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Nervous System
Functions of Nervous System• The nervous system is the major controlling,
regulatory, and communicating system in the body.
• It is the center of all mental activity including thought, learning, and memory.
• Together with the endocrine system, the nervous system is responsible for regulating and maintaining homeostasis.
• Through its receptors, the nervous system keeps us in touch with our environment, both external and internal.
Central Nervous System (CNS)• Includes Brain and
Spinal Cord• Responsible for
integrating motor and sensory information
• Seat of intelligence memory and emotion
Peripheral Nervous System (PNS)• Includes all nerve
tissue outside the CNS– Afferent division –
brings sensory information TO CNS
– Efferent division – sends commands FROM CNS to muscles and glands
Somatic Nervous System (SNS)• Part of the efferent
system of the PNS• Voluntary control
over skeletal muscles
A. Central nervous system B. Peripheral nervous systemB1. Somatic nervous systemB2. Autonomic nervous system
Diagram :
Autonomic nervous system (ANS)• Part of the PNS • Automatic regulation of smooth muscle, cardiac
muscle and gland activity or secretions
Cellular Organization in Neural Tissue
Neuron with synapse
Classes of Neurons
Neuron transmission – sending & receiving
Cellular Organization in Neural Tissue• Neuroglia
– Regulate environment around neuron
– Provide support for neural tissue
– Act as phagocytes– Aka glial cells– More numerous than
neurons
Neuroglia, aka glial cells
Diagram pg 201 (black book)• Interaction of neurons and glial cells
Neuroglia- Astrocytes• Most numerous• Maintain the blood brain
barrier• Repair damaged neural tissue
Neuroglia- oligodendrocytes• Create myelin• Improves the speed of impulse conduction on an axon
Neuroglia- microglia• Smallest and rarest• Phagocytic white blood cells• Protect neurons
Neuroglia- ependyma• Produce cerebral spinal fluid (CSF)
Neuroglia- Schwann cells• Most important glial cells• Also create myelin
Neurotransmitters• Chemical that send messages from neuron to
neuron or from neuron to other tissues– Ach – stimulates muscle contraction– Norepinephrine – creates an excited state in the
organism– Dopamine and serotonin – effects are inhibitory
Dopamine and CocaineCocaine is a mood-altering drug that interferes with normal transport of the neurotransmitter dopamine, which carries messages from neuron to neuron. When cocaine molecules block dopamine receptors, too much dopamine remains active in the synaptic gaps between neurons, creating feelings of excitement and euphoria.
Blood Brain Barrier• Maintained by astrocytes• Cause capillaries of CNS to
become impermeable to many compounds
• Example: some antibiotics can not help heal brain infections because they can’t cross the barrier
Great Animations to help
An Unbelievable Brain!!!
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