Chapter 36 – Digestive and Excretory System

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					Chapter 36 – Digestive and Excretory System



2/2 Classwork – Copy vocabulary terms from the board




Homework 2/2 (due Wednesday)
Keep a record of what you eat (breakfast, lunch,
dinner) on Tuesday and bring in on Wednesday.
Food and Energy

 Nutrients are substances that the
 body requires for energy, growth,
 repair and maintenance.

   Fuel                Other Essential Nutrients

  Carbohydrates          Vitamins

  Proteins               Minerals

  Fats                   Water
Calories vs. calories
When the body breaks
down food through
digestion, the chemical
bonds in nutrients are
broken and energy is
released.




The energy release when bonds break is measured in calories. 1000
calories is equal to 1 Calorie (information found on food labels).
Calorie Determination

Calories are determined by a process called
calorimetry.
Energy Requirements
The body needs energy to carry out both
voluntary (Running, swimming, biking) and
involuntary (breathing, growing, blinking)
activities.

                                          Exercise

                    Calories




 When you consume more calories than you burn, those calories get store in
                           the body as fat.
Body Fuels

Carbohydrates
 Simple sugars (Glucose)


              Found in fruits, honey and onions




 Complex Sugars (starch and cellulose)

                                              Found in fruits,
                                              vegetables, cereal grains,
                                              potatoes, and corn.
Body Fuels, cont.

Proteins
Amino Acids (made                Essential Amino Acids
   in the body)                    (found in foods)


                                                      Eggs
                                                      Milk
                    Proteins                          Fish
                                                     Poultry
                    Enzymes                           Beef
                    Antibodies
                                           Contain all of the essential
                    Muscles                      Amino acids

                                          Only some are found in plants
Body Fuels, Cont

Fats (One type of lipid)

Used for storing energy, padding and insulating
organs, making hormones and cell membranes,
and dissolving fat soluble vitamins
Essential Nutrients
Water
Regulates body temperature, and transports gases, nutrients and
wastes.


Vitamins
Fat soluble vitamins – A, D, E, K
        Stored in body fat and can become toxic in large amounts
Water soluble vitamins – B, C
        Excess amounts are excreted in the urine and can be replaced
        by the diet.


Minerals
Naturally occurring substances that are not made by the body (Na, K, Fe, Ca)
These substances are needed for nervous system function, muscle
contraction, transporting oxygen in the blood and normal immune function.
Healthy Eating Habits
Nutritional and Health
Body Mass Index (BMI)
 Healthy Adult Weight Range (BMI = 18.5-25.0)

                     .......... .......... ......
                      (Weight in pounds)
           BMI                                     x703
                      (Height in inches)2


 Excess body fat can result in increased risk of:
 Heart disease
 Osteoarthritis
 Type II diabetes
Eating Disorders

Anorexia
 Obsession with being thin
Bulemia
 Binge eating followed by behaviors to
 reduce weight (vomiting, fasting, over-
 exercising)

    Abnormal eating habits may result in
 dehydration, fatigue, organ failure and death.
Breaking Down Food Into Nutrients
Digestion
The body takes in food, breaks it down into
molecules that the body can use, and gets rid of
undigested molecules and waste.
     Chemical Digestion – breaking of chemical bonds
           Complex carbohydrates       Simple sugars
           Proteins      Amino acids
           Fats       Fatty Acids

     Mechanical Digestion – Physical breakdown of food
           Chewing and churning
Starting Digestion – Mouth

Mouth
Mechanical breakdown of food by teeth
Chemical breakdown of food by saliva
   Contains amylase – an enzyme that breaks down
    starches
Swallowing
   The epiglottis covers the trachea and food moves into
    the esophagus
   Peristalsis begins in the esophagus
 Starting Digestion – Stomach

Stomach
Chemical breakdown of proteins by Gastric
  juices (HCL and pepsin)
    HCL unfolds proteins
    Pepsin breaks bonds in proteins to form amino acid
     chains
Mechanical breakdown occurs as the
 stomach churns food and mixes it with
 gastric juices
Absorbing Nutrients

 Absorption of nutrients mostly takes place
 in the small intestine and is aided by
 secretions from the liver and pancreas.
  Liver- Secretes bile that breaks fat
  globules into tiny fat droplets and aids in
  the absorption of vitamins A, D, E, and K

  Gallbladder – Stores bile

  Pancreas – Secretes lipases to
  breakdown fat droplets
Other Important Functions of the Liver
and Pancreas
 Homeostasis – Blood sugar regulation
 The liver converts extra sugar into glycogen (a stored
 source of energy). When energy is needed, the liver
 breaks down glycogen and releases glucose. The
 pancreas makes insulin that regulates the conversion of
 glycogen to glucose.


 Storage and Detoxification
 Besides glycogen, the liver stores fat soluble vitamins
 and iron. It also, removes poisons from the bloodstream
 and monitors the production of cholesterol.
 Small Intestine
The small intestine further
breaks down food and
reabsorbs nutrients through
the villi and microvilli that
cover its lining.

Capillaries in the villi,
transport nutrients to the
blood stream.
Removing Waste

The Large Intestine (No digestion occurs here)
Water and minerals are absorbed
Vitamins B and K are synthesized here by
 bacteria
Bacteria transform undigested material into
 feces
Excretion

Osmotic (amount of dissolved particles) and pH
balance of the blood is maintained through
excretion.
 Excretory Organs
 Skin       removes excess water, salts and nitrogen
 Lungs      remove carbon dioxide
 Kidneys    primary excretory organs that remove all of the
            above and other cellular wastes.
 Water
Most chemical reactions must take place in water
  Water absorbs and distributes heat
  Water transports gases, nutrients and wastes in
   and out of cells


                  DRINK WATER
  A health person should drink at least 2.5qt of water
      each day to replenish the water lost through
                       excretion
Cleaning the Blood
Kidneys contain Nephrons that carry out 3
main functions:
Filtration of blood (Glomerulus)
Reabsorption of water and other nutrients (renal tubule)
Secretion of wastes, toxins and water (collecting ducts)
Urinary Excretion

The resulting product of filtration, absorption
and secretion is Urine.

Urine flows through:
Ureters
Bladder
Urethra
Kidney Disease
Kidneys are vital to maintaining homeostasis,
so damage to the kidneys may eventually
become life threatening.
Most common causes of kidney damage:
Infection
Diabetes
High blood pressure
Autoimmune diseases
Treatment for Kidney Disease

Dialysis (not a cure)
A process for filtering blood to remove
substances from the blood.

Kidney Transplant

				
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