Unit 10 The Human Body

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Unit 10 The Human Body Powered By Docstoc
					   Unit 10 The Human Body



Ch. 38 Digestive & Excretory
          Systems
           Food & Energy
 The energy available in food can be
  measured by burning the food
 When food is burned, the energy content of
  the food is converted to heat, which is
  measured in calories
             Food & Energy
   The average energy needed for a teenager is
    2200 Calories per day
                Nutrients
 The nutrients that the body needs are water,
  carbohydrates, fats, proteins, vitamins, &
  minerals
 Every cell in the body needs
  water because many body
  processes, including chemical
  reactions, take place in water
                   Nutrients
   Carbohydrates – main source of energy for
    the body
    – Sugars & starches are main source of carbs
    – Starches are broken down by digestive system
      into simple sugars &
      carried to cells
      through blood
               Nutrients
– Sugars not immediately used for energy are
 converted into complex carbs & stored in the
 liver & in skeletal muscles
                 Nutrients
   Fats – lipids – important to the body to
    produce cell membranes, myelin sheaths, &
    certain hormones
                   Nutrients
   Proteins – supply raw materials for growth
    & repair of structures like skin & muscle
    – Also have regulatory & transport functions
                 Nutrients
   Vitamins – organic molecules that help
    regulate body processes, often working with
    enzymes
Vitamins
                  Nutrients
   Minerals – inorganic nutrients the body
    needs
    – Includes: calcium, iron, & magnesium
Important Minerals
    Nutrition & a Balanced Diet
   The Food Guide Pyramid classifies foods
    into 6 groups & indicates how many
    servings from
    each group
    should be eaten
    every day
    The Process of Digestion
 The digestive system includes: the mouth,
  pharynx, esophagus, stomach, small
  intestine, & large intestine
 Several major accessory structures,
  including the salivary glands, the pancreas,
  & the liver, add secretions to the digestive
  system
The Digestive System
               The Mouth
 The function of the digestive system is to
  help convert foods into simpler molecules
  that can be absorbed & used by the cells of
  the body
 Teeth cut & grind the food, while the
  salivary glands secrete saliva, which helps
  to moisten the food & make it easier to
  chew
                The Mouth
   Amylase – enzyme found in saliva, that
    breaks the chemical bonds in starches &
    releases sugars
           The Esophagus
 Esophagus – food tube, connects to the
  stomach
 Food travels through esophagus by process
  of peristalsis – contractions of the smooth
  muscle tissue in the esophagus
              The Stomach
   Stomach – large muscular sac, continues the
    mechanical & chemical digestion of food
          The Small Intestine
   Small intestine – where almost all of the
    digestive enzymes enter the intestine
    – Most chemical digestion & absorption of food
      occurs in the small intestine
       Accessory Structures of
             Digestion
   Pancreas – gland that serves 3 important
    functions:
    – 1. Produce hormones that regulate blood sugar
      levels
    – 2. Produces enzymes that break down carbs,
      proteins, lipids, & nucleic acids
    – 3. Produces sodium bicarbonate, a base that
      neutralizes stomach acid so enzymes can be
      effective
       Accessory Structures of
             Digestion
   Liver – large organ just above & to the right
    of the stomach
    – Produce bile, a fluid loaded with lipids & salts
    – It acts like detergent, dissolving & dispersing
      the droplets of fat found in fatty foods
    – Bile is stored in the gallbladder
Accessory Structures
          The Large Intestine
   Large intestine – primary function is to
    remove water from undigested material that
    is left
    Digestive System Disorders
 Peptic ulcer – when powerful acids released
  into the stomach damage the organ’s own
  lining, producing a hole in the wall
 Diarrhea occurs when not enough water is
  absorbed
 Constipation occurs when too much water is
  absorbed
      The Excretory System
 The kidneys play an important role in
  maintaining homeostasis
 They remove waste products from the
  blood; maintain blood pH; &
  regulate the water content of
  the blood &, therefore, blood
  volume
             The Kidneys
 Kidneys – located on either side of the
  spinal column near the lower back
 Ureter – tube that leaves each kidney,
  carrying urine to the urinary bladder
 Urinary bladder – saclike organ where urine
  is stored before being excreted
          Kidney Structure
 Nephron – the functional units of the kidney
 As blood enters a nephron through the
  arteriole, impurities are filtered out &
  emptied into the collecting duct
 The purified blood exits the nephron
  through the venule
                 Filtration
 Filtration – passing a liquid or gas through a
  filter
 Glomerulus – where the filtration of blood
  takes place
             Reabsorption
 Reabsorption – process where liquid is
  taken back into a vessel
 Material that remains, called urine, is
  emptied into a collecting duct
 Urine contains urea, excess salts, & water
 Urine is stored in the urinary bladder until
  released from the body through the urethra
Structure Of The Kidneys
              Kidney Stones
   Sometimes, calcium, magnesium, or uric
    acid salts in the urine, crystallize & form
    kidney stones

				
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posted:11/5/2012
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