Essay 3 Shubham Tyagi
How do our sensory systems work? Write about taste, sight, hearing and touch.
Sensory systems are important to us; they let us perceive the environment. The senses can be broadly divided in to the sense of touch, smell, taste, vision and hearing. The seemingly simple perception is in fact not as simple as it sounds there is a lot of chemistry and physics that takes place. When we touch a hot surface, smell that delicious food, see beautiful colors, or hearing that beautiful music, our nervous system is working at an incredible rate, to make sense of these signals and let us enjoy them or run away from them.
Sense of Taste: Sense of taste is related to the sense of smell but there are only five kinds of tastes that we can detect. They are sweet, sour, bitter, salty and umami. Detection of taste is done via special epithelial cells in the taste buds of the tongue. In case of salty taste the sodium ions leads to opening of ion channels and the signal is sent as an electrical impulse to the brain. In case of sweet, bitter an umami 7TM receptors are involved, when a “tastent “ binds to these receptors they produce cAMP, which in turn open channel proteins which allow ions to pass through and the neuron send the impulse to the brain which detects it.
Sight: Sense of sight or vision is the ability to see, this is done through the photoreceptor cells, which are either Rods or cones. Rod cells contain a pigment rhodopsin, which in turn consists of opsin protein and retinal. When retinal is exposed to light it changes its conformation. This then lead to activation of a G Protein called Transducin. Transducin then breaks cGMP to GMP, which leads to closing of ion channels, sending an electrical signal to the brain. Cone cells on the other hand contain pigment specific receptors; there are receptors of...
References: Jermey M Berg, John LTymokzo, Lupert Stryer. (2012). Sensory systems Biochemistry (7th ed,). New York : W.H. Freeman and Company.
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