nervous system Flashcards
what is the main goal of the nervous system
to maintain homeostasis
what are the 2 divisions of the NS
central NS and peripheral NS
what is the CNS
brain and spinal cord
integration and command centre
what are the 3 divisions of the PNS
somatic NS
autonomic NS
enteric NS
afferent is ___
efferent is ___
how many nerves are a part of the PNS
12 cranial and 31 spinal
which is the “voluntary” NS
somatic
SNS motor neurons to ___ ONLY
what are the special senses
SNS does what type of movements
voluntary
ANS
AND
what are the 2 divisions of ANS
sympathetic and parasympathetic
sympathetic division is what response
parasymp division is what response
what do sensory neurons monitor in the ENS
chemical changes
stretching walls of GI tract
the ENS motor neurons control what
(voluntary/involuntary)
contractions and secretions
involuntary
what are the 3 functions of the nervous system
what is the sensory function
what is the integration function
what is the motor function
what are the 2 histology types of nervous tissue
neurons and neuroglia
can axons (PNS) regenerate
yes, but very slowly
can neurons in the CNS regenerate?
no
what do neurons do
generate and propagate nerve impulses
how much more plentiful are neuroglia than neurons
25x more
can neuroglia transmit nerve impulses
no
what do neuroglia do
support, nourish, and protect the neurons
what is a key point of neuroglia
they divide throughout their entire life
do neuroglia have anything to do with the actual nerve impulses
no!!
what are the 3 parts of neurons
cell body
dendrites
axon
what does the cell body of the neurons contain
the nucleus
what do the neurons dendrites do
receiving and input part
what do neural axons do
what is the axon hillock
where the cell body meets the axon
where are action potentials initiated
at the axon hillock
what are the 3 functional classifications of neurons
90% of neurons are ___
where are interneurons located
CNS
sensory neurons do what
motor neurons do what
what are the 6 types of neuroglia
astrocytes
oligodendrocytes
microglia
ependymal cells
Schwann cells
satellite cells
which neuroglia are in the CNS
which neuroglia are in the PNS
schwann cells
satellite cells
PS (peripherals start with p)
what do satellite cells do
what do Schwann cells do
what does the melin sheath do
what forms the myelin sheath in the CNS
what forms the myelin sheath in the PNS
what is multiple sclerosis
demyelination preventing normal travel of impulses
what does the myelin sheaths allow the electrical impulse to do
jump from node to node
whare are the collections of cell bodies
PNS - ganglion
CNS - nucleus
what are collections of axons
PNS -
CNS -
what is gray matter (6)
anything decision making
neuronal cell bodies, dendrites, UNmyelinated axons, axon terminals, neuroglia
why is it gray matter
what is white matter
myelinated axons
for high speed travel
what is a resting membrane potential
a building of neg charges inside membrane
a buildup of pos charges outside memrane
what is a typical resting membrane potential (give the charge)
-70 mV
why are cells negative when resting potentials
cells are more permeable to potassium than to sodium
what maintains the potential difference
sodium-potassium pump
what are the 4 Io channel types
what are leaks channels
THE WHOLE REASON FOR A RESTING MEMBRANE POTENTIAL
what are ligand-gated channels
gates open and close due to chemical stimulus
what are mechanically-gated channels
gates open or close due too vibrations, stretching, or pressure
what are voltage-gated channels
responsible for conduction of action potentials across the axon
what are the 2 types of electrical signals in neurons
graded poentials
action potentials
what is a graded potential
small deviations from resting membrane potential (more or less polarized)
how can a graded potential start an action potential
mechanically gated channel
chemically gated channel
where do graded potentials mainly occur
dendrites and cell bodies
how far to graded potentials travel
what is the most common stimulus for action potentials
what is propagation
where is the trigger zone for the action potential
what needs to be reached for the action potential to occur
threshold level
According to the all-or-nothing principle, if a
stimulus reaches threshold, the action potential
is always the same.
– A stronger stimulus will not cause a larger impulse.
will a stronger signal create a bigger impulse?
no. not size, just frequency
what is the synapse
what are the 2 synapse types
chemical and electrical
what makes up the white matter in the spinal cord
oligodendrocytes
how is white matter divided
into columns
what are the 3 white matter columns
white matter columns contain:
tracts
what are tracts
sensory tracts are (ascending/descending)
motor tracts are (ascending/descending)
sensory ascending
motor descending
the posterior column tracts are (ascending/descending)
ascending (only sensory)
the lateral and anterior columns’ tracts are (ascending/descending)
both!!
what is the hole between the anterior and posterior gray commissures
what is a plexus
a network
what do spinal nerves branch into, and when
rami, after passing through the intervertebral foramina
which are the only nerves that go directly to the area they supply
except for the intercostal nerves T2-T12
name the 5 network types
cervical
brachial
lumbar
sacral
coccygeal
what level is the cervical plexus
C1 to C5
where do the phrenic nerves arise from
C3, C4, C5
what do the C3-C5 phrenic nerves do
supply the motor neurons to the diaphragm
what are the 3 muscles associated with the cervical plexus
sternocleidomastoid
erector spinae
levator scapulae
what is referred pain distribution
sensory stimuli from diaphragm is often interpreted as pain over shoulder and lower neck
what rami form the brachial plexus
what are the division of the brachial plexus
what 6 major nerves are supplied by the brachial plexus
musculocutaneous
axillary
radial
median
ulnar
long thoracic
what does wrist drop indicate
damage to radial nerve
what does median nerve palsy indicate
median nerve damage
what does ulnar nerve palsy indicate
damage to the ulnar nerve
what does winging of the right scapula indicate
damage to the long thoracic nerve
what is shown here?
median nerve palsy
what is shown here?
wrist drop
what is shown here?
ulnar nerve palsy
what is shown here?
winging of the scapula
what roots supply the lumbar plexus
L1 to L4 (NOT 5)
what does the lumbar plexus supply
anterolateral abdominal wall
external genitals
the anterior part of our lower limbs
what nerves are involved with the lumbar plexus
what roots supply the sacral plexus
L4 to S4
what areas are involved with the sacral plexus
what is the biggest nerve in the body
the sciatic nerve
the sciatic nerve branches into what
what is a dermatome
an area of skin supplied by a single spinal nerve
what are dermatomes useful for
to determine neurologic levels
name 2 refelxes
patellar and plantar
what is the integration centre for some reflexes
the spinal cord
what is a babinsky sign
toes fan, great toe moves outwards (instead of flexing)
normal for infants, not adults
where do the spinal nerves exit
through the intervertebral foramina
