Chapter 11 - Nervous Tissue Organization Flashcards
Ganglion
Collection of neuron cell bodies outside the brain and spinal cord
Plexus
Extensive network of axons, and sometimes neuron cell bodies, located outside the CNS
Functions of the nervous system
-Maintain homeostasis
-Receiving sensory input
-Integrating information
-Controlling muscles and glands
-Establishing and maintaining mental activity
Sympathetic division of ANS
Prepares body for physical activity
Parasympathetic division of ANS
Regulates resting functions such as digesting food or emptying the bladder
Enteric division of ANS
Plexuses within the walls of the digestive tract
Nissl bodies
Rough ER of neurons
Glial cells of the CNS
-Astrocytes
-Ependymal cells
-Microglia
-Oligodendrocytes
Glial cells of the PNS
-Schwann cells
-Satellite cells
Astrocytes
-Processes form feet that cover surfaces
-Regulate (blood brain barrier)
-Regulate extracellular brain fluid composition
Ependymal cells
-Line brain ventricles and central canal
-Specialized versions form choroid plexus
Choroid plexus
-Secrete CSF
-Cilia help CSF move through brain
-Long processes that extend through brain tissue, similar functions to astrocytes sometimes
Microglia
Specialized macrophages
Oligodendrocytes
-Form myelin sheaths of surrounding axon
-Can form sheaths around several axons
Schwann cells
-Form myelin sheath around only one axon
-Wrap around many times
Satellite cells
-Surround neuron cell bodies in sensory ganglia
-Provide support and nutrients
Gray matter
-Unmyelinated axons
-Cell bodies
-Dendrites
-Glia
-Integrative functions
-Outer cortex in brain, deeper in spinal cord
White matter
-Myelinated axons
-Nerve tracts propagate actin potentials from one area to another in CNS
-Deep to cortex in brain, outer part of spinal cord (forms nerve tracts)
Ganglia
-PNS gray matter
-Groups of cell bodies
What is the most common way neuron cells become depolarized?
Sodium ions - if the gated sodium channels open, sodium ions diffuse into the cells and the inside becomes more positive
What is the most common way neuron cells become hyperpolarized?
Potassium ions - if their gated channels open, they diffuse out of the cell, and the inside of the cell becomes more negative
Subthreshold stimulus
Does not cause a graded potential that is great enough to initiate an action potential
Threshold stimulus
Causes a graded potential that is great enough to initiate an action potential
Maximal stimulus
Just strong enough to produce a maximum frequency of action potentials