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Mechanoreceptors
- Receptors in the skin that respond to touch, vibration, or pressure
- Stretch receptors in many internal organs
- Position receptors in the joints
- Receptors in the inner ear that allow us to detect sound
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How to catch a fly?
- Mechanoreceptors are important to all animals
- Spiders: detect vibrations of their webs
- Cockroaches: detect tiny puffs of air that move ahead of predators, and run off in the opposite direction
- Fish: lateral lines detect movement and vibration
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How Does the Ear Detect Sound?
- The ear: sound waves into electrical signals
- outer ear: pinna and the auditory canal
- middle ear: tympanic membrane, or eardrum; three tiny bones
- hammer (malleus)
- anvil (incus)
- stirrup (stapes);
- and the auditory tube (Eustacian tube)
- Inner ear: cochlea
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outer ear
- pinna and the auditory canal
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middle ear:
- tympanic membrane, or eardrum; three tiny bones
- hammer (malleus)
- anvil (incus)
- stirrup (stapes);
- and the auditory tube (Eustacian tube)
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The ear: sound waves into electrical signals
- outer ear: pinna and the auditory canal
- middle ear: tympanic membrane, or eardrum; three tiny bones
- hammer (malleus)
- anvil (incus)
- stirrup (stapes);
- and the auditory tube (Eustacian tube)
- Inner ear: cochlea
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Vibrations are converted into electrical signals in the cochlea
- oval window passes vibrations from the bones of the middle ear to the fluid in the cochlea
- consists of three fluid-filled compartments
- hair cells sit on top of basilar membrane
- movement bends the hairs of the hair cells,
- receptor potentials that induce the hair cells to release neurotransmitters onto neurons whose axons form the auditory nerve
- The auditory nerve axons produce action potentials that travel to the auditory centers of the brain
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vestibular apparatus
- The vestibular apparatus detects gravity and movement
- hair cells in a gelatinous matrix containing tiny stones of calcium carbonate
- gravity pulls the stones downward, causing the hairs to bend, depending on the tilt of the head
- the bending hair cells release neurotransmitter triggering action potentials that travel to balance and equilibrium centers in the brain
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The mammalian eye collects and focuses light, converting it into electrical signals
- structures that hold the eye in a fairly fixed shape, control the amount of light that enters, and focus the light rays
- Cornea, aqueous humor, Iris,Pupil, Lens, Vitreous Humor, Choroid, Sclera
- 2) The retina: photoreceptors
- fovea
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rods and cones
- rods and cones because of their shapes, gather light at the rear of the retina (Each kind of photopigment is most strongly stimulated by a particular light wavelength corresponding to red, green, and blue )
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The retina detects light and produces action potentials in the optic nerve
- Rods and cones because of their shapes, gather light at the rear of the retina (Each kind of photopigment is most strongly stimulated by a particular light wavelength corresponding to red, green, and blue )
- Receptors absorb light by photopigment molecules
- neurons process the signals from the photoreceptors
- These neurons enhance our ability to detect edges, movement, and changes in light intensity
- The retinal layer nearest the vitreous humor consists of ganglion cells, whose axons make up the optic nerve
- ganglion cell axons pass through the retina at a location called the blind spot; it lacks receptors, so objects focused there cannot be seen
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Chemoreceptors
allow animals to find food, avoid poisonous materials, locate homes, find mates, and maintain homeostasis
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Olfaction
- the sense of smell
- Olfactory receptor neurons bear long dendrites that protrude into the nasal cavity and are embedded in the mucus
- Odorous molecules in the air diffuse into the mucus layer and bind to receptor proteins on the dendrites; their axons extend directly to the olfactory bulb in the brain
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We perceive a great variety of tastes through two mechanisms:
- a particular substance may stimulate two or more receptor types to different degrees, making the substance taste “sweet and sour”
- 2) a substance being tasted usually releases molecules into the air inside the mouth, and these molecules diffuse to the olfactory receptors, which contribute an odor component to the basic flavor
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pain receptors
- Pain is a subjective feeling arising in the brain produced by the stimulation of pain receptors
- pain receptors are free nerve endings that occur in most parts of the body
- thermal nociceptors respond to high and low skin temperatures;
- mechanoreceptors that respond to excessive stretching
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thermal nociceptors
respond to high and low skin temperatures
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mechanoreceptors
- hair cells located in the inner ear. free nerve endings and endings surrounded by accessory structures.
stimulated by vibration,pressure, touch
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vertebrate receptors
- thermoreceptor= skin, feel hot/cold
- Mechanoreceptor- hair cells in inner ear, vibration motion gravity
- Photoreceptors- rods, cones. light
- Chemoreceptors- olfactory/taste receptor,
- Pain receptor
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