Download Nervous System Period 3 - Mercer Island School District

Nervous System - Period 3
BY KATE, SIERRA, KATHRYN, AND CARSON
WHAT IS THE NERVOUS SYSTEM AND WHAT ARE ITS
FUNCTIONS?
• Complex series of nerves and specialized cells (neurons or nerve
cells) that transmit electrical signals between parts of the body
• Similar to electrical wiring
• Takes in and processes information through the senses and triggers
reactions
• Coordinates muscle activity, monitors organs, constructs and
processes data received from senses and initiates actions
• Metabolic processes also included
ORGANS AND THEIR FUNCTIONS
• Brain and spinal chord – analyze and respond to information accordingly;
sends signals to rest of the body; controls simple musculoskeletal
reflexes
• Eyes – send information to the brain and convert into vision
• Ears – send information to brain and convert it into sounds
• Sensory organs of taste (taste buds, etc.) – send information to the brain
and convert into taste
• Sensory organs of smell - send information to the brain and convert into
smell
• Sensory receptors located in the skin, joints, muscles, and other parts of
the body – send information to the brain and convert into feelings and
response such as touch or heat
HOW DOES THE NERVOUS SYSTEM WORK?
THE NERVE AND ITS PARTS
A. CELL BODY - contains the nucleus
and much of the cytoplasm; most of
the metabolic activity of the cell,
including the generation of ATP and
synthesis of protein.
B. DENDRITES - Short branch
extensions spreading out from the cell
body. Dendrites receive STIMULUS
and carry IMPULSES from the
environment or from other neurons
towards the cell body
C. AXON - Long fiber that carries
impulses away from cell body. Each
neuron has only ONE axon. The axon
ends with AXON TERMINALS
TYPES OF NEURONS
Sensory neuron
Length of Fibers
Long dendrites and
short axon
Location
Cell body and dendrite
are outside of the
spinal cord; the cell
body is located in a
dorsal root ganglion
Function
Conduct impulse to
the spinal cord
Interneuron
Motor Neuron
Short dendrites and
short or long axons
Short dendrites and
long axons
Entirely within the
spinal cord or CNS
Dendrites and the cell
body are located in
the spinal cord; the
axon is outside of the
spinal cord
Interconnect the
Conduct impulse to an
sensory neuron with
effector (muscle or
appropriate motor
gland)
neuron
• Axon is covered by lipid layer called MYELIN SHEATH that speeds up
transmission of messages
• Axon terminals may come into contact with dendrites, effectors, or
receptors to pass on messages
• Receptors are in sense organs; effectors are muscles or glands that
coordinate a response
• Impulses are passes from one cell to another through SYNAPSES
(gap between axon of one neuron and dendrite or cell body of
another neuron)
• Chemicals, or neurotransmitters, bridge this gap to transfer
information to each other through electrical signals received from
receptors or effectors; neurotransmitters are released when an
electrical impulse reaches the end of a neuron
QUICK SUMMARY
• Nerve has a cell body with multiple extensions
• The shorter extensions (dentrites) act like antennae and receive
signals
• The longer extension (axon) passes along signals to other cells
which are relayed to the brain
• Synapses and neurotransmitters bridge the gap between cells to
relay messages to the brain
TWO MAIN PARTS OF THE SYSTEM
CENTRAL
PERIPHERAL
• Composed of the brain and spinal Composed of everything but the
brain and spinal chord
chord
Purpose: to connect the limbs and
• Purpose: to collect information
organs
to
the
central
nervous
and respond accordingly
system
• Living nervous tissue has
• Consists of 12 pairs cranial nerves
consistency of jelly and must
and 31 pairs of spinal nerves, some
are exclusively sensory
have special protection from
damage
• Sensory cells carry messages to the
• Interprets messages from the
peripheral nervous system
central nervous system and motor
cells carry the signal from the CNS to
the organs, muscles, etc.
THE NERVOUS SYSTEM AND OTHER SYSTEMS
BODY SYSTEM
INTERACTION
• Cardiovascular • The brain receives information about blood pressure
• Endocrine
• Lymphatic
• Respiratory
• Digestive
through baroreceptors; regulates heart rate and blood
pressure
• Hormones provide information to affect neural processing;
controls pituitary gland and other glands
• Brain stimulates defense mechanisms against infection
• Brain monitors respiratory volume, blood-gas levels, and
respiratory rate
• Digestive system provides building blocks for
neurotransmitters; sends information relating to thirst or
hunger; controls muscles for eating and waste removal
THE NERVOUS SYSTEM AND
OTHER SYSTEMS
WHAT ARE RECEPTORS AND WHAT ARE THEIR FUNCTIONS?
• Receptor: an organ or cell that responds to an external stimulus and
transmits a signal to a sensory nerve
• Interoceptors-transmits pulses to detect stimuli inside of the body
• Exteroceptors- similar to interoceptors but detects stimuli outside of the
body
• Chemoreceptors-detects the concentration of oxygen in the blood
stream
• Photoreceptors-respond to the presence of light
• Mechanoreceptors-responds to mechanical pressure or distortion, touch
• Thermoreceptors- responds to absolute and relative changes in
temperature
DISEASES THAT AFFECT THE NERVOUS SYSTEM
MULTIPLE SCLEROSIS
• Affects brain and spinal cord
• Myelin sheath is damaged (material that
surrounds and protects nerve cells)
• Slows or blocks messages between brain
and body
• Symptoms include: weak muscles,
difficulty with coordination or balance,
difficulty thinking or remembering,
feelings of numbness or prickling
• Cause is unknown; disease can be mild to
severe depending on the affected person
• Currently no cure but medicine and
physical therapy can manage and lessen
symptoms
PARKINSON’S DISEASE
• Malfunction of vital nerve cells, mostly in the
substanita nigra portion of the brain
• Malfunctioning neurons die and release dopamine
(a chemical that messages the part of the brain
that controls movement and coordination)
• Progressive movement disorder, which means
symptoms continue and worsen over time
• As the disease worsens, dopamine levels decrease
and the person loses control of their movements
• Symptoms include: tremor, slowness of
movement, rigidity, poor balance or posture
• Cause is unknown; no cure currently but
medication and surgery can manage symptoms
HOW DOES THE NERVOUS SYSTEM HELP MAINTAIN HOMEOSTASIS?
• The central nervous system is comprised of the brain and the spinal
cord, whereas the peripheral nervous system is composed of the
nerve extensions beyond those central pathways. Both, when
combined, interconnect all of the parts of the body and allow for
the processes creating homeostasis to occur. The autonomic
nervous system regulates involuntary bodily functions. Without
interpretation and responses to sensations such as becoming too
warm, the body would become imbalanced.
BIBLIOGRAPHY
• http://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0024762/?figure=1
• https://faculty.washington.edu/chudler/nsdivide.html
http://www.hopkinsmedicine.org/healthlibrary/conditions/nervous_syst
em_disorders/overview_of_nervous_system_disorders_85,P00799/
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0024762/
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0025454/
• http://www.livescience.com/22665-nervous-system.html
• http://www.ninds.nih.gov/disorders/parkinsons_disease/parkinsons_dis
ease.htm
• https://faculty.washington.edu/chudler/organ.html
• http://leavingbio.net/the%20nervous%20system_files/the%20nervous%
20system.htm