Download Chapter 02: Neurons and Glia

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Chapter 02: Neurons and
Glia
Slide 1
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Introduction
“Neurophilosophy”
Brain is the origin of mental abilities
Glia and Neurons
Glia: Insulates, supports, and nourishes
neurons
Neurons
Process information
Sense environmental changes
Communicate changes to other neurons
Command body response
Slide 2
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Neuron Doctrine
Histology
Study of tissue
structure
The Nissl Stain
Facilitates the
study of
cytoarchitecture in
the CNS
Slide 3
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Neuron Doctrine
Golgi-stain shows two parts of neurons:
Soma and perikaryon
Neurites: Axons and dendrites
Slide 4
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Neuron Doctrine
Cajal’s Contribution
Neural circuitry
Neurons communicate by
contact, not continuity
Neuron doctrine
Neurons adhere to cell
theory
Slide 5
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Prototypical Neuron
Neuronal membrane
The Soma
Cytosol: Watery fluid inside the cell
Organelles: Membrane-enclosed
structures within the soma
Cytoplasm: Contents within a cell
membrane (e.g., organelles, excluding
the nucleus)
Slide 6
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Prototypical Neuron
The Soma
Gene expression
Protein synthesis
RNA splicing
Molecular biology
Slide 7
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Prototypical Neuron
The Soma
Rough Endoplasmic
Reticulum (ER)
Major site for protein
synthesis
Free ribosomes
Polyribosomes
Slide 8
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Prototypical Neuron
The Soma
Rough ER
Protein synthesis in neurons
Slide 9
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Prototypical Neuron
The Soma
Smooth ER and Golgi Apparatus
Sites for preparing/sorting proteins for
delivery to different cell regions
(trafficking) and regulating substances
Slide 10
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Prototypical Neuron
The Soma
Mitochondrion
Site of cellular
respiration (inhale
and exhale)
Krebs cycle
ATP- cell’s energy
source
Slide 11
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Prototypical Neuron
The Neuronal Membrane
Barrier that encloses cytoplasm
~5 nm thick
Protein concentration in membrane varies
Structure of discrete membrane regions
influences neuronal function
Slide 12
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Prototypical Neuron
The Cytoskeleton
Not static
Internal scaffolding of
neuronal membrane
Three “bones”
Microtubules
Microfilaments
Neurofilaments
Slide 13
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Prototypical Neuron
The Axon
Axon hillock (beginning)
Axon proper (middle)
Axon terminal (end)
Differences between axon
and soma
ER does not extend into
axon
Protein composition:
Unique
Slide 14
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Prototypical Neuron
The Axon
The Axon Terminal
Differences between the cytoplasm of
axon terminal and axon
No microtubules in terminal
Presence of synaptic vesicles
Abundance of membrane proteins
Large number of mitochondria
Slide 15
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Prototypical Neuron
The Axon
Synapse
Synaptic transmission
Electrical-tochemical-to-electrical
transformation
Synaptic transmission
dysfunction
Mental disorders
Slide 16
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Prototypical Neuron
The Axon
Axoplasmic transport
Anterograde (soma to terminal) vs.
Retrograde (terminal to soma) transport
Slide 17
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
The Prototypical Neuron
Dendrites
“Antennae” of
neurons
Dendritic tree
Synapse - receptors
Dendritic spines
Postsynaptic
(receives signals
from axon terminal)
Slide 18
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Classifying Neurons
Classification Based on
the Number of Neurites
Single neurite
Unipolar
Two or more neurites
Bipolar- two
Multipolar- more
than two
Slide 19
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Classifying Neurons
Classification Based on
Dendritic and Somatic
Morphologies
Stellate cells (starshaped) and
pyramidal cells
(pyramid-shaped)
Spiny or aspinous
Slide 20
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Classifying Neurons
Further Classification
By connections within the CNS
Primary sensory neurons, motor neurons,
interneurons
Based on axonal length
Golgi Type I
Golgi Type II
Based on neurotransmitter type
e.g., – Cholinergic = Acetycholine at
synapses
Slide 21
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Glia
Function of Glia
Supports neuronal
functions
Astrocytes
Most numerous glia in
the brain
Fill spaces between
neurons
Influence neurite
growth
Slide 22
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Glia
Myelinating Glia
Oligodendroglia (in
CNS) and Schwann cells
(in PNS)
Insulate axons
Node of Ranvier
Region where the
axonal membrane is
exposed
Slide 23
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Glia
Myelinating Glia
(Cont’d)
Oligodendroglial
cells
Node of Ranvier
Other NonNeuronal Cells
Microglia as
phagocytes
(immune)
Slide 24
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Concluding Remarks
Structure Correlates
with Function
Structural
characteristics of a
neuron tell us about
its function
NEURONS
Soma
Axons
Dendrites
Synapse
e.g., Dense Nissl
stain = protein;
suggests
specialization
Elaborate
structure of
dendritic tree =
receiver
Slide 25
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
End of Presentation
Slide 26
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins