Sensory System
rename
Updated
2007-05-10 22:52
Terms
| Term | Function |
|---|---|
| sensory system | Body’s system of sense organs which perceives environmental stimuli and is a part of the peripheral nervous system. |
| Peripheral nervous system | the part of the vertebrate nervous system constituting the nerves outside the central nervous system and including the cranial nerves, spinal nerves etc. |
| This acts as a Transducer | sensory receptor-changes energy from one form like light or sound to electrochemical energy. |
| List the four steps of the sensory system | 1.sensory system perceives environmental stimuli.2.Senosry system sends stimuli to the central nervous system which includes the brain and spinal cord. 3. A message is sent from central nervous system to the other component of the nervous system. The motor system. 4.Response is directed. |
| What are these sensory receptors able to detect? | light, touch, sound, chemicals etc |
| What is the sensory system composed of? | specialized neurons called nerve cells which are used as sensory receptors. |
| What do sensory receptors convert physical stimuli (one form of energy) into? | action potentials which represent electrochemical energy. |
| How do receptors convert stimuli into action potentials? | The stimulus causes a change in the receptor cell’s membrane which is then communicated from the receptor through a chain of nerve cells to central nerve system. |
| Chemoreceptors | detect chemicals |
| Photoreceptors | sense light |
| Tactile receptors | sensitive to pressure and temperature (skin sense of touch) |
| How do humans receive stimuli? | Molecules carried by water enter the mouth and are sensed by taste buds on the tongue or airborne molecules are sensed by cells in the nasal cavity. |
| What do taste buds detect? | Dissolved chemicals |
| Papillae | bumps on the tongue |
| What are papillae separated by? | Trenches |
| Where are the taste buds located? | The walls of the trenches |
| What causes bad breath? | Particles of food can get lodged in between the papillae and rot. |
| How many taste buds do adult humans have? | 10,000 and children have more! |
| What is responsible for the sense of pleasure or distaste of certain foods? | Tongue and mucous membrane in mouth also have receptors for pressure temperature and pain or “mouth feel” |
| How many receptor cells are there in each taste bud? | 20-30 |
| What are the receptor cells in the mouth constantly doing? | Dying and being replaced every 10 days |
| How are the receptor cells situated in the taste bud? | One end is in contact with the pore of the taste bud to contact chemicals and the other end is connected with a neuron. |
| Olfactory receptor cells | responsible for the sense of smell they have cilia on one end that extend into the mucous layer |
| Where are olfactory receptor cells located? | In the mucous membrane in the upper part of the nasal cavity |
| How is an odor experienced? | It must release molecules which are then dissolved into the mucous layer and interact with receptors. |
| How many olfactory receptors do humans have in a space of a dime? | 40 million |
| How many olfactory receptors do wolfs have? | 10 times more than humans! |
| Umami | a taste that is characteristic of monosodium glutamate and is associated with meats and other high protein foods. |
| What does MSG stand for? | Monosodium glutamate |
| Glutamate | the most abundant amino acid which is present in many protein containing foods |
| What causes the salty taste? | Various ionized salts |
| What causes the sweet taste? | Sugars and other numerous chemicals |
| What causes the sour taste? | More acid equals more sour |
| What causes the bitter taste? | Various chemicals esp. alkaloids |
| Alkaloids | complex molecules that occur naturally in many plants |
| Vision | a result of our ability to sense light energy |
| Eye | contructed so images or patterns of light will be focused on light sensitive photoreceptors in the retina |
| Retina | part of eyeball that receives the image produced by the lens |
| Question | Answer |
|---|---|
| lens = | lens of camera which focuses light |
| Iris = | diaphragm which regulates size of light opening |
| pupil = | light opening which allows light to enter |
| retina= | film which senses light |
| sclera = | camera body which protects the eye and helps maintain shape of the eyeball |
| cornea = | colorless filter which covers and protects light opening and bends light |
| choroid coat = | black paint inside camera which absorbs light to prevent internally reflected light from blurring the image |
| If the curvature of the cornea is too great what is the result? | nearsightedness |
| optic nerve | transmits information from the sensory cells of the eye to the brain |
| If the curvature of the cornea is too great what is the result? | nearsightedness |
| What does the cavity between the cornea and iris contain? | A watery substance which holds the eyes shape |
| In locating the lens what will it look like? | A hard white transparent disk |
| Cataract- | clouding of the lens that prevents light from passing through it clearly and is therefore the image is distorted. |
| What will the retina look like? | A yellowish layer that contains the rods and cone (the actual sensory cells of the eye.) |
| What is the inner surface of the eye lined with and what does this do? | Choroid coat which is a black coating that absorbs stray light rays that could interfere with clear vision. |
| In many mammals but not humans what happens to stray light not absorbed by the retina | bounces off the tapetum lucidum which is a reflective layer between the choroid coat and retina. This gives the inner eye an iridescent look. |
| Why do animals eyes glow in the beam of a flashlight? | The tapetum lucidum reflects the light. |
| What causes a blind spot? | The gathering of neurons inside the eye. |
| What does the retina consist of? | Neurons modified into photosensitive cells called rods and cones. |
| What are inside the rods and cones? | Pigments that absorb light energy causing the breakdown of the pigments which stimulates the nerve fiber leading to the brain. |
| What is the final product of the breakdown of pigments inside the rods and cones? | Formation of Vitamin A which can be stored in the retina and later reconverted to photosensitive pigments. |
| What causes night blindness? | If your retina is exposed to strong light over a long period of time most of the photosensitive form of the pigment is convened into vitamin A and your eyes get less sensitive to light. When you walk in the dark your eyes will not be sensitive enough to distinguish the light and dark spots. |
| Which is more rapid…adaptation to light or adaptation to dark? | Adaptation to light |
| What are cones responsible for? | Bright light vision and perception of detail |
| Where are cones located? | In the retina in an area called the fovea which is directly in line with the senter of the cornea and lens. |
| What are the three types of cones? | Blue green and red which absorbs diff pigments |
| Accomodation | the ability to focus on a close object which requires the lens to become almost spherical |
| What is one measure of sense of touch? | The two-point threshold which is the min distance that must be between two points before they are felt as separate points. |
| Why is our sense of temperature complicated? | Different areas of the body have different amounts of cold and warm receptors. Some have more cold than others and vise versa. |
