Se ha denunciado esta presentación.
Utilizamos tu perfil de LinkedIn y tus datos de actividad para personalizar los anuncios y mostrarte publicidad más relevante. Puedes cambiar tus preferencias de publicidad en cualquier momento.
SCIENCE
FORM 2
CHAPTER 1
THE WORLD THROUGH OUR
SENSES
1.1 Sensory Organs
Sensory organs, stimuli and senses
a) Sensory organs : organs that detect
stimuli.
b) Stimuli : Any cha...
sense sensory organs stimuli detected
touch skin
touch, pressure,
heat, cold, pain
taste tongue taste
smell nose smell
sig...
d) HOTS
Without sensory organs, we will not be
able to know what is happening in our
surroundings. So, we must take care o...
Responses to stimuli
• response: a reaction
• receptor: a structure that recognize a stimulus in
the internal/ external en...
Common pathway from the stimulus to
response in humans
1.2 Sense of touch
The Skin - largest organ in the body.
The sensitivity of the skin
• Different parts have different degrees of
sensitivity.
• Depends on:
1.how close together th...
Examples:
• The back of the body is less sensitive as
it has very few touch reseptor.
• The knees and elbows are less sens...
HOTS- APPLICATION
• Blind people use the high sensitivity
of their fingertips to read in Braille.
Raised dots are used to ...
• Doctors give
injections to their
patients at the
forearms or hips.
One of the reasons
for this is these
areas are less
s...
• The back of the
hands has a lot of
heat and cold
receptors
(temperature).
Mother test the
temperature of
their babies' m...
1.3 Sense of smell
1.Two holes, called nostrils, open into a
large hollow space called nasal cavity.
2.The nasal cavity is lined with mucus. ...
• Smell receptors are located at the roof of
the nasal cavity. This position allows the
receptors to have the maximum expo...
Detecting smell.
• Smells are actually chemicals present in
the air.
• Food, perfume .............air.
• When we breathe i...
HOTS!!!!!
• When a person catches a cold, they
cannot detect smell well. The nose
produces too much mucus which prevents
c...
1.4 Sense of Taste
• draw figure 1.8 pg 9
draw figure 1.9 pg 10
1.Tongue is sensitive to chemicals in
food that give taste to food.
2.Can detect 4 tastes: _____, _____,
_____ and _______...
How tastes are detected?
• When we chew our ..................saliva.
• The dissolved.......................impulses.
• Th...
The senses of taste and smell.
• Both senses are needed to detect the
flavour of food/ drink accurately.
• The nasal cavit...
• When we have cold, chemicals in the
food cannot reach the smell receptors
because excessive mucus or blocked
nose. So, t...
Chapter 1 form 2
Chapter 1 form 2
Chapter 1 form 2
Chapter 1 form 2
Chapter 1 form 2
Próxima SlideShare
Cargando en…5
×

Chapter 1 form 2

eye

  • Inicia sesión para ver los comentarios

Chapter 1 form 2

  1. 1. SCIENCE FORM 2
  2. 2. CHAPTER 1 THE WORLD THROUGH OUR SENSES
  3. 3. 1.1 Sensory Organs Sensory organs, stimuli and senses a) Sensory organs : organs that detect stimuli. b) Stimuli : Any changes that occur in the surroundings which lead to respond. c) Senses: detectors used to find out the stimuli.
  4. 4. sense sensory organs stimuli detected touch skin touch, pressure, heat, cold, pain taste tongue taste smell nose smell sight eyes light hearing ears sound
  5. 5. d) HOTS Without sensory organs, we will not be able to know what is happening in our surroundings. So, we must take care of our sensory organs from injuries.
  6. 6. Responses to stimuli • response: a reaction • receptor: a structure that recognize a stimulus in the internal/ external environment of an organism. • nerve impulses: electrical messages produced by receptor. • effector: part of the body that carry out responses. Example: muscle and gland
  7. 7. Common pathway from the stimulus to response in humans
  8. 8. 1.2 Sense of touch The Skin - largest organ in the body.
  9. 9. The sensitivity of the skin • Different parts have different degrees of sensitivity. • Depends on: 1.how close together the receptors are - the higher the concentration of receptor, the more sensitive the skin is 2.how deep the receptor are - the thicker the epidermis, the deeper the receptors lie in the skin, the less sensitive the skin is.
  10. 10. Examples: • The back of the body is less sensitive as it has very few touch reseptor. • The knees and elbows are less sensitive as they have a thick epidermis. • The lips and fingertips are very sensitive to touch due to the large number of touch receptor. They have thin epidermis too.
  11. 11. HOTS- APPLICATION • Blind people use the high sensitivity of their fingertips to read in Braille. Raised dots are used to represent letters and numbers.
  12. 12. • Doctors give injections to their patients at the forearms or hips. One of the reasons for this is these areas are less sensitive to pain.
  13. 13. • The back of the hands has a lot of heat and cold receptors (temperature). Mother test the temperature of their babies' milk on the back of their hands.
  14. 14. 1.3 Sense of smell
  15. 15. 1.Two holes, called nostrils, open into a large hollow space called nasal cavity. 2.The nasal cavity is lined with mucus. Its roof has many smell receptors/ sensory cell. 3.Adaptation: The smell receptors are always covered with mucus. Smells must dissolve in the mucus before they can be detected.
  16. 16. • Smell receptors are located at the roof of the nasal cavity. This position allows the receptors to have the maximum exposure to the air current.
  17. 17. Detecting smell. • Smells are actually chemicals present in the air. • Food, perfume .............air. • When we breathe in, .........cavity. • The ......cells. • These ........smell. • After smelling ......brain. • Then we ....... smell it.
  18. 18. HOTS!!!!! • When a person catches a cold, they cannot detect smell well. The nose produces too much mucus which prevents chemicals from stimulating the smell receptors. • A dog's sense of smell is hundred times more sensitive than human. Therefore, dogs are being used to track criminals and to sniff out drugs or explosives.
  19. 19. 1.4 Sense of Taste • draw figure 1.8 pg 9
  20. 20. draw figure 1.9 pg 10
  21. 21. 1.Tongue is sensitive to chemicals in food that give taste to food. 2.Can detect 4 tastes: _____, _____, _____ and _______. 3.The tongue is lined with taste buds which contain many taste receptor.
  22. 22. How tastes are detected? • When we chew our ..................saliva. • The dissolved.......................impulses. • These are ................................tastes. pg 10
  23. 23. The senses of taste and smell. • Both senses are needed to detect the flavour of food/ drink accurately. • The nasal cavity and mouth are connected. When we eat/ drink, chemicals from food move up to nasal cavity and stimulate the smell receptors in the nose as well.
  24. 24. • When we have cold, chemicals in the food cannot reach the smell receptors because excessive mucus or blocked nose. So, the food become less tasty.

×