Nervous System

Components of The Nervous System:

Brain

Spinal Cord

Nerves

Sensory Organs

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Nervous System

General Organization

Central Nervous System (CNS)

Brain- surrounded by the skull

Spinal Cord- encased within the vertebral column

Peripheral Nervous System (PNS)

12 Pairs of Cranial Nerves

31 Pairs of Spinal Nerves

One pair emerges at each level of the spinal cord

Each nerve is like a cable consisting of thousands of nerve fibers (Nerve fibers = Nerve cells = Neurons)

Two types of nerves

Sensory (afferent)

Brings information from the body to the CNS

Somatic sensory: skin, skeletal muscles, and joints

Visceral sensory: visceral organs

Motor (efferent)

Sends information from the CNS back for action to the effector cells

Somatic Nervous System: conducts information to the voluntary muscles

Autonomic Nervous System: regulates the activity of smooth muscles, cardiac muscles, and glands.

Notice that the spinal cord ends at L1 or L2

31 pairs of spinal nerves

8 Cranial Nerves

12 Thoracic Nerves

5 Lumbar Nerves

5 Sacral Nerve

1 Coccygeal Nerve

An Epidural Nerve Block Injection

You may have heard of the epidural --the pain-relieving shot (anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical purposes) that some pregnant women get when they’re giving birth. But it has other uses, too.

It’s an injection that goes into your “epidural space,” which is right outside of the membrane that protects your spinal cord. Doctors use epidural injections to relieve pain during and after surgery, as well as managing chronic pain.

This procedure isn’t right for every case. But if it’s an option, it requires a lower dose of medicine and as a result, has fewer side effects. Epidurals may even give you longer-lasting pain relief while helping you stay more alert and mobile.

Please review the following:

Please develop and submit a presentation giving explain when an epidural nerve block may be called for. Make sure to include the injection procedure.

Three types of nerve cells

Three types of neurons. The one below is typically the one used to exhibit the anatomy.

The soma or cell body of the neuron contains the nucleus and organelles necessary to carry out cells function.   

Dendrites exit from the soma. The dendrites receive information across the synapses. These electrical impulses come in two forms inhibitory and excitatory.

The axon is a long, slender projection leaving the cell body that normally carries the electrical impulse away from the cell body toward the axon terminals. Commonly called nerve fibers, the axons in the leg may be very 1 meter long. 

The axon terminal is the area of the axon that forms a synapse with the dendrites of the neighboring neuron. The axon terminal contains neurotransmitters. The electrical impulse may cause the release of the neurotransmitter across the synapse. The synapse is the area located between the axon terminals and the dendrites of the next neuron. 

The function of the myelin sheath is to allow for the transmission of the electrical impulse quickly along the axon. Myelin is an insulating layer or sheath that forms around nerves, including those of the CNS as well as the PNS. It is made up of protein and fatty substances. 

 The myelin sheath is created by the Schwann Cells in the Peripheral Nervous System. The Schwann Cells wraps around a single nerve axon. 

The oligodendrocytes cells form the myelin sheath in the Central Nervous System. These cells can form a sheath around as many as 50 axons

Nerve cells are highly specialized cells and do not undergo mitosis. Nerve cells do not reproduce and have limited respiration capabilities. The accessory cells surrounding neurons called ganglia cells tend to the needs of the neuron.

Please draw a neuron and identify the anatomy of a neuron and send a picture to your mentor.

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