Download Nervous System

Nervous System
NERVOUS SYSTEM
•
Two major divisions
1. Central Nervous System (CNS)
2. Peripheral Nervous System (PNS)
•
Three specific functions
1. Receives sensory input
2. Performs integration of all input
3. Generates motor output
Nervous System Overview
• Nervous System
–Brain
–Spinal cord
–Nerves
NERVOUS TISSUES
• 1- NEURON
• 2- NEUROGLIA
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Neuron
structural unit of nervous system that transmits impulses
•
Cell body
–
•
Dendrites
–
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Receives input from dendrites, then produces
single impulse
Receive signals from other nerve cells
Axon
– Signal sent to several other neurons. Axons are
bundled together to form nerves. Many axons are
insulated by a mylein sheath.
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Myelination
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Nervous Tissue (cont’)
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Neurons
1. Three types of neurons
a. Sensory neurons – transmit nerve
impulses from stimulus to the CNS
b. Interneurons – in central nervous
system
c. Motor neurons – instructions away
from to muscles or glands.
NEUROGLIA
• SUPPORTING CELLS PROVIDING SUPPORT AND
NOURISHMENT FOR NEURONS
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Divisions of the Nervous System
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Nervous System Divisions
Nervous System Divisions
• Central Nervous System (CNS)
– Brain
– Spinal Cord
BRAIN
• The brain has four main parts
–Brain stem + midbrain
–Diencephalon
–Cerebellum
–Cerebrum
PERIPHERAL NERVOUS SYSTEM
• Peripheral Nervous System (PNS)
– 12 Pairs of Cranial Nerves
– 31 Pairs of Spinal Nerves
• Transmits sensory and motor impulses back and forth
between CNS and rest of body
Peripheral Nervous System
• Somatic Nervous System (SNS)
– Provides voluntary control over skeletal muscle
contractions
• Autonomic Nervous System (ANS)
– Provides involuntary control over smooth
muscle, cardiac muscle, and glandular activity
and secretions in response to the commands of
the central nervous system
Autonomic Nervous System
• Sympathetic nerves
– Increase heart rate
– Raise blood pressure
• Parasympathetic nerves
– Slow heart rate
– Increase glandular secretions