Transcript Ch 8 Neurons and Network properties part-1

Chapter 8
The Nervous System
Organization of nervous system

Central Nervous System

Peripheral Nervous System
Integration of CNS and PNS
The Neuron is the

Functional unit of the nervous system
The “model” neuron
Peripheral Nervous System
Afferent Neurons

Sensory Receptors send information to CNS
Efferent Neurons

Carry information to effector cells of the body
PNS is divided into

1. Autonomic Division
– Sympathetic branch
– Parasysmpathetic branch
PNS is divided into

2. Somatic Motor division
– Controls skeletal muscle
PNS divided into

3. Enteric division
Glial cells of the PNS
Schwann Cells
 Satellite Cells

The PNS and Schwann Cell
Nodes of Ranvier: Are not
covered by myelin
Central Nervous System
Glial cells of CNS


Astrocytes
– Nutrition

Ependymal
– barrier

Microgilia
– Immune
Oligodendrocytes
– Myelin
An overview of glial cells
Remember the neuron…

Communicates information throughout the
body, but how?
Another picture of vertebrate
neuron
By Action Potentials!
Action Potentials are our
nerve impulses.
It’s all to do with communication.
We can look at an action
potential as an electrical event.
First we remember how ions
influence the membrane
potential (Em) of a cell.
Is the charge across this cell zero?
Permeable only to K+
K+
Chemical gradient
Electrical Force
K+
Large non-diffusible
anionic proteins
Volt meter
No!
It is –90 mV! Why?
Now let’s try to think about a living
excitable cell…
Resting Neuron Membrane
Potential
Volt meter
Now what does the volt meter
read?
-70 mV at rest but the Em can
change when a nerve is
“excited”.
But why do we care about these
values?
A change in Em results in NT release!
But how does this change in
charge occur so that the
neurotransmitter can be
released?
A simple flow chart of electrical
events

Graded potentials

Action potentials

Neurotransmitter release
Graded potentials decrease in strength as
they spread out from the point of origin
but may bring about an action potential.
The end of Part 1