Chapter 11. Functional Organization of Nervous Tissue. Functions of the Nervous System. Collect Sensory Information: Sensory RECEPTORS detect stimuli Monitor internal and external stimuli/change Integration:
Nervous system = PNS + CNS
--Receives sensory input with receptors, sends/conducts sensory info to CNS,
Carry commands to effectors from the CNS
-- links the CNS to sensory information and effector
Processes/integrates sensory information and generates responses
Receptor Sensory NS CNS Motor NS Effector
Basic Organization of the Nervous System
More Complete Description of NS organization
Not from your text, chapters don’t match up
NS Organization and Function: worked example
1. Stimulus: light receptors in eye send afferent impulses through sensory neurons (PNS).
2a. CNS integrates (processes) sensory information: you see a bear and are afraid, you decided to run away
2b. CNS generates instructions to run away.
3a. Efferent impulses travel through somatic motor neurons (PNS) to cause you skeletal muscle—effectors--to cause you to run away.
3b. Efferent impulses travel through visceral motor neurons (ANS/PNS) to smooth muscle (effector) and glands (effector) to do things like increase heart, respiratory rate, and dilate blood vessels so that your skeletal muscles have oxgyen and blood flow they need to function.
Types of Neurons, Structural Categories
Types of Neurons, Structural Categories:Types of neurons based on shape and arrangement of parts
*except in specific, limited areas of the brain
These Electrical Impulses:
Myelin sheath = repeated wrapping, creating a layer of lipid & proteins rich PM over the axon surface.
The Myelin sheath:
“insulates” axons from one another,
speeds transmission of action potential
Nodes of Ranvier
Completion of Development of myelin sheaths at 1 yr.
Degeneration of myelin sheaths occurs in multiple sclerosis and other disorders (de-myelination disorders).
Schwann Cells in PNS
Oligodendrocytes in CNS
Rest/are located in in invaginations of Schwann cells
Not wrapped around the axon
Don’t speed impulse
Two influences on speed of action potential
of unipolar neuron