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Chapter: Nutrients and Digestion

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Title: Chapter: Nutrients and Digestion


1
Table of Contents
Chapter Nutrients and Digestion
Section 1 Nutrition
Section 2 The Digestive System
2
Nutrition
1
Why do you eat?Energy Needs
  • Nutrients (NEW tree unts) - substances in foods
    provide energy and materials for cell
    development, growth, and repair
  • body mass, age, and activity level affect how
    much energy you need
  • comes from the foods you eat

3
Nutrition
1
Why do you eat?Energy Needs
  • Calories (Cal) - amount of energy available in
    food
  • amount of heat necessary to raise the temperature
    of 1 kg of water 1C

4
Nutrition
1
Classes of Nutrients
  • Six kinds of nutrients - proteins, carbohydrates,
    fats, vitamins, minerals, and water
  • Organic nutrients - contain carbon - Proteins,
    carbohydrates, vitamins, and fats

5
Nutrition
1
Classes of Nutrients
  • Inorganic nutrients - do not contain carbon -
    water and minerals
  • Carbohydrates, fats, and proteins need to be
    digested
  • Water, vitamins, and minerals dont require
    digestion absorbed directly into bloodstream

6
Nutrition
1
Proteins
  • Proteins - large molecules contain carbon,
    hydrogen, oxygen, nitrogen and sometimes sulfur.
  • used for replacement, repair, and growth of body
    cells
  • amino acids - smaller units that make up protein

7
Nutrition
1
Proteins
  • only 20 amino acids in various combinations make
    thousands of proteins used in cells
  • essential amino acids - eight amino acids that
    cannot be made in your bodys cells

8
Nutrition
1
Proteins
  • Complete proteins provide all essential amino
    acids
  • Incomplete proteins are missing one or more
    essential amino acids
  • Vegetarians get all essential amino acids by
    eating a wide variety of protein-rich vegetables,
    fruits, and grains.

9
Nutrition
1
Carbohydrates
  • Carbohydrates (kar boh HI drayts) - usually are
    main sources of energy for your body
  • made of carbon, hydrogen, and oxygen atoms
  • Energy holds atoms together
  • broken down in presence of oxygen in your
    cellsenergy is released for use by your body

10
Nutrition
1
Carbohydrates
  • Three types - sugar, starch, and fiber
  • simple carbohydrates - Sugars
  • cells break down glucose

11
Nutrition
1
Carbohydrates
  • complex carbohydrates - starch and fiber
  • Starch - in potatoes grains such as pasta.
  • Made of many simple sugars in long chains

12
Nutrition
1
Carbohydrates
  • Fiber - found in the cell walls of plant cells
    (cellulose)
  • whole-grain breads and cereals, beans, peas, and
    other vegetables and fruits are good sources of
    fibers
  • You cannot digest fiber, but it is needed to keep
    your digestive system running smoothly.

13
Nutrition
1
Carbohydrates
  • Nutritious snacks can help your body get
    nutrients it needs, especially when you are
    growing rapidly and are physically active
  • Choose smacks that provide nutrients such as
    complex carbohydrates, proteins, and vitamins, as
    well as fiber

14
Nutrition
1
Fats
  • Fats (lipids) - necessary to provide energy and
    help your body absorb vitamins
  • cushions your internal organs
  • major part of every cell membrane
  • A gram of fat can release more than twice as much
    energy as a gram of carbohydrate can.

15
Nutrition
1
Fats
  • fat is broken down into smaller molecules - fatty
    acids and glycerol (GLIH suh rawl)
  • fat is a good storage unit for energy excess
    energy is converted to fat and stored for later
    use

16
Nutrition
1
Fats
  • Fats classified as unsaturated or saturated -
    based on chemical structure
  • Unsaturated fats - usually liquid at room
    temperature
  • Vegetable oils fats found in seeds

17
Nutrition
1
Fats
  • Saturated - found in meats, animal products, and
    some plants usually solid at room temperature
  • associated with high levels of blood cholesterol
  • can lead to heart disease and strokes

18
Nutrition
1
Vitamins
  • Vitamins - Organic nutrients needed in small
    quantities for growth, regulating body
    functions, and preventing some diseases
  • bone cells need vitamin D to use calcium
  • blood needs vitamin K in order to clot
  • Most foods supply some vitamins, but no food has
    them all

19
Nutrition
1
Vitamins
  • classified into two groups
  • water-soluble vitamins - dissolve easily in water
  • not stored by your body so you have to take them
    daily

20
Nutrition
1
Vitamins
  • fat-soluble - dissolve only in fat
  • They are stored by your body.
  • some vitamins are made by your body
  • Vitamin D is made when your skin is exposed to
    sunlight.

21
Nutrition
1
Minerals
  • Minerals - lack carbon and regulate many
    chemical reactions in your body
  • Your body uses about 14 minerals
  • build cells, take part in chemical reactions in
    cells, send nerve impulses throughout your body,
    and carry oxygen to body cells

22
Nutrition
1
Minerals
  • calcium and phosphorus are used in the largest
    amounts for a variety of body functions.
  • trace minerals - required only in small amounts

23
Nutrition
1
Minerals
  • This table lists several minerals, what they do,
    and some food sources for them

24
Nutrition
1
Water
  • Next to oxygen, water is the most important
    factor for survival
  • Different organisms need different amounts of
    water to survive
  • You could live a few weeks without food but only
    a few days without water - your cells need water
    to carry out their work
  • Most nutrients have to be dissolved in water
  • chemical reactions take place in solutions

25
Nutrition
1
Water
  • human body is about 60 percent water by weight
  • two thirds of your body water is located in body
    cells
  • found around cells and in body fluids such as
    blood

26
Nutrition
1
Water
  • Your body loses water as perspiration
  • When you exhale, water leaves your body as water
    vapor
  • also is lost every day when your body gets rid of
    wastes
  • you need to drink about 2 L of liquids to replace
    water lost each day

27
Nutrition
1
Why do you get thirsty?
  • When your body needs to replace lost water,
    messages are sent to your brain that result in a
    feeling of thirst.
  • Drinking water satisfies your thirst and usually
    restores the bodys homeostasis (hoh mee oh STAY
    sus).

28
Nutrition
1
Food Groups
  • Food group - contain the same type of nutrient
  • five groupsbread and cereal, vegetable, fruit,
    milk, and meat
  • The recommended daily amount for each food group
    will supply your body with the nutrients it needs
    for good health.

29
Nutrition
1
Daily Servings
  • Each day you should eat
  • six to eleven servings from the bread and cereal
    group
  • three to five servings from the vegetable group
  • two to four servings from the fruit group
  • two to three servings from the milk group
  • two to three servings from the meat group
  • Only small amounts of fats, oils, and sweets
    should be consumed.

30
Nutrition
1
Daily Servings
  • The size of a serving is different for different
    foods
  • a slice of bread or one ounce of ready-to-eat
    cereal for bread-and-cereal
  • one cup of raw leafy vegetables or one-half cup
    of cooked or chopped raw vegetables for
    vegetables
  • one medium apple, banana, or orange for fruit
  • one cup of milk or yogurt for milk
  • two ounces of cooked lean meat or one egg for
    meat

31
Nutrition
1
Food Labels
  • The nutritional facts found on all packaged foods
    can help you plan meals that supply the daily
    recommended amounts of nutrients and meet special
    dietary requirements (for example, a low-fat
    diet).

32
Section Check
1
Question 1
A _______ is the amount of heat necessary to
raise the temperature of 1 kg of water 1 degree
Celsius.
Answer
The answer is Calorie. The amount of energy
available in food is measured in Calories.
33
Section Check
1
Question 2
The foods in this illustration are rich in
_______.
A. carbohydrates B. fat C. minerals D. protein
34
Section Check
1
Answer
The answer is D. Your body uses proteins for
replacement and repair of body cells.
35
Section Check
1
Question 3
Organic nutrients needed in small quantities for
growth, regulating body functions, and preventing
some diseases are called _______.
A. carbohydrates B. fats C. minerals D. vitamins
36
Section Check
1
Answer
The answer is D. Taking extra vitamins or eating
a well- balanced diet helps give your body all
the vitamins it needs.
37
The Digestive System
2
Functions of the Digestive System
  • ingestion - food enters your mouth

38
The Digestive System
2
Functions of the Digestive System
  • Digestion process that breaks down food into
    small molecules so it can be absorbed and moved
    into blood.
  • From blood, molecules are transported across cell
    membrane to be used by cell
  • Unused molecules pass out of your body as wastes
  • Digestion is mechanical and chemical

39
The Digestive System
2
Functions of the Digestive System
  • Mechanical digestion - food is chewed, mixed, and
    churned
  • Chemical digestion - chemical reactions break
    down large molecules of food into smaller ones

40
The Digestive System
2
Enzymes
  • enzyme - type of protein that speeds up chemical
    reaction in body
  • By reducing amount of energy necessaryfor a
    chemical reaction to begin
  • work without being changed or used up

41
The Digestive System
2
Enzymes
Click image to view movie.
42
The Digestive System
2
Enzymes in Digestion
  • help you digest carbohydrates, proteins, and fats
  • Amylase (AM uh lays) - enzyme produced glands
    near mouth.
  • speeds up breakdown of complex carbohydrates

43
The Digestive System
2
Enzymes in Digestion
  • Pepsin In stomach - break down complex proteins
  • other enzymes continue to speed up breakdown of
    proteins into amino acids in your small intestine

44
The Digestive System
2
Enzymes in Digestion
  • Pancreas - organ on back side of stomach
    releases several enzymes into small intestine
  • sugars are turned into glucose and used by cells
  • Different enzymes from the pancreas breakdown
    fats into fatty acids

45
The Digestive System
2
Organs of the Digestive System
  • two partsdigestive tract and accessory organs
  • major organs of digestive tract are1) mouth, 2)
    esophagus (is SAH fuh guhs), 3) stomach, 4)
    small intestine, 5) large intestine, 6) rectum,
    and 7) anus.

46
The Digestive System
2
Organs of the Digestive System
  • accessory organs 1) tongue, 2) teeth, 3)
    salivary glands, 4) liver, 5) gallbladder, and
    6) pancreas

47
The Digestive System
2
Organs of the Digestive System
  • liver, gallbladder, and pancreas - produce or
    store enzymes and chemicals

48
The Digestive System
2
The Mouth
  • Mechanical and chemical digestion begin in mouth.
  • Mechanical digestion - chew food with teeth and
    mix with tongue
  • Chemical digestion - begins with saliva (suh LI
    vuh) - watery substance

49
The Digestive System
2
The Mouth
  • tongue moves food around and mixes it with
    saliva
  • Saliva produced by three sets of glands

50
The Digestive System
2
The Mouth
  • saliva is mostly water also contains mucus
    and an enzyme (amylase)
  • Food mixed with saliva becomes a soft mass
    moved to back of mouth by tongue
  • swallowed and passes into esophagus

51
The Digestive System
2
The Esophagus
  • passes over epiglottis (ep uh GLAH tus)
  • automatically covers opening to windpipe so you
    dont choke.
  • about 25 cm long muscular tube
  • 4 s to 10 s for food to move down esophagus to
    stomach

52
The Digestive System
2
The Esophagus
  • No digestion takes place in esophagus
  • Mucous glands in wall keep food moist
  • peristalsis (per uh STAHL sus) - waves of smooth
    muscle contractionsmove food through entire
    digestive tract.

53
The Digestive System
2
The Stomach
  • muscular bag
  • sausage shaped with folds on the inside when empty
  • stomach expands and folds smooth out as food
    enters

54
The Digestive System
2
The Stomach
  • Mechanical - food is mixed by peristalsis
  • Chemical - food is mixed with enzymes (Pepsin)
    and hydrochloric acid solution

55
The Digestive System
2
The Stomach
  • about 2 L of hydrochloric acid solution each day
  • Acidic solution works with pepsin to digest
    protein
  • destroys bacteria in food

56
The Digestive System
2
The Stomach
  • Mucus makes food slippery and protects stomach
    from strong digestive solutions
  • chime (KIME) - thin, watery liquid 2 hours to 4
    hours in your stomach
  • chime moves out of stomach into small intestine

57
The Digestive System
2
The Small Intestine
  • small in diameter, but 4 m to 7 m in length
  • Duodenum (doo AH duh num) first part of small
    intestinewhere most digestion takes place
  • Bile - greenish fluid from liveradded to break
    up large fat particles

58
The Digestive System
2
The Small Intestine
  • Chemical digestion - bicarbonate ions and enzymes
    from the pancreas
  • neutralize stomach acid
  • Insulin - a hormone from your pancreasallows
    glucose to pass from bloodstream into cells

59
The Digestive System
2
The Small Intestine
  • Absorption takes place in small intestine

60
The Digestive System
2
The Small Intestine
  • Villi increase the surface area so nutrients in
    chime have more places to be absorbed

61
The Digestive System
2
The Small Intestine
  • Peristalsis continues to move and mix
  • Villi move and are bathed in soupy liquid
  • Nutrients move into blood vessels within villi

62
The Digestive System
2
The Small Intestine
  • Then blood transports nutrients to all cells
  • undigested and unabsorbed materials forced by
    peristalsis into large intestine

63
The Digestive System
2
The Large Intestine
  • When chime enters large intestine it is still
    thin, watery mixture
  • main job is to absorb water from undigested mass

64
The Digestive System
2
The Large Intestine
  • undigested materials become more solid after
    excess water is absorbed
  • Rectum and anus - musclear last section of large
    intestine
  • Feces (FEE seez) - semisolid wastes released

65
The Digestive System
2
Bacteria Are Important
  • Bacteria live in many organs of digestive tract
    including mouth and large intestine
  • bacteria in large intestine feed on cellulose
  • make vitamins you needvitamin K and two B
    vitamins
  • also converts bile pigments into new compounds

66
Section Check
2
Question 1
This illustration represents _______.
A. absorption B. digestion C. elimination D.
ingestion
67
Section Check
2
Answer
The answer is D. Ingestion occurs as food enters
your mouth.
68
Section Check
2
Question 2
_______ are a type of protein that speeds up the
rate of a chemical reaction in your body.
Answer
The answer is enzymes. Enzymes reduce the amount
of energy necessary for a chemical reaction to
begin.
69
Section Check
2
Question 3
Which is a major organ in your digestive tract?
A. esophagus B. gallbladder C. pancreas D.
salivary glands
70
Section Check
2
Answer
The answer is A. The major organs of the
digestive tract are mouth, esophagus, stomach,
small intestine, large intestine, rectum, and
anus. Food passes through all of these organs.
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