anat exam 2 Flashcards
graded potential
A small deviation from the RMP that makes the membrane either more polarized (more negative inside) or less polarized (less negative inside).
can either be hyperpolarizing or depolarizing
types of graded potentials
receptor or generator potentials (occur in sensory receptors or sensory neurons), excitatory or inhibitory
free nerve endings
bare dendrites associated with pain, thermal, tickle, itch, and some touch
encapsulated nerve endings
dendrites enclosed in a connective tissue capsule
separate cells
receptor cells synapse with first order sensory neurons. eye, inner ear, taste buds
exteroreceptors
located at or near the body’s surface, sensitive to stimuli originating outside the body, convey info about external environment, convey visual, smell, taste, touch, pressure, vibration, thermal, pain sensations. CONSCIOUS
interoreceptors
located in blood vessels, internal organs, nervous system. provide info about internal environment; usually SUBCONSCIOUS, conscious only as pain in internal organs
proprioreceptors
located in muscles, tendons, joints, and inner ear; provide info about body position, muscle length and tension, joint position, and balance
mechanoreceptors
detect mechanical pressure, provide sensations of touch, pressure, vibration, proprioception, hearing and equilibrium, stretching of blood vessels and internal organs
thermoreceptors
detect changes in temp
nocioceptors
respond to painful stimuli
photoreceptors
detect light that strikes the retina of the eye
chemoreceptors
detect chemicals in mouth, nose, and body fluids
osmoreceptors
sense osmotic pressure of body fluids
root hair plexus
touch or movement of hair
merkel cells
fine touch and pressure receptors
tactile corpuscle
fine touch, pressure, low frequency vibration
lamellated corpuscle
deep pressure, high frequency vibration
ruffini corpuscle
pressure and distortion of the skin, located in dermis
first order neuron
delivers sensations to CNS. cell body is in dorsal root ganglion or cranial nerve ganglion
second order neuron
interneuron, in brain or spinal cord
third order neuron
in thalamus, synapse with neurons on primary sensory cortex
spinothalamic pathway
carries sensations of crude touch, pressure, pain, and temp. divided into an anterior and lateral tract. first order neurons synapse with second order in posterior gray horns, second order decussates in spinal cord
anterior spinothalamic pathway
crude touch and pressure sensations
lateral spinothalamic tract
pain and temp sensations
posterior column pathway
carries sensations of fine touch, proprioception, vibrations. fasciculus gracilis and cuneatus are involved
fasciculus gracilis
carry sensations from lower half of the body
fasciulus cuneatus
carry sensations from upper half of the body
medial lemniscus
enter after decussating in posterior column tract
protopathic modalities
thermal sensation, pain (fast and slow), crude touch, pressure
epicritic modalities
tactile discrimination, proprioception, vibratory sensation
lacrimal caruncle
produces eye crust
conjunctiva
covers inside of the eyelids and outside of eye (not the cornea though)
accessory structures of the eye
includes eyelids, superficial epithelium of the eye, and structures associated with tears
lacrimal apparatus
produces, distributes, and removes tears
function of tears
provides nutrients and oxygen to eye and cornea
anterior cavity
divided into anterior chamber and posterior chamber, contains aqueous humor
anterior chamber
between the cornea and iris
posterior chamber
between iris and lens
posterior cavity
contains vitreous humor, provides shape and stability for eye
aqueous humor
constantly produced (from blood plasma at ciliary body), circulated, and reabsorbed at same rate (at scleral venous sinus)
fibrous layer
outermost layer of the eye, contains sclera and cornea. supports and protects, provides attachment for muscles, contains structures to help in focusing
sclera
“white of the eye”, dense fibrous connective tissue of collagen and elastic, attachment for extrinsic muscles
cornea
transparent, no blood supply, largest point of refraction in the eye occurs here
vascular layer
includes iris, ciliary body, and choroid. contains blood vessels, lymphatic vessels, and intrinsic muscles of the eye. functions include providing route for blood vessels and lymphatic vessels, regulating the amount of light that enters the eye, secreting and reabsorbing aqueous humor, controlling shape of lens
iris
pigmented 2 layers of smooth muscle (constrictor and dialator)
constrictor muscles of the iris
circular smooth muscle, diameter decreases, parasympathetic stimulation
pupillary dialator muscle
wagon wheel spokes, enlarges pupil, sympathetic stimulation
ciliary body
consists of ciliary muscle
suspensory ligaments
attach to the tips of the ciliary processes
choroid
vascular layer that separates the fibrous layer and inner layer. delivers oxygen and nutrients to retina. contains melanocytes
inner layer
contains retina and optic nerve
two layers of the retina
- pigmented part (outer layer, thin, contains photoreceptors, retinal detachment occurs here)
- neural layer (inner layer, thick)
macula
contains no rods, highest concentration of cones is in the center (fovea centralis)
optic disc
“blind spot”, contains no photoreceptors, 1 mili ganglionic cells converge
lens
focuses visual image on photoreceptors, covered by a dense fibrous capsule that makes lens rounder
cataract
when lens becomes older and loses its transparency
accomodation
lens flattens when we focus on a distant object, becomes rounder when we focus on a near object. when ciliary body relaxes»_space;lens is flatter
myopia
nearsightedness, distant images are blurry, eyeball is too deep and image is projected in front of retina
hyperopia
farsightedness, close objects are blurry, lens may be too flat and image is projected behind retina
cones
detect blue, green, and red color vision. (red-green color blindness is most common)
visual pathway
- optic nerve
- optic chiasm
- optic tract
- lateral geniculate nucleus of thalamus
- optic radiations
- primary visual area of occipital cortex
external ear
auricle, external acoustic meatus, tympanic membrane is medial boarder
middle ear
contains auditiory ossicles (malleus, incus, stapes), oval window, tympanic membrane is lateral border. communicates with throat through the auditory tube
internal ear
fluid filled, semicircular canals and cochlea, continuous with temporal bone (bony labyrinth)
tensor tympani muscle
inserts on malleus, pulls malleus medially and stiffens the tympanic membrane in response to very loud noise, innervated by trigeminal
stapedius muscle
inserts on stapes, prevents movement at the oval window in response to a loud noise, innervated by facial nerve
benign tumor on schwann cells of N VIII
causes hearing deficit and disturbances in balance and equilibrium, possible facial paralysis
vestibular apparatus
balance and equilibrium, consists of vestibules and semicircular canals, indirectly goes to inferior colliculus
perilymph
between bony labyrinth and membranous labyrinth
endolymph
inside membranous labyrinth
ampulla
expanded part of semicircular canals that contain sensory receptors for balance and equilibrium
cupula
cristae are bound to this, contain hair cells, gelatinous
utricle and saccule
contain equilibrium sensations about whether the body is moving or stationary
maculae
contain hair cells of utricle and saccule, contain otolith
spiral organ of corti
sensory structure for hearing in the cochlea, sits on the basilar membrane (hair cells), in contact with tectorial membrane (ceiling)
scala tympani and scala vestibulae contain…
perilymph
cochlear duct contains…
endolymph
travel of sound waves
- arrive at tympanic membrane
- displacement auditory ossicles
- stapes at oval window, sound waves go up scala vestibulae
- distort basilar membrane, move hair cells against tectorial membrane
- sound waves go down scala tympani and to round window
low frequency sounds are heard at ___ of cochlea.
bottom
lower motor nerons
alpha and gamma motor neurons, cell body lies in the nucleus of brain stem or spinal cord, controlled by upper motor neurons
alpha motor neurons
- large and multipolar
- heavily myelinated
- high conduction velocity
- innervate extrafusal muscles
- located in all spinal nerves and some cranial nerves
gamma motor neurons
- not as large, less myelin
- slower conduction velocity
- innervate intrafusal fibers
- located in all spinal nerves and some cranial
upper motor neurons
cell bodies located in cerebral cortex of frontal lobe (primary motor cortex), some located in brain stem
LMN disease
flaccid paralysis, decreased muscle tone, fibrillations, decreased reflexes, limited to muscles innervated by LMN
UMN disease
spastic paralysis, increased muscle tone, abnormal superficial reflexes (babinski), and exaggerated deep reflexes, lesion in CNS
corticospinal pathways
sometimes called the pyramidal system, provides voluntary control over skeletal muscles, three pairs of descending tracts, all enter internal capsule
corticobulbar tract
axons synapse on lower motor neurons in motor nuclei of cranial nerves. provide conscious control over skeletal muscles that move the eye, jaw, face, neck and pharynx. decussation in brain stem.
lateral corticospinal tract
conscious motor control of skeletal muscles.
upper motor neurons: primary motor cortex
destination: LMN of anterior gray horns
decussation: pyramids of medulla
anterior corticospinal tract
conscious motor control of skeletal muscles.
UMN: primary motor cortex
destination: LMN of anterior spinal gray
decussation: level of LMN
cerebellum
coordination of voluntary movement, functions at a level unconsciousness (reflex center), influences ipsilateral musculature
direct injury to cerebellum = ?
ipsilateral ataxia
white matter of cerebellum
afferent fibers coming into brain from spinal cord
spinal cord to cerebellar input
proprioceptive info from skeletal muscle
cerebral cortex to cerebellar input
sensory, motor, and association cortical areas
cerebellar fuction
monitors intentions for movement, monitors actual movement, compares intention with actual movement, sends out corrective feedback
vestibulocerebellum
truncal ataxia
spinocerebellum
ataxia of gait
cerebrocerebellum
increase in muscle tone, tremor of intention, dysmetria, difficulty performing repetitive movements, dyssynergia, dysarthria (trouble speaking)
basal ganglia
located in each cerebral hemisphere: caudate nucleus, putamen, globus pallidus
located in diencephalon: subthalamic nucleus
located in midbrain: substantia nigra
functions of basal ganglia
influences muscle tone, posture, gross movements, executes programmed movements, influences proper sequencing of movement, suppresses unwanted movements, influences contralateral musculature
injury to basal ganglia = ?
dyskinesias (impairment of voluntary movement)
basal ganglia disorders
huntington’s disease, ballismus, parkinson’s disease
ataxia
loss of full control of bodily movements
parkinson’s disease
caused by degeneration of substantia nigra, insufficient dopamine. alterations in muscle tone, akinesia (hesitation in initiation of movement), bradykinesia (slow movement), resting tremors, masked expression
Injury above decussation
Contra lateral loss
rhodopsin
derivative of visual pigments, consists of protein optin bound to retinal (synthesized from vitamin A
