System (PNS)

The network of nerves outside the CNS.

Somatic Nervous System

Controls voluntary movements and transmits sensory information.

• Sensory Neurons: collect data from the environment.

• Motor Neurons: innervate skeletal muscles for movement.

• Reflex Arcs: simple neural pathways for reflexes.

Autonomic Nervous System

Manages involuntary bodily functions.

• Sympathetic Division: prepares the body for stress or action.

• Parasympathetic Division: conserves energy and supports 'rest and digest' functions.

• Enteric Division: controls the digestive system independently.

Cranial Nerves

Twelve pairs of nerves that directly emerge from the brain.

• Sensory Nerves: carry sensory information to the CNS.

• Motor Nerves: control movements of head and neck muscle.

• Mixed Nerves: include both sensory and motor functions.

Ganglia and Plexuses

Clusters of neuronal cell bodies.

• Dorsal Root Ganglia: contain sensory neurons' cell bodies.

• Sympathetic Chain Ganglia: part of the sympathetic nervous system.

• Plexuses: network of nerves combining to form major peripheral nerves.

Cells of the Nervous System

The building blocks of the nervous system.

Neurons

Electrically excitable cells that transmit information.

• Structure: consist of soma, axons, and dendrites.

• Types: sensory, motor, and interneurons.

• Synapses: sites of communication between neurons.

Neuroglia (Glia Cells)

Supportive cells that aide neuron function.

• Astrocytes: regulate neurotransmitters and blood flow.

• Microglia: partake in immune responses within the CNS.

• Oligodendrocytes: myelinate CNS neurons; Schwann cells serve this role in the PNS.

Ependymal Cells

Line the brain and spinal cord cavities.

• Function: create and circulate cerebrospinal fluid (CSF).

• Types: columnar ependymal cells and tanycytes involved in metabolic regulation.

Neuron Communication

How neurons transmit signals.

Action Potentials

The way neurons communicate through electrical impulses.

• Process: involves depolarization and repolarization of the neuron's membrane.

• Threshold: the level of stimulation required to trigger an action potential.

Neurotransmitters

Chemical substances facilitating communication between neurons.

• Examples: acetylcholine, dopamine, serotonin, and GABA.

• Receptors: sites on the post-synaptic neuron that bind neurotransmitters.

Synaptic Transmission

Exchange of neurotransmitters across the synaptic gap.

• Synapse: the junction between neurons where communication occurs.

• Vesicles: contain neurotransmitters ready for release into the synaptic cleft.

Development and Regeneration

The growth and healing processes of the nervous system.

Neurulation

The formation of the neural tube which develops into the CNS.

• Neural Crest: cells migrate to form PNS structures.

• Neural Plate: a key structure that folds to create the neural tube.

Regeneration in PNS

The ability of peripheral nerves to repair.

• Wallerian Degeneration: process of degeneration that allows peripheral nerves to regrow.

• Nerve Growth Factors: proteins that promote the growth and survival of neurons.

Neuroplasticity

The brain's capacity to change and adapt.

• Synaptic Plasticity: the ability of synapses to strengthen or weaken over time.

• Neurogenesis: the birth of new neurons, primarily occurring in the hippocampus.