5 Mechanoreceptors pain heat cold touch and pressure Nociceptors are

5 mechanoreceptors pain heat cold touch and pressure

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5.) Mechanoreceptors: pain, heat, cold, touch, and pressure. Nociceptors are concentrated where injury is probable to occur (pain, noxious substances and tissue damage, free nerve endings). Thermoreceptors respond to temperature changes, contain TRP ion channels responsive to hot and cold. Found in skin and hypothalamus. Several receptors have a Transient Receptor Potential (TRP) ion channel to respond to changes in temperature. RESPOND TO TOUCH: Phasic receptors , not always activated, are hair follicle receptors. Tonic receptors are continuously activated, near surface of skin, contain Ruffini corpuscles, Merkel’s Disks. Proprioceptors monitor position/movement of the body. Muscle tension = muscle spindles and Golgi tendon organs. Baroreceptors monitor blood pressure. Located in arteries that supply blood to the brain, Aortic arch (heart) and Carotid Sinus. - Taste (taste buds), Smell (cilia on the dendrites of receptors in nasal passage and into cerebral cortex), pH (monitored by peripheral chemoreceptors in the aortic bodies) Increased CO2 in blood lowers pH. 6.) Sound is detected by mechanoreceptors, waves travel through air and water, causing land and sea animals to have different hearing apparatuses. Otoliths (aquatic) different density hearing structure = denser than water, allow fish to detect sound. Terrestrial hearing = outer, middle (convert sound waves into motion), and inner (contains receptors for sound waves) ear. Tympanic membrane -> Middle Ear -> Oval Window - The inner ear houses the cochlea , a complex structure that is fluid. The sound waves travel through the fluid of the cochlear duct to vibrate the Basilar membrane , in which hair cells are embedded (good picture in power point). - Gravity receptors make it possible to detect gravity and acceleration. Vertebrates have structures in their ears: - Utricle : detects horizontal motion - Saccule : detects vertical motion - Semicircular Canals : detect angled motion 7.) Vertebrate Eye Structure: Light enters and is focused by the cornea and lens . The amount of light allowed in is determined by the pupil , which is the opening in the iris , which can contract/dilate to change the size of the pupil. After passing through the lens, the light is focused on the retina , made of 3 layers: (1) furthest back, rods (light/dark) and cones (color) (photoreceptors), (2) bipolar cells (3) ganglion cells: send signal to brain. Axons bundled together in the third layer cause our blind spot. In Mollusks/Insects, no process to brain/complication because retinal layers arranged in opposite order, resulting in no blind spot. 8.) Sensory transduction works differently with light: A stimulus depolarizes a receptor and causes an action potential that sends and excitatory signal to the postsynaptic neuron. In photoreceptors, darkness causes depolarization because sodium ions enter through open ion channels, which sends an inhibitory signal to bipolar cells. When light impinges on the photoreceptor it becomes hyperpolarized, closing of sodium ion channels, inhibitory signal to bipolar cells, which send signal to ganglion cells, which send it to the brain.
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