Transcript the structure of the nervous system

THE STRUCTURE OF
THE NERVOUS
SYSTEM
By: Andrea
Tremper
Annabelle
Afra
Yarshar
Kermue
Central Nervous System (CNS)
• The central
nervous system
is the part of the
nervous system
that consists of
the brain and
spinal cord.
• It is one of the
two major
divisions of the
• The brain is protected by the skull, while
the spinal cord is protected by the
vertebrae.
• The CNS is contained within the dorsal
cavity, with the brain in the cranial cavity
• The CNS is responsible for integrating,
processing, and coordinating sensory data
and motor commands.
• Sensory data convey information about
conditions inside or outside the body.
• Motor commands control or adjust the
activities of peripheral organs, such as
skeletal muscles.
• The CNS- specifically the brain- is also the
seat of higher functions, such as
intelligence, memory, learning , and
Peripheral Nervous System
(PNS)
• The peripheral
nerves include
the 12 cranial
nerves, the spinal
nerves and roots.
• The Cranial
Nerves are
connected to the
brain, while the
spinal nerves are
connected to the
• The nerves in the
peripheral nervous
system connect the
central nervous
system to sensory
organs, other
organs of the body,
muscles, blood
vessels and
glands.
• It delivers sensory information to the CNS
and carries motor commands to peripheral
tissues and systems.
• Bundles of axons, or nerve fibers, carry
sensory information and motor commands
in the PNS.
• The PNS is divided into afferent and
efferent divisions.
• It is also divided into two major parts, the
somatic nervous system and the automatic
Peripheral Nerves
Afferent
Efferent
vs.
Afferent Neurons
• The afferent nerves
bring sensory
information to the
CNS from receptors
in peripheral tissues
and organs.
• Receptors are
sensory structures
that detect changes
in the internal
environment or
respond to the
• A touch or painful stimulus, for example,
creates a sensation in the brain only after
information about the stimulus travels there
via afferent nerve pathways.
• Just outside the spinal cord, thousands of
afferent neuronal cell bodies are
aggregated in a swelling in the dorsal root
known as the dorsal root ganglion.
• Afferent neurons have a single long
dendrite and a short axon, and a smooth
Efferent Nerves
• Also known as motor neurons, they carry
nerve impulses away from the central
nervous system to effectors such as
muscles and glands.
• These target organs, which respond by
performing an action, are called effectors.
• The cell body of the efferent neuron is
connected to a single, long axon and
several shorter dendrites projecting out of
the cell body itself.
• The cell body of the motor neuron is
satellite-shaped.
• The motor neuron forms an
electrochemical pathway to the effectors'
organ or muscle.
• The Efferent division has both automatic
Somatic Nervous System
(SNS)
• Controls skeletal
muscle contractions
which include both
voluntary and
involuntary
contractions.
• Voluntary
contractions are
under conscious
control, while
involuntary actions
Automatic Nervous System
(ANS)
• Also known as visceral motor system, it
provides automatic regulation of smooth
muscle, cardiac muscle, and glandular
secretions at the subconscious level.
• The ANS includes a sympathetic division
and a parasympathetic division, which
commonly have antagonistic effects.
Somatic
vs.
Automatic
Sympathetic
vs.
Parasympathetic
• It increases the heart • The parasympathetic
rate and blood
system is rest and
pressure and also
digest system.
activates the body's
• It increases the
mechanisms to
blood supply to gut
provide immediate
and increases the
energy to face the
digestion.
stressful state.
• It tries to restore the
• This system utilizes
body's energy
the body's energy
sources.
resources just to
Bibliography
• Martini, H. Fredrick, Garrison, W, Claire, Welch,
Kathleen, Hutchings, T. Ralph. (2006). Fundamentals of
Anatomy & Physiology. The Spinal Cord, Spinal Nerves,
and Spinal Reflexes. San Francisco, CA: Pearson
Education, Inc.
• http://www.templejc.edu/dept/biology/RHicks/biol2404Int/
cavities.gi
• http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/
CNS.html
• http://www.medterms.com/script/main/art.asp?articlekey=
Next Presentation
Neurons
Marissa, Matt, Katelyn
Period 4/5
What is a Neuron?
• Cells in nervous system
• Transmit information
• Communicate chemically and electrically
Types of Neurons
• Sensory- Carry information from receptor cells
to brain
• Motor- transmit information from brain to
muscles
• Inter- communicates between neurons
Structure
• Dendrites- nerve impulses that are generated
in short branch fibers
• Soma/cell body- signals from dendrites are
joined and passed on
• Axon- central nervous system conduct
impulses on hair like cytoplasmic extensions
Structure continued
• Initial segment- point of cell body emergence to
point of myelin initiation
• Axon Hillock- the conical area of origin of the axon
from the nerve cell body
• Telodendria- structures at the terminal branches of
axon that contain neurotransmitters
• Synaptic terminal- a bulb at the end of the axon in
which the neurotransmitter molecules are stored
and released
Function
• Sensory Neurons
– Delivers the information from the Sensory
Receptors to the CNS.
• Motor Neurons
– Carry instructions from the CNS to the Peripheral
Effectors in the Peripheral tissue, Organ, or Organ
System.
Functions Continued.
• Neurons conduct impulses along the Nerve
Fibers or Axons.
References
•
•
•
•
•
•
Boeree, C. G., Dr. (2003). The Neuron. Retrieved February 4, 2010, from
http://webspace.ship.edu/
cgboer/theneuron.html
Initial segment. (2010). Retrieved February 3, 2010, from Farlex website:
http://medical-dictionary.thefreedictionary.com/initial+segment
Lefers, M. (2004, July 26). Synaptic Terminal. Retrieved February 3, 2010, from North Western
University website:
http://www.biochem.northwestern.edu/holmgren/Glossary/Definitions/Def-S/
synaptic_terminal.html
Neurons. (2009, December 27). Retrieved February 3, 2010, from http://users.rcn.com/
jkimball.ma.ultranet/BiologyPages/N/Neurons.html
Telodendria . (2010). Retrieved February 4, 2010, from Farlex, Inc. website:
http://www.definition-of.com/telodendria
Van Wagner, K. (2010). What Is a Neuron? Retrieved February 4, 2010, from
http://psychology.about.com/od/biopsychology/f/neuron01.htm
Next Presentation
The Classification
of Neurons
By Adam, Carly and Evan
Anaxonic
• The anaxonic neurons are located in the
brain and in other special sense organs in
the body.
• These neurons are small and it is hard to
tell the difference between dendrites and
axons.
Bipolar Neurons
• The small neurons have two distinct
processes one is the dendritic process the
other is the axon extending from the cell
body.
• Are found only in sensory neurons. (ex.
retina, olfactory, and auditory systems)
Unipolar Neuron
• These are the large neurons that have the
cell body lying to one side of the
continuous dendritic process and axon
• This makes it appear that the cytoplasmic
process splits the axon into two portions
• A peripheral process takes the action
potential to the cell body
Multipolar neurons
• Neurons that have more than three
processes on their cell bodies are
classified as a multipolar
• The processes contained extend from the
soma.
• Multipolar neurons have one axon and
multiple dendrites.
Sensory neurons
Send information about the stimuli collected
by sensory receptors (eyes, ears, nose,
skin, tongue) to the central nervous
system (brain)
Sensory Neurons (cont’d.)
• The cell bodies of sensory neurons are located
in peripheral sensory ganglia. [A ganglion is a
collection of neuron cell bodies in the PNS. (The
PNS is the Peripheral Nervous System)]
• Somatic sensory neurons monitor external
conditions and our position in it.
• Visceral sensory neurons monitor internal
conditions and the status of other organs in it.
Motor Neurons
• There are 3 categories:
• 1. Somatic motoneurons- involved in
contraction of muscles.
• 2. Special visceral motoneurons- involved
in the motion of neck and facial muscles.
• 3. Visceral motoneurons- involved in
contraction of heart, muscles of arteries,
and viscera not consciously controlled.
Links
Neurons
By Han Shi & Melinda Song
A&P Lecture 16
Chapter 12: Neural Tissue
Part 1
References
• McGraw Hill. (2010, February 2). Nerve Cells. In Neurons [Nervous
System]. Retrieved February 4, 2010, from McGraw Hill website:
http://www.getbodysmart.com/index.htm
• Prentice Hall Inc., & Pearson Co. (1999-2000). Neuron
Classification. In Neural Tissue [Neurons]. Retrieved February 3,
2010, from Prentice Hall Inc. website: http://cwx.prenhall.com
• National Institute of Aging, US National Institute of Health, &
ADEAR. (2008, November 25). Neurons. Retrieved February 4,
2010, from US National Institute of Health website:
http://www.nia.nih.gov/Alzheimers/Publications/Unraveling/Part2/hall
marks.htm
• PSYweb.com. (n.d.). Psyweb [Bipolar Neurons]. Retrieved February
4, 2010, from PSYweb website:
http://psyweb.com/Physiological/Neurons/bineuron.jsp