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What are neurons?

cells that respond to stimuli through electrochemical mechanisms

– Excitable or inhibitory


What are Glia?

support cells involved in conduction speed, repair, neurotransmitter maintenance


Describe the cell body of a "Typical" neuron.

Cell body is large & has a large, euchromatic nucleus with a well-developed nucleolus

- Nissl substance/bodies


What happens to a neuron, when you increase the amount of dendritic spines?

it increases receptive area


Where does the long axon of a "Typical" neuron emerge from?

emerges from an axon hillock


What are Nissl substances/bodies of a "Typical" neuron?

large, basophilic masses of free polysomes & RER


What is the distal end of an axon called?

Terminal arborization

- some have branching, collateral branches


Ends of axons usually have small what?


- dilation of branch ends & contact postsynaptic cell


Describe a multipolar neuron.


Describe bipolar neuron.


Describe unipolar neuron.


Describe anaxonic neuron.


For neuronal synapse communication, is the transmission unidirectional or bidirectional?

synaptic transmission is unidirectional

Synapses = Sites where nerve impulses are transmitted from one neuron to another, or from neurons and other effector cells


Synapses convert an electrical signal (nerve impulse) from the _____________ into a chemical signal that affects the ___________.

1. presynaptic cell

2. postsynaptic cell


Most synapse communication between nerves act by releasing what?

Neurotransmitters - small molecules that bind receptor proteins


Describe what the presynaptic terminal bouton of a chemical synapse contains.

mitochondria & synaptic vesicles --> release NT via exocytosis


Describe what the postsynaptic cell membrane of a chemical synapse contains.

receptors for the neurotransmitter

ion channels to initiate a new impulse


What is a 20- to 30-nm-wide intercellular space that separates pre- & postsynaptic membranes in a chemical synapse?

synaptic cleft


Describe the electrical synapse of a neuron.

Permit direct, passive flow of electrical current from one neuron to another

- potential difference (voltage) generated locally by presynaptic action potential


How does current flow occur and links pre- & postsynaptic membranes (2nm) in electrical synapses of neurons?

Gap junctions


What proteins permit diffusion of small molecules & electric current flow in an electrical synapse of neurons?



What are the five (5) types of Glial cells?

1. Neuropil

2. Astrocyte

3. Ependymal cell

4. Microglial cell

5. Oligodendrocyte


What is a neuropil?

type of Glial cell

fibrous intercellular network of cellular processes emerging from neurons & glial cells


What are characteristics of Astrocytes?

- large number of long, branching processes

- proximal regions are reinforced with intermediate filaments made of glial fibrillary acid protein (GFAP)

They form a vast network of delicate terminals contacting synapses & other structures

Terminal processes of a single astrocyte typically associate 1M+ synaptic sites


What are characteristics of Oligodendrocytes?

Type of Glial cell.

- Extend many processes that wrap repeatedly around a portion of a nearby axon

- Cytoplasm gradually moves out: leaves compacted layers of cell membrane, collectively termed myelin. Forms a myelin sheath.

Will enwrap axons from multiple neurons - a given axon is covered by many oligodendrocytes

Usually appear as small cells with rounded, condensed nuclei & unstained cytoplasm


What are characteristics of Ependymal cells?

• Columnar or cuboidal cells that line the fluid-filled ventricles of the brain & the central canal of the spinal cord

• Apical end may cilia & long microvilli

– Facilitate movement of CSF

– Likely involved in absorption

• Joined apically by apical junctional complexes & there is no basal lamina


What are characteristics of Microglia?

A type of Glial cell.

• Less numerous than oligodendrocytes or astrocytes

• Migratory, will remove damaged or unactive synapses or other fibrous components

• Major mechanism of immune defense in the CNS, removing any microbial invaders

• Originate from monocytes


What has a central mass of grey matter that has the shape of a butterfly?

- Ventral, dorsal, & lateral horns



What lies in the central commisure of grey matter of a spinal cord?

Central canal

- lined by ependymal cells and contains CSF


What does white matter consist of for a spinal cord?

White matter consists of ascending tracts of sensory fibers & descending motor tracts