Detecting

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15
Detecting Environmental Conditions
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• 15.1 Irritability
• 15.2 The five senses
• 15.3 The eye
• 15.4 Structure and functions of the eye
• 15.5 The control of the amount of light entering
  the eye
• 15.6 The accommodation of the eye

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15.1 Irritability
Irritability
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15.1 Irritability
Irritability
senses our surroundings
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15.1 Irritability
Body
Part B
Part C
Part A
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15.1 Irritability
Body
Central Nervous System (CNS)
Part B
Stimulus
Effector
Part C
Receptor
Part A
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15.1 Irritability
Receptor
CNS
Effector
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15.1 Irritability
Receptor
CNS
Effector
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15.1 Irritability
Stimuli
Internal environment
External environment
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15.1 Irritability
Receptor
CNS
Effector
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15.1 Irritability
1
Receptors
is detected by
Central Nervous System (CNS)
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produce
Nerve
impulses
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15.1 Irritability
Receptors
1
Detect stimuli
2
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15.1 Irritability
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15.1 Irritability
Receptor
CNS
Effector
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15.1 Irritability
Effector
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15.1 Irritability
Behaviour
Lower animals
Higher animals
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15.2 The five senses
Ch 15. 2
Five senses
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15.2 The five senses
Touch
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Touch
15.2 The five senses
1
2
3
4
5
How many kinds of receptor are found in the skin?
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Touch
15.2 The five senses
Distribution of receptors
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15.2 The five senses
Taste
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Taste
15.2 The five senses
Taste bud
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Taste
Soluble chemicals in food
Brain
Taste bud
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Taste
15.2 The five senses
Types of taste
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15.2 The five senses
Smell
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Smell
15.2 The five senses
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Smell
15.2 The five senses
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Smell
Brain
Air
Soluble gaseous chemicals
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Smell
15.2 The five senses
Smell
Nose
Sense
Detects soluble chemicals
Tongue
Taste
2
Detects harmful substances
1
Stimulates appetite
Flavour of food
Initiates secretion of digestive juices
3
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15.2 The five senses
Hearing
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Hearing
15.2 The five senses
Middle Ear
Inner Ear
Outer Ear
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Hearing
15.2 The five senses
Pinna collects the sound wave
Eardrum vibrates
Air vibration
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Hearing
15.2 The five senses
Vibration of ear bones
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Hearing
15.2 The five senses
Vibration of fluid in cochlea
Sensory hair cells are stimulated
Impulses are produced
Auditory nerve transmits impulses
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15.3 The eye
15. 3
The Eye
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15.3 The eye
Eye muscles
Skull
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15.3 The eye
Skull
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15.3 The eye
Eye muscles
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15.3 The eye
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15.3 The eye
Tear gland
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15.3 The eye
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15.4 Structure and functions of the eye
15. 4
Structure functions of
Eye
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15.4 Structure and functions of the eye
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15.4 Structure and functions of the eye
Three layers in the wall of eyeball
1
2
3
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15.4 Structure and functions of the eye
Keeping the shape
1
Protection
2
For muscle attachment
3
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15.4 Structure and functions of the eye
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15.4 Structure and functions of the eye
1
is transparent
is curved
2
Cornea
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15.4 Structure and functions of the eye
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15.4 Structure and functions of the eye
is continuous with
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15.4 Structure and functions of the eye
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15.4 Structure and functions of the eye
Lens
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15.4 Structure and functions of the eye
Contracts
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15.4 Structure and functions of the eye
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15.4 Structure and functions of the eye
Internal reflection of light
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15.4 Structure and functions of the eye
Internal reflection of light
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15.4 Structure and functions of the eye
For material exchange
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15.4 Structure and functions of the eye
1
Help in refracting light
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2
Diffusion of food and oxygen to the lens and
cornea
Maintaining the shape of eyeball
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15.4 Structure and functions of the eye
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15.4 Structure and functions of the eye
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15.4 Structure and functions of the eye
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How do you perceive the colours?
Three types of cones
Blue cone
Green cone
Red cone
15.4 Structure and functions of the eye
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How do you perceive the colours?
If blue light strikes on , blue colour can
be perceived.
Blue cones
It is the same for red cones and green cones
15.4 Structure and functions of the eye
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Cone
15.4 Structure and functions of the eye
How do you perceive the colours?
Blue
Green
Red
White
Black
All colours in between are produced by
stimulation of various combinations of the
different types of cones.
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15.4 Structure and functions of the eye
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15.4 Structure and functions of the eye
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15.4 Structure and functions of the eye
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15.4 Structure and functions of the eye
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15.4 Structure and functions of the eye
No vitamin A
Rod
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15.4 Structure and functions of the eye
Image formation
on the retina
vision
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15.4 Structure and functions of the eye
Light rays reflected from an object pass through
cornea, aqueous humour, lens and vitreous humour
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15.4 Structure and functions of the eye
Image formed is real, upside down and smaller
than the object.
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15.4 Structure and functions of the eye
Image is detected by rods cones on retina
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15.4 Structure and functions of the eye
Impulses pass along the optic nerve to the brain
Vision is produced
Brain
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15.4 Structure and functions of the eye
Experiment 15.1 To dissect and examine an oxs eye
1. Obtain an oxs eye from a butcher. 2.
Examine the eye muscles and the optic nerve. 3.
Remove the fat from the back of the eye.
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15.4 Structure and functions of the eye
Experiment 15.1 To dissect and examine an oxs eye
4. Cut through the cornea at right angles. Pick
up the flaps of the cornea and examine the iris.
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15.4 Structure and functions of the eye
Experiment 15.1 To dissect and examine an oxs eye
5. Cut through the iris and into the sclera to
about half-way around the walls of the eye.
Examine the inner parts of the eye.
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15.4 Structure and functions of the eye
Experiment 15.1 To dissect and examine an oxs eye
6. Remove the lens. Place it on a piece of
paper. Press it. 7. Remove the vitreous humour.
Identify the blind spot.
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15.5 The control of the amount of light entering
the eye
How to control
the amount of light
entering the eye
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15.5 The control of the amount of light entering
the eye
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15.5 The control of the amount of light entering
the eye
Under bright light
Circular muscles contract and radial muscles relax
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15.5 The control of the amount of light entering
the eye
Under dim light
Circular muscles relax and radial muscles contract
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15.6 The accommodation of the eye
Accommodation
How to focus
on the retina
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15.6 The accommodation of the eye
Compare the two figures
In figure A,
A
Focal length
Thicker lens
Shorter focal length
B
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15.6 The accommodation of the eye
The ability of the eye
to adjust the thickness of the lens for viewing
near distant objects
is called accommodation
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15.6 The accommodation of the eye
Near object
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15.6 The accommodation of the eye
Distant object
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15.6 The accommodation of the eye
Summary
Ciliary muscles
Suspensory ligaments
Lens
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15.6 The accommodation of the eye
Long sight

Short sight
Colour blindness
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Short sight
15.6 The accommodation of the eye
Distant object
Near or Distant object ?
but not clear
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Short sight
15.6 The accommodation of the eye
Correction
Wearing concave lens
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Long Sight
15.6 The accommodation of the eye
Correction
Wearing convex lens
cannot see the near object clearly
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15.6 The accommodation of the eye
Colour blindness
If a certain type of cone is missing,
certain colours may not be distinguished
Common type is red-green colour blindness
It is a hereditary disease
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Mind Map
Detecting of environmental conditions
mainly by
is called
irritability
five senses
change in external or internal environment is
called
include
stimulus
hearing
taste
sight
smell
touch
detected by
sense organ
sense organ
sense organ
sense organ
sense organ
receptors
ear
tongue
eye
nose
skin
examples
nerve impulses sent to
common eye defects
structures include


brain or spinal cord
1. aqueous humour
5. sclera
1. long sight
consists of

1. circular muscles
6. cornea
2. short sight
to

2. vitreous humour

effectors include muscles and glands
7. choroid

3. colour blindness

2. radial muscles
8. lens
3. retina
produce
for
9. iris


4. optic nerve
controlling the size of pupil
response
10. pupil
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