Transcript Nervous System - Lemon Bay High School

Nervous System:
An Introduction
HAP
Susan Chabot
Lemon Bay High School
Function of the Nervous System
3 overlapping functions
• SENSORY INPUT - Monitor changes
inside and outside of the body; these
changes are called STIMULI.
• INTEGRATION - Processes and
interprets changing stimuli to decide.
• MOTOR OUTPUT - Effects a response
via activating effectors (muscles or
glands).
Working Together
The Nervous System works with the
Endocrine System to provide electrical and
chemical control of ALL body processes.
Structural Organization
Nervous System
Central Nervous
System
Peripheral
Nervous System
Brain and Spinal
Cord
All neurons not in
brain or spinal
cord
Responsible for
Integration
Responsible for
sensory input
and motor output
Functional Organization
Peripheral
Nervous System
Motor/Efferent
Moves information
AWAY FROM the
CNS
A) Sensory/Afferent
Moves information
TOWARD the CNS
B) Autonomic
Involuntary control of
smooth and cardiac muscles
and all glands
D) Sympathetic
Fight-or-Flight
C) Somatic/Motor
Voluntary control of
skeletal muscles
Parasympathetic
Resting-orDigesting
Autonomic Continuum
Rest
or
Digest
Fight
or
Flight
Cells of the Nervous System
• 2 categories
– Neurons transmit electrical impulses
• Sensory neurons = receptors
• Integration neurons = integrate/think
• Motor neurons = effect a change through
muscles and/or glands
– Neuroglia = Nerve glue
• Protect, insulate, and support delicate neurons
Cells of the Nervous System
• Neuroglia = Nerve Glue
– Astrocytes
• Star-shaped cell that provides a scaffold to
hold neurons in specific locations.
– Oligodendrocytes
• Insulates neurons for speedy transmission of
electrical impulses; similar to insulation for
electrical wires.
– Ependymal Cells
• Produces cerebrospinal fluid (CSF)
– Microglial cells
• Small white blood cells that destroy pathogens
and cell debris.
Meninges
Protection of the CNS
• Meninges
– What Are They? Connective tissue outer
protection covering of the brain.
– Layers
• Dura mater
• Arachnoid mater – Circulates CSF
• Pia mater
• CSF: Cerebrospinal fluid
– What is It? A watery substance
– How Does it Offer Protection? It bathes the
brain and cushions from trauma.
– How is it Formed? In a Dense capillary bed
by called the CHOROID PLEXUS
Protection of the CNS
• Blood-brain barrier
– What is It? A tight network of capillary beds
that are both
SELECTIVE - Keeps some things out and
other allows other things in.
DIRECTIONAL - Moves INTO the brain not
OUT OF the brain
– How Does it Work? Acts as a successively
smaller filters to keep substances from
entering the circulation of the brain and
spinal cord.
Cells of the Nervous System
Neurons/Nerves
3 main parts
• Dendrite: receives
info from
neighboring neurons.
• Cell body: living
portion of the neuron;
contains the nucleus
and organelles.
• Axon: sends info to
neighboring neurons.
Cells of the Nervous System
Synapse
– Space in between neighboring neurons.
– Contains neurotransmitters; chemicals
that are released to control info/activity
in brain.
Types of Synapses
• Neuron-to-Neuron
Found throughout Nervous
System
• Neuron-to-Muscle
Neuromuscular
• Neuron-to-Gland
Neuroglandular
Bipolar
Unipolar
Multipolar
Anaxonic
Appearance
Location
Function
2 extensions on opposite
ends of cell body
Special senses in
skull
Collect sensory
info for sight,
hearing, smell,
taste
1 continuous extension,
cell body pushed to side
Special senses far
from brain
Collect sensory
info for pain,
pressure, touch
Brain
MultiPolar
Many dendrites, single
long axon
Form networks
that span distance
Brain
Anaxonic
Cannot tell dendrites from
axon
Form close-knit
networks
BiPolar
UniPolar
The Brain
Divisions of the Brain
• Cerebral Cortex: high order processes;
speech, language, cognition.
• Cerebellum: responsible for the
coordination of muscle activity.
• Pons: relays sensory info from the
cerebellum to the cerebral cortex.
• Medulla oblongata: the “primitive” brain;
controls heart rate, respirations, hunger,
thirst.
• Diencephalon: important in the
integration of the nervous and endocrine
system/temperature control