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111 Cards in this Set

  • Front
  • Back
Special senses:
Taste
Chemoreceptor (detects chemicals in air or mouth)
Special senses:
Smell
Chemoreceptor
Special senses:
Hearing
Mechanoreceptor (air movements)
Special senses:
Equilibrium
Mechanoreceptor (Balance fluid in head)
Special senses:
Sight
Photoreceptor
Taste
About 10,000 taste buds

Mostly found on projections of tongue.
Taste:
Papillae
Projections on tongue, where taste buds are found
Fungiform papillae
Appears in long sections, like muschrooms - large top, small bottom
Circumvallate papillae
Large ones on back of tongue
Folliate papillae
Look like leaves
Taste:
Taste buds
Sensory receptor organs for taste, are located in the oral cavity with the majority located on the tongue.
Taste sensations can be grouped into five basic qualities:
Sweet, sour, bitter, salty, and umami.
Taste:
Basal cells
Produce the supporting and gustatory cells which are replaced every 10-14 days
Taste:
Sensory nerves
VII (facial)
IX (glossopharyngeal)
X (vagus)
For a chemical to be tasted
It must be dissolved in saliva, move into the taste pore, and contact the gustatory hairs.
Each taste sensation appears
To have its own special mechanism for transduction.
Afferent fibers carrying taste information from the tongue are found
primarily in the facial nerve and glossopharyngeal cranial nerves.
Taste impulses from the few taste buds found
On the epiglottis and the lower pharynx are conveyed via the vagus nerve.
Taste is strongly influenced by
Smell and stimulation of thermoreceptors, mechanoreceptors, and nociceptors
Sweet tastes are elicited by
Sugars, alcohols, and some amino acids.
Sour taste is produced by
Acids, specifically H+ ions
Bitter taste is elicited by
Alkaloids such as quinine, nicotine, cyanide.
Umami is elicited by
The amino acid glutamate, found in high amounts in meat
Taste reactions are
Partly genetic, partly learned
Sweet + salty are
Natural cravings

–most sweet things in nature are safe and nutritious

–salt satisfies our need for electrolytes.
Bitter taste you
Naturally avoid

Many naturally occurring toxins (like cyanide and many fungal toxins) have a bitter taste.

Our receptors are most sensitive to bitter tastes.
Smell:
Olfactory epithelium is in
Located in roof of nasal cavity

Contains olfactory receptor cells

Recieves data by olfactory cilia
Smell:
To smell a particular odor it must be
Volatile and it must be dissolved in the fluid coating the olfactory epithelium
Smell:
Axons of the olfactory receptor cells synapse in the
Olfactory bulbs sending impulses down the olfactory tracts to the thalamus, the hypothalamus, amygdala, and other members of the limbic system
Olfactory receptor cells are
Neurons which send fiber bundles of axons through the cribriform plate of the ethmoid
Smell:
The receptor cells are replaced about every 60 days. (why?)
Neurons rarely have a mitotic rate
Smell:
Anosmias are
Olfactory disorders resulting from head injuries that tear the olfactory nerves, nasal cavity inflammation, or aging
Smell:
Uncinate fits are
Olfactory hallucinations
Sight:
Vision is our (humans) dominant sense with
70% of our body’s sensory receptors are found in the eye
Sight:
Nearly half of the cerebral cortex is involved
In processing of visual information
Sight:
Eyebrows are
Short, coarse hairs overlying the supraorbital margins of the eye that shade the eyes and keep perspiration out
Sight:
Eyelids (= palpebrae) are
Thin skin-covered folds supported by connective tissue plates called tarsal plates
Sight:
Meibomian glands produce
Oils to lubricate the eyelids
Sight:
Eyelashes secrete
Oils from their associated sebaceous glands
Sight:
Eyelids (palpebrae), eyelashes, and their associated glands help to
Protect the eye from physical danger as well as from drying out.
Sight:
Eyelid - Meibomian gland infection
Creates a large cyst (chalazion)
Sight:
Eyelid - oil gland infection
Called a sty
Sight:
Conjunctiva
Transparent mucous membrane which lines the eyelids (the palpebral) and covers the anterior surface of the eye (the ocular conjunctiva).

It produces a lubricating mucus that prevents the eye from drying out
Sight:
Palpebral
The eyelid
Sight:
Ocular conjunctiva
Covers anterior surface of eyeball
Sight:
Conjuctiva - blood shot
Has many tiny blood vessels which can get irritated
Sight:
Conjuctivitis
An inflammation of the conjunctiva

It can be caused by bacteria or viruses.
Vision:
Lacrimal glands
Which secretes a dilute saline solution that cleanses and protects the eye as it moistens it, and ducts that drain excess fluid into the nasolacrimal duct.
Lacrimals:
Tears contain
water
salts
mucus
lysozyme

Tear production declines with age, so the eyes become drier and more subject to infection.
Sight:
Extrinsic muscle
Smallest motor unit of any muscle

Movement of each eyeball is controlled by six extrinsic eye muscles that are innervated by the abducens and trochlear nerves
Sight:
Eyeball - Fibrous tunix
The outermost coat of eyeball is dense avascular connective tissue, has two regions: sclera and the cornea
Sight:
Eyeball - Sclera
Is tough, protective, white and opaque
Sight:
Eyeball - Cornea
Is transparent, forming a window that lets light enter the eye
Sight:
Eyeball - Vascular tunic (=uvea)
Is the middle layer and has three regions: the choroid, the ciliary body, and the iris
Sight:
Vascular tunic - Choroid
Supports blood vessels and absorbs light to prevent glare.

(In some animals, the choroid reflects light.)
Sight:
Vascular tunic - Ciliary body
Is a thickened ring of tissue around the lens

Largely consists of smooth muscle called ciliary muscle which controls the shape of the lens. The muscles are attached to the lens via suspensory ligaments.
Sight:
Vascular tunic - Iris
Is the visible colored part of the eye.

Lies between the cornea and the lens and is anchored to the ciliary body at its edges. It is made of smooth muscle which can control the size of its central opening, the pupil
Sight:
Iris - Pupil
Centrally located circular muscles cause constriction of the pupil

Marginal radial muscles dilate the pupil
Sight:
Iris - Pigment
The only pigment is melanin (brown)

The iris can display other colors if the amount of melanin is small and concentrated at the posterior surface of the iris.

The refraction of light causes other colors (called structural colors) to appear.
Sight:
Iris - Structural colors
The refraction of light causes other colors to appear
Sight:
Sensory tunic or Retina
The innermost tunic of the eye

It has 2 layers
Sight:
Retina - 1rst layer
The outer pigmented layer abuts the choroid. It contains phagocytes and stores Vitamin

Outer pigmented layer absorbs light
Sight:
Retina - 2nd layer
The inner neural layer contains the functional cells of the eye, the photoreceptors

the inner neural layer contains millions of photoreceptors (rods and cones) that transduce light energy.
Sight:
Retina - 3 major cell types
Photoreceptors (rods and cones)

Bipolar cells

Ganglion cells
Sight:
Retina - 3 major cell types - Ganglion cells
The ganglion cell axons unite to form the optic nerve.

The point where the optic nerve exits is called the optic disk, or, blind spot. The spot lacks photoreceptors.
Sight:
Retina - 3 major cell types - Photo receptors
The rods: dim-light and peripheral vision; they do not provide sharp images or color vision

The cones: high acuity color vision; they require bright light.

Human eyes are adapted for acuity; we have a high proportion of cones, giving us good color vision, but relatively poor night vision.
Sight:
Retina - 3 major cell types - Ganglion cells (blind spots)
Near the blind spot is an area called the macula lutea, with a central pit called the fovea centralis.

This area has mostly cones and provides high acuity in the center of the visual field. We move our eyes constantly to get everything in our field of view exposed to this area.
Sight:
Chambers + fluids - anterior segment
The anterior segment lies between lens and cornea.

It contains aqueous humor, a fluid which diffuses out of blood capillaries.

It provides nutrients to the lens and cornea. Constantly replaced, it drains into the scleral venous sinus.
Sight:
Chambers + fluids - anterior segment(aqueous humor)
A fluid which diffuses out of blood capillaries
Sight:
Chambers + fluids - posterior segment
Lies between lens and retina.

Contains vitreous humor, a gel-like fluid with a network of collagenous fibers.

Physically supports the eye. Formed during embryonic growth, it is not replaced.
Sight:
Chambers + fluids - posterior segment (vitreous humor)
Gel-like fluid with a network of collagenous fibers.
Physiology of light 1:
Wavelengths
The wavelengths of light to which our photoreceptors respond is called the human visible spectrum.

Spectrum differs for different organisms;
Lens
A flexible, transparent structure that can change shape to focus light on the retina.

Made of proteins called crystallins, the lens fibers are constantly replaced.

The lens becomes thicker and less flexible with age.
Physiology of light 2:
Lens change shape
The lens changes shape to focus light on the retina. When the ciliary muscles are relaxed, the eye is focused for distance

For close focusing, the muscles pull on the lens, causing it to bulge.

As you age, the lens gets less flexible and the muscles get weaker - you lose the ability to focus on close objects.
Physiology of vision:
Emmetropic
In normal eyes, the lens focuses light on the retina
Physiology of vision:
Myopia
(Nearsightedness), the lens, when relaxed (for distance vision), the lens focuses in front of the retina, making distant objects blurry.

It typically results from an eyeball which is too long.
Physiology of vision:
Hyperopia
(Farsightedness), the lens cannot be flexed enough to focus on close objects.

It is the result of an eyeball which is too short or an inflexible lens.
Physiology of vision:
Visual pathway (retinal ganglion cells)
Merge in the back of the eyeball to become
the optic nerve, which crosses at the optic chiasma to become the optic tracts.
Physiology of vision:
Visual pathway (optic tracts)
Send their axons to neurons within the lateral geniculate body of the thalamus.
Physiology of vision:
Visual pathway (Axons from the thalamus)
Project through the internal capsule to form the optic radiation of fibers in the cerebral white matter.

These fibers project to the primary visual cortex in the occipital lobes.
Physiology of vision:
Visual pathway (visual processing)
Occurs when the action of light on photoreceptors hyperpolarizes them, which causes the bipolar neurons from both the rods and cones to ultimately send signals to their ganglion cells.
Physiology of vision:
Rods and cones contain photopigments which are
chemically altered by light, exciting the cells and sending a nerve impulse to the brain.

The pigment in rods (rhodopsin) responds to all wavelengths of human visible light
Physiology of vision:
Rhodopsin
Pigment in rods

formed and broken down within the rods.
Physiology of vision:
3 different cones
(Green, blue, and red) which have different photopigments (iodopsins) responding to different wavelengths of light.
Physiology of vision:
Stimulation of the Photoreceptors
Is exposed to light which cause pigment breakdown, which hyperpolarizes the receptors inhibiting the release of neurotransmitter conveying the information.
Physiology of vision:
Light adaptation
Occurs when we move from darkness into bright light.

Retinal sensitivity decreases dramatically and the retinal neurons switch from the rod to the cone system.
Physiology of light:
Dark adaptation
Occurs when we go from a well-lit area into a dark one.

The cones stop functioning and the rhodopsin starts to accumulate in the rods increasing retinal sensitivity.
Structure of ear
The outer (external) ear consists of the auricle (pinna)

The external auditory canal, which is lined with skin bearing hairs, sebaceous glands, and ceruminous glands.
Structure of ear:
Auricle
Directs sound into the canal.

The canal is lined with ceruminous (wax) glands.

The tympanic membrane (eardrum) separates the outer ear from the middle ear.
Structure of ear:
The middle ear or tympanic cavity
Is a small, air-filled, mucosa-lined cavity in the petrous portion of the temporal bone.

Contains the ear bones (ossicles): malleus, incus, and stapes.

It is spanned by the auditory ossicles.
Structure of ear:
Ossicles
The ossicles vibrate when sound waves hit the tympanum.

Vibrations are transferred malleus -> incus -> stapes to the oval window.

The tensor tympani and stapedius muscles prevent excessive vibration of the ossicles.
Structure of ear:
Inner ear
Contains the organ of hearing, the cochlea, and the organs of equilibrium, the vestibule and the semicircular canals.
Hearing of ear
Sound waves strike the tympanum

The ear ossicles vibrate, pushing on the oval window

Fluid in the cochlea vibrates, pushing on hair cells within

The hair cells cause excitation of sensory neurons of the cochlear nerve which sends signals to the brain
Hearing of ear:
Sound waves
has a characteristic amplitude and frequency.
Hearing of ear:
Sound waves - amplitude
Height of the wave

It represents loudness
Hearing of ear:
Sound waves - frequency
The frequency (or wavelength) is the pitch of the sound.
Hearing process
When a sound wave enters the ear, it is amplified in the middle ear, because the oval window is smaller than the tympanic membrane.
Hearing process
Fluid inside the scala vestibuli, the perilymph, starts to move.

The organ of Corti rests on the basilar membrane. It is composed of some 16,000 cochlear hair cells. The movement of the perilymph stimulates the hair cells, which causes depolarization of fibers of the auditory nerve (a branch of the vestibulocochlear, VIII).
Hearing of ear:
Different wavelengths of sound
Different parts of the basilar membrane are stimulated by different wavelengths of sound. This gives us our perception of pitch
Hearing disorders:
Conduction deafness
Occurs when sounds do not get conducted to the inner ear. –blockage of the auditory canal

perforated eardrum
otosclerosis, a growth of bone which fuses the stapes to the oval window
Hearing disorder:
Sensorineural deafness
Results from damage to the inner ear or nervous tissues.

Exposure to loud noises (damages cilia)

Degeneration of the cochlear nerve

Brain damage in the auditory cortex
Equilibrium of ear
Not only upon the organs in the inner ear, but also involves vision and information from proprioceptors.

The organs in the ear involved in equilibrium are the vestibule and the semicircular canals.
Equilibrium of ear:
Static equilibrium
Refers to your sense of position (i.e., your sense of gravity).

This one is just about always turned on.
Equilibrium of ear:
Dynamic equilibrium
Refers to the sense of change of momentum (acceleration or deceleration).

This one turns off if you are not moving or if you are moving at constant velocity
Static equilibrium:
Organs
The organs of static equilibrium are located in the vestibule, which contains membranous sacs, the saccule and utricle.

Within these sacs are the maculae (sing., macula)
Static equilibrium:
Organs - Maculae
A macula is a flat epithelial patch with supporting cells and hair cells.

Within each macula is a jellylike otolithic membrane.

It is covered with CaCO3 crystals called otoliths.
Equilibrium:
When head moves
When the head moves, the otolithic membrane falls to a different position, deforming hair cells.

The brain receives the information on the position of the membrane, and thus determines the position of the head
Equilibrium:
Macula give us a
Sense of “up and down”, or, static equilibrium
Equilibrium:
Semicircular canals
Sense changes in momentum, or dynamic equilibrium (changes in velocity only, acceleration or deceleration)

Has 3 canals running in different directions to detect all kinds of movement.
Equilibrium:
Endolymph
The fluid within the ampullae of the semicircular canals
Equilibrium:
Crista ampullaris is a
Small elevation which can be deformed by movements of the endolymph