Classification of the Nervous System Flashcards
what are the ways to subdivide the nervous system?
into:
topographical subdivisions
functional subdivisions
directional subdivisions
what are the topographical subdivisions?
Central nervous system (brain and spinal cord)
and
Peripheral nervous system (cranial and spinal nerves)
what are the functional subdivisions?
Somatic system (voluntary)
Visceral system (involuntary) incl. Autonomic nervous system further subdivided into –> sympathetic and parasympathetic
what are the directional subdivisions?
Afferent = towards brain and spinal cord
Efferent = away from brain and spinal cord
inside the head, the neural tube expands and develops into three main regions, what are these?
The prosencephalon (forebrain)
The mesencephalon (midbrain)
The rhombencephalon (hind brain)
what is the prosencephalon divided into?
telencephalon
diencephalon
what is the rhombencephalon divided into?
metencephalon
myelencephalon
etmology - telecephalon?
tele - far away
cephalon - brain
di?
diaganol
mye?
marrow or medulla - implies inside
encephalon means?
brain
mesos?
middle
meta?
beside
olfactory bulb?
part of the brain that deals with sense of smell
peripheral nervous system made up of?
cranial nerves
spinal nerves
ganglia (cell bodies): sensory, autonomic motor
how is myelination achieved in the PNS?
a separate Schwann cell
how is myelination achieved in the CNS?
arms of a myelin-forming oligodendrocyte
what is the advantage of myelination?
myelination speeds up action potential velocity
enhances speed of induction
axons originating in the brain and travelling down the spinal cord?
tracts
nerves called what in CNS?
in CNS, bundles of neurone axons are ‘tracts’
whereas in PNS they are known as ‘nerves’ by definition
what is functional classification due to?
the nervous system can be functionally divided on the direction of nerve transmission
afferent - functional classification?
towards spinal cord or specific brain regions
Afferent are Arriving nerve axons
Within spinal cord, can be called ascending
Sometimes also termed ‘sensory’
efferent - functional classification?
away from spinal cord or specific brain regions
Efferent are Exiting nerve axons
Within spinal cord, can be called descending
Sometimes also termed ‘motor’
as well as general afferent and efferent components - there is also special afferent, what is this?
concerned with special senses (taste and smell, vision, hearing and balance)
Somatic - is the voluntary nervous system, describe it?
senses and controls body relative to external environment -
sensory perceptions (touch, pressure, heat, pain, proprioception)
special senses (vision, balance, hearing)
Motor neurones to skeletal muscles (upper and lower motor neurones)
Related ascending and descending pathways in the CNS
What do Upper motor neurones (UMN) do?
initiate voluntary movements, regulate muscle tone
What do Lower motor neurones (LMN) do?
directly control muscle contraction
nerve paralysis - UMN stopped working but LMN still working?
the muscle will still work but there is no control over it and the muscle reaction can be really exaggerated
Visceral - involuntary nervous system?
senses and maintains the internal environment within permissible limits
Sensing internal environment (receptors in organs and blood vessels)
Special senses (taste and smell)
Adjusting internal environment through innervation of organs (the Autonomic nervous system)
Hypothalamus = an important integration centre
Hypophysis (pituitary gland) also produces + stores important hormones
facial nerve for example - classification?
visceral function due to taste and submandibular salivary gland
also
somatic function as it helps with movement of facial muscles
somatic?
deals with pain
visceral?
sensing stretch receptors in intestines etc
somatic?
voluntary nervous system
visceral?
involuntary nervous system
