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Lecture

The peripheral nervous system.docx

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Department
Biological Sciences
Course Code
BIO 121
Professor
Jason Ramsay

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The peripheral nervous system
-Afferent:
Somatic sensory portion: monitors skeletal muscles and joints
Visceral sensory portion: monitors smooth muscles, cardiac muscle and
other internal organs.
-Efferent:
Somatic motor: controls skeletal muscle contraction
Visceral motor (autonomic): controls internal
The autonomic nerves can be further subdivided to form:
Parasympathetic nerves: cause pupil constriction, decrease heart rate,
and tense the urinary bladder
Sympathetic nerves: cause pupil dilation, increase heart rate, and
relax urinary bladder.
Neural tissue consists of two cell types:
1. Neurons: nerve cells that are responsible for the transfer and processing of
information in the nervous system. Consist of soma, axon, and dendrites.
2. Neuroglia: supporting cells & protect the neuron
Functions of Neuroglia
1. Provide the framework for the neural tissue
2. Maintain the intercellular environment
3. Act as phagocytes
Over one billion
Roughly
Types of Neuroglia
Astrocytes: in the CNS
Have the large number of cytoplasmic processes
Control the chemical content of the interstitial environment
Maintain the blood-brain barrier.
Oligodendrocytes: CNS
Cytoplasmic extensions contact the soma and axons
Cytoplasmic extensions tie axons together in a sheath of myelin
Microglia
Phagocytic cells
Protect the neuron by removing waste and debris
Ependymal cells
Line the ventricles of the brain
Line the central canal of the spinal cord
Monitor the CSF (cerebral spinal fluid)
Some of the ependymal cells secrete CSF
Satellite cells
regulate the exchange of material between the cell body and the
environment
Schwann cells
Also called neurolemmocytes

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Description
The peripheral nervous system -Afferent:  Somatic sensory portion: monitors skeletal muscles and joints  Visceral sensory portion: monitors smooth muscles, cardiac muscle and other internal organs. -Efferent:  Somatic motor: controls skeletal muscle contraction  Visceral motor (autonomic): controls internal  The autonomic nerves can be further subdivided to form:  Parasympathetic nerves: cause pupil constriction, decrease heart rate, and tense the urinary bladder  Sympathetic nerves: cause pupil dilation, increase heart rate, and relax urinary bladder. Neural tissue consists of two cell types: 1. Neurons: nerve cells that are responsible for the transfer and processing of information in the nervous system. Consist of soma, axon, and dendrites. 2. Neuroglia: supporting cells & protect the neuron Functions of Neuroglia 1. Provide the framework for the neural tissue 2. Maintain the intercellular environment 3. Act as phagocytes  Over one billion  Roughly Types of Neuroglia  Astrocytes: in the CNS  Have the large number of cytoplasmic processes  Control the chemical content of the interstitial environment  Maintain the blood-brain barrier.  Oligodendrocytes: CNS  Cytoplasmic extensions contact the soma and axons  Cytoplasmic extensions tie axons together in a sheath of myelin  Microglia  Phagocytic cells  Protect the neuron by removing waste and debris  Ependymal cells  Line the ventricles of the brain  Line the central canal of the spinal cord  Monitor the CSF (cerebral spinal fluid)  Some of the ependymal cells secrete CSF  Satellite cells  regulate the exchange of material between the cell body and the environment  Schwann cells  Also called neurolemmocytes  Form the myelin sheath Details of Neuron Structure -Axon (nerve fiber) consists of: o Axon hillock area o Axoplasm o Axon vesicles containing neurotransmitters -Dendrites: stimulated by environmental changes or the activities of the other cells -Cell body: contains the nucleus, mitochondria, ribosomes, and other organelles and inclusions. -Axons: conduct nerve impulse (action potential) toward synaptic terminals. -Terminal boutons: affect another neuron or effector organ (muscle or gland) 1. Synapses with another neuron 2. Neuromuscular synapses 3. Neuroglandular synpases -Nissl bod
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