Transcript Organization of the nervous system

The Nervous System
Neurons, Nerves, the Brain and
Neurotransmitters
Organization of the
nervous system
The central nervous system
= The Brain + Spinal Cord
Spinal cord: A collection of
neurons and supportive
tissue running from the base
of the brain down the center
of the back
–Protected by spinal column
But the central nervous system is only one part…
Spinal Reflexes: Who Needs a
Brain?
• For example, pulling your hand away from
something hot
• No need to involve the brain
• “Spinal reflexes” go right from the skin to the
spinal cord back to the muscle
• Neurons that serve the skin and muscles in arms
and legs are part of the peripheral nervous
system
• So, spinal reflexes involve the central and
peripheral nervous systems
Organization of the
nervous system
Peripheral Nervous System
• 43 pairs of nerves
– Nerves are bundles of many, many neurons
• 12 pairs go straight to the brain
• 31 pairs go to the spinal cord (remember
the spinal reflexes?)
Peripheral Nervous System
• Autonomic (think “automatic”): controls
heart, stomach, etc.
• Somatic: Arms and legs – things you
control voluntarily
Autonomic Nervous System
• Sympathetic: Prepares the body for
ACTION!
• Parasympathetic: Rests the body and
restores to get ready for next round.
Organization of the
nervous system
A Neuron is a very special
cell: You have about 100
billion of them!
•Dendrites: Receive
information from other
neurons and transmit
toward the cell body
A Neuron is a very special
cell: You have about 100
billion of them!
•Cell body: Keeps the
neuron alive and
determines whether it will
fire
•Axon:Extending fiber that
conducts impulses away
from the cell body and
transmits to other cells.
Neurotransmitter
Chemical released by a
transmitting neuron at the synapse
and capable of affecting the
activity of a receiving neuron
Major neurotransmitters
Serotonin – involved in treatment of
depression
Dopamine
Acetylcholine (Ach)
Norepinephrine
Gamma aminobutyric acid (GABA)
Glutamate
Endorphins – “runner’s high”
The brain stem
Pons: Involved in
sleeping, waking,
and dreaming
chapter 4
The brain stem
Medulla:
Responsible for
certain automatic
functions such as
breathing and heart
rate
chapter 4
The brain stem
Reticular
activating system:
Arouses cortex and
screens incoming
information
The cerebral cortex: curly