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.