Special Senses (Part 2)
These overcome the loss of specificity by varing the pattern of activities in their receptive field, which improves the detection of the edges of objects.
These neurons are excited by light arriving in the center of their sensory field and are inhibited when light strikes the edges of their receptive field.
These neurons are inhibited by light in the central zone and are stimulated by illumination at the edges of their receptive field.
These are ganglion cells that monitor rods.
M Cells are relatively large cells that provide information about what?
General form of object
Shadows in dim lighting
These ganglion cells are smaller than M cells and more numerous, monitor the cones, and provide information about edges, fine detail, and color.
The 2 optic nerves (1 from each eye) reach the diencephalon at what point?
The optic chiasm
At the optic chiasm, half the fibers proceed toward what? The other half proceeds toward what?
The lateral geniculate of the same side of the brain. the opposite side of the brain
Visual data from each lateral geniculate nucleus travels to the what?
The occipital cortex of the cerebral hemisphere on that side.
Collaterals from the fibers synapsing within the lateral geniculate continue to subconscious processing centers within the diencephalon and brain stem is reffered to as what?
Give the visual pathway.
Photoreceptors in retina
Optic nerve II
Lateral geniculate nucleus
Projection fibers (optic radiation)
Visual cortex of cerebral hemispheres
Collaterals that bypass the lateral geniculate can synapse where?
in the superior colliculi or hypothalamus
The hypothalamus works with what to use the visual info to establish a daily pattern of visual activity?
What happens to visual images when we look straight ahead?
What is obtained by comparing relative positions of objects between the right and left eye images?
This surrounds the entrance to the external acoustic meatus and protects it. it provides directional sensitivity as well.
This is a thin, semitransparent sheet that separates external ear from middle ear.
These are integumentary glands along the external acoustic meatus that secrete a waxy material.
The waxy material secreted by ceruminous glands is called what?
Cerumen (ear wax)
What does cerumen (ear wax) do?
Keeps out foreign objects
slows growth of microorganisms
What is the other name of the middle ear?
How does the nasopharynx communicated with the middle ear?
auditory tube (Eustachian tube)
What are the inner ear bones known as?
Name the three auditory ossicles.
The auditory ossicles conduct sound vibrations from the tympanic membrane to where?
The oval window
What are the two muscles that protect the ear drum and ossicles from violent movements under high noise levels?
Tensor tympani muscle
This muscle stiffens the tympanic membrane, reducing movement.
Tensor tympani muscle
This muscle reduces movement of stapes at the oval window.
The superficial contours of the internal ear are formed by the what?
The boney labyrinth surrounds and protects what?
The membranous labyrinth contains fluid called what?
The space between the bony labyrinth and the membranous labyrinth contains a fluid called what?
What are the three subdivisions of the boney labyrinth?
This encloses a pair of membranous sacs called the saccule and utricle.
These have receptors within them that provide a sensation of gravity and linear acceleration.
Saccule and utricle
These have receptors within ducts and are stimulated by the rotation of the head.
The combination of the vestibule and semicircular canals is called the what?
This contains the cochlear duct and has receptors that provides a sense of hearing.
The walls of the boney labyrinth are consist of dense bone everywhere except what two locations?
The round and oval windows
This is a thin, membranous partition that seperates perilymph of the cochlea from air space in the middle ear.
This is formed of collagen fibers that connect to base of stapes.
Sense of gravity and acceleration originates where?
from hair cells in vestibule
Sense of rotation originates where?
from semicircular canals
Sense of sound rotates where?
These are the basic receptors of the inner ear.
Hair cells are always surrounded by supporting cells and monitored by what?
Dendrites of sensory neurons
The free surface of each cell supports 80-100 what?
Each hair cell in the vestibule contains a single large cilium known as what?
In the semicircular ducts, what region contains the hair cells?
These are oval structures where hair cells cluster and are embedded in a gelatinous mass.
This is the densely packed calcium carbonate crystals on the surface of the gelatinous mass.
This is the gelatinous matrix and statoconia.
Otolith (ear stone)
Hair cells of the vestibule and semicircular ducts are monitored by sensory neurons located in the what?
What are the 4 functions of vestibular nuclei?
integrate sensory info of balance
relay information from vestibular complex to cerebellum
relay information from vestibular complex to cerebral cortex
send commands to motor nuclei in brain stem and spinal cord
This receives input from cerebrum and cerebellum and sends motor commands that affect upper limb positions and background muscle tone.
The red nucleus
This receives information over the vestibulocochlear nerve from receptors in jthe inner ear.
Automatic movements of the eyes that occur in response to sensations of motion are directed by what?
Superior colliculi of the midbrain
This is when an individual has trouble controlling eye movements, and is caused by damage to brain stem or inner ear.
The frequency of sound is determined by the stimulation of what?
which part of the cochlear duct
The intensity or volume is determined by what?
The number of hair cells stimulated
The cochlear duct lies between what two chambers?
Scala vestibule and scali tympani
The cochlear duct contains hair c3ells that are located within what structure?
Organ of Corti
This seperates the cochlear duct from the scali tympani and has hair cells that lack kinocilia.
The basilar membrane moves in response to pressure fluctuations within the perilymph chambers. these pressure changes are created by what?
sound waves hitting the tympanic membrane
As the basilar membrane bounces up and down, the stereocilia are pressed against what?
The tectorial membrane
Stimulated hair cells are monitored by sensory neurons which carry information to what?
Pressure waves traveling through a medium is known as what?
The sound waves that consist of regions where air molecules are crowded together and adjacent zones where molecules are farther apart is known as what?
Our sensory response to frequency is what?
The intensity of sound waves is known as what?
The combination of frequencies and amplitude is known as what?
As hair cells are distorted, ion channels within their plasma membrane are opened resulting in what?
depolarization of hair cells
This is formed by afferent fibers of spiral ganglion neurons
The temporal cortex contains a map of what?
the spiral ganglion
What effects does aging have on the ear?
tympanic membrane gets less flexible
articulations between ossicles stiffen
round window may begin to ossify