Download Neurons and Functional Neuroanatomy

How is your nervous
system like a computer?
There are four primary functions of
the nervous system
 Sensing the world
– Vision, Hearing, Smell, Taste, Touch
 Transmitting information
 Processing information
 Producing a response
The evolution of the nervous system
reflects increasing complexity and
centralized control
 All animals except sponges have
nervous system tissue
 The most basic nervous system is
the nerve net (e.g. Hydra)
 Increasing centralized control
(ganglia) is evident in worms and
insects (e.g. leech)
 Fish, birds and mammals have
evolved a central control center,
the brain
The human nervous system can be
divided into two components

The central nervous
system
–

Brain and Spinal cord
The peripheral
nervous system
–
–
Any nervous tissue not
contained within bone
Composed of the
sympathetic and
parasympathetic
divisions
The nervous system is composed of
two basic types of cells
Neurons
– The communication mechanisms
• Three types: Sensory, Inter-neuron,
Motor
Glial cells
– The support mechanisms
•Provide myelin
(oligodendrocytes, Schwann
cells)
•Bring nutrients (astrocytes)
•Remove damaged cells
(microglia)
Each part of a neuron has a
particular function
 Dendrites - input
 Cell body (Soma)- integration
 Axon - output
Neurons are always ready to send
information
 An inactive neuron is at its resting potential
– The resting potential is due to more
negatively charged ions inside the cell
(intracellular Cl-, Anions(-), K+)
compared to outside the cell
(extracellular Na+)
When a neuron is stimulated, it may
send an action potential (nerve
impulse) to the next cell in a circuit

Animation
During the action
potential, the charge
across the cell
membrane reverses,
making the inside of
the neuron positive
due to the positive
ions (Na+) moving
from the extracellular
space to the inside of
the cell
 The cell returns to the
resting potential when
K+ ions move to the
extracellular space
The action potential moves down the
length of the axon in one direction
The action potential moves in one direction
because the membrane is refractory (unable to
respond) once the action potential has been
initiated at any particular place on the membrane
The action potential initiates a
chemical process at the synapse

Neurotransmitters
are released into
the synapse
between neurons
when an action
potential reaches
the end of the axon
 There are many
different
neurotransmitters in
the nervous system
Animation
– Each neuron
produces only one
type of
neurotransmitter
The reflex arc illustrates information
flow in the nervous system
Reflexes are automatic. You do not have control
over whether they happen, but you may be able
to control how strong they are.
Functional Neuroanatomy
What does “localization of function”
mean in the nervous system?
Functions are well organized in
the central nervous system
Organization
of the nervous
system begins
in the spinal
cord
Peripheral N.S.
Dermatome
Reflexes
Pattern generation
The reflex arc illustrates information
flow in the nervous system
Reflexes are automatic. You do not have control
over whether they happen, but you may be able
to control how strong they are.
The anatomy and function of the
brain can be best understood in
3 dimensions
This is the
middle of
your brain
This is the
side of your
brain
The brainstem controls basic life
functions
Heart-rate,
breathing
and control
of other
internal
organs is
controlled
here.
Damage
here will
usually kill
Coma
Cranial nerves you.
Pupil function
Fight or Flight
Medulla
The Limbic System controls your
emotions and memories
Damage to
these areas
of the brain
can lead to
amnesia or
emotional
disturbances
Declarative amnesias
Partial seizures
Attention deficits
Fear/Aggression
The basal ganglia and cerebellum
control movement and output from
the brain
The basal ganglia put movements in order and the
cerebellum makes them happen at the right time
Sequence and Timing
Eye movements
Motor tasks
Procedural amnesia
balance and coordination
Parkinson’s Disease
Huntington’s Chorea
Ataxia
The cortex is where anything you
experience and/or learn is stored
Frontal
There are four main lobes of the cortex, each with
different functions
Parietal
Movement
Planning and decisions
Temporal
Declarative Memory
Hearing
Emotion
Sense of Space
Touch
Occipital
Vision
The sensory and motor homunculi are a
perfect example of functional organization
in the nervous system
‘Little man’ Homonculus