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PNS & CNS - Biology Hw
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PNS & CNS – Biology Hw

The key terms of Biology Homework include, PNS & CNS.


PNS

– Conducts impulses to or away from the CNS. PNS is anatomically and operates continuous with the CNS
– Spinal nerves are part of CNS; CN are part of CNS except 1 and 2
– Ganglion: Collection of neuronal cell bodies outside the CNS


CNS

– Brain and spinal cord
– Retina/optic nerve (CN II)
– Olfactory nerve (CN I)
– Tracts are bundles of axons in CNS
– Development of neocortex allows for higher cognitive functions


Landmarks on Brainstem

– Dorsal: Inferior colliculus (auditory pathway), superior colliculus (eye movements)
– 4th ventricle: Cannot be seen on dorsal view, is only a space
-Ventral: Pontine protuberance (belly of pons)
– GENERAL SENSORY pathways are found in dorsal brainstem
– VOLUNTARY MOTOR pathways are found in ventral brainstem


Cross Sections of Brainstem

– Pontine protuberance is unique to pons
– Inferior olivary nucleus is unique to medulla
– Upper medulla: Open medulla with view of 4th ventricle
– Lower medulla: Closed medulla, no view of 4th ventricle
– Cell bodies stained PINK or WHITE/LIGHT GREY
– Axons are stained BLACK


Other Ways to Classify Neurons

– Types of dendrites: Spiny v aspinous
– Types of connections: Primary sensory v motor
– Axon length: Golgi type 1 (long) v golgi type 2 (short)
– Based on neurotransmitter: Cholinergic (uses acetylcholine) etc


Glia Overview

– Glia support neurons, without glia brain cannot function
– Outnumber neurons 10-50 times
– Glia regenerate much more readily than neurons
– Part of CNS and PNS


Microglia

– Exception to development rule. Development from mesoderm and only seen in CNS where BVs invade
– Important in phagocytosis. BVs have same origin
– Called phagocytes or macrophages during inflammation


PLP Proteolipid Protein

– More than half of the total protein in CNS myelin is this proteolipid
– Involved in spiraling and compaction of myelin
– Hypomyelination and death of oligodendrocytes


MPZ or P0

– Myelin protein zero: Major protein in PNS
– Important in spiraling and compaction
– Tremors, poor motor coordination, etc


Myelin Oligodendrocyte Glycoprotein

– Only in CNS
– A myelin protein expressed on the outermost surface of myelin sheaths and oligodendrocyte membranes
– Minor component of myelin
– Exact mechanism not well known but likely functions as a cell surface receptor or adhesion molecule
– Tends to be targeted by autoantibodies and immune responses in inflammatory demyelinating disease (other than MS)
– Patients may present with vision loss due to optic neuritis


Aberrant Regeneration

– Regeneration to a different target organ
– Regeneration occurs when some of the axons go to other destinations that the nerve may innervate
– Ex. degeneration and regeneration of the axon to the IR -> aberrant regeneration to the LPS -> when pt looks down the lid goes up (can also occur with MR)
– Regeneration of MR may lead to aberrant regeneration of the ciliary ganglion leading ot pupillary constriction with adduction


General Receptor Sensation

– Pain, temperature, touch (many types), and proprioception


Touch

– Subclass of tactile sense
– Tactile stimuli are:
1. 2-point touch or discriminating touch
2. Superficial (gross, light, general) touch, not discriminating
3. Pressure
4. Vibration


Mechanoreceptors

– Cutaneous and subcutaneous
– Tactile, 2-point touch, pressure, and vibration


PNS

– Conducts impulses to or away from the CNS. PNS is anatomically and operates continuous with the CNS
– Spinal nerves are part of CNS; CN are part of CNS except 1 and 2
– Ganglion: Collection of neuronal cell bodies outside the CNS


CNS

– Brain and spinal cord
– Retina/optic nerve (CN II)
– Olfactory nerve (CN I)
– Tracts are bundles of axons in CNS
– Development of neocortex allows for higher cognitive functions


Landmarks on Brainstem

– Dorsal: Inferior colliculus (auditory pathway), superior colliculus (eye movements)
– 4th ventricle: Cannot be seen on dorsal view, is only a space
-Ventral: Pontine protuberance (belly of pons)
– GENERAL SENSORY pathways are found in dorsal brainstem
– VOLUNTARY MOTOR pathways are found in ventral brainstem


Cross Sections of Brainstem

– Pontine protuberance is unique to pons
– Inferior olivary nucleus is unique to medulla
– Upper medulla: Open medulla with view of 4th ventricle
– Lower medulla: Closed medulla, no view of 4th ventricle
– Cell bodies stained PINK or WHITE/LIGHT GREY
– Axons are stained BLACK


Other Ways to Classify Neurons

– Types of dendrites: Spiny v aspinous
– Types of connections: Primary sensory v motor
– Axon length: Golgi type 1 (long) v golgi type 2 (short)
– Based on neurotransmitter: Cholinergic (uses acetylcholine) etc


Glia Overview

– Glia support neurons, without glia brain cannot function
– Outnumber neurons 10-50 times
– Glia regenerate much more readily than neurons
– Part of CNS and PNS


Microglia

– Exception to development rule. Development from mesoderm and only seen in CNS where BVs invade
– Important in phagocytosis. BVs have same origin
– Called phagocytes or macrophages during inflammation


PLP Proteolipid Protein

– More than half of the total protein in CNS myelin is this proteolipid
– Involved in spiraling and compaction of myelin
– Hypomyelination and death of oligodendrocytes


MPZ or P0

– Myelin protein zero: Major protein in PNS
– Important in spiraling and compaction
– Tremors, poor motor coordination, etc


Myelin Oligodendrocyte Glycoprotein

– Only in CNS
– A myelin protein expressed on the outermost surface of myelin sheaths and oligodendrocyte membranes
– Minor component of myelin
– Exact mechanism not well known but likely functions as a cell surface receptor or adhesion molecule
– Tends to be targeted by autoantibodies and immune responses in inflammatory demyelinating disease (other than MS)
– Patients may present with vision loss due to optic neuritis


Aberrant Regeneration

– Regeneration to a different target organ
– Regeneration occurs when some of the axons go to other destinations that the nerve may innervate
– Ex. degeneration and regeneration of the axon to the IR -> aberrant regeneration to the LPS -> when pt looks down the lid goes up (can also occur with MR)
– Regeneration of MR may lead to aberrant regeneration of the ciliary ganglion leading ot pupillary constriction with adduction


General Receptor Sensation

– Pain, temperature, touch (many types), and proprioception


Touch

– Subclass of tactile sense
– Tactile stimuli are:
1. 2-point touch or discriminating touch
2. Superficial (gross, light, general) touch, not discriminating
3. Pressure
4. Vibration


Mechanoreceptors

– Cutaneous and subcutaneous
– Tactile, 2-point touch, pressure, and vibration


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