Download The Human Nervous System

The Human Nervous System
Major Organs
Brain, Spinal Chord, Nerves
Major functions
• Sensory
– Millions of sensory receptors detect changes, called
stimuli, which occur inside and outside the body.
• Integration
– Decisions that are made based on the sensory input.
• Motor
– The response of the nervous system by sending
signals to muscles, causing them to contract, or to
glands, causing them to produce secretions.
The Neuron ~functional unit of the
nervous system!
All neurons have 3 main parts:
1. Dendrites receive information from another cell
and transmit the message to the cell body.
2. The cell body contains the nucleus, mitochondria
and other organelles typical of eukaryotic cells
3. The axon conducts messages away from the cell
body.
Types of Neurons
• Neurons can also be classified by the direction
that they send information.
– Sensory (or afferent) neurons: send information
from sensory receptors (e.g., in skin, eyes, nose,
tongue, ears) TOWARD the central nervous system.
– Motor (or efferent) neurons: send information
AWAY from the central nervous system to muscles or
glands.
– Interneurons: send information between sensory
neurons and motor neurons. Most interneurons are
located in the central nervous system.
Neuron Communication
• Neurons
communicate with
each other through
the use of
neurotransmitters.
• Neurotransmitters
are released from
the axon into the
synaptic cleft
between an
adjacent axons
dendrite
Pathway of a Nerve Stimulus
Tip of axon
releases
neurotransmitter into the
synaptic cleft
Dendrite
receives
stimulus
(impulse)
Axon takes impulse
away from
the cell body
Impulse travels
through the cell
body
CNS & PNS
Central Nervous System & Peripheral
Nervous System
Nervous System Regulation
• The
sympathetic
& parasympathetic
systems are
in control of
the major
organs of
the body.
Common
Nervous System
Diseases
Depression
& Addictions
(neurotransmitters)
Alzheimer’s
& Schizophrenia
(physiology)
Carpel Tunnel
&
Spina Bifida
(nerves)
Bacterial & Viral disease
Rabies is spread by infected
saliva that enters the body
through a bite or broken skin.
The virus travels from the
wound to the brain, where it
causes swelling, or
inflammation, and if
untreated…death
Haemophilus influenzae ,
Streptococcus neumoniae,
group B Streptococcus, Listeria
monocytogenes, and Neisseria
meningitidis can all cause
meningitis. Symptoms include
brain damage, hearing loss,
learning disabilities and
possible death. It is spread
through secretions, air and
contaminated food.
Career Opportunities
•
•
•
Child Neurology - specializes in the
diagnosis and management of
neurologic conditions in children.
Clinical Neurophysiology- A
neurologist who specializes in the
diagnosis and management of central,
peripheral, and autonomic nervous
system disorders using a combination
of clinical evaluation and
electrophysiologic testing such as
electroencephalography (EEG),
electromyography (EMG), and nerve
conduction studies (NCS), among
others.
Pain Medicine - provides a high level
of care, either as a primary physician
or consultant, for patients experiencing
problems with acute, chronic or cancer
pain in both hospital and ambulatory
settings.
Drugs & the Nervous System
Nicotine causes the nervous system to become more
sensitive & stimulated. This leads to short term effects:
– increase in blood pressure
– heart rate
– faster respiration constriction of the arteries.
Long-term effects of smoking on the
nervous system are quite dangerous.
People who smoke are more susceptible
to cancers and muscular sclerosis.
Drugs, continued
Anabolic Steroids have
many effects on many
different organ systems. For the nervous
system, steroids cause an increase in
aggression ~ “Roid Rage”, irritability and severe
fluctuation in moods. Users can also develop a
dependency on this drug ~ they can become
addicted. Users are also at an increased risk of
committing suicide because of severe
depression caused by steroid use.
Drugs, Continued
Alcohol has profound effects on neurons and the
nervous system. Alcohol:
• Impairs memory, judgment & reasoning
• Depresses the actions of the Central Nervous
System; therefore, decreasing reaction times and
vital organ function.
• Causes neuropathy,
dementia, Wernicke's
encephalopathy and clinical
depression
• Can lead to suicide and
sleep disorders
Drugs, continued
Methamphetamine is a
stimulant that causes actual physical changes to
the brain. It effects the level of dopamine in the
brain and is highly addictive.
Stimulants will increase the activity of the Central
Nervous System
Anxiety, confusion, insomnia, depression and
mood disturbances and displays of violent
behavior are common with “meth” use.
Psychotic episodes are prevalent, such as
paranoia, hallucinations and delusions.