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Sensory System

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Updated 2007-05-10 22:52

Summary

Terms having to do with the human body's sensory system.

Terms

TermFunction
sensory systemBody’s system of sense organs which perceives environmental stimuli and is a part of the peripheral nervous system.
Peripheral nervous systemthe 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 Transducersensory receptor-changes energy from one form like light or sound to electrochemical energy.
List the four steps of the sensory system1.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.
Chemoreceptorsdetect chemicals
Photoreceptorssense 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
Papillaebumps 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 cellsresponsible 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!
Umamia taste that is characteristic of monosodium glutamate and is associated with meats and other high protein foods.
What does MSG stand for?Monosodium glutamate
Glutamatethe 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
Alkaloidscomplex 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
memorize

 

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 nervetransmits 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 retinabounces 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
Accomodationthe 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.
memorize

To add

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.

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