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=**Chapter 10 Section 2 : Receptors & Sensations**﻿﻿ =

***Sensory receptors are broken up into 5 different types according to their sensitivity.**
**__Chemoreceptors__ : stimulated by changes in the chemical concentrations of substances.** **__Pain receptors__ : stimulated by tissue damage** **__Thermoreceptors__ : stimulated by the changes in temperature** **__Mechanoreceptors__ : stimulated by changes in pressure or movement** **__Photoreceptors__ : stimulated by light energy**

- allows a person to pinpoint the region of stimulation. - the cerebral cortex causes this feeling to seem to come from the stimulated responces.
 * *Sensations : **
 * __﻿Sensation__ : **also known as a perception, is a feeling that occurs when the brain interprets sensory impulses.
 * - the sensation depends on which region of the brain recieves the impulse. **
 * __Projection__ : **the process by which the brain causes a sensation to seem to come from the region of the body being stimulted.

***Sensory Adaptation :** So the brain doesn't get over whelmed with the sensory input it recieves it has learned to use __**Sensory Adaptation**__, giving the brain the ability to ignore the unimportant stimuli. - Sensory Adapation may involve receptors becoming unresponsive //(peripheral adaptation)// or inhibition along the central nervous system pathways leading to the sensory regions of the cerebral cortex.

 **Chapter 10 Section 4 : Special Sences **

- Special Sences are those whose sensory recpetors are within large, complex sensory organs in the head. <span style="border-collapse: separate; color: #000000; font-family: Arial,Helvetica,sans-serif; font-size: 130%; line-height: 19px;"> <span style="border-collapse: separate; color: #000000; font-family: Arial,Helvetica,sans-serif; font-size: 130%; line-height: 19px;">* Smell --> Olfactory organs <span style="border-collapse: separate; color: #000000; font-family: Arial,Helvetica,sans-serif; font-size: 130%; line-height: 19px;">* Taste -->Taste Buds <span style="border-collapse: separate; color: #000000; font-family: Arial,Helvetica,sans-serif; font-size: 130%; line-height: 19px;">* Hearing -> Ears <span style="border-collapse: separate; font-family: Arial,Helvetica,sans-serif; font-size: 130%; line-height: 19px;">* Equalibrium > Ears <span style="border-collapse: separate; color: #000000; font-family: Arial,Helvetica,sans-serif; font-size: 130%; line-height: 19px;">*Sight --> Eyes <span style="font-size: 1.4em; margin: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 5px;">**<span style="color: #00c7ff; font-family: 'Comic Sans MS',cursive; font-size: 150%;">Chapter 10 Section 6 : Sence of Taste ** <span style="font-family: Arial,Helvetica,sans-serif; font-size: 105%;">- __**taste buds**__ : special organs of taste
 * <span style="color: #800080; font-family: 'Courier New',Courier,monospace; font-size: 16px; line-height: 23px;">*Taste Receptors: **

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<span style="border-collapse: collapse; font-family: Arial,Helvetica,sans-serif; font-size: 17px; line-height: 23px;">-Each taste bud includes modified epithelial cells, **__taste cells__**, which function as receptors.<span style="border-collapse: collapse; font-family: Arial,Helvetica,sans-serif; font-size: 110%; line-height: 23px;">

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<span style="border-collapse: collapse; font-family: Arial,Helvetica,sans-serif; font-size: 110%; line-height: 23px;">-Each bud has about 50 to 150 receptors cells, which are replaced about every 3 days.There are also epithelial //supporting cells//. The bud itself has a spherical shape with an opening called the **__taste pore__**. It has tiny projections called **__taste hairs__** protruding from the outer ends of the taste hair extending to the taste pore. <span style="border-collapse: collapse; font-family: Arial,Helvetica,sans-serif; font-size: 105%; line-height: 23px;"> - the taste hairs are believed to be the sensitive parts of the receptor cells

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<span style="border-collapse: collapse; font-family: Arial,Helvetica,sans-serif; font-size: 14px;"> -Interwoven and wrapped around the taste cells are a network of nerve fibers. Stimulation of a receptor cell triggers an impulse on a nearby nerve fiber, then impulse travels into the brain. =====

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<span style="border-collapse: collapse; font-family: Arial,Helvetica,sans-serif; font-size: 105%; line-height: 19px;">-There is a watery fluid that the salivary glands provide and before a particular chemical can be tasted it has to be desolved in the fluid. Food molecules bind to receptors and the pattern generates a sensory impulse on nearby nerve fibers and then is interpreted as a particular taste sensation. =====

**- Each part of the tounge taste different things.**
 * <span style="color: #800080; font-family: 'Courier New',Courier,monospace; font-size: 120%;">*Taste Sensations : **

**<span style="color: #00c7ff; font-family: 'Comic Sans MS',cursive; font-size: 27px;">Chapter 10 Section 8 : Sense of Equilibrium **

**<span style="color: #000000; font-family: Arial,Helvetica,sans-serif;">﻿- ** The sence of equilibrium is really two sences, static and dynamic equilibrium, that come from different sensory organs. - __**Static equilibrium :**__ the sense of position of the head, maintaining the stability and posture when the head and body or still. - __**Dynamic Equilibrium**__: detects sudden movement or rotation of the head and body to aid in maintaining balance.


 * <span style="color: #800080; font-family: 'Courier New',Courier,monospace; font-size: 105%; line-height: 27px;">*Static Equilibrium :﻿﻿ **

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">- the organs of static equilibrium are located with in the __**vestibule:**__ a bony chamber between the semicircular canals and the cochlea. <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; font-size: 110%; line-height: 27px;">- The membranous labyrinth inside the vestibule consists of two expanded chambers : **__utricle__** and a __**saccule.**__ <span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%; line-height: 27px;">- each of these chambers has a tiny structure called a __**macula.**__ Macula contain many hair cells which serve as sensory receptors. The nerve impulses travel into the CNS on the vestibular branch of the vestibulocochlear nerve. These impulses inform the brain of the head's new position. The brain responds by sending motor impulses to skeletal mucles, which contract or relax to maintain balance.


 * <span style="color: #800080; font-family: 'Courier New',Courier,monospace; font-size: 120%; line-height: 27px;">* Dynamic Equilibrium : **

- The detect motion of the head and aid in balancing the head and body during sudden movement - Suspended in the perilymph of the osseous portion of each semicircular canal is a membranous canal that ends in swelling called __**ampulla**__, which contains the sensory organs of the semicircular canals. Each of those organs, called __**crista ampullaris**__ which contain many sensory hair cells and supporting cells. - Rapid turns of he head or body stimulate the hair cells of the crista ampullaris. At the same timethe semicircula canals move with the hed or body, but the fluid inside the membraneous canals staying stationary. This bends the culpula in one or more of the canals in a direction opposite thast of the head or body moveent, and the hairs embedded in it also bend. The stimulated hair cells signal their associated nerve fibers, sending impulses to the brain. -the cerebellum helps interpret the impulses from the semicirular canals. The analysis allows the brain to predict the consequences of rapid body movements, and by modifying signals to appropirete skeletal musclesm the cerebellum can maintain balance.
 * <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; font-size: 105%; line-height: 27px;">﻿- ** The organs of dynamic equilibrium are the three semicircular canals within the labyrinth.

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