Sensory receptors

1. SENSORYSENSORY RECEPTORS RECEPTORS

2. What are sensory receptors?What are sensory receptors?
Structures that are specialized to respond Structures that are specialized to respond
to the changes in the environmentto the changes in the environment
These are called stimuliThese are called stimuli
Sensory receptors in periphery detects the Sensory receptors in periphery detects the
stimulistimuli
Sensation and interpretation takes place in Sensation and interpretation takes place in
the brainthe brain

3. How sensory receptors are How sensory receptors are
classified?classified?
LocationLocation - location of the stimulus - location of the stimulus
to which they respondto which they respond
Stimulus typeStimulus type- named by the stimulus- named by the stimulus
that activates themthat activates them
Structure Structure - the anatomy of the - the anatomy of the
receptorreceptor

4. Classification according to locationClassification according to location
Exteroceptors Exteroceptors
- any receptor that responds to stimuli- any receptor that responds to stimuli
outside the body such vision, sound, touch, smell, outside the body such vision, sound, touch, smell,
temperature and smelltemperature and smell

6. Interoceptors or visceroceptorsInteroceptors or visceroceptors
- respond to stimuli arising within the - respond to stimuli arising within the
body such as chemical stimuli, deep body such as chemical stimuli, deep
pressure, and many others.pressure, and many others.

8. ProprioceptorsProprioceptors
- respond to muscle or tendon stretch - respond to muscle or tendon stretch
and help the body monitor body position and help the body monitor body position

9. Classification according to stimulus typeClassification according to stimulus type
MechanoreceptorsMechanoreceptors
- respond to a mechanical stimulus: - respond to a mechanical stimulus:
examples are touch, pressure, stretch, examples are touch, pressure, stretch,
hearing, balance, position and movement, hearing, balance, position and movement,
vibration, muscle contraction, as well as vibration, muscle contraction, as well as
press receptors and bar receptors.press receptors and bar receptors.

11. ThermoreceptorsThermoreceptors
-respond to temperature change: -respond to temperature change:
example heat and cold. example heat and cold.

12. PhotoreceptorsPhotoreceptors
-respond to light: example vision -respond to light: example vision

14. ChemoreceptorChemoreceptor
-respond to various chemicals such as -respond to various chemicals such as
glucose, oxygen, carbon dioxide, glucose, oxygen, carbon dioxide,
hormones and many, many more hormones and many, many more

15. This pseudostratified columnar epithelium This pseudostratified columnar epithelium
is composed of olfactory cells, is composed of olfactory cells,
sustentacular cells and basal cells. sustentacular cells and basal cells.
Modified cilia on the surface serve as Modified cilia on the surface serve as
olfactory receptors. olfactory receptors.

16. NocireceptorsNocireceptors
- pain receptors from any noxious - pain receptors from any noxious
stimulus stimulus

18. Classification according to structureClassification according to structure
Simple ( large majority )Simple ( large majority )
- similar to modified dendritic endings- similar to modified dendritic endings
- found on skin, mucous membrane,- found on skin, mucous membrane,
muscles and connective tissuesmuscles and connective tissues

19. Location of simple receptorsLocation of simple receptors

20. Complex (sense organs)Complex (sense organs)
- localized collection of cells that works- localized collection of cells that works
together to perform a specific processtogether to perform a specific process
- also known as special senses- also known as special senses

21. Vertebrates Sensory ReceptorsVertebrates Sensory Receptors
Chemoreception Chemoreception
-Vertebrates usually accomplish -Vertebrates usually accomplish
chemoreception by moving chemically rich chemoreception by moving chemically rich
air or water into a canal or sac that air or water into a canal or sac that
contains the chemical receptors. contains the chemical receptors.

22. Specialized receptors of vertebratesSpecialized receptors of vertebrates
Gustatory receptorsGustatory receptors
- The receptors for the gustatory nerves are known - The receptors for the gustatory nerves are known
as taste buds located on the tongue and the roof of the as taste buds located on the tongue and the roof of the
mouth. Sweet, sour, bitter, and salty are the four basic mouth. Sweet, sour, bitter, and salty are the four basic
taste sensations resulting from stimulation of the taste taste sensations resulting from stimulation of the taste
buds and the stimulation of the olfactory receptor. This is buds and the stimulation of the olfactory receptor. This is
why it is harder to taste when one has a cold. These four why it is harder to taste when one has a cold. These four
basic tastes may evolutionarily developed to show some basic tastes may evolutionarily developed to show some
basic food properties. Sweet taste signals foods high in basic food properties. Sweet taste signals foods high in
calories, salty foods signal for food that helps maintain calories, salty foods signal for food that helps maintain
water balance, sour tastes may help to signal foods that water balance, sour tastes may help to signal foods that
could be dangerous if eaten in excess, and bitter taste could be dangerous if eaten in excess, and bitter taste
sensations signal toxic foods.sensations signal toxic foods.

24. Taste budsTaste buds

25. Olfactory receptorsOlfactory receptors
- - The receptors for the olfactory nerves are located in the The receptors for the olfactory nerves are located in the
upper part of the nasal cavity. The olfactory sense organ upper part of the nasal cavity. The olfactory sense organ
consists of hair-like cells at the end of a neuron and is consists of hair-like cells at the end of a neuron and is
simple compared to the complex visual and auditory simple compared to the complex visual and auditory
organs. The olfactory receptors are very sensitive to organs. The olfactory receptors are very sensitive to
stimuli; however, they also become very fatigued. This stimuli; however, they also become very fatigued. This
explains why odors seem to go away after being easily explains why odors seem to go away after being easily
noticeable. Canals lined with sheets of receptors with the noticeable. Canals lined with sheets of receptors with the
nasal cavity are called turbinate. Protruding from the end nasal cavity are called turbinate. Protruding from the end
of the nerve are thin cilia that are covered by mucus. of the nerve are thin cilia that are covered by mucus.
Molecules are absorbed into the mucous layer and passed Molecules are absorbed into the mucous layer and passed
to the cilia where the chemical is detected. Notice the to the cilia where the chemical is detected. Notice the
chemicals must be dissolved in the mucus and absorbed in chemicals must be dissolved in the mucus and absorbed in
order for the olfactory receptors to react. This is a lot order for the olfactory receptors to react. This is a lot
like the gustatory mechanisms.like the gustatory mechanisms.