2. Introduction
Our “senses” continually provide us with
information about our surroundings.
Sense organs are complex organs like
the eye or specialized receptors in areas
such as the nasal mucosa or tongue.
3. Introduction
Conversion of a stimulus to a sensation:
Stimuli (light, sound, temperature, etc. are
changed into an electrical signal or nerve
impulse.
4. Cutaneous Sensations
Receptors of the general sense organs
are found in almost every part of the
body.
Encapsulated nerve endings – located in the
dermis; touch and pressure.
Free nerve endings – mainly in the dermis of
the skin, mucosa, internal organs. They
sense pain or crude touch.
6. Sense of Touch
The nerve endings in your skin can tell you if
something is hot, cold, smooth or rough .
They can also feel if something is hurting you.
Your body has different types of nerve
endings that all send messages to your brain.
7. Sense of Taste
Taste buds – chemical receptors that
generate nervous impulses resulting in
the sense of taste. There are about
10,000 microscopic taste buds located
on the papillae of the tongue.
Gustatory cells
8. Sense of Taste
Taste Sensations
Sweet, sour, bitter, salty
Other flavors results from a combination of
taste bud stimulations and olfactory receptor
stimulation.
14. The Ear
External ear
Pinna
External Auditory canal – a curving tube about one
inch long; extends into the temporal bone and end
at the tympanic membrane (eardrum)
Middle ear
Tympanic membrane
3 tiny bones called ossicles (bones) transmit
sound waves.
16. The Ear
Inner Ear – contains mechanoreceptors
that are activated by vibration and
generate nerve impulses that result in
hearing and equilibrium.
-Cochlea is the auditory portion of the inner
ear
Vestibule – membranous sacs (utricle and
saccule) adjacent to the oval window and
between the semicircular canals. Contains
receptors for equilibrium.
19. The Eye
Contains receptors for vision and a
refracting system that focuses light rays
on the receptors in the retina.
Eyelids – contain skeletal muscle that allow us to
close them and totally cover the exterior eyeball.
Eyelashes – help to keep dust out of our eyes.
Tears
20.
21.
22.
23. The Eye
Cranial Nerves
Optic – vision
Oculomotor – eye movment
The eye contains 3 layers
24.
25. The Eye
Structure of the eyeball
Sclera – tough fibrous tissue.
○ Front surface is the “white” of our eyes and
the cornea. The cornea is transparent
○ Sclera is covered by the conjunctiva in the
front of the eyeball.
26. The Eye
Structure of the eyeball
Choroid - contains a dark pigment to prevent
scattering of light that enters the eyeball.
Also contains blood vessels and 2
involuntary muscles.
○ Iris
○ Ciliary body (muscle)
27.
28. The Eye
Structure of the eyeball
Lens – composed of transparent, elastic
protein; no blood supply
Retina – contains microscopic receptor cells
called rods and cones
○ Rods
○ Cones
○ Fovea