ZOO 2090 Lecture Notes - Lecture 19: Afferent Nerve Fiber, Motor Neuron, Schwann Cell
ZOO2090 – Nervous System
Function: the nervous system (along with endocrine system) determines the response of
the body to changes in its environment
*a sensory-motor integration system
Types of Cells
• Neurons
o Can be classified according to function (sensory, motor, interneuron) or
morphology (unipolar, bipolar, multipolar)
o Cell body (soma) usually bears dendrites receiving information and sends
one or more axons transmitting impulses (action potentials)
• Glia (neuroglia)
o Two types of axon-ensheathing cells (olgiodendrocytes and Schwann
cells)
o Astrocytes mostly involved in structural and metabolic support and
microglia are part of the immune system
Synapse: an axon of one neuron with a dendrite/nerve cell body of another neuron
• Directional transmission of signal from one neuron to another = synaptic
transmission (through synaptic cleft)
Composition:
• Division by location:
o CNS
▪ Brain and spinal cord (also interneurons)
o PNS
▪ Nerves and ganglia outside CNS
▪ Two types of neurons:
• Afferent (sensory) – impulse from receptor organ to CNS
• Efferent (motor) – CNS to receptor organ
*a nerve can be all sensory/motor or mixed
• Division by function:
o Somatic Nervous System
▪ Sensory/motor fibers to skin and derivatives plus voluntary
muscles
o Visceral Nervous System
▪ Sensory/motor fibers to viscera and derivatives (smooth muscle
and glands)
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Document Summary
Function: the nervous system (along with endocrine system) determines the response of the body to changes in its environment. Synapse: an axon of one neuron with a dendrite/nerve cell body of another neuron: directional transmission of signal from one neuron to another = synaptic transmission (through synaptic cleft) Composition: division by location, cns, brain and spinal cord (also interneurons, pns, nerves and ganglia outside cns, two types of neurons, afferent (sensory) impulse from receptor organ to cns, efferent (motor) cns to receptor organ. *a nerve can be all sensory/motor or mixed: division by function, somatic nervous system, sensory/motor fibers to skin and derivatives plus voluntary muscles, visceral nervous system, sensory/motor fibers to viscera and derivatives (smooth muscle and glands) Reflex arcs (know dorsal and ventral roots: afferent fiber to receptor organ & efferent fiber to muscle, from a sense organ & to excite a muscle (or inhibit antagonistic muscle) Somatic reflex arc how posture is maintained.