chapter 15 special senses
What are the special senses
smell, taste, sight,hearing and equilibrium
What is the dominant sense
Vision - 70 % of all the sensory receptors in the body are in the eyes and nearly 1/2 of the cerebral cortex is in involved in some aspect of visual processing
What part of the eye is called "the white of the eye"? Is it A) the sclera or B) the choroid?
A) the sclera. This opaque outer layer appears white due to the presence of collagen fibers.
In which layer is the retina found? Is it the A) uvea or B) neural layer?
B) the neural layer. The retina contains the neural cells whereas the uvea contains the iris.
Which iris color has more melanin? Is it A) green or B) blue?
A) green. Color variation is due to concentration and distribution of melanocytes. Blue has the least amount of
What are the protein fibers called that make up the lens? Are they A) collagens or B) crystallins?
The answer is B) crystallins. Collagen is important in the connective tissues and cornea. Crystallins appear in a precisely packed pattern in the lens.
What do we call the gel-like substance in the posterior chamber of the eyeball? Is it A) the aqueous humor or B) the vitreous body?
The answer is B) the vitreous body. The aqueous humor is the fluid in the anterior chamber.
Which photoreceptor cells are responsible for sharp vision? Is it A) the rods or B) the cones?
The answer is B) the cones. The cones are stimulated by color and intense light.
Which neural cells regulate action potential generation in the eye? Is it A) the ganglion cells or B) the bipolar cells?
The answer is B) the bipolar cells. They regulate action potentials of the ganglion cells based on stimulation of the rods and cones.
What is the area called where your vision is the sharpest? Is it A) the optic disc or B) the fovea?
The answer is B) the fovea. The fovea contains the highest concentrations of cones, resulting in the sharpest vision.
the process of increasing the refractive power of the lens of the eye - focusing
1. any change in structure or respone to suit a new environment 2. decline in the transmission of a sensory nerve when a receptor is stimulated continuously and without change in stimulus strength
a localized dialation of a canal or duct
watery fluid in the anterior segment of the eye
a condition in which unequal curvatures in different parts of the cornea or lense of the eye lead to blurred vision
the trhee tiny bones serving as transmitters of vibrations and located within the middle ear, the malleus, incus, and stapes
tube that connects the middle ear and the pharynx - also called the eustachian tube
an indentation of the surface ectoderm in the embryo; the external acoustic meatus developes from it
the vascular middle layer of the eye
snail shaped chamber of the bony labyrinth that houses the receptor for hearing [the spinal organ (of corti)]
one of the two types of photoreceptor cells in the retina of the eye: provide for color vision
thin protective mucus membrane lining the eyelids and covering the anterior surface of the eye itself
transparent anterior portion of the eyeball: part of the fibrous layer
sensory receptor organ within the ampulla of each semicircular canal or the inner ear, dynamic equilibrium receptor
sense that reports on angular (rotatory) acceleration or deceleration of the head in space
emitted photons (wave packets) of energy ex. light, x ray, infared
extrinsic eye muscles
the six skeletal muscles which attach to and move each eye
base of an organ part farthest from the opening of the organ for example the posterior wall of the eye
condition in which intraocular pressure increases to levels that cause the compression of the retina and optic nerve; results in blindness unless detected early
a condition in which visual images are routinely focused behind rather than on the retina - commonly known as farsightedness
body cavities and membranes of the inner ear
pertaining to the tears
a condition in which visual images are focused in front of rather than on the retina - nearsightedness
pertaining to the eye
pertaining to the eye or vision
the partial crossover of fibers of the optic nerves
same as auditory ossicles
tube that connects the middle ear and the pharynx - also called the auditory tube eustachian tube
specialized receptor calls that respond to light energy- roda and cones
condition that results in the loss of near focussing ability - typical onset is around age 40
opening in the center of the iris through which light enters the eye
the bending of a light ray when it meets a different surface at an oblique rather than a right angle
neural layer of the eyeball contains photo receptors (rods - cones)
one of the two types of photosensitive cells in the retina
white opaque portion of the fibrous layer of the eyeball
taste, smell, vision, hearing and equilibrium
sense of head position in space with respect to gravity
sensory receptor oragans that house gustatory cells which respond to dissolved food chemicals
an enlarged area at the begining of a canal - inner ear, nose, larynx
the field of view seen when the head is still
The receptors for taste and smell are classified as:
chemoreceptors. Both receptors respond to the chemical content
Anosmia, an olfactory disorder, may be caused by a deficiency of:
zinc .About a third of cases of anosmia are said to be caused by zinc deficiency.
The accessory structures of the eye do NOT include:
cornea. The cornea of the eye is part of the eyeball structure and NOT an accessory organ.
The conjunctival mucous membrane covers:
both the inner surface of the eyelids and the visible portion of the sclera. ith the exception of the cornea, the conjunctival membrane covers the visible portion of the sclera and the palpebral conjunctiva.
When a person cries, he or she tends to keep on wiping their dripping nose. The nose drips because:
lacrimal gland secretions wash the eyeball and drain into the lacrimal duct, which empties into the nasal cavity.The drainage system for tears goes through the lacrimal duct into the nasal cavity.
The horizontal rotation of the eyeball towards the nose is the function of the:
medial rectus. he medial rectus inserts into the medial side of the eyeball and moves the eyeball medially.
Rotational movement of the head is monitored by receptors located in the:
semicircular canals.The ampulla of the semicircular canals houses the receptors that monitor angular movements of the head
Arrange the tunics of the wall of the eyeball in their correct sequence from inside out.
Retina, choroid, sclera Surrounding the cavity of the eyeball, the wall of the eyeball is formed by the sensory tunic, followed by the vascular tunic, and then the fibrous tunic.
Which sequence follows the correct passage of light entering the cornea?
Cornea, anterior segment, pupil, lens, posterior segment The anterior segment and the pupil are in front of the lens, and the posterior segment is behind the lens.
The organ of Corti is found in the:
cochlea. The receptor organs for hearing are housed in the cochlear duct.
Which of the following types of stimulation results in an increase in the diameter of the pupil?
Sympathetic nerves The contraction of radial muscles in the iris causes the pupil to dilate.
The near point of vision is the shortest:
in children. The near point of vision recedes with age and is the shortest in young children.
The tiny skeletal muscles associated with the ossicles of the middle ear function to:
protect the hearing receptors from loud sounds. he stapedius and the tensor tympani muscles minimize the excessive vibration of the ossicles caused by loud noise.
The receptors for sound reception and equilibrium are located in the
inner ear cavity. These receptors are found within the bony labyrinth.
The blind spot on the retina is:
where the optic nerve leaves the eye. Because of the numerous axons where the optic nerve leaves the eye, there is no room for photoreceptors, causing a blind spot.
The pharyngotympanic tube
allows equilibration of air pressure between the middle ear and outside air.The pharyngotympanic tube connects the pharynx and middle ear and allows equilibration of air pressure.
When focusing on a distant object, the lens is:
more flattened.A flat lens bends distance light less, allowing it to focus on the retina.
Seventy percent of the sensory receptors in the body involved with:
sight. Seventy percent of the sensory receptors in the body are located in the eye and are involved with sight.
Ciliary glands are modified:
sweat glands. Ciliary glands are modified sweat glands
Pink eye is caused by an inflammation of the ______.
conjunctiva PInk eye is caused by an inflammation of the conjunctiva.
Strabismus is caused by:
congenital weakness of the extrinsic muscles of the eye. Congenital weakness of the extrinsic muscles of the eye would lead to strabismus.
Our eyes are best adapted for:
distant vision.Our eyes are best adapted for distant vision
Ninety-nine percent of refractive problems in the eye are related to the
length of the eyeball. Ninety-nine percent of refractive problems in the eye are related to the length of the eyeball.
Retinitis pigmentosa is a disease of the _____.
rods Retinitis pigmentosa is a disease of the rods that occurs when the pigment epithelial cells are unable to recycle the tips of rods as they are sloughed off.
_______ are one of the few types of neurons that can replace themselves in adult life
Olfactory receptors Cones cannot replace themselves in adult life. Olfactory receptors are one of the few types of neurons that can replace themselves in adult life.
The bleaching of the pigment refers to the:
process of breaking down the retinal-opsin combinations that form the rhodopsin found in the rods and cones.The oxidation of vitamin A leads to the formation of rhodopsin, not its breakdown, which occurs durning the the bleaching of the pigment.
Which adaptation does NOT take place when one moves from a well-lit room to a dark room?
The retina becomes less sensitive When one moves from a well-lit room to a dark room, the retina becomes more sensitive, not less sensitive.
Which of the following would NOT be found in the outer ear?
Ceruminous glands are modified sweat glands found in the outer ear.
The only special sense not fully functional at birth is _______
vision Vision is the only special sense that is not fully functional at birth
Which of the following neurotransmitters is involved with hearing in the inner ear?
Glutamate Norepinephrine is not involved with hearing in the inner ear.
true or False Taste sensation is heavily dependent on olfactory receptors.
true -Taste is about 80% smell.
true or False Olfactory adaptation means that the olfactory receptors become more sensitive to the presence of an odor.
When exposed to an odorant for a longer time, olfactory receptors become less sensitive and stop sending action potentials to the sensory cortex.
true or False When the eyeballs rotate down, the inferior oblique muscle contracts.
False This muscle is inserted to the inferior surface of the eyeball. It rotates the eye up and laterally
true or False The size of the pupil is dependent on the contraction of the muscles of the iris.
True The circular and radial muscles of the iris reflexively contract and control the diameter of the pupil.
true or False The rods of the retina operate in bright light and provide high-acuity vision.
False The rods are adapted for dim light and peripheral vision.
true or False The area of the retina with the highest vision is called the optic disc.
False Fovea centralis has high cone density and is the focus of acute vision.
true or False The posterior segment of the eyeball is filled with clear gel, called the aqueous humor.
False The clear transparent gel filling the posterior segment is called vitreous humor.
true or False The malleus in the middle ear is attached to the tympanic membrane on one end and to the oval window on the other end.
False The malleus is attached to the tympanic membrane and to the incus.
true or False Sounds of low frequency cause the vibration of the basilar membrane closer to the oval window. Sounds of higher frequencies vibrate the oval window further away from the oval window.
False High-frequency waves stimulate receptors closer to the oval window, and low-frequency waves stimulate the receptors in the organ of Corti, further away from the oval window.
true or False The cornea is part of the vascular tunic.
false The cornea is the clear portion of the fibrous tunic.
true or False Impulses from the olfactory epithelium are sent to the brain via cranial nerve II.
False Cranial nerve I is the olfactory nerve.
true or False Cranial nerve V is one of the nerves that carry the sensation of taste.
False The cranial nerves that carry taste sensations are VII, IX, and X.
true or False The auditory tube allows pressure equalization between the middle ear and the external environment.
True The auditory tube connects to the nasopharynx and allows for pressure equalization.
true or False The semicircular canals respond to rotational movements.
True The three semicircular canals are oriented in the three planes of movement and evaluate head movements in each of those planes.