Transcript Chapter_10

Chapter 10
Somatic and Special
Senses
Introduction to the Senses:
Objective #1: List 5 types of Sense Receptors
Types of Receptors
1. Chemoreceptors- taste and smell
2.Pain receptors-respond to tissue damage
3. Temperature- detect hot and cold.
4. Mechanoreceptors- detect pressure ..in skin
and blood vessels
5. Photoreceptors- respond to light
Objective #2: Describe what
sensations are
A sensation is-a feeling which occurs
when a sensory impulse is interpreted
by the brain
Projection of a sensation occurs when
the brain sends the sensation back to
the receptor
• Phantom pain occurs when arms or legs
have been lost and the person feels pain in
area even though it is not there….the stump
is generating impulses and the brain
projects feeling back to area of missing limb
• Sensory Adaptation- occurs when the
receptor gets tired of sending impulses due
to overstimulation.
• Examples of Adaptation- 1. nose ..something
when you enter a room smells bad…after a
while…you do not smell it.
2. Jumping into a cold swimming pool..it
seems warm after awhile.
Objective #3: Describe the somatic
senses
Types of Somatic Senses (3 types)
1. Touch and Pressure receptors
a. Sensory nerve fibers- light touch
and pain…located in the epidermis
b. Meissner’s corpuscle receptorslight touch- located in the upper
dermis
c. Pacinian corpuscles – respond to heavy
pressure…located deep in the dermis
Light touch
receptors are
Meissners
Pain
receptors are
sensory fibers
Strong pressure are
Pacinian
Sense-Sational Facts!
• The least sensitive area
of your body is the
middle of your back.
• The most sensitive
areas of your body are
your hands, lips, face,
neck, tongue,
fingertips, and feet.
• There are about 100
touch receptors in each
of your fingertips.
2. Temperature Receptors
a. Hot receptors
b. Cold receptors
3. Pain
receptors
Not found in brain- headaches due to pain
a.
receptors in blood vessels
Referred pain- appears to be
coming from another part of the body
other than the one which is being
stimulated…during a heart attack…left
b.
arm may ache…both arm nerve pathway and heart
nerve pathway combine at spine and brain does not
know which area sent the impulse…projects pain
back to wrong one…the arm
Notice that two
nerves go to the
spine …but only one
nerve goes to the
brain
Special Senses
Objective #4: Describe what makes up
the sense of smell
1. cilia-hair-like
2. olfactory receptors cells
3. olfactory bulb
4. olfactory tract….leads to brain
How the sense of smell works:
• Olfactory receptor cells are located in
epithelium in the roof of the nasal
cavity.
• Chemicals that you smell bind to
receptor’s cilia creating nerve
impulses that go to brain
cont.
• The odor that you smell is determined
by the type of olfactory cells
stimulated.
• The effects of smell and taste combine.
Olfactory Sense
Pathway of smell- cilia-to olfactory receptor-to
olfactory bulb-to olfactory tract- to brain
Your Sense of Smell
• When you smell something
like roses for example you
smell tiny things called odor
particles. There are millions
of them floating around
waiting to be sniffed.
• Our sense of smell is
connected well to our
memory. For example, the
smell of popcorn can remind
you of being at the movies
with a friend.
• Humans have seven primary
odors that help them
determine objects.
Sense-Sational Facts!
• Dogs have 1 million smell cells per nostril and their
smell cells are 100 times larger than humans.
• People who cannot smell have a condition called
Anosmia.
• If your nose is at its best, you can tell the difference
between 4000-10,000 smells.
• As you get older your sense of smell gets worse.
Children are more likely to have better sense of
smell than their parents or grandparents.
Objective 5: Explain the sense of taste
The sense of taste is know as gustation
The bumps on your tongue are
papillae…not taste buds! Taste buds
are found in the papillae
Taste buds contain the following:
1. Taste hairs
2. Taste sense receptors
Your taste buds can recognize four basic kinds of
tastes: sweet, salty, sour, and bitter.
• Have you ever thought about
why foods taste different?
• Your tongue and the roof of your
mouth are covered with
thousands of tiny taste buds.
The receptor cells located in
your taste buds send messages
through sensory nerves to your
brain and your brain tells you
what flavors you are tasting.
• Your taste buds can recognize
four basic kinds of tastes:
sweet, salty, sour, and bitter.
Complete view of sense of taste
• A taste bud, protruding into a crevice between
papillae.
• Some fish have taste buds all over their body. Some
insects have taste buds on their feet.
Sense-Sational Facts!
• We have almost 10,000 taste buds inside our
mouths; even on the roof of our mouths.
• Insects have the most highly developed sense of
taste. They have taste organs on their feet, antennae,
and mouthparts.
• In general, women have more taste buds than men.
• Taste is the weakest of the five senses.
Obj. 6 Explain the Sense of
Hearing
Ear – organ of hearing
3 Sections
• External
•Middle
• Inner
Your Sense of Hearing
• Your ears serve two very
important purposes. They
help you hear and they help
you keep your balance.
• When an object makes a
noise, it sends vibrations
speeding through the air.
These vibrations are
funneled into your ear canal
by your outer ear. Then the
vibrations hit your eardrum
that is located in your
middle ear and cause it to
vibrate.
• The vibration goes
through several other
places then the auditory
nerve carries the
messages from 25,000
receptors in your ear to
your brain. Your brain
makes sense of the
messages and tells you
what sounds you are
hearing.
The ear
External Ear
1.auricle- collects sound waves
2. external auditory meatus
•lined with ceruminous glands
• carries sound to tympanic
membrane
• terminates with tympanic
membrane
3. tympanic membrane
(eardrum
• vibrates in response to sound
waves
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Middle Ear
1. tympanic cavity
• air-filled space in temporal
bone
2.auditory ossicles
• vibrate in response to tympanic
membrane
• malleus, incus, and stapes
3.oval window
• opening in wall of tympanic
cavity
• stapes vibrates against it to
move fluids in inner ear
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4. Eustachian tube
• connects middle ear to
throat
• helps maintain equal
pressure on both sides
of tympanic membrane
• usually closed by
valve-like flaps in throat
Inner Ear
3 Parts:
• cochlea
• functions in hearing
• semicircular canals
• functions in
equilibrium
• vestibule
• functions in
equilibrium
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3 parts of the cochlea
1. Scala vestibuli canal
• upper canal
• leads from the oval window
2. Scala tympani canal
• lower canal
• leads to the round window
3. Cochlear canal
in between the scala vestibuli
and scala tympani
Contains the Organ of Corti
Organ of Corti
• Made up of the following parts:
1. Basilar membrane- membrane
which moves up and down due to
fluid flowing in the scala
tympani
2. Hair cells- attached to the basilar
membrane.
3. Tectorial membrane- does not
move. Hair cells bend into it as
they move up and down which
creates electrical impulses
How Sound Travels Through The
Ear...
1. Sound waves caught by the pinna enter ear canal.
2. Sound waves strike the tympanic membrane, causing it
to vibrate like a drum, and changing sound waves into
mechanical energy.
3. The malleus, incus, and stapes vibrate
4. The stapes moves in and out of the oval window of the
cochlea creating a fluid motion.
5. The fluid movement within the cochlea causes
membranes in the Organ of Corti to shear against the
hair cells.
6. This creates an electrical signal which is sent via the
Auditory Nerve to the brain, where sound is interpreted!
Cancer and Tumors
Cancerinvolving the
pinna
More TM Perforations
The top slide shows an
example of a small
non-healing perforation
in the pars tensa
The bottom slide shows a
larger defect in the pars
tensa
Serous Otitis Media-middle ear
infection
Sense-Sational facts!
• Children have more sensitive ears than adults, and
can recognize a wider variety of noises.
• Dolphins have the best sense of hearing among all
animals. They can hear 14 times better than humans.
• Animals hear more sounds than humans.
• When you go up high elevations, the change in
pressure causes you ears to pop.
Obj. 7: Explain the Sense of
Equilibrium
• Static Equilibrium
– vestibule
– sense position of head when body is not
moving
• Dynamic Equilibrium
– semicircular canals
– sense rotation and movement of head and
body
Obj. # 8: Explain the sense of sight
Accessory organs: Tear glands
•
•
•
•
lacrimal gland-tear gland
– located above eye
– secretes tears
canaliculi
– collect tears
– people sometimes
believe that tears come
out here
This is really the drainage
hole for tear.
lacrimal sac
– collects from canaliculi
nasolacrimal duct
– collects from lacrimal
sac
– empties tears into nasal
cavity-this is why one
sniffles when they cry!
Obj. Structure of the Eye
• hollow
• spherical
• wall has 3 layers
– outer fibrous layer
– middle vascular
layer
– inner nervous layer
Outer Tunic
1.Cornea
–
–
–
–
–
clear window of eye
covers pupil
light transmission
light refraction
contains no blood
vessels
2.Sclera
– Whites of eyeball
– protection
Sc
Pink eye
• The sclera blood vessels are dilated and
broken.
Rarely, the sclera grows over the
cornea when the fetus is
developing
Middle Layer
1.
•
•
2.
•
•
3.
Iris
pigmented
controls light
intensity
Ciliary body
holds lens in place
moves lens for
focusing
Choroid coat
•
provides blood supply
Anterior part of eye
• filled with aqueous humor
Lens of the eye
Characteristics of the lens
1. transparent
2. biconvex
3. lies behind iris
4. largely composed of lens fibers
5. elastic- bends easily
6. held in place by ciliary muscle
Normal Vision
Cataracts
A cataract is a painless, cloudy area in the lens
of the eye. A cataract blocks the passage of
light from the lens to the nerves at the back of
the eye, and it may cause vision problems.
Changes in the lens of the eye are part of the
aging process but normally do not develop into
cataracts. However, cataracts are very
common in older adults. Cataracts can also
occur after an eye injury, as a result of eye
disease, after the use of certain medications or
as a result of medical conditions such as
diabetes.
Cataracts are caused by clouding of the
lens….can occur in children
http://oftalmologo.bravepages.com/Leucocoria%201.jpg
Inner Tunic
1.retina
• contains visual receptors
rods for night vision and cones for day vision
2.macula lutea – yellowish spot in retina…
3.fovea centralis – center of macula lutea; produces
sharpest vision…contains the most cones
4.optic disc – blind spot; contains no rods or cones
5. vitreous humor – thick gel that holds retina flat
against choroid coat…fills posterior part of eyeball
Focusing On Retina
• as light enters eye,
it is refracted by
– convex surface of
cornea
– convex surface of
lens
• image focused on
retina is upside
down and reversed
from left to right
Clinical Application
Refraction Disorders
• concave lens corrects
nearsightedness…lens thick
on the sides and thin in the
middle
• convex lens corrects
farsightedness….lens are
Thin on the side and thick in
the middle
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