2. The sensory organs are primarily responsible
for the reception of stimuli and pass them on
to the neuro-muscular system.
The main sense organs are your eyes, ears,
olfactory organs in your nose, taste buds on
your tongue and your skin which sense for
taste, sight, hearing, touch and smell.
Sensory Receptors is a specialized cells to
detect specific stimuli
3. TYPES OF SENSORY RECEPTORS
FUNCTIONAL TYPES
Chemoreceptor's
respond to changes in chemical concentration
Mechanoreceptors
Respond to mechanical energy (touch, pressure vibration)
Photoreceptors
Respond to light
Thermoreceptors
respond to temperature changes
Nociceptors
respond to tissue damage (pain)
5. The eyes are the organs of the special sense of sight.
They sit in the orbit of the skull which provides them
with positional protection.
Humans have two eyes which work together, this is
known as binocular vision
6. ANOTONMY
CORNEA
Transparent covering of the front of the eye
Allows for the passage of light into the eye and
functions as a fixed lens.
SCLERA
a tough white skin (made of tissue) that covers all
of the eyeball except the cornea.
supports eyeball
provides attachment for muscles
7. IRIS
colored part of eye
controls light entering
PUPIL (black hole)
black hole in iris
where light enters
Pupil size is controlled by iris muscles
LENS (lens behind pupil)
converging lens
allows us to see objects near and far
o RETINA
internal membrane
contains light-receptive cells (rods and cones)
converts light to electrical signals
8. BLIND SPOT
Small spot on the back of the retina
No rod or cone cells
OPTIC NERVE
Transmits electrical impulses from retina to the
brain
Creates blind spot
Brain takes inverted image and flips it so we can
see
9. Between the iris and cornea is the anterior
chamber. This chamber is filled with a special
transparent fluid that gives the eye oxygen, protein,
and glucose (a type of sugar in the body) to keep it
healthy.
The vitreous body forms two thirds of the eye's
volume and gives the eye its shape. It's filled with a
clear, jelly-like material called the vitreous humor
10. HOW THE EYE WORKS
Light enters the eye, the amount of which is
controlled by the iris and is bent (refracted) slightly
by the cornea.
It is then focused by the lens (controlled by the
ciliary muscles) onto the retina.
Retina contains 5 types of cells and they are
interconnected by synapse. These cells are
photoreceptor cells (rod and cone), bipolar cell,
ganglion cell, horizontal cell and amacrine cell.
Photoreceptor cells, bipolar cells and ganglion cells
transmit impulse directly from retina to brain.
The nerve fiber of ganglion cells from both eyes
carries impulse along two optic nerve
11. The optic nerves meets at optic chiasma
The optic nerve after crossing the chiasma is called
as optic tract.
Each optic tract continues posteriorly until it
synapse with neuron in thalamus called lateral
geniculations body which project to primary visual
cortex in occipital lobe of cerebrum and image is
perceived.
12. EAR ( HEARING )
The ears are the sense organs for hearing. The ears perform
two sensory functions HEARING and MAINTENANCE of
body balance
13. ANATOMY OF THE EAR
The ear are divided into three major section called :
the outer ear , middle ear , and inner ear.
OUTER EAR
Pinna is composed of thin plate of elastic cartilage
covered by layer of skin.
The funnel like curves of pinna collects sound wave
and direct them to middle ear.
External auditory canal-short chamber in the
temporal bone. The walls are covered in
ceruminous glands which produce earwax
Tympanic membrane- end of external ear.
Vibrates when sound hit it.
14. MIDDLE EAR
The TYMPANIC MEMBRANE (ear drum), also called
the tympanum, vibrates in response to sound.
Attached to it are 3 bones (auditory ossicles): The
MALLEUS (hammer), INCUS (anvil), and the STAPES
(stirrup) are the smallest bones in the body. Together,
they are only one inch long.
Their function is to amplify sound vibrations. The
malleus vibrates the incus, which vibrates the stapes.
15. The middle ear is open to the nasopharynx (back
of the throat) by way of the AUDITORY TUBE
(also called eustachian tube or nasopharyngeal
tube), which is only the thickness of a pencil lead,
and it is lined by a mucous membrane.
If this tube is closed from mucous or has a watery
secretion in it from infection, the ears feel plugged
up.
The function of the auditory tube is to equalize the
pressure of the middle ear and the outside air so
the ear bones can vibrate.
Tubes are put in the tympanic membrane to drain
fluids in kids with frequent ear infections.
16. INNER EAR
Cochlea
Coiled like a snail shell
Contains approximately 300,000 hair cells
Is filled with fluid, through which sound can travel
easily.
These tiny hairs bend because of the vibrations caused
by the sound waves.
Auditory Nerve
The tiny hair cells of the cochlea are set in motion by
vibrations
The vibrations stimulate tiny nerve cells.
The nerve cells then send signals along the auditory
nerve to the brain.
18. Sound wave are pressure wave that enter the external ear.
After crossing the external auditory meatus, the wave
reaches the tympanic membrane.
The air molecule under pressure causes vibration of
tympanic membrane. Low frequency sound wave causes
slow vibration while high frequency wave causes rapid
vibration.
The vibration of tympanic membrane moves the malleus in
middle ear.
The vibrating malleus produce vibration to incus and
vibrating incus moves stapes in and out of oval window
causing vibration of perilymph in scala vestibuli.
Vibration of perilymph are transmitted across the vestibular
membrane to endolymph in scala media (cochlear duct) and
also up the scala vestibuli and down the scala tympani.
The vibration of scala tympani are dissipated out of cochlea
through round window into Eustachian tube.
19. During transmission of vibration from perilymph to
endolymph in scala media, the basilar membrane
ripples. This ripple is concern with frequency and
intensity of sound.
The vibration causes bending of receptor of hair
cells of organ of corti to generate potential.
These potential excites the cochlear nerves to
generate action potential.
When the hair or microvilli of hair cells are
displaced toward the basal body, hair cells get
excited and when the hair are displaced away from
basal body hair cells are inhibited.
The nerve impulse from cochlear nerve are
conveyed to auditory area of CNS via common
vestibule-cochlear nerve. The auditory area is
located in temporal lobe where sound is perceived.
21. EPIDERMIS
oPrimarily made up of keratinized stratified
squamous epithelium
oThe EPIDERMIS is the layer that gives
strength to the skin.
oIt does not have any vascularization
(blood supply), so it relies on absorbing
oxygen and nutrients from the blood
vessels in the dermis deep to it.
oThe nails are made in the epidermis.
23. Papillary layer
Regulates body temperature
Supplies epidermis with
nutrient-filled blood
Reticular layer
Provides structure and
elasticity
Supports components of skin
Hypodermis
Network of fat and collagen
Functions as:
Shock-absorber for body
Insulator
Stores fat as energy reserve
24. Touch is a proximal sense, i.e., we feel things close
to us or in contact with us.
Touch receptors in the skin known as
the somatosensory system.
Within the somatosensory system, there are four
main types of receptors: mechanoreceptors,
thermoreceptors, pain receptors, and
proprioceptors.
Mechanoreceptors that respond to stimuli
such as pressure, stretching, and vibration.
Thermoreceptors: These receptors
perceive sensations related to the
temperature of objects the skin feels
25. Pain receptors: The scientific term is nocireceptor.
“Noci-” in Latin means “injurious” or “hurt” which is a
good clue that these receptors detect pain .
Proprioceptors: In Latin, the word “proprius”
means “one's own” and is used in the name of
these receptors because they sense the position of
the different parts of the body.
26. When your hand touches an object, any one of
receptor in the skin are activated, and they start a
chain of events by signaling to the nearest neuron
that they touched something. This neuron then
transmits this message to the next neuron which
gets passed on to the next neuron and on it goes
until the message is sent to the brain. Now the
brain can process what your hand touched and
send messages back to your hand via this same
pathway to let the hand know if the brain wants
more information about the object it is touching or if
the hand should stop touching it.
