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What are olfactory receptor cells
are bipolar neurons (1 main dendrite and 1 axon) with dendrites and an axon projecting through cribriform plate that ends in olfactory bulb
What are supporting cells
• Columnar epithelial cells of mucous membrane lining nose
what are basal cells
• Stem cells located between bases of supporting cells
• Continually undergo mitosis
What is the purpose of Bowman's glands?
produce mucus that moistens the surface of olfactory epithelium, aiding the dissolution of odorants.
Olfactory pathway to brain
1. Through the cribriform plate
2. Synapse with the olfactory bulb
3. Impulses travel along the olfactory tract
4. Interpretation in the primary olfactory area in the cerebral cortex (temporal lobe)
What are the steps in the olfactory transduction process?
Odorant binds to receptors. 2. G protein is activated. 3. cAMP opens Na+ channels. 4. Na+ influx causes depolarization. 5. If depolarization reaches threshold, an action potential is generated.
What is gustation?
chemical sense responsible for taste, detecting five primary tastes: sour, sweet, bitter, salty, and umami.
Where are gustatory receptors located?
within taste buds on the tongue.
What are the different types of papillae on the tongue?
Vallate, fungiform, foliate papillae contain taste buds; filiform papillae contain tactile receptors but no taste buds.
How do nerve impulses for taste travel to the brain?
Taste signals propagate along cranial nerves to the medulla oblongata, then to the thalamus, and finally to the primary gustatory area in the parietal lobe.
What is the function of the conjunctiva?
The conjunctiva is a thin, protective mucous membrane that lines the eyelids and covers the sclera.
what are palpebrae
The palpebrae are the eyelids, which protect the eye and help to moisten it by spreading tears.
what is palpebral fissure
is the opening between the eyelids that allows light to enter the eye, playing a crucial role in protecting the eye and maintaining moisture.
what are palpebral muscles
muscles that control the movement of the eyelids, allowing them to open and close.
what are the lateral and medial commissure
the points where the upper and lower eyelids meet on the outer and inner corners of the eye, respectively, playing a role in eye closure and tear drainage.
what is lacrimation
Group of structures that produces and drains lacrimal fluid (tears) (protective mechanism)
What are the layers of the eyeball?
Fibrous tunic (cornea and sclera), 2. Vascular tunic (choroid, ciliary body, iris), 3. Retina.
What is the function of the retina?
The retina detects light and color, containing photoreceptors (rods and cones) that facilitate vision.
function of ciliary body
alter shape of lens
function of choroid
provides nourishment to the outer layers of the retina and absorbs excess light.
function of sclera
gives shape to eye
function of cornea
covers colored iris and helps focus light onto retina
function of iris
regulate amount of light entering pupil
what is the macula lutea
exact center of the retina
what is the fovea centralis
the area of the retina responsible for sharp central vision, located in the macula lutea. most cones are here
What are rods and cones?
Rods are photoreceptors that function in low light and provide black and white vision; cones function in bright light and provide color vision.
Where do light rays refract(bends) within the eye? There are 2 locations
cornea and lens
what is the anterior chamber
(between the iris and cornea) is filled with aqueous humor (a clear, watery liquid)
what is the posterior chamber
lies behind the iris and in front of the lens and is also filled with aqueous humor
what is the vitreous chamber
(behind posterior chamber) filled with a transparent, gelatinous substance, called the vitreous humor
what is the aqueous humor
thin, watery fluid that fills the space between the cornea and the iris
• produced by the ciliary body
• fluid nourishes the cornea and the lens and gives the eye it's shape
what is the vitreous humor
- clear gel that fills the space between the lens and the retina
• maintains structural stability of eye
What does the anterior chamber and posterior chamber of the eye contain?
Both chambers are filled with aqueous humor, which nourishes the cornea and lens.
What happens to light rays as they pass through the eye?
Light rays are refracted at the cornea and lens to focus an image on the retina.
what is emmetropic
A term used to describe a normal vision condition where the eye can focus light correctly on the retina, resulting in clear vision.
what is myopia
nearsightedness. A vision condition where distant objects appear blurry because light rays are focused in front of the retina, often due to an elongated eyeball.
what is hyperopia
farsightedness. A vision condition where close objects appear blurry because light rays are focused behind the retina, often due to a shortened eyeball.
How does light make its way to the retina? What about refraction
As light rays enter eye: rays are refracted at cornea and lens so they come into exact focus on retina. Images focused on retina are upside down and reversed. Brain corrects this image
What structures make up the outer ear
Contains the auricle (pinna), external auditory canal and the tympanic membrane (eardrum). Ceruminous glands secrete cerumen (earwax) to protect the canal and eardrum
what structures make up middle ear
Contains 3 auditory ossicles; Malleus, incus, and stapes. (Eustachian tube) extends from the middle ear into the nasopharynx to regulate air pressure in the middle ear
what structures make up inner ear
- Cochlea- Semicircular canals -
What do the structures of the outer, middle, and inner ear include?
Outer ear includes the auricle and external auditory canal; middle ear contains auditory ossicles; inner ear includes cochlea and semicircular canals.
How does sound translate into electrical signals?
Sound waves vibrate the tympanic membrane, transmitting vibrations through the auditory ossicles to the cochlea, creating fluid pressure waves.
What structure functions in dynamic equilibrium?
The semicircular canals function in dynamic equilibrium.
Where do sound impulses travel within the brain?
Sound impulses travel from the cochlear nerve fibers to the medulla oblongata and pons, then to the thalamus and primary auditory area in the temporal lobe.
what does the auricle (pinna) do
captures sound
what does the external auditory canal do?
transmits sound to the eardrum
what does the tympanic membrane (eardrum do)
vibrates in response to sound waves, transmitting them to the ossicles in the middle ear.
what does the cochlea do?
translates vibrations into neural impulses that brain can interpret as sound.
26. How does sound enter the ear and how does it translate into electrical signals?
1. Auricle directs sound waves into external auditory canal
2. Waves strike and vibrate tympanic membrane
3. Vibrations continue along malleus, incus, and then to stapes (inner ear)
4. Vibrations continue through oval window
5. Movement of stapes set up fluid pressure waves in perilymph in cochlea into scala vestibuli(channel above cochlea duct)
27. How do sound impulses enter the brain?
Cochlear nerve fibers form part of vestibulocochlear (VIII) nerve
1. Axons synapse with neurons in medulla oblongata and pons
1. Midbrain (inferior colliculi)
Impulses travel to thalamus and end in the primary auditory area of the temporal lobe
What structure of the inner ear functions in dynamic equilibrium?
semicircular canals
What structure of the ear functions in static equilibrium?
otolithic organs . utricle and saccule
Equilibrium pathway. How do nerve impulses reach the brain?
Nerve impulses pass along axons of sensory neurons and form vestibulocochlear nerve and enter the medulla and pons of brain. Thalamus and inferior colliculi. Temporal lobe for processing
