Anatomy and Physiology

Nervous System Notes

Central Nervous System (CNS)◦ Brain◦ Spinal Cord

Peripheral Nervous System (PNS)◦ 31 pairs of spinal nerves◦ 12 cranial nerves

Organization of the NS

Sensory◦ gathers info about changes occurring within and around the

body - Sensory receptors, at ends of peripheral nerves send signals (nerve impulses) to the CNS. Sensory Neuron

Motor◦ responses to signals (impulses). Signals sent from the CNS

to effectors (muscles or glands). The goal is usually to maintain stable conditions (especially internal) – Homeostasis. Motor neurons.

Somatic Nervous System (voluntary skelteal muscles) Autonomic Nervous System (involuntary smooth muscles; glands)

Integrative / Association◦ information is “brought together,” interpreted, to create

sensations, create thoughts, add to memory, make decisions, etc. Association neuron or interneuron

Functions of the NS

Neuronal◦ Neurons (pictured here)◦ Conduct action potentials

(nerve impulses)

Non-Neuronal (Neuroglial/Glial Cells)◦ Supportive Cells

Astrocytes Ependymal Cells Microglial Cells

Cells of the NS

1. Astrocytes- Forms tight junctions between endothelial cells of capillaries to form Blood-Brain-Barrier

BBB:- Exchange sight for

-Nutrients-Wastes

- Ultimate protection layer around brain & spinal cord

Glial Cells

2. Ependymal Cells- secrete Cerebrospinal Fluid (CSF)

within the ventricles of the brain

Glial Cells

3. Microglial Cells- Phagocytic (engulf/eat) in response to

inflammation -Necrotic (dead) tissue-Bacteria-Foreign substances

Glial Cells

4. Oligodendrocyte- form the myelin sheath in CNS

Myelin Sheath:

- Insulates neurons, speeding up the rate of the action potential

- Involved in many neurodegenerative problems:- MS (multiple sclerosis)- ALD (adrenoleukodystrophy)- ALS (Lou Gehrig’s Disease)

Glial Cells

Dendrites Cell Body Axon Myelin Sheath Presynaptic Knobs Direction of Nerve Impulse

The Neuron

-Pre & Post synaptic membranes -Synaptic Cleft -Synaptic Vesicles -Neurotransmitters (Ex: acetylcholine,

nor-epinephrine, dopamine, serotonin)

The Synapse