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This illustration shows the snail shell-shaped cochlea, which widens into the vestibule. Two circular organs, the utricle and the saccule, are located in the vestibule. Three ring-like canals, the horizontal canal, the posterior canal, and the superior canal, extend from the top of the vestibule. Each canal projects in a different direction.
The structure of the vestibular labyrinth is shown. (credit: modification of work by NIH)

The fluid-filled semicircular canals are tubular loops set at oblique angles. They are arranged in three spatial planes. The base of each canal has a swelling that contains a cluster of hair cells. The hairs project into a gelatinous cap called the cupula and monitor angular acceleration and deceleration from rotation. They would be stimulated by driving your car around a corner, turning your head, or falling forward. One canal lies horizontally, while the other two lie at about 45 degree angles to the horizontal axis, as illustrated in [link] . When the brain processes input from all three canals together, it can detect angular acceleration or deceleration in three dimensions. When the head turns, the fluid in the canals shifts, thereby bending stereocilia and sending signals to the brain. Upon cessation accelerating or decelerating—or just moving—the movement of the fluid within the canals slows or stops. For example, imagine holding a glass of water. When moving forward, water may splash backwards onto the hand, and when motion has stopped, water may splash forward onto the fingers. While in motion, the water settles in the glass and does not splash. Note that the canals are not sensitive to velocity itself, but to changes in velocity, so moving forward at 60mph with your eyes closed would not give the sensation of movement, but suddenly accelerating or braking would stimulate the receptors.

Vision

Vision is the ability to detect light patterns from the outside environment and interpret them into images. Animals are bombarded with sensory information, and the sheer volume of visual information can be problematic. Fortunately, the visual systems of species have evolved to attend to the most-important stimuli. The importance of vision to humans is further substantiated by the fact that about one-third of the human cerebral cortex is dedicated to analyzing and perceiving visual information.

Light

As with auditory stimuli, light travels in waves. The compression waves that compose sound must travel in a medium—a gas, a liquid, or a solid. In contrast, light is composed of electromagnetic waves and needs no medium; light can travel in a vacuum ( [link] ). The behavior of light can be discussed in terms of the behavior of waves and also in terms of the behavior of the fundamental unit of light—a packet of electromagnetic radiation called a photon. A glance at the electromagnetic spectrum shows that visible light for humans is just a small slice of the entire spectrum, which includes radiation that we cannot see as light because it is below the frequency of visible red light and above the frequency of visible violet light.

Certain variables are important when discussing perception of light. Wavelength (which varies inversely with frequency) manifests itself as hue. Light at the red end of the visible spectrum has longer wavelengths (and is lower frequency), while light at the violet end has shorter wavelengths (and is higher frequency). The wavelength of light is expressed in nanometers (nm); one nanometer is one billionth of a meter. Humans perceive light that ranges between approximately 380 nm and 740 nm. Some other animals, though, can detect wavelengths outside of the human range. For example, bees see near-ultraviolet light in order to locate nectar guides on flowers, and some non-avian reptiles sense infrared light (heat that prey gives off).

Questions & Answers

What is stock market?
JOHN Reply
explain the various types of cost curve
Ruth Reply
Short-run average fixed cost (SRAFC) Short-run average total cost (SRAC or SRATC) Short-run average variable cost (AVC or SRAVC) Short-run fixed cost (FC or SRFC) Short-run marginal cost (SRMC) Short-run total cost (SRTC)
Romy
supply function Qs=0+20P price of bread 30
Maricar Reply
what's economic development and growth
Popoola Reply
gamitin Ang supply function na Qs=0+20P Presyo ng tinapay 30.Dami ng ibebenta
Maricar
what do you understand by Ceteris Paribus?
Gabriel Reply
explain the uses of microeconomics
Nikita Reply
uses of microeconomics
Nikita
Adam Smith's definition of economics
Sylvia Reply
what is economic deficit
Amjad
this is a situation whereby a nation's outcome or available resources are not enough to the people thereby causing scarcity
Ariel
prices of Quality demanded is equal to Quality supplied
NABUBOLO Reply
it's quantity demand and quantity supplied that's called equilibrium
Romy
no
NABUBOLO
they deal With prices
NABUBOLO
define the elasticity
NABUBOLO
explain different types of elasticity
NABUBOLO
oops 😬 you are right you talk about quality I tell about quantity
Romy
elasticity is the measurement of the percentage change of one economic variable in response to a change in another
Romy
Cross Elasticity of Demand (XED) Income Elasticity of Demand (YED) Price Elasticity of Supply (PES)
Romy
anything else?
Romy
I need to know everything about theory of consumer behavior
Grace
How does one analyze a market where both demand and supply shift?
Gabriel Reply
That's equilibrium market
Ramon
but an equlibrum can appear twice on the same market... both in Movement along the Demand/supply curve of shift in the Curve
Gabriel
I Mean on the same curve..
Gabriel
how can consumer surplus be calculated
Franklyn
How can we analyze the effect on demand or supply if multiple factors are changing at the same time—say price rises and income falls? 
Gabriel Reply
because of fall of income, less will be demanded and much will be supply as a result of price rises. Rise in price always motivate new supplier to enter into the system. But it only possible in the short run
Kweku
yeah.. I think Ceteris Paribus is applied in this case
Gabriel
that is the law of Demand is Inversely related to the law of Supply... so that mean a positive change in demand may produce a negative return to supply I think.
Gabriel
what are the difference between Wants and Needs
Gabriel Reply
When the price is above the equilibrium, explain how market forces move the market price to equilibrium. Do the same when the price is below the equilibrium.
Gabriel
economic problems
Manishankar
yeah please Explain
Gabriel
I don't know this is my question
Manishankar
no it was a mistake...😂😂 can you explain how Wants and needs differs 😌
Gabriel
wants is what human desire but might not need them, human want are mostly articles of ostentatious while need is what human must get to live e.g inferior goods
Ramon
what's equilibrium price
james
equilibrium prices is a situation whereby the price of goods supplied equates to the demand
Ariel
this whereby the prices of quality demanded is equivalent to quality demanded
NABUBOLO
wants are numerous desire man that man can do without if not purchased e.g. cosmetic while need are desires that you cannot do without e.g. food
Franklyn
equilibrium price is that level of output were quantity demanded is equal to quantity supplied
Arthur
what are the importance of studying economics
Bherla Reply
To know if the country is growing or not through the country's GDP
Ariel
to manage our resources
TOBI
compare base years GDP and the current years GDP
james
To tell whether a country is growing there are many factors to be considered not necessarily only the GDP due to weaknesses of GDP approach
james
What is the law of demand
Yaw Reply
price increase demand decrease...price decrease demand increase
Mujahid
ıf the price increase the demand decrease and if the demand increase the price decrease
MUBARAK
all other things being equal, an increase in demand causes a decrease in supply and vice versa
SETHUAH
yah
Johnson
how is the economy of usa now
Johnson
What is demand
jude Reply
Demand is the quantity of goods and services a consumer is willing and able to purchase at various prices over a given period of time.
Yaw
yea
SETHUAH
Okay congratulations I'll join you guys later .
Aj
yes
MUBARAK
demand is the quantity and quality of goods and services a consumer is willingly and able to purchase at a particular price over a given period of time.
TOBI
calculate elasticity of income exercises
HABANABAKIZE Reply
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Source:  OpenStax, Principles of biology. OpenStax CNX. Aug 09, 2016 Download for free at http://legacy.cnx.org/content/col11569/1.25
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