Nerves/ Nervous system Flashcards
central nervous system
- brain and spinal cord
- command center, processes nervous information
peripheral nervous system
- sensory NS
- motor NS
somatic sensory
sensory input from receptors (eyes, skin, mouth)
visceral sensory
sensory input not consciously perceiving
somatic motor
motor output consciously controlled
*effector is skeletal muscle
autonomic motor
motor output not consciously controlled
*effectors are cardiac, smooth muscle and glands
what is a neuron body
basic cell component
- nucleus, mitochondria etc
contains dendrites and axon hillock
what is a dendrite
conduct nerve impulses toward cell body
what is an axon hillock
triangular region, start of axon
what is an axon
long nerve cell process, make contact with other neurons, muscle cells etc
what is a Schwann cell
supportive nervous cells made of myelin that surround the axon, permits faster conduction of impulses
what are nodes of Ranvier
points of unmyelinated axon
what is axon terminal/ synaptic knob
site of neurotransmitter release
classification of neurons
unipolar
bipolar
multipolar
describe unipolar classification of neuron
- most common sensory neuron
- single short cell process extends from cell body, fusion of 2 processes into 1 long axon
ex) motor sensory neurons
describe bipolar classification of neuron
- uncommon, 2 nerve cell processes extend from cell body
ex) olfactory epithelium, retina of eye
describe multipolar classification of neuron
- most common type of neuron
- multiple nerve cell processes extend from the body usualy one axon, many dendrites
ex) interneurons, motor neurons
afferent neurons
-sensory
-detect stimuli from body and transmit to CNS
-unipolar
a for arrive
efferent neurons
-motor
-conduct nerve impulses from CNS to muscle or glands
-multipolar
interneurons
-found only in the CNS
-facilitates communication between afferent and efferent neurons
-multipolar
CNS glial cells
(AMEO)
neuron support cells
- astrocytes
- microglial cells
- ependymal cells
- oligodendrocytes
what is an astrocyte
-star-shaped, most common type of glial cell.
-in contact with neurons and capillaries
- form BBB and replace damaged neurons
what is a microglial cell
- small cell with slender branches, least common type
*defend against pathogens and remove debris (phagocytizes- eats garbage)
what is an ependymal cell
- simple cuboidal epithelia cell lining in brain and spinal cord
- secrete cerebral- spinal fluid
- lines ventricles of brain and central canal of spine
what is an oligodendrocyte
- rounded, bulb cell with small projections
- extensions wrap around CNS
- myelinates and insulated CNS axon, allows for faster nerve impulse conduction
PNS Glial cells
(SN)
satellite cells
neurolemmocyte (Schwann)
what is a satellite cell
- flattened cell clustered around neuronal cell bodies in ganglion
- protects/ regulates nutrients for cell bodies in ganglion
what is a neurolemmocyte (Schwann)
myelinated and insulates PNS axon which allows for faster nerve conduction through axon
what is the myelin sheath
- high lipid content that wraps around axon and gives nerves their glossy- white appearance
- neurolemmocyte myelinates one axon
- oligodendrocytes myeline many axons
cranial nerves
nerves of the brain
olfactory nerve
- CN I
- very large
function: sensory for smell (olfaction)
exit from cranium: olfactory foramina in cribriform plate
optic nerve
- CN II
function: special sensation for vision
exit from cranium: optic foramen/ canal
oculomotor nerve
- CN III
function: somatic motor to most extraocular muscles
exit from cranium: superior orbital fissure
trochlear nerve
- CN IV
function: somatic motor to one extraocular muscle
exit from cranium: superior orbital fissure
trigeminal nerve
- CN V
funciton: 3 divisions- ophthalmic, maxillary and mandibular (V1,2,3)
abducens nerve
- CN VI
function: somatic motor to one extra ocular muscle
exit from cranium: superior orbital fissure
ophthalmic division of trigeminal
- V1
function: general sensation from skin of face, cornea and sinuses
exit from cranium: superior orbital fissure
maxillary verve of trigeminal
- V2
function: general sensation from skin of face, palate, and maxillary teeth, paranasal sinuses
exit from cranium: foramen rotundum
mandibular nerve of trigeminal
- V3
function: general sensation from skin of face, anterior tongue, mandibular teeth
exit from cranium: foramen ovale
somatic motor to: muscles of mastication (temporalis/ masseter) and mylohyoid
facial nerve
- CN VII
- 5 branches and 1 single nerve
- temporal, zygomatic, buccal, mandibular, and cervical branches
- posterior auricular nerve
vestibulocochlear nerve
- CN VIII
function: special sensation- hearing, vestibular sense (balance)
exits from cranium: internal auditory meatus
glossopharyngeal nerve
- CN IX
function: sensation from posterior tongue and middle ear cavity
special sensation from: taste from posterior tongue, baroreception from carotid sinus, chemoreception from carotid body
parasympathetics: to pharynx muscle
exits from cranium:jugular foramen
vagus nerve
- CN X
function: general sensation from larynx and pharynx
special sensation: taste from epiglottis
somatic motor to: most of palate muscles, pharyngeal muscles, and muscles of larynx
parasympathetics: to thoracic/ abdominal viscera
exits from cranium: jugular foramen
accessory nerve
- CN XI
function: somatic motor to trapezius, sternocleidomastoid
exits from cranium: jugular foramen
hypoglossal nerve
- CN XII
function: somatic motor to muscles of tongue
exits from cranium: hypoglossal foramen
where does the cervical nerve travel through?
C1- C8
where does the thoracic nerve travel through?
T1- T-12
where does the lumbar nerve travel through?
L1- L5
where does the sacral nerve travel through?
S1- S5
conus medullaris
end inverted triangular part of the spinal cord where all the nerves are still bundled together
cauda equina
dorsal and ventral nerve roots that are no longer surrounded by dura mater
filum terminale
extension of Pia mater from the conus medullar is that attaches to coccyx and anchor spinal cord
horn=?
gray matter (inner stuff)
funiculus/ funiculi=?
white matter (outer layer)
what does the lumbar plexus include?
femoral nerve
obturator nerve
*can’t see on leg model
femoral nerve
L2-L4
Motor innervation to:
- quad muscles (4)
- iliopsoas
- sartorius
- pectinous
sensory innervation to:
- anterior/ medial aspect of thigh
- medial aspect of leg
- medial aspect of foot
obturator nerve
L2-L4
motor innervation to:
- adductor muscles
- gracilis
- pectinous
sensory innervation to:
- superior medial thigh
what does the sacral plexus include?
L5- S4
sciatic nerve
tibial nerve
common fibular nerve
deep fibular nerve
superficial fibular nerve
sciatic nerve
L4-S3
take off gluteus Maximus to see
composed on 2 nerves wrapped around in common CT sheath
tibial nerve
L4- S3
motor innervation to:
- hamstring muscles, excluding short head of biceps femoris
- posterior leg muscles
- foot muscles
sensory innervation to:
- heel and sole of the foot
common fibular nerve
L4- S2
motor innervation to:
- short head of biceps femoris
- others once split into deep and superficial
sensory innervation to:
- see deep and superficial nerve parts
deep fibular nerve
L4- S1
motor innervation to:
- anterior leg muscles
- foot muscles
sensory innervation to:
- space between hallux and second digit (flip flop area- big toe and 2nd toe)
superficial fibular nerve
L5- S2
motor innervation to:
- fibulas longus and brevis
sensory innervation to:
- anterior inferior part of leg
- dorm of the foot
parasympathetic functions
- maintain homeostasis
- pre-ganglionic cell bodies (found in brainstem, S2, S3, S4)
- local response
- long preganglionic axon
- short postganglionic axon
- no rami communicates
sympathetic functions
- prepares body for emergencies
- preganglionic cells found in T1- L2 (thoracolumbar)
- short preganglionic axon with many branches
- white rami attach T1-L2
- mass and local activations
sense of touch
receptive fields, varies across the body
- don’t need super specific touch on back
- DO need specific touch detection in fingers because they are in charge of precise movementthy
types of sensory receptors
exteroreceptors
interoceptors
proprioceptors
exteroceptors
detect stimuli in external environment
ex) sensory receptors within skin, nose, mouth
interoceptors
detect stimuli within body
ex) sensory receptors within blood vessel walls
proprioceptors
detect stimuli within joint, skeletal muscle and tendons
ex) joint receptors, spindles
what are chemoreceptors
chemicals dissolved in fluid
ex) taste
what are thermoreceptors
changes in temperature
ex) skin
what are photoreceptors
changes in light intensity, color and movement
ex) eye
what are mechanoreceptors
physical deformation of plasma membrane due to touch, pressure, or vibration
ex) tactile receptors in skin
what are noiciceptors
detect pain stimuli
ex) pain receptors present in almost all organs
sense of taste is called
gustation
where are gustatory cells found
taste buds
3 things taste buds contain
- gustatory cells: detect tastant
- supporting cells: sustain gustatory cells
- basal cells: replace short-lived gustatory cells
papillae of the tongue
filiform
fungiform
vallate
foliate
filiform papillae
short, bristle-like, found on anterior 2/3 of tongue.
mechanical function
no gustation role
fungiform papillae
mushroom shaped
found on tip/sides of tongue
each contain only a few taste buds
vallate papillae
least numerous, but very large.
found as inverted V on back on tongue
surrounded by deep depression where taste buds are found
foliate papillae
extend as ridges on posterior lateral tongue.
have few taste buds during infancy/ childhood, but go away as we age
Gustatory discrimination
what are the 5 tastes we can taste
- sweet
- salty
- sour
- bitter
- umami (meaty flavor)
sense of smell
olfaction
describe olfaction
molecules must be dissolved in the mucus of nasal cavity to be detected
4 parts to olfactory epithelium
- olfactory receptor cells
- supporting cells
- basal cells
- lamina propria
olfactory receptor cells
detects odor, olfactory neurons
supporting cells
sandwich olfactory neurons and sustaint the receptors, sustentacular cells
basal cells
function as neuronal stem cells, continually replace olfactory receptor cells
olfactory cells are one of the few neuronal types that get replaced
lamina propria
areolar CT that houses the olfactory glands that produce mucus that convert the olfactory epithelium
sense of sight
vision
external anatomy of the eyes
- eyebrows
- eyelashes
- eyelids
- medial and lateral palpebral commissures (corner of eye)
conjunctiva
external accessory structure of eye
- special stratified columnar epithelia
- forms continuous lining over external portion of eye
- maintains goblet cells that lubricate the eye
cornea
fibrous tunic/ external layer
2 layers of epithelium with collagen in the middle, forms anterior layer of the eye, transmits/ retracts incoming light
sclera
fibrous tunic/ external layer
dense regular CT
posterior covering of the eye: the ‘white’ of the eye
supports eye shape/ protects it
choroid
vascular tunic/ middle layer
areolar CT, highly vascularized.
forms posterior 2/3 of middle wall of eye. supplies nourishment to retina***
ciliary body
vascular tunic/ middle layer
ciliary smooth muscles and inner secretory epithelium.
between choroid and iris anteriorly
iris
vascular tunic/ middle layer
2 layers of smooth muscle with central opening (pupil)
control pupil diameter- which allows a certain amount of light in
pigmented layer
retina/ internal layer
pigmented epithelial cells/ supporting cells.
outermost portion of retina- directly adheres to choroid.
absorbs extraneous light, provides vitamin A to photoreceptors
neural layer
retina/ internal layer
photoreceptors, bipolar neurons and ganglion cells.
inner portion of retina
detects incoming light rays; which are converted to nerve impulses and transmitted to the brain
lens
cavity of eye
strong, deformable transparent structure held in place by dense fibrous capsule
aqueous humor
cavity of eye
gel-like substance found in anterior and posterior chambers between cornea and iris & iris and lens
vitreous humor
cavity of eye
gel-like substance found in space between lens and retina
equilibrium and hearing
ears and hearing
auricle
(external ear)
skin covered cartilaginous structure
external acoustic meatus
(external ear)
funnel-shaped tube
tympanic membrane
(external ear)
delicate epithelial sheet, partition between external and middle ear
auditory tube
(middle ear, tympanic cavity)
Eustachian tube
auditory ossicles
(middle ear, tympanic cavity)
connects middle ear and where our mouth/ nose connect
- malleus
- incus
- stapes
*stapes articulates with oval window to transmit sound waves to the inner ear
what does the malleus look like?
hammer
what does the incus look like?
anvil
what does the stapes look like?
stirrup
semicircular canals
(inner ear) CN VII
anterior, posterior, horizontal fluid movement within these canals help the brain determine movement of body
vestibule
(inner ear) CN VII
utricle and saccule= sense gravity and linear acceleration to maintain equilibrium and balance
cochlea
(inner ear) CN VII
sense sound as vibrations and turn these vibrations into nerve impulses which are perceived as audible sound in the brain
