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Chapter 18: Nutrients and Digestion


Title: Chapter 18: Nutrients and Digestion Author: Natalie Fascianella Last modified by: Natalie Fascianella Created Date: 5/5/2009 1:46:56 AM Document presentation ... – PowerPoint PPT presentation

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Title: Chapter 18: Nutrients and Digestion

Chapter 18 Nutrients and Digestion
Aim Why do you eat?
  • We need food to carry out our daily activities
  • Does it matter what we eat??.....
  • YES
  • Our body needs a certain amount of nutrients a
  • Nutrients are substances in food that provide
    energy and materials for cell development, growth
    and repair
  • The body needs energy for every activity it does,
    whether its voluntary or involuntary

  • The amount of energy you need depends on body
    mass, age and activity level
  • Amount of energy in food is measured as calories
  • The number of calories varies depending of the
    food that you are eating

Aim What are the classes of nutrients?
  • Vitamins
  • Are organic nutrients needed in small quantities
    for growth, regulating body functions and
    preventing some diseases
  • Most foods supply some vitamins, but no food has
    them all
  • 2 groups
  • Water Soluble
  • Need to be replenished daily
  • Fat Soluble
  • Stored in the body fat tissue

  • Minerals
  • Inorganic (lack carbon)
  • Your body uses 14 minerals
  • Regulate chemical reactions in your body
  • Build cells
  • Send nerve impulses
  • Carry oxygen to body cells
  • Trace minerals are only needed by in small
    amounts, like copper and iodine
  • Table 1 pg 518

  • Water
  • Is one of the most important factors for your
  • Can only live a few days without water
  • Other nutrients have to be dissolved in water to
    be used
  • Human body is 60 water
  • 2/3 of body water is located in your cells
  • Water leaves your body when you breathe, sweat
    and you get rid of body wastes

  • To replace water you need to drink 2L a day
  • Water is also found in foods
  • Water is important to cells because it aids in
    chemical reactions

Aim What are the functions of the digestive
Functions of the Digestive System
  • Food is processed in four stages ingestion,
    digestion, absorption and elimination
  • Digestion is the process that breaks down food
    into small molecules so they can be absorbed and
    moved into the blood
  • 2 types of digestion
  • Mechanical-food is chewed, mixed and churned
  • Chemical- chemical reactions break down food into
    small molecules

  • Make chemical digestion possible
  • Enzyme is a type of protein that speeds up the
    rate of a chemical reaction
  • They reduce the amount of energy needed for a
    chemical reaction to begin
  • Help you digest carbohydrates, proteins, and fats
  • Amylase helps speed up the break down of complex
    carbohydrates (starchsugar)

  • Pepsin is found in the stomach and breaks down
  • The pancreas releases enzymes into the small
    intestine, which continue to break down starches
    into glucose
  • Also break down fats into fatty acids
  • Enzymes also aid in the blood-clotting process
    and in the process that builds your body

Aim What role do the organs of the digestive
system play?
Digestive System
  • 2 parts
  • Digestive tract
  • mouth, esophagus, stomach, small intestine, large
    intestine, rectum and anus
  • Accessory organs
  • (tongue, teeth, salivary gland, liver,
    gallbladder and pancreas)

  • Mouth
  • Mechanical and chemical digestion begin
  • Mechanical digestion happens when you chew your
    food and mix it with your tongue
  • Chemical digestion happens when saliva is mixed
    with your food
  • Ingestion is now over
  • Esophagus
  • Epiglottis covers your windpipe
  • About 25 cm long muscle

  • Takes 4 to 7 s for food to move through the
    esophagus into the stomach
  • No digestion takes place
  • Mucous glands keep the food moist
  • Stomach
  • As food enters from the esophagus, the stomach
  • Food is digested both mechanically and chemically
  • Food is changed into chyme within 2-4 hours
  • Little by little food moves into the small

  • Small Intestine
  • Chyme leaves the stomach and enters the duodenum,
    where most of the digestion takes place
  • Bile is released from your liver, and breaks up
    the large fat particles
  • Pancreas releases another solution that breaks
    down carbohydrates, proteins and fats
  • Pancreas also produces insulin, which always
    glucose to pass from your bloodstream into your

  • The villi aids in the absorption of food
  • Peristalsis forces the undigested food into your
    large intestine
  • Large Intestine
  • Its main job is to absorb the water from the
    undigested food
  • This helps maintain homeostasis
  • Chyme can stay in here for as long as 3 days
  • Wastes are released by your rectum and anus

  • Help break down intestinal material to make
  • Produce Vitamin K, which is needed for blood
  • Make 2 B vitamins, niacin and thiamine, which are
    important to you nervous system
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