Nervous System Organization- Wk 12

Flashcards on the organization of the nervous system

Central Nervous System (CNS)

Comprises the brain (and its divisions) and the spinal cord; involved in central nervous system processes.

Peripheral Nervous System (PNS)

Comprises peripheral nerve fibres and nerve plexuses; involved in bringing information into the central nervous system (afferent) and sending out responses (efferent); has both a voluntary (skeletal) division and an involuntary (autonomic) division.

Neurons

Specialised communication cells of the nervous system that communicate via electrical activity (action potentials).

Dendrites

Input areas of the neuron.

Axon

Output areas of the neuron leading to the synapse.

Multipolar Neuron

Most common type of neuron in the nervous system; integrates lots of inputs to create an output; typical of a motor neuron.

Pseudo-unipolar Neuron

Neuronal components are arranged so that very specific inputs trigger an AP at the axon hillock located in the periphery; typical of a sensory neuron.

Nerve

A bundle of axons in the PNS, enclosed by connective tissue layers.

Sensory Neurons (Afferent)

Carry sensory information to the CNS.

Motor Neurons (Efferent)

Carry motor information away from the CNS.

Dorsal Root

Contains the processes (axons) of sensory neurons carrying information to the CNS; cell bodies are located in the dorsal root ganglia.

Ventral Root

Contains motor nerve fibres, which carry signals away from the CNS; cell bodies of these motor neurons are located in the grey matter of the spinal cord.

Somatic Nervous System

Refers to the skeletal muscle and dermis; nerves carry conscious sensations and innervate voluntary muscles.

Visceral Nervous System (Autonomic)

Refers to the organ systems; concerned with detecting and responding to information from the internal environment; sensory nerves monitor changes in the viscera and motor nerves control smooth muscle, cardiac muscle, and glands.

Look at this image

How many thoracic nerves are there?

• 12 Thoracic (T1 – T12)

How many cervical nerves are there?

8 Cervical (C1 – C8)

How many lumbar nerves are there?

• 5 Lumbar (L1 – L5)

How many sacral nerves are there?

• 5 Sacral (S1 – S5)

How many coccygeal nerves are there?

• 1 Coccygeal (Co)

Look at this diagram