Transcript Human Senses

Human Senses
What you will do today . . .
• Name five kinds of sense receptors and
explain their functions
• Explain how a sensation arises
• Identify the locations of the receptors of
the special senses
• Describe the accessory structures of each
of the special senses
Specialized Sensory Neurons
Sensory Regions of the Brain
The Sensations in the Skin
A. The skin is full of receptors that allow us
to detect touch, pain, and pressure
1. Touch receptors are concentrated in
the fingertips, face, and tongue
2. Body hair also helps to detect touch;
the base of the hair follicles are loaded
with receptors
The Sensations in the Skin
The Sensations in the Skin
B. Thermoreceptors monitor temperature
change
The Sensations in the Skin
C. Pain receptors are sensory receptors
that are found throughout the epidermis
and interior of the body. They can be
stimulated by four types of energy . . .
1. Mechanical
2. Thermal
3. Chemical
4. Electrical
The Sensations in the Skin
5. Pain receptors are most abundant in
the hands and mouth
6. Pain receptors generally follow the
reflex arc
The Chemical Senses: Taste and
Smell
A. Taste buds are the sensory receptor
organ for taste; most are on the tongue
itself
1. Five general taste groupings
a. Sweet
b. Sour
c. Salty
d. Bitter
e. Umami
A Map of the Tongue
The Chemical Senses: Taste and
Smell
2. Different tastes have a purpose
3. Chemicals must be dissolved in saliva
to be tasted
4. Three cranial (connected directly to the
brain) nerves are involved in the process
of gustation
a. Facial
b. Glossopharyngeal
c. Vagus
The Chemical Senses: Taste and
Smell
5. Taste triggers digestion
6. Taste is 80% smell
The Chemical Senses: Taste
and Smell
The Chemical Senses: Taste and
Smell
B. The olfactory epithelium, located in the nasal
cavity, allow us to smell odors
1. The trigeminal nerves and olfactory nerves
send signals to the olfactory bulbs, which lie in
the limbic system of the brain
2. Smell signals also travel to the amygdala,
which trigger emotions, memories, and eating
behaviors
3. Chemicals must be in a gaseous (volatile)
state to be smelled
The Eye and Vision
A. 70% of all sensory receptors are located
in the eye
The Eye and Vision
B.
Accessory Structures
1. Eyebrows
a. Shade eyes from sunlight
b. Keep perspiration out of eye
2. Eyelids
a. Closed by orbicularis oculi
b. Protect the eye and keeps it from drying out
3. Conjunctiva
a. Thin, outer layer of eyeball
b. Produces mucus to lubricate eye
c. Infection is called Pink Eye
The Eye and Vision
B. Accessory Structures
4. Lacrimal Glands
a. Release tears
b. Cleans eye with lysozyme, an
antibacterial enzyme
5. Eye Muscles
The Eye
The Eye and Vision
C. Parts of the Eye
1. Sclera: the white part that shapes the
eyeball
2. Cornea: clear structure on surface of
eye that bends light
3. Choroid layer: blood vessels that
provide nutrients to the eye
4. Ciliary body: alters the shape of the
lens in response to light
The Eye and Vision
C. Parts of the Eye
5. Iris: colored part of eye that regulates
the amount of light that enters the eye
6. Pupil: center of eye where light enters
7. Rods: peripheral vision, dark
conditions
8. Cones: operate in bright light and
allow color vision
The Eye and Vision
C. Parts of the Eye
9. Retina: light-sensitive inner layer of
the eye
10. Optic nerves: pathway from eye to
brain
The Ear, Hearing, and Balance
The Ear, Hearing, and Balance
A. Sound is transmitted as vibrations, usually of
air
B. The external air is connected to the tympanic
membrane (eardrum) by the auditory canal
C. Air pressure in the ear can be regulated by the
eustachian tube, which is an opening into the
throat
D. Vibrations of the tympanic membrane are sent
to the hammer, anvil, and stirrup
The Ear, Hearing, and Balance
E. These three bones send vibrations to the
cochlea, a coiled tube
1. Cochlea contains the Organ of Corti,
the organ of hearing
2. Organ of Corti contains sensory
receptors called hair cells which send
sound to the brain via the auditory nerve
F. Semicircular canals of the inner ear
contain fluid that regulate balance
References
• http://activity.ntsec.gov.tw/lifeworld/english
/content/images/en_brain_c25.jpg
• http://www.sfn.org/skins/main/images/rd/vi
sion/eye.jpg
• http://www.colorado.edu/intphys/Class/IPH
Y3730/image/figure7-8.jpg
• http://www.health.state.ny.us/nysdoh/antibi
otic/ear.gif