SLP528 Neurology

Neuron- cell/unit of the nervous system

 

• Building blocks of the central nervous system (CNS)

• Neurons transmit information throughout the body

• There are several different types of neurons responsible for different tasks

• Just like the brain in its entirety, the nerve cell is made up of white matter, axons, and gray matter, or the cell bodies (soma)

 

The axon is the longest part of the neuron

• Signals/information travels down the axon quickly in a jumping fashion, via the nodes of Ranvier

• Myelin Sheath is adipose/fat tissue that helps the information flow faster down the axon

 

Structure of a typical neuron:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Neurons communicating/synapsing within the body:

 

 

 

 

 

 

 

 

 

 

 

 

 

Information flow: Information is received initially from the dendrites, and then travels down the axon, and is sent through the synaptic gap where the receptors of the postsynaptic neuron will retrieve the information/neurotransmitters, and so on. The neural networking of the brain is highly complex.

 

There are 2 ways that neurotransmitters enter a dendrite, and/or cell body:

• Spatial Summation- Neurotransmitters enter the cell at the same time via multiple dendrites

• Temporal Summation- Neurotransmitters enter the cell via the same dendrite

 

Basic Neuron Types:

Bipolar- Interneuron; Soma is in the middle of the axon

Unipolar- Sensory neuron; Soma also in center of the axon, but almost hangs off a bit

Multipolar- Motor neuron; typical nerve cell

Pyramidal Cell- Small soma within the dendrites; no axon terminal end buttons

 

 

 

 

 

 

 

 

 

 

 

 

The soma, or body of the cell, houses the nucleus and in a typical nerve cell soma will have the dendrites branching off of it waiting to receive information from other neurons

• The dendrites may have axo-dendritic synapses, and/or synapses on dendritic spines

• These synaptic gaps are the landmark of communication between neurons

• Dendritic spines increase the surface area of the dendrites, which in turn increases the information uptake. An advantage of dendritic spines is:

  • They allow for stronger impulse activation, needed for fine motor movements

 

**Dendrites have specific receptors for particular signals/neurotransmitters; for instance, it is impossible for a dopamine receptor to retrieve a serotonin neurotransmitter:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Examples of neurotransmitters transmitted throughout the body:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

http://www.slideshare.net/damarisb/neurotransmitters-27039224

 

 

Neuroglial Cells: Glial cells aid neurons, there are 3 different types:

• Oligodendrocytes- produce myelin on the axon (white matter)

• Microglia- cleaning, and produce immune response

• Astrocytes- largest of the glial cells; form blood-brain barrier and have plasticity