Does that make sense?

1. Does That
Make Sense?
Crosswords

2. Exteroceptors are sensory receptors that Types, distribution,
receive external stimuli located in hands,
feet, face and other sensitive body party.
Viceroreceptors are receptors that include
and functions of
those located in visceral organs such as
the heart, liver and kidney. receptors
Proprioceptors are sensory nerve receptors
situated in the muscles, tendons, and joints
that furnish information to the central
nervous system concerning the
movements and positions of the limbs,
trunk, head, and neck, and, more
specifically for dentistry, the oral cavity
and its associated structures. (5)
Mechanoreceptors detect changes in
pressure, position, or acceleration; include
receptors for touch, stretch, hearing, and
equilibrium.
Chemoreceptors detect ions or molecules.
Smell (olfaction) and taste rely on
chemoreceptors.
Thermoreceptors detect hot or cold
temperatures.
Photoreceptors have pigments in receptor
cells that absorb light energy and trigger
action potentials. (6)
nociceptor is a sensory receptor that sends
signals that cause the perception of pain
in response to potentially damaging
stimulus. (7)

3. Balance & Hearing
Hearing
Balance
• The outer ear includes both the fleshy protrusion from the head and the
The human balance system works from the collaboration of three
components: the visual (eyes), skeletal systems (the muscles and canal that leads to the ear drum. The ear canal is where cerumen (i.e. ear
joints and their sensors), and the vestibular system (inner ear wax) is generated and stored. The outer ear acts as a funnel for sound,
balance organs). Nerve signals from those three components directing sound towards the ear drum.
are accurately sent to and processed by the brain to keep • The inner ear is composed of a series of interconnected fluid-filled canals
human balance. (17)
encased in the dense bone of the skull (the temporal bone). Lining portions
The function of the utricle and the saccule is to detect the
position of the head. Both these two cavities contain a pad of of these canals are the cells that have tiny hairs at their tops that vibrate with
cells, laid with a jelly-like substance, which in turn has small movement of the inner ear fluids. Vibration of these hairs induce these cells –
granules of chalk embedded inside. When the body is straight, appropriately called “hair cells” -- to begin the chain reaction that leads to
the gravitational force makes these granules press against nerve impulses carried along the hearing and balance nerves.
sensitive hairs in the jelly. The hairs then send nerve signals to the
brain that tell it, 'upright'. When the head leans front, back or • The middle ear is an air-filled cavity that bridges the ear drum with the
sideways, the chalk granules push against the hairs, and bend membranous window of the inner ear fluids. The middle ear contains the
them in a different direction. This sends off new messages to the three smallest bones in the body – the incus, malleus, and stapes – that form
brain, which can then, if needed, send out instructions to the this bridge. These three bones, or “ossicles,” are interconnected so as to
muscles to immediately adjust the position of the body. The
utricle is also springs into action when the body starts to move focus the forces of ear drum motion in order to drive the inner ear fluids to
forwards or backwards. If a child, for example, begins to run, the vibrate during sound stimulation. The middle ear in abnormal cases can
chalk granules get pushed back against the hairs, which makes collect body fluid and bacteria, and this situation is what occurs in the typical
it seem as if the child were falling backwards. As soon as the “ear infection” commonly seen primarily in children.
brain receives this information it sends out signals to the muscles;
this makes the body lean forwards thus restoring its balance. (18) • The external ear acts as a funnel for sounds. Sound travels inside the ear to
Dynamic equilibrium - The special sense which interprets the tympanic membrane (eardrum). The sound waves that come into
balance when one is moving, or at least the head is moving; the contact with the tympanic membrane are converted into vibrations that are
semicircular canals contain the receptors for dynamic sensed by a group of tiny bones, known as the middle ear ossicles. They are
equilibrium; within each semicircular canal is a complex comprised of the malleus (hammer), incus (anvil) and stapes (stirrup). The
mechanoreceptor called a crista ampullaris which contains the
mechanoreceptors (Hair cells) for dynamic equilibrium; when the malleus is the first to conduct the vibration, which then continues through the
perilymph in one of the semicircular canals moves, the hair cells incus and ends at the stapes, which is in contact with the oval (vestibular)
in the crista ampullaris are stimulated to send nerve impulses to window, which separates the middle ear from the inner ear. The function of
the brain; this advises the brain of whether or not a person has the inner ear starts when conduction of the sound wave reaches the oval
their balance during body movements or if their body is in
motion, e.g, riding in a car or turning one's head from side to side. window. The sound wave then travels through the cochlea, which looks like a
(19) snail’s shell. The cochlea is divided into three fluid-filled chambers. Different
chambers are receptive to different frequencies. The signal then goes into
the cochlear duct causing vibration of endolymph (a specialized fluid) where
the signal is converted into an electrical impulse that is transferred to the
cochlear and vestibular nerves. The brainstem sends the signal to the
midbrain and then subsequently to the auditory cortex of the temporal lobes
of the brain where the electrical impulses are interpreted as the sounds that
we experience.
(20)

4. Golgi tendon organs are receptor organs that
gives the body information about the force
that a muscle is developing as it contracts.
Muscle spindles are stretch receptors in muscle
cells involved in maintaining muscle tone.
Pacinian corpuscles are receptors deep in the
dermis that detects pressure on the skin
surface.
Structure of receptors
Meissner corpuscle are sensory receptors
located in the skin close to the surface that
detects light touch.
Merkel disks are expanded dendrite endings.
Root hair plexuses are entwined around the
root of each hair is a twirl of dendrites.
Free nerve endings are dendrites of sensory
neurons that are specialized receptors in the
skin that respond to pain.
(9)
(11)
(8)
(12)
(10)

5. Olfactory receptors expressed in the cell
membranes of olfactory receptor neurons are
responsible for the detection of odor molecules.
Olfactory pathways are a set of nerve fibers
conducting impulses from olfactory receptors to
the cerebral cortex.
Compare Olfaction
in a Human and Smell & Taste
with a canine: dogs
have an olfactory
sense
approximately
100,000 to
1,000,000 times
more acute than a
human's.
Taste buds any of the
clusters of bulbous
nerve endings on the
tongue and in the
lining of the mouth
that provide the sense
of taste.
Neural pathways are
neural tracts
connecting one part
of the nervous system
with another.

6. The pupil, which is the opening in the colored part of
Structures of the Eye
the eye (iris). The iris controls the size of the pupil in
response to light outside the eye so that the proper Cavities and Humors
amount of light is let into the eye.
The lens, which is located behind the iris and is The front of the eye houses the anterior cavity which is
normally clear. Light passes through the pupil to the subdivided by the iris into the anterior and posterior
lens. Small muscles attached to the lens can change chambers. The anterior chamber is the bowl-shaped
its shape. Tightening or relaxing these muscles causes
the lens to change shape, allowing the eyes to focus cavity immediately behind the cornea and in front of the
on near or far objects. iris. The posterior chamber of the anterior cavity lies behind
Vitreous gel (also called vitreous humor), which is a the iris and in front of the lens. The aqueous humor forms in
thick liquid that fills the eye. It helps the eyeball
maintain its shape. this chamber and flows forward to the anterior chamber
The retina, which is a thin nerve membrane that through the pupil.
detects light entering the eye. Nerve cells in the retina The posterior cavity is lined entirely by the retina, occupies
send signals of what the eye sees along the optic 60% of the human eye, and is filled with a clear gel-like
nerve to the brain.
The optic nerve, which is the nerve at the back of the substance called vitreous humor. Light passing through the
eye that carries visual information from the eye to the lens on its way to the retina passes through the vitreous
brain. humor.
The macula, which is near the center of the retina at
the back of the eyeball. The macula provides the The vitreous humor consists of 99% water, contains no cells,
sharp, detailed, central vision a person uses for and helps to maintain the shape of the eye and support its
focusing on what is directly in the line of sight. internal components.
Eye Muscles The aqueous humor is a clear watery fluid which facilitates
2 Types Of Eye Muscles: good vision by helping maintain eye shape, regulating the
Accessory Structures
intraocular pressure, providing support for the internal
Extrinsic: Skeletal muscles that Eyebrow &
structures, supplying nutrients to the lens and cornea, and
attach to the outside of the Eyelashes: Cosmetic
disposing of the eye's metabolic waste.
eyeball and to the bones of purpose and give
the orbit. They move the protection against
eyeball in any desired foreign objects.
Eyelids: Consist
direction and are, voluntary
mainly of voluntary
muscles. muscle and skin.
Intrinsic: smooth, involuntary Lacrimal Apparatus:
muscles located within the Secrete tears to
eye. Consist of the iris and remove foreign
ciliary muscles, which control objects from the
the shape of the lens. face of the eyeball.
(2)

7. • Formation of retinal image: There are four processes that
focus light so that they form a clear image.
Refraction- bending of light rays
Accommodation- increase in curvature,
constriction of pupils, and convergence of two eyes
Constriction- called near reflex of the pupil and
Retinal Image
occurs simultaneously with accommodation of the lens in near
vision
Convergence- seeing only one object when
both eyes are used. Light rays from an object fall on
corresponding points of two retinas.
• Photopigments are light sensitive compounds. All
photopigments can be broken down into a glycoprotein
called opsin and vitamin A derivative called retinal.
• Rods are highly light sensitive. Light causes the opsin to
expand. When opsin and retinal open a process called
bleaching takes place and active sites cause action
potential to be created in the cell. The objects are seen in
shades of grey until the opsin is back to its original shape.
• Red, green, and blue reflect light rays of a different
wavelength. On a certain cone the photopigment breaks
down and initiates impulse conduction by the cone. Cone
photopigments are less sensitive to light and rods so brighter
light is necessary in order for them to break down. (2)
(21)

8. Questions:
Q: Why don't deer see Hunters who wear Bright
orange?
A: Deer do not have red-sensitive cone cells in their
eyes, so they can't tell red or orange from green and
brown. (4)
Q: What is the difference between "nearsighted" and
"farsighted"? How are each of these corrected?
A: Nearsighted means someone is able to see things
close to them but not far from them, and farsighted
means someone is able to see things far from them
but not close to them. Nearsightedness and
farsightedness can both be corrected by glasses,
contacts, or sometimes through LASIX eye surgery.