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The Senses 35-4. BIO 1004 Flora. Senses. Sensory receptors – react to a specific stimulus such as light or sound by sending impulses to the CNS Sense organs – Eyes Ears Nose Mouth skin. 5 Categories of Sensory Receptors. Pain – located throughout body – except brain
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The Senses 35-4 BIO 1004 Flora
Senses • Sensory receptors – react to a specific stimulus such as light or sound by sending impulses to the CNS • Sense organs – • Eyes • Ears • Nose • Mouth • skin
5 Categories of Sensory Receptors • Pain – located throughout body – except brain • Respond to chemicals released by damaged cells • Thermo – located in skin, body, and hypothalamus • Detect variations in temperature • Mechano – skin, skeletal muscle, ears • Detect sensation of touch, pressure, and sound
5 Categories of Sensory Receptors • Chemo – Nose/Taste buds – senses to chemicals in the environment • Photo – eyes – sensitive to light
Vision Process • Light enters through cornea • Cornea – focuses light • Light passes through aqueous humor • Aqueous humor – fluid chamber • Iris – colored disk structure at back of aqueous humor • Pupil – small opening in iris • Muscles adjust the size of the pupil regulating the amount of light that enters the eye
Vision Process Cont. • Lens – behind the iris, helps the eye focus on or near distant objects • Vitreous humor – large chamber of the eye that is filled with fluid • Retina – light is focused here • Photo receptors are located here • Optic nerve - carries impulses assembled in the eye to the brain
2 Types of Photoreceptors • Rods – Sensitive to light, not color • Cones – not sensitive to light • Responsible for our color vision
Hearing and Balance • 2 Functions of ear • Hearing • Balance
Hearing Process • Vibrations enter through auditory Canal • Vibrations cause tympanum (ear drum) to vibrate • Vibrations are picked up by hammer, anvil, and stirrup • Stirrup transmits vibrations to oval window • Vibrations cause pressure waves in fluid-filled cochlea • Cochlea is lined with hairs that move as a result of the waves, thus sending nerve impulses to the brain through cochlear nerves
Balance • Semicircular Canals – monitor position of the body in relation to gravity • Process: • Fluid in canals changes with position of head • Fluid moving causes hairs to bend and send impulses to brain that determine body position
Smell, Taste, and Touch • Chemoreceptors in nasal passages respond to chemicals and communicate with the brain • Taste of food is actually smell (hold nose when you eat) • Taste buds – sense organ • Skin – largest sense organ • Contains the most sensory receptors that respond to temp, pain, and touch • Face, fingers, and toes have the most