Download Ch. 40-Nervous Lecture #3

 What’s
in the bag? Blind fold students
or (take away other senses) and have
them identify different objects. Explain
that senses help us receive information
about our surroundings (and more than
one sense can be used)
 Also discuss the difficulty that comes
with loosing a sense
 See which student can identify the most
objects
The Senses
Ch. 36.2
I. Use Your Senses
A. Your body has 5 senses:
1. Sight
2. Hearing
3. Touch
4. Taste
5. Smell
I. Use Your Senses
B. Senses are often linked
together in the brain
1. Chemicals from an
orange stimulate sensory
neurons in your nose and
you smell the citrus smell
I. Use Your Senses
2. Chemicals from the
orange stimulate the
sensory neurons of the
tongue when you eat it so
you taste the flavor.
3. Food doesn’t have much
flavor with a stuffy nose
because you can’t smell it
II. Taste
A. Taste Buds- The sensory
receptors on your tongue
1. Young adults have appx.
10,000 taste buds
2. The # of taste buds
decreases over time and
smells and tastes are dulled
II. Taste
B. Taste buds categories
1. Salty
2. Sour
3. Bitter
4. Sweet
5. The “Pill Spot?”
III. Sight
A.
Sight depends on light
energy reaching sensory
receptors in the eye.
1. Light passes through the
cornea first
a. The outside window of
the eye
III. Sight
b. Astigmatism is caused
by an uneven cornea
1) Special lenses are
needed to correct it
III. Sight
2. Light passes through the
iris and into the pupil
a. The iris regulates the
size of the pupil and how
much light enters
b. The iris also gives
they eyes color
III. Sight
3. The light image is then
focused by the lens on to
the retina.
a. The image is smaller
& up-side-down &
backwards
III. Sight
b. When objects viewed are
distance the lens is flat
c. When objects viewed are
near the lens becomes more
rounded
d. The lens is associated with
glaucoma (too much fluid)
III. Sight
e. If the eyeball is naturally too
long or short, corrective lens
(glasses) may be needed
1) Near sighted (long
eyeball) = Concave Lens
2) Farsighted (short
eyeball) = Convex Lens
III. Sight
4. The retina contains the
cones and rods
a. Cones are receptor
cells adapted for sharp
vision in bright light
b. Cones also detect
color
III. Sight
c. Rods are receptor cells
adapted to detect shape
and movement in dim light
d. There is a place with no
rods or cones called the
blind spot
1) Paper demo
III. Sight
e. Sensory neurons in the
retina form the optic nerve
that carries the image to the
brain
f. The brain interprets the
message, flips and rotates it
and responds (or not)
IV. SOUND
A. 3 parts of the Ear
1. Outer Ear
2. Middle Ear
3. Inner Ear
B. Sound is caused by
vibrations in the air around it
(sound waves)
IV. SOUND
C. Outer Ear
1. Sound waves are
captured by the cup shape
of the ear (Pinnea)
2. They travel through the
ear canal
IV. SOUND
C. Outer Ear (cont)
3. The sound waves strike
the ear drum (tympanic
membrane) and cause it to
vibrate
IV. SOUND
D. Middle Ear
1. The vibrations then pass
to 3 small bones of the
middle ear:
a. Malleus
b. Incus
c. Stapes
IV. SOUND
D. Middle Ear (cont)
2. As the stapes vibrates, it
causes the oval window to
move back and forth
a. Oval window is the
membrane between the
middle and inner ear
IV. SOUND
E. Inner Ear
1. The movement of the
oval window causes the
fluid inside the cochlea to
move.
a. Cochlea is snail
shaped structure
IV. SOUND
2. The movement of fluid
causes the hair cells lining
the cochlea to move
a. Damage to hair cells
causes hearing loss
IV. SOUND
3. Electrical impulses are
sent along the auditory nerve
to the brain.
a. Sound is interpreted by
the cerebrum
b. Auditory nerve damage
also causes hearing loss
IV. SOUND
P innea
E ar canal
T ympanic membrane
M alleus
I ncus
S tapes
O Val window
C ochlea
A uditory nerve
V. BALANCE
A. Spin Demo
B. The inner ear also sends
messages to the brain about
the position of the head.
C. Semicircular Canals-
V. BALANCE
C. Semicircular Canals
1. Fluid filled
2. Lined with hair cells
3. Tilting the head causes
the fluid to move and the
hair cells to bend.
V. BALANCE
C. Semicircular Canals (cont)
4. Nerve impulses are sent
to the brain to be interpreted
a. Cerebellum?
5. Motor neurons cause the
neck muscles to adjust the
position of the head.
VI. TOUCH
A. Sensory neuron receptors
are found in the skin
1. Temperature Neurons
a. Cold- Found near the
skin surface
b. Heat-Found deeper in
the dermis
VI. TOUCH
c. Indicates that cold is
more of a threat than
heat
VI. TOUCH
2. Light Pressure Neurons
1. Found in fingertips,
eyelids, lips and the tip of
the tongue
2. More sensitive areas
of the body
VI. TOUCH
3. Heavy Pressure Neurons
1. Found in joints,
muscle tissue and
certain organs
2. Also found in hands,
and feet
VI. TOUCH
4. Pain Receptors
1. Found in all body
tissues except brain
tissue