Neurons

Neurons, or nerve cells, receive stimuli and transmit action potentials to other neurons or to effector organs.

STRUCTURE OF NEURONS

Cell Body: contain a single, relatively large and centrally located nucleus with a prominent nucleolus.

Axon: a long cell process extending from the cell body.

Dendrite: short, often highly branched cytoplasmic extensions that are tapered from their bases at the neuron cell body to the tips.

TYPES OF NEURONS

Bipolar: have two processes, one dendrite and one axon. Located in some sensory organs such as the retina and nasal cavity.

Unipolar: have single process extending from the cell body.

Multipolar: have many dendrites and single axon. Most of the neurons within the CNS and motor neurons are multipolar.

GLIAL CELLS

Glial cells are the major supporting cells in the CNS.

Astrocytes: provide structural support for neurons and blood vessels. Influence the functioning of the blood-brain barrier and process substances that pass through it. They also isolate damage tissue and limit the spread of inflammation.

Ependymal Cell: line the ventricles and the central canal of the spinal cord. Some are specialized to produce cerebrospinal fluid.

Microglial Cell: phagocytize microorganism, foreign substances, and neurotic tissue.

Oligodendrocytes: form myelin sheaths around the axons of several CNS neurons.