1.2 |
Stimulus and Response in Humans |
Definition |
Sensory organs are organs that can detect stimuli
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Humans have five sensory organs:
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Skin (touch)
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Nose (smell)
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Tongue (taste)
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Ears (hearing)
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Eyes (Sight)
The function of eyes:
The structure of eyes:
The function of each eyes structure:
The mechanism of vision:
- Light from an object enters the eye through the pupil
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Light is refracted by the cornea, aqueous humor, eye lens, and vitreous humor
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Inverted and small images are formed on the retina
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The retina produces nerve impulses and the optic nerve transmits them to the brain
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The brain translates impulses and produces upright images
The function of ears:
The structure of ears:
The function of each ears structure:
The structure of ears
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Function
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Ossicles
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Amplifies the vibration of sound and sends it to the oval window
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Earlobe
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Receives sound waves
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Ear canal
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Transmits sound waves to the eardrum
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The eardrum
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Vibrates when sound waves hit it
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Semicircular canal
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Controls body balance
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The auditory nerve
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Sends impulses from the cochlea to the brain
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Cochlea
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Converts sound vibrations into impulses
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Oval window
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Transmits sound vibrations from the middle ear to the inner ear
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Eustachian tube
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Balances the air pressure on both sides of the eardrum
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The mechanism of hearing:
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Sound waves enter the ear canal
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The eardrum receives sound waves and vibrates
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The vibrations are amplified by the ossicle bone and transmitted to the oval window
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The oval windows vibrated
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The cochlea converts vibrations into impulses
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Impulses are carried by the auditory nerve to the brain
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The brain interprets it as sound
The function of the nose:
The structure and mechanism of the nose:
The function of the tongue:
The structure and mechanism of the tongue:
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The surface of the tongue is covered by taste buds that contain many taste receptors and are scattered on the surface of the tongue
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Taste receptors are sensitive to chemicals in food
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The tongue has 5 types of taste receptors, namely sweet, sour, bitter, and umami (savory taste).
The function of the skin:
The structure of skin:
Skin sensitivity:
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The concentration of the skin depends on the number of receptors present and the thickness of the epidermis
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The more receptors, the more sensitive that part of the skin is
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The thinner the epidermis, the more sensitive the skin is to stimuli
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Blind people read Braille using their fingertips
Very sensitive parts of the skin
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Part of the skin that is less sensitive
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Fingertips, back of neck, lips, and earlobes
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Elbows and knees
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- The sensory organs are interconnected with each other and can balance the human body on a single daily basis
The limit of sensory:
The visual sensory limitations:
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The eye cannot detect an image that falls on a blind spot
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Human vision can also be affected due to farsightedness, nearsightedness, astigmatism, and presbyopia
The structure of the normal eye, farsightedness, and nearsightedness:
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Farsightedness cannot see distant objects clearly because light from the object is focused in front of the retina
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Requires a concave lens
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Nearsightedness cannot see near objects clearly because light from the object focuses behind the retina
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Requires a convex lens
The structure of the astigmatism eye:
The structure of the presbyopia eye:
Hearing sensory limitations:
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Humans can only hear between 20Hz to 20,000Hz
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Deafness is caused by the ossicle bones joining together due to infection, the aging process or exposure to loud noise for a long period of time
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Only surgery or hearing aids can help deaf people
Technology to enhance the ability of sensory organs:
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Technology
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Sensory organ capacity
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Limitation of vision
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Magnifying glass & microscope
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Can see art/small objects
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Binoculars & telescopes
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Can see distant objects
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Limitation of hearing
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Stethoscope
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Amplifies the sound of the heartbeat
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Loudspeaker
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Amplifies the sound
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