Download The Nervous System

The Nervous System
Functions of the Nervous System
 Respond to internal and external stimuli
 Transmit nerve impulses to and away from CNS
 Interpret nerve impulses at the cerebral cortex
 Assimilate experiences in memory and learning
 Initiate glandular secretions and muscle contraction
 Program instinctual behavior
Divided into…
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Central Nervous System (CNS)
 Composed of:
 Brain
 Spinal Cord
Peripheral Nervous System (PNS)
 Composed of:
 Cranial Nerves (from the brain)
 Spinal Nerves (from the spinal cord)
 Ganglia (clusters of cell bodies of
neurons)
 Plexuses (networks of nerves)
Autonomic Nervous System (ANS)
 Functional division of nervous system
 Structures in the brain are the control
centers of the ANS
 Nerves are the pathways for conduction of
these nerve impulses
 Functions to automatically speed up or
slow down body activities
Neurons
 Nerve cells found in both CNS and PNS
Parts of a neuron
 Cell Body
 Similar to other types of cells
 Contains a nucleus
 Dendrites
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Extensions that project from the cell body
Short and branching
Receive signals from other neurons
Transmit impulses to the cell body
 Axon
 Covered in a myelin sheath (like insulation on a wire)
 Myelin is produced by Schwann cells
 Transmit impulses away from the cell body
Types of Neurons
 Sensory Neurons: transmit impulses to the CNS
 Somatic sensory: carry impulses from receptors in the skin,
bones, muscles, and joints
 Visceral sensory: carry impulses from the visceral organs
 Motor Neurons: transmit impulses away from the CNS
 Association neurons (interneurons): conduct impulses
from sensory to motor neurons
CNS: The Brain
 Five Regions
Brain Region
Structures
Telencephalon
Cerebrum
Diencephalon
Thalamus, Hypothalamus, Pituitary Gland
Mesencephalon
Superior & Inferior colliculus, Cerebral peduncles
Metencephalon
Cerebellum and Pons
Myelencephalon
Medulla oblongata
Cerebrum (Telencephalon)
 Two hemispheres
 Connected by the corpus collosum
 Five lobes
 Frontal, Parietal, Temporal, Occipital, Insular
 Responsible for higher functions
 Perception of sensory impulses, instigation of voluntary
movement, memory, thought, and reasoning
 Cortex (outer surface) has elevated fields (gyri/gyrus)
and grooves (sulci/sulcus)
5 Lobes
 Frontal Lobe: voluntary control
of skeletal muscles; personality;
intellectual process; verbal
communication
 Parietal Lobe: cutaneous and muscular sensations;
understanding and utterance of speech
 Temporal Lobe: interpretation of auditory sensations; auditory
and visual memory
 Occipital Lobe: integration of movements in focusing the eye;
correlation of visual images with previous experiences;
conscious seeing
 Insular: memory; integration of other cerebral activities
Diencephalon
 Thalamus: a relay center for all sensory impulses to the
cerebral cortex, except for smell
 Hypothalamus: cardiovascular regulation, body
temperature regulation, water and electrolyte balance,
gastrointestinal activity and hunger, sleeping and
wakefulness, sexual response, emotions, and control of
endocrine functions through stimulation of the anterior
pituitary
 Pituitary Gland: has endocrine functions
Mesencephalon (Midbrain)
 Short section of the brain stem
 Contains:
 Superior colliculi (visual reflexes)
 Inferior colliculi (auditory reflexes)
 Cerebral peduncles (coordinates reflexes)
Metencephalon
 Pons
 Relays impulses from one region of the brain to another
 Many cranial nerves originate here
 Involved with regulating respiratory rate
 Cerebellum
 Consists of two hemispheres
 Involuntary coordination of skeletal-muscle contractions
within muscles, tendons, joints, and sensory organs
Mylencephalon
 Medulla oblongata
 Connects to spinal cord
 Makes up much of the brain stem
 Controls autonomic functions (heart rate, contraction of
blood vessels, rate and depth of breathing)
CNS: The Spinal Cord
 Extends through the vertebral canal of the vertebral
column
 Conducts nerve impulses to and from the brain
PNS: Cranial Nerves
 Innervate structures of the head, neck, and trunk
 Identified by Roman numerals in order of appearance
from front to back
 12 cranial nerves
PNS: Spinal Nerves
 31 pairs
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8 cervical
12 thoracic
5 lumbar
5 sacral
1 cocccygeal
 After exiting the vertebral column, they split, combine, and
split again forming a plexus (there are 4)
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Cervical plexus
Brachial plexus
Lumbar plexus
Sacral plexus
 http://health.nih.gov/category/BrainandNervousSystem