Life sciences sense organs

1. UNIT 2:
SENSE ORGANS –
EYES, TONGUE AND
SKIN
•
Campbell et.al, 2010 –
CHAPTER 50

2. INTRODUCTION: SENSE ORGANS
Sensations and perceptions begin with
sensory reception, detection of stimuli by
sensory receptors.
Sensory receptors can detect stimuli
outside and inside the body.
Sensory receptors fall into five categories:
 Mechanoreceptors
 Chemoreceptors
 Electromagnetic receptors
 Thermoreceptors
 Pain receptors

3. 2. CHEMICAL SENSES: TASTE
The receptors responsible for taste are
called– CHEMORECEPTORS
Gustation (taste) is dependent on the
detection of chemicals called tastants.

4. SENSE OF TASTE
Taste receptors = TASTE BUDS
Taste buds are located on tongue(mainly),
hard palate, pharynx and epiglottis.

5. The tongue very rough, due to
numerous papillae.
4 Types of papillae:
- Fungiform- found on front and
sides of tongue.
- Foliate found on front 2/3 of
tongue
- Circumvallate- found on the
back of the tongue.
• Filliform papillae – in middle of
tongue
The taste buds are located on
the papillae.

6. PAPILLAE ON TONGUE

7. 3 TYPES OF PAPILLAE

8. STRUCTURE OF TASTE BUDS

9. FUNCTIONS OF TASTE BUDS
Chemical molecules in food, dissolve in the
saliva.
The molecules bind to the receptor proteins in
the microvilli of the taste buds.
This stimulates the taste cells to send an
impulse through the sensory nerve fibers.
Impulse move to the parietal lobe of
cerebrum.
Taste is interpreted
https://www.youtube.com/watch?v=JJyQz0152t
8

10. 5 PRIMARY TASTE PERCEPTIONS
Sweet
Sour
Bitter
Salty
Umami (Japanese
savory taste)
- Certain regions of the
tongue are more sensitive
to particular tastes.

11. 3. SENSE ORGAN: SKIN
Mechanoreceptors sense physical
deformation caused by stimuli such as
pressure, stretch, motion, and sound
The sense of touch in mammals relies on
mechanoreceptors
Thermoreceptors, which respond to heat
or cold, help regulate body temperature by
signalling both surface and body core
temperature.
https://www.youtube.com/watch?v=IZ8WOC
U5jYw