Chapter 2: Neuronal cell Biology

Major nueron components

1. dendrites (from synapses)

2. soma/cell body

3. axon

4. presynaptic terminals

5. Synaspe

Synapse

Gap between nuerons that transmits/recieves info

presynaptic nueron

a nerve which sends the signal

postsynaptic nueron

a nerve that receives the signal

How are neuronal types defined?

By the # of poles (axon ends) they have sticking out of their cell bodies

Bipolar neuron

• cell body with 2 poles

Unipolar neuron

• cell body has 1 pole sticking out of it (“side mass”)

• The only cell with this is a sensory neuron

Multipolar nueron

1 axon, 2+ dendrites extending from cell body

• Looks like a dendrite explosion

Types of multipolar nuerons

• stellate

• fusiform

• pyramidal

stellate nueron

looks like a firework/star

Fusiform nueron

• fat middle, taper at the ends

• this is really weird

Pyramidal Neuron (W/ example!)

• Triangle around the cell body, dendrites branch off the pyramid base

  • These look really messy

  • Ex. Neurons in the prefrontal cortex

dendrites

branching fibers that are lined with synaptic receptors that receive info from other neurons

Dendrite spines

“Spikes” on a dendrite that receive information from other neurons; very high in plasticity and can adapt quickly to postsynaptic info

• Spine head = postsynaptic membrane

Cell Body/Soma/Perikaryn

Contains the main cell structures found in other cells

• Everything that’s not a synapse

Axon

Thin fiber that transmits the electrical impulses (APs) to other nuerons/mucles/organs

• Neurons have 1 axon, which can bifurcate (branch off)

Prysynaptic terminals/boutons

axon end points where chemicals are released to communicate with other neurons

mylean sheath

Insulating material (lipids) around the axon that helps speed up electrical conduction within the axon

• make the AP go faster

Nodes of Ravier

Interruptions in the mylean sheath

Oligodendrocytes

“Pockets” that produce and disperse the sheath around the axon

• Central nervous system = Oligodendrocytes

• Peripheral nervous system = Schwann Cells

Afferent Neuron

bringing info towards a structure; driving to the post office

efferent Nueron

carrying info away from the structure

• Driving to your house with a letter

interneurons

nerve cells that do both and connect sensory and motor neurons

active zone

Area in the presynaptic bouton that regulates neurotransmitters

Nuerotrasmitters

chemicals used to communicate with the next nueron

Synaptic vesicles

tiny spheres in the presynaptic axon terminals that contain neurotransmitters

receptors

specialized proteins that capture neurotransmitters, bind to them, and then react to them

postsynaptic density

a protein-dense structure attached to the postynaptic membrane that is home to the receptors; VERY complex

Ways to view a nueron

• light microscopy

• electron microscopy

• florescence/confocal microscopy

Light microscopy

shows cells/processes via staining

electron microscopy

uses staining to show synapses and organelles

florecence/confocal microscopy

a light-based format that allows you to label specific cells

Glia

Other nervous system componenets that exchange chemicals with adjacent neurons

types of gila

1. Oligodendrocytes

2. Schwan cells

3. astrocytes

4. microglial cells

5. radial glia

Schwan cells

Pockets that produce/disperse the myelin sheath for the axon

• Central nervous system = Oligodendrocytes

• Peripheral nervous system = Schwann Cells

astrocytes

Star-shaped cells that participate in synaptic formation and pruning

• Making and killing connections

microglial cells

extend and retract when needed; activate in response to injury and “contain” a damaged area + remove debris

• “immune system of the nervous system”

Radial Glia

guide nuerons/axon growth during brain development

Blood brain barrier

The cells separating the blood vessels in the brain from the extracellular fluid (brain fluid)

Types of blood brain barrier cells

1. endrothelial cells

2. astrocytes

endothelial cells

limits the diffusion of chemicals into the brain

Astricytes

provide support to the endothelial cells

Passive transport in the BBB

When chemicals are allowed to freely pass through the BBB

• Ex. Oxogyn, CO2, alchol

Active transport

When energy is needed to move chemicals through the BBB

• Ex. Glucose, amino acids

Function division of a neuron

1. input zone

   1. Dendrites; where info is received

2. integration zone

   1. cell body; info is processed, decision is made to send AP

   2. Decision is made in the axon hillock

3. Conduction zone

   1. Axon; AP is sent down neuron

4. output zone

   1. axon terminals; neurotransmitters are sent across the synapse