BIOLOGY 220 LECTURE #20 - Animal defenses 2 - Sensory and Musculoskeletal Systems - 11-16-07

BIOLOGY 220 LECTURE - BIOLOGY 220 LECTURE#20 ANIMAL DEFENSES 2 SENSORY AND MUSCULOSKELETAL SYSTEMS NERVOUS SYSTEM 2 The Sensory system is often

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BIOLOGY 220 – LECTURE #20 – ANIMAL DEFENSES 2: SENSORY AND MUSCULOSKELETAL SYSTEMS NERVOUS SYSTEM – 2 The Sensory system is often thought of as an extension of the nervous system SENSORY SYSTEM – 3 Sensory Perception 1.) Stimulus - We have a stimulus from either inside or outside of the body – detected by some sort of receptor protein – signal or stimuli binds to receptor protein and causes it to change conformation and induces what is called a signal cascade 2.) Transduction – Stimulus undergoes transduction – it moves through into the cell, changing the membrane potential of that cell – activating energy of the stimulus is converted into some other form of energy, usually in the form of membrane potential. 3.) Transmission – Action potential is transmitted to a sensory neuron 4.) Interpretation – Eventually the signal moves into the brain or at least into the spinal cord and the information is interpreted – spinal cord or brain can start sending a response signal. SENSORY SYSTEM – 4, 5 What can be sensed? o Mechanical – pain (can be caused by mechanical and chemical stimuli), pressure, sound, texture o Chemical – Pain, smell, taste, humidity (a change in pressure in your cells due to the amount of moisture) o Electromagnetic – Heat/cold, pain, light, electricity SENSORY SYSTEM – 6 - WE CONCENTRATE ON JUST 3 DIFFERENT TYPES OF sensory receptor cells Sensory receptor cells – little proteins embedded in the membrane of a cell o Chemoreceptors o Photoreceptors o Mechanoreceptors
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These are the 3 major types! CHEMORECEPTORS -7 How does your tongue work? o Food particles work past taste buds and into receptor cells – causes depolarization of the receptor cell – causes release of neurotransmitter o There are only 5 categories from which we can taste Sweet Salty Sour Bitter Amonate CHEMORECEPTORS - 8 Odor detection – very sensitive (can detect thousands of different smells) Taste is derived from the sensory receptors in our nose and on our tongues Infinite possibilities for smell The way this works is: o Nasal cavity – Olfactory receptor cells lining the inner part of nasal cavity – depolarized when a stimuli (chemical) binds to it Causes an action potential that moves into the nerves Radiated into this area called the olfactory bulb Contains nerves that take the signal directly to the brain. This is one of the most direct routes to the brain (olfactory bulb) The receptors on the tongue are not as receptive as those in those nose o Smelling your food is just as important as tasting (to “taste” the food) Chemoreceptor - Anything that has a chemical physically bind to it is some kind of a chemoreceptor in the body o Sensory stimuli
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PHOTORECEPTORS – 9 Photoreceptors – Receptors that pick up on light stimuli or electromagnetic stimuli – eye structures Vertebrate eye PHOTORECEPTORS – 10 o Light enters the eye through the cornia in through the pupil (which is
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This note was uploaded on 04/15/2008 for the course BIO 220 taught by Professor Cassiemajetic during the Fall '07 term at Allegheny.

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BIOLOGY 220 LECTURE - BIOLOGY 220 LECTURE#20 ANIMAL DEFENSES 2 SENSORY AND MUSCULOSKELETAL SYSTEMS NERVOUS SYSTEM 2 The Sensory system is often

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