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Some on the eye

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Humans don't have the best eyes by a long shot. The mantis shrimp has eyes divided into three parts; trinocular vision. ... foods determined by cooking oil ... – PowerPoint PPT presentation

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Title: Some on the eye


1
Some on the eye
  • Myopia Near sightedness
  • The image focuses in front of the retina

2
Pathology of myopia varies
  • Japan -44 of adult pop.
  • U.S. 20-25 of adults
  • Reading and education level
  • Are risk factors
  • During one of the Chinese revolutions, they
    killed people with glasses because it meant they
    had read

3
Hyperopia
  • Farsightedness
  • At times confused with loss of vision at onset of
    age
  • Note ostrich eyes are bigger than its brain

4
Ostriches are ridiculous
5
Presbyopia
  • Greek Presby old person
  • Theory is that with age the crystallin lens loses
    elasticity.
  • Become far sited
  • So they get bifocals
  • Ben Franklin

6
Astigmatism
  • defect of the eye, where vision is blurred by an
    irregularly shaped cornea.
  • A refractive problem
  • Might be able to focus in horizontal plane, but
    not vertical

7
Evolution of the Eye
  • Homologous organ
  • First eyes 540 mya
  • arms race idea

8
  • Adaptation Birds have better vision
  • Night birds can pick up U.V. Light
  • Euglena bacteria has a light sensitive patch (2)
  • Planarians have eyespots

9
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10
  • Is it too complex to evolve piece by piece?
  • what good is half an eye?
  • Argument from personal belief
  • But there are a lot of sub optimal eyes in
    nature.
  • Even in people a myopic person has an advantage
    over the blind.
  • Humans dont have the best eyes by a long shot
  • The mantis shrimp has eyes divided into three
    parts trinocular vision.
  • We have 4 visual pigments, they have 16. Can
    pick up U.V. and polarized light

11
Sea Sickness
  • In Part results from your brain focusing on
    stable side of boat, waves moving closs, and
    waves moving far away on the horizon.

12
Decibels
  • Logarithmic unit, measures sound levels
  • Originally a bell was the amount of sound lost
    over 1 mile of telephone line

13
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14
Ear Wax
  • Cerumen
  • Cleans, lubricates (prevents itching), and
    protects
  • From sebaceous and apocrine glands
  • Two genetic types Wet Dominant, Dry recessive
  • Asians, Am Indians Dry
  • Africans, Europeans Wet
  • Builds up in whales like rings in a tree

Wet type ear wax flouresces under U.V. light
15
Taste Smell Chemical senses
16
  • McDonalds Fries
  • Win best taste competitions
  • Not the method, potatoes, or machinery
  • Taste of fried foods determined by cooking oil
  • McDs uses 7 cottonseed oil, 93 beef tallow a
    fry has more beef fat/ oz than a burger
  • McDs world
  • locations ?

17
Obviously there was criticism
  • McDs changed to pure veg. oil 1990
  • Problem how to make them taste like beef without
    using beef?
  • natural flavor
  • Explains why most of our food taste the way it
    does.

18
Natural Flavor vs. Artificial Flavor
  • Both are man made
  • 90 of our food is for processed food
  • Canning, freezing, dehydrating destroy flavor
  • Big money in making flavor
  • Name food brands
  • Name the companies that makes flavor

19
International Flavors Fragrances (IFF)
  • Worlds largest flavor company
  • Also makes smell of best selling perfumes,
    deodorant, and soaps
  • 2005 1.9 Bil.
  • Givaudan 2nd
  • Haarman Reimer Largest German
  • Takasago Largest Japanese

20
Smell owns taste
  • Aroma can be 90 of a foods flavor
  • What evolutionary benefit would organisms with a
    better sense of smell have?
  • Find food
  • Distinguish good food from bad

Evolution puts pressure on us.
21
Flavors vs. smells
  • Taste buds can detect 5 basic flavors
  • Sweet, sour, bitter, salty, astringent, umami
  • About 4-10K taste buds on tongue, cheek, pharynx,
    epiglottis
  • Bumps called papillae
  • Olfactory system can percieve thousands of
    different chemicals

22
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23
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24
Mastication releases gases
  • Thin layer of nerve cells called olfactory
    epithelium receives gases and transduces them
    into smell signals
  • Brain combines smells signals with simple taste
    signals and decides if its something you want to
    eat.

25
Food preferences personality form early in life
  • Babies will adjust to hot spicy, bland health
    food, or fast food depending on what the people
    around them eat.

Baby eating sushi
26
We dont know it all yet
  • Psychosomatic effects happen
  • Color of food can determine perception of its
    taste
  • People can grow accustomed to bad smells.
  • Come back from a long vacation and immediately
    take a good whiff of what your house smells like.
    Other people smell that whenever they visit you

27
Aroma memory
  • Nerve signals for smell go right past parts of
    our brain associated with memory.
  • Smelling salts (ammonium carbonate can wake you
    up by causing an inhalation reflex
  • Smells can bring back memories
  • Comfort foods
  • McDs makes billions on this (Happy Meals)

28
Flavor in history
  • Empires built, seas crossed, religions and
    philosophies changed over taste.
  • Columbus went looking for flavor
  • Salzburg Germany Founded to protect salt trade
  • Saffron is 12 a gram

29
  • So artificial flavors cropped up from perfume
    companies after canning started
  • German scientist playing with chemicals suddenly
    lab smells like grapes ? methyl anthranilate ?
    grape Kool-Aid? purplesaurus rex

30
1.4 Bil a year
  • 10K new food products a year
  • 9/10 fail

31
Tech
  • Spectrometers
  • Gas chromatographs
  • Vapor detectors
  • Can discern chemicals at 1 ppb
  • Human nose can tell 0.000000000003
  • Dogs better still

32
Complex flavors
  • Coffee, roast beast, strawberries thousands of
    chemicals at once
  • Chemical responsible for flavor of Bell pepper
    only need 0.02 ppb a drop could flavor a
    swimming pool
  • And its cheap flavor in 12oz of Coke ½ cent

33
  • Often though, 1 chemical provides the over-riding
    sense of the food.
  • Ethyl-2-methyl butyrate apple
  • Methyl-2-peridylketone popcorn
  • Ethyl-3-hydroxybutanoate marshmallow
  • Hexanal fresh cut grass
  • 3-methyl butanoic acid B.O.

34
So what?So natural flavor means its made using
old technology
  • Natural
  • Getting amyl acetate from distilling bananas with
    a solvent
  • Artificial
  • Getting amyl acetate from mixing vinegar with
    amyl alcohol, adding H2SO4 as a catalyst

Both taste exactly the same, both happen in the
same factory, but people want to see natural on
their label.
35
Art or Science?
  • Mouthfeel Its not just flavor,
  • TA.XT2i Texture analyzer uses 250 probes to
    create an artificial mouth that senses bounce,
    creep, crunch, density, chewiness, gumminess,
    lumpiness, rubberiness, slipperiness, softness,
    wetness, spread, spring-back, tackiness
  • How do you juggle all of this with subtleties of
    flavor?

36
Genetics
  • Dominant gene
  • Phenylthiocarbamide, also known as PTC, or
    phenylthiourea tastes very bitter or not at all
    depending on genetics
  • Discovered when a guy at duPont accidently
    spilled a bunch of crystalline PTC, some
    complained, some did not
  • May explain why some people are more offended by
    cig. smoke

37
Super Taster
  • 25 of people of European dissent
  • Maybe more fungiform papillae
  • Linked to food preference, body type
  • Coffee, alcohol, may be too intense
  • Olives too salty

38
Things go horribly awry
  • Ageusia (pronounced ay-GOO-see-uh) Loss of sense
    of taste
  • From neural damage
  • anosmia - a loss of the sense of smell.
  • Cold
  • Parkinsons
  • Alzheimer's
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