Transcript Nervous System

Nervous System
A major control and
communication system
Neuron
• “neur-” means nerve, so a neuron is a
nerve cell
• Cell body is the part where the organelles,
such as the nucleus, are located
• Dendrite is the receiving end of the neuron
• Axon is the transmitting or conducting end
of the neuron
Nerve
• A group of neurons (specifically their
axons) that are bundled together
anywhere except the brain/spinal cord, is
termed a nerve
Nerve impulse
• A nerve impulse is an electrical message
traveling along a neuron.
Synapse
• A junction between adjacent neurons
• Neurotransmitters are chemicals carrying
nerve message across the synapse
Myelin
• Some neurons have their axons coated in
a fatty substance called myelin.
• Myelin increases the speed of nerve
impulse transmission – as high as 200
mph
• White matter
Central Nervous System
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Brain
Spinal Cord
Control, information processing
Thoughts are formed
Memory is stored
Peripheral Nervous System
• Carries messages to and from the CNS
• Sensory – carries information towards the
CNS
• Motor – carries information away from the
CNS to the muscles and glands
PNS
• Somatic motor information travels to
skeletal muscles
• Autonomic motor information travels to
cardiac muscle, smooth muscle and
glands; responsible for your Fight or Flight
response
Brain
• “enceph-” means brain
• Located in skull
• Medulla oblongata is part of the brainstem
and controls important reflexes that control
breathing, heart rate and blood pressure.
Also is the site where motor and sensory
pathways cross.
Brain
• Hypothalamus is a center of homeostasis
mechanisms such as hunger, thirst, water
balance, temperature regulation; makes
hormones, and controls the Autonomic
Nervous System.
Brain
• Thalamus is a sensory relay center
Brain
• Cerebrum is the largest and highest center
of the brain
• Responsible for conscious awareness,
thinking, intelligence, memory and
deciding your response to sensory input.
Brain
• Electroencephalogram, or EEG, is a
recording of the brain’s electrical activity,
commonly called brain waves.
Spinal cord
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“myel-” means spinal cord
Located within your vertebrae
Sends sensory messages to your brain
Carries motor messages away from your
brain
Spinal Reflexes
• A reflex is an autonomic, quick response
to a stimulus. The reflex is repeatable.
• Spinal reflexes involve the spinal cord and
do not involve conscious thought from the
brain.
CNS Meninges
• Meninges are tough, protective
membranes that surround the brain and
spinal cord.
• Within the meninges is Cerebrospinal
Fluid (CSF) that cushions and provides
nourishment for the CNS
• What is meningitis?
Nervous System Pathology
• Brain damage
• The brain requires oxygen for aerobic
metabolism. Lack of oxygen for more than
5 minutes can kill brain cells.
• The brain requires glucose for metabolism.
Lack of glucose for more than 15 minutes
kills brain cells.
• Neurons cannot undergo mitosis.
Epilepsy
• Brain fires abnormal signals that travel to
skeletal muscles.
• Skeletal muscles contract leading to
seizures.
• May lose consciousness in larger seizures
• Causes are injury, infection, genetic
predisposition, and many causes are
unknown
Epilepsy
• Treatments include correcting the cause, if
known;
• Decreasing the frequency and magnitude
of the seizures with medications.
Multiple Sclerosis
• Many “hard” scars form along the myelin
sheaths of neurons
• Autoimmune disease
• Numerous short circuits occur resulting in
difficulty in vision, memory, walking and
judgment
• Chronic disease that progresses slowly
Cerebral Palsy
• Motor centers are damaged at the time of
birth
• Causes include German Measles,
radiation exposure, oxygen starvation to
the baby’s brain at the time of delivery
• Results in varying degrees of impairment
of motor abilities.