Lab 13

- brace and protect

- act as phagocytes (microglial cells)

- capilary exchange and chemical enviornment control (astrocytes)

- mylenation - (schawn cells and oligodendrocytes)

basic functional units of the neurvous tissues. Highly specialized to transmit messages via electical signals.

a large central area of which long extensions extend. It is the biosynethic center of the neuron as well as the receptive region. It contains a large round nucleus surrounded by cytoplasm.

CNS - make up the grey matter of the CNS forming clusters called nuclei

PNS - Clusters of neuron cell bodies are called ganglia

1. Neurofibrils - provide support for the cell and a means for transport of substances through the neuron.

2. Chromatophilic substance (Nissl bodies) - an elaborate type of rough ER involved in the metabolic activity of the cell.

Dendrites and Axons

receptive regions that bear receptors for neurotransmitters released by the terminal boutons of other neurons.

Also called nerve fibers, form the impulse-generating and impulse-conducting region of the neuron.

Axons

CNS - tracts

PNS - nerves

One. Though it may form branches called AXON COLLATERALS.

Axon Hillcock narrows into the inital segment

Terminal boutons or axon terminals

The junction that the axon forms with the effector cell - a gap in which neurotransmitter is released. Also called the synaptic cleft.

They are covered in a fatty material called MYELIN. These fibers are refered to as Myelinated fibers.

Schwann cells.

Myelin sheath.

Outter collars of perinuclear cytoplasm

Myelin sheath gaps - or nodes of ranvier.

Oligodendroytes. These cells don't exhibit the outer collars of perinuclear cytoplasm.

It insulates the fibers and greatly increases the transmission speed of nerve impulses.

1. Unipolar

2. pseudouniplar

3. Bipolar

4. Multipolar

they have one very short process, which divides into peripheral and central process that extend from the cell body. Only the most distal portion of thep eripheral process acts as a receptive ending. The rest acts as an axon along with the central process.

Because they are dervied from bioplar neurons.

Unipolar

They have two processes attached to the cell body. It's a rare type of neuron typically found only as a part of the receptor apparatus of the eye, ear and olfactory mucosa

Many processes issue from the cell body all classified as dendrites except for the single axon. Most nuerons in the brain and psinal cord and those whose axons carry impulses away from the CNS fall into this category.

Afferent (sensory)

Effert (motor)

Interneurons.

They are sensory neurons. Their receptive endings are equipped with specialized receptors that are stimulated by specific changes in their immediate environment. They are always found in a ganglia outside the CNS and are typically unipolar.

Also called motor neurons - they carry impulses from the CNS to the viscera and or body muscles and glands. They are often multipolar and their cell bodies are almost always located in the CNS.

Situated between and contribute to pathways that connect afferent and efferent neurons. Their cells bodies are always located within the CNS, and they are multipolar neurons structurally.

A bundle of axons found in the PNS - wrapped in connective tissue coverings extends to and/or from the CNS and viseceral organs or structures of the body periphery, such as skeletal muscles, glands and skin.

Like neurons, nerves are classified according to the direction in which they transmit impulses - Sensory (afferent)  and Motor (efferent). and Mixed nerves which both sensory and motor.

Sensory nerves that carry information TOWARDS THE CNS. A few of the cranial nerves are purse sensory nerves.