Download Sensory neurons - Russell-Moro

The neurons are the cells
of the nervous system
The neurons are specialized cells.
They deliver «messages»
The Nervous System
Central Nervous System
Brain
Spinal Cord
Peripheral Nervous System
Motor Neurons
Somatic Nervous System voluntary
movements via skeletal muscles
Sympathetic
Sensory Neurons
Autonomic Nervous System
innervate the heart, the glands
Parasympathetic
STRUCTURE OF THE NEURON
Neurons have extensions that are called dendrites and axons
Cell Body or Soma
the control center of the neuron
Function: Direct impulses from the dendrites to the axon
Nucleus
Control center of the Soma.
Dendrites
Thin and short
branches
Function: take information to
the neuron
Axon single and long nerve fibre
Function : take information (electrical message) from the soma
to the opposite end of the neuron.
Neuron
at the microscope
Message transmission
3 main types of nerve cells
sensory
neurone
relay
neurone
motor
neurone
Sensory neurons receive a stimulus from::
eyes - sight
ears - hearing
nose - smell
skin - touch
mouth - taste
Relay neurons interpret incoming sensory information
Glial cells
nutrono i
neuroni
Motor neurons send impulses to effector organs and
tissues (muscles and glands)
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How do Neurons Communicate?
On average the impulse goes
through an axon
one metre per second
- Electrical Communication
- Chemical Communication
A medullary sheath protects some axons,
working as an insulator
The cells of Schawnn form the medullary sheath
Nodes of Ranvier : these are areas discovered between Schwann cells.
The impulse jumps from node to node and it spreads
at a speed 100 times superior
What is a synapse ?
The nerve cells communicate among
them through areas called synapse
Dendrites
Cell Body
Myelin
Sheath
Axon of another
neuron
Axon
Dendrites of
another neuron
Electron microscope photo
A lot of synapses surround a neuron
The Cerebral Cortex is the most evolved and complex
structure of our brain
Our cerebral cortex
contains about
125 thousand billion
synapses
SINAPSE
The two neurons are
separated by a small
space.
The communication
takes place via
messengers: the
neurotransmitters
Communication
• The Impulse releases
neurotransmitter from
vesicles
• The Neurotransmitter
enters synaptic gap
• The Neurotransmitter
binds the receptors on the
receiving neuron
• The signal moves forward
Other cells of the brain
Glial cells: Nourish and support nerve cells .
Cover neurons with myelin
The astrocytes are particular glial cells that regulate the spreading
of the neurotransmitters
At the microscope
Glial cells
Synapse
Leonardo’s drawing
About 500 million years ago
the first organisms with
neurons appeared.
This is the first elementary
nervous system. Today in
the human brain only the
complexity in which neurons
are organized has changed