The world through our senses
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Transcript of The world through our senses
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The world through our senses
Chapter 1
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1.1 Sensory organs and their functions
• Sensory organs = detect changes that happen in its environment.eg/ eye
• Stimulus (s) / stimuli (p) = change in the environment that causes the body to respond.eg/ light
• Senses = ability of a sensory organ to detect stimuli.eg/ sight
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Sense
Touch
Smell
Taste
Hearing
Sight
Sensory organs
Skin
Nose
Tongue
Ears
Eyes
Types of
stimuli Pressure, pain, heat, cold
Chemicals in the air
Chemicals in food
Sound
Light
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The pathway from stimulus to response
Stimulus Sensory organs
Nerves impulse
Brain Nerves impulseRespons
e
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1.2 The sense of touch
Types of receptors in the skin
Pain Touch
Heat Cold
Pressure
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Cross section of human skin.
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Doctors usually give injections on the patients
forearms. Why???
Think!!!
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The skin on the area is less sensitive to touch and pain
compared to the skin on other parts of the body
Answer
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Sensitivity of the skin depends on:
The distance between
receptors.
The thickness
of epidermis.
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1.3 The sense of smell
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Detection of smells
Chemicals in the air
Chemicals dissolve in mucous lining
Stimulate smell receptors
Messages
Brain interprets the messages
Smell identified
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Structural adaptations of the nose to detect smell
1) Smell receptors located at the roof of nasal cavity → maximum exposure to the air that enter nasal cavity.
2) Smell receptors are covered by mucus → keep nasal cavity moist.
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When a person had a cold, they cannot
detect smell very well. Why?
THINK!!!!
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This is because too much mucus produce in the nasal
cavity and it prevent chemicals in the air to stimulates the smell
receptors.
Answer
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1.4 The sense of taste
Taste receptors
Sour
Sweet
Salty
Bitter
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Salty Salty
Location of various taste receptors.
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Detection of tastes
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Sense of taste and smell
• The nasal cavity and mouth are connected.
• The sense of taste is influenced by the sense of smell.
• When nose is blocked, food become tasteless or different from its original taste.
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Exercise 1. Name 5 senses in our body.2. State the pathway from stimulus to
response. Give example.3. Name 5 receptors found in the skin. 4. What are the 2 factors that
influence the sensitivity of skin?5. Name receptors found in:
a) epidermis layerb) dermis layerc) adipose/fatty layer
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6. The smell receptor is always dampened by mucus liquid. What is the mucus function?
7. The smell receptors in the nose are sensitive to the ……
8. What tastes can be detected by the taste buds in the tongue?
9. Why is it dry tongue cannot taste food well?
10. Why is it a person who has cold seems to find his food less tasty?
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touch
Sensory
organs
Stimuli
Senses
Conclusion
1
3
2
4 5