Digestion, Absorption, and Transport - PowerPoint by grapieroo5

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									Digestion, Absorption,
    and Transport




        Chapter 3

      FON 241; Digestion: L. Zienkewicz
To become part of your body, food must first be
          digested and absorbed.
           FON 241; Digestion: L. Zienkewicz
Digestion: The process by which
 food is broken down into
 absorbable nutrients



Absorption: The passage of
 nutrients from the GI tract into
 either the blood or the lymph

          FON 241; Digestion: L. Zienkewicz
  Anatomy of the
gastrointestinal (GI)
       tract:




      FON 241; Digestion: L. Zienkewicz
        The Gastrointestinal Tract


Salivary glands
Pharynx
                                                                               Mouth
Epiglottis
Upper esophageal sphincter                                         Trachea (to lungs)


Esophagus
                                             Lower
                                             esophageal
                                             sphincter
                                                                            Stomach
                                 Liver
Gall bladder                                                                Pancreas
Pyloric sphincter
                                                                      Pancreatic duct
Bile duct
                                                                      Small intestine
Ileocecal valve                                           (duodenum, jejunum, ileum)

                      Appendix                                 Large intestine (colon)

                                           Rectum
                                    Anus



                    FON 241; Digestion: L. Zienkewicz
Start at the beginning…
The mouth- Teeth crush your
 food; saliva blends with the
 food.




          FON 241; Digestion: L. Zienkewicz
                           The Teeth
                          Incisors have chiseled
                          edges that cut
                          Canines (cuspids) have
                          pointed crowns that tear

                          Premolars (bicuspids)
                          and molars have ridged
                          surfaces that crush
                          and grind

                          Tongue




FON 241; Digestion: L. Zienkewicz
            The Teeth
                                            Enamel

Crown                                       Dentin

                                            Pulp cavity
 Neck

                                            Gum (gingiva)

                                            Bone

 Root
                                            Blood vessels
                                            and nerves
                                            in pulp


                                            Root canal



        FON 241; Digestion: L. Zienkewicz
Digestion:
Pharynx- Tube shared by the
 digestive and respiratory
 systems.

Epiglottis- Cartilage that
 prevents food from entering
 the lungs during swallowing.

         FON 241; Digestion: L. Zienkewicz
                Normal Swallowing and Choking


                    Tongue




                      Food




Larynx rises                 Esophagus (to stomach)



Epiglottis closes                  Trachea (to lungs)
over larynx




                     FON 241; Digestion: L. Zienkewicz
Next…
Esophagus- the food pipe; a long tube that
carries a food bolus from the pharynx to the
stomach.

Preventive measures: Esophageal sphincters
two sphincters on each end of the esophagus.

They function to:
   1. Upper ES- allow food into the esophagus
   2. Lower ES- allow food into the stomach
   and prevents backflow of stomach contents.


              FON 241; Digestion: L. Zienkewicz
           An Example of a Sphincter Muscle
              Esophagus
                                              Circular muscle

                                              Longitudinal muscle

                                              Esophagus muscles relax,
                                              opening the passageway.



                                              Diaphragm muscles relax,
                               Stomach        opening the passageway.




                                              Esophagus muscles contract,
                                              squeezing on the inside.

                                              Diaphragm muscles contract,
                                              squeezing on the outside.


When the circular muscles of a sphincter contract, the
passage closes; when they relax, the passage opens.
               FON 241; Digestion: L. Zienkewicz
FON 241; Digestion: L. Zienkewicz
     What happens in the
         stomach?
• A bolus enters the stomach via the lower
  esophageal sphincter.

• The stomach gradually transfers the
  bolus from the upper portion to the lower
  portion of the stomach.

• Stomach acids are added and the food is
  ground by muscular forces

• The bolus is now called chyme.

• The stomach slowly releases chyme
  through the pyloric sphincter into the
  small intestine.
             FON 241; Digestion: L. Zienkewicz
Stomach Muscles
                            Longitudinal




             Circular
Diagonal




   The stomach has three layers of muscles.
 FON 241; Digestion: L. Zienkewicz
Still going…
• Small intestine: Made of three
  parts-
          1. The duodenum
          2. The jejunum
          3. The ileum

 In beginning of the small intestine, fluids
 from the gallbladder and pancreas, flow
 through the common bile duct and
 interact with the chyme. The chyme then
 moves through the 3 parts of the small
 intestine.
             FON 241; Digestion: L. Zienkewicz
The Small Intestine




     Pyloric
     Sphincter




     FON 241; Digestion: L. Zienkewicz
 The surface area of the
small intestine is roughly
the size of a tennis court.




        FON 241; Digestion: L. Zienkewicz
And going… through the
large intestine
• Chyme passes through the Ileocecal valve, the
  entrance to the large intestine.

• Chyme bypasses the appendix.

• Chyme travels through the large intestine;
  water is withdrawn and a semi-solid mass
  forms.

• The mass moves to the rectum; rectal muscles
  relax.

• 2 sphincters of the anus relax, thus passing
  the mass through the anus.
              FON 241; Digestion: L. Zienkewicz
                           The Colon or Large Intestine

                                              Transverse colon




                                           Ascending colon


                                               End of small intestine
Opening from small
                                                                          Descending
intestine to large intestine
                                                                          colon
                               Appendix

                                    Rectum

                                    Anus
                                                          Sigmoid colon
                                 FON 241; Digestion: L. Zienkewicz
The whole picture:



                                               Esophagus

 Stomach

                                               Large Intestine

                                               Small Intestine



           FON 241; Digestion: L. Zienkewicz
  The Digestive Fate of a Sandwich

MOUTH: CHEWING AND SWALLOWING, WITH LITTLE DIGESTION




STOMACH: COLLECTING AND CHURNING, WITH SOME DIGESTION




          FON 241; Digestion: L. Zienkewicz
  The Digestive Fate of a Sandwich

SMALL INTESTINE: DIGESTING AND ABSORBING




LARGE INTESTINE: REABSORBING AND ELIMINATING




          FON 241; Digestion: L. Zienkewicz
   How does food move
        through?
• Peristalsis- wavelike muscular
  contractions that push contents
  along.
• Segmentation- the circular muscles
  of the small intestine rhythmically
  squeeze and contract the contents;
  chyme is mixed with digestive
  juices, etc.
• Sphincter contractions- opening
  and closing of a sphincter to allow
  contents to enter or exit.

           FON 241; Digestion: L. Zienkewicz
Peristalsis and
Segmentation




  FON 241; Digestion: L. Zienkewicz
Digestive Secretions:
    Source                                   Secretion
Salivary Glands                          Saliva
Stomach                                Gastric juice
Pancreas                             Pancreatic juice
Liver (via gallbladder)                   Bile
Small intestine                      Intestinal Flora



             FON 241; Digestion: L. Zienkewicz
                  The Salivary Glands




Salivary glands




                    FON 241; Digestion: L. Zienkewicz
             The pH Scale
       pH’s of common substances:
  Basic          14   Concentrated lye

                 13   Oven cleaner

                 12

                 11   Household ammonia

                 10

                  9   Baking soda
                      Bile
                  8   Pancreatic juice
                      Blood
pH neutral        7   Water
                      Saliva
                  6   Urine

                  5   Coffee

                  4   Orange juice

                  3   Vinegar
                      Lemon juice
                  2   Gastric juice

                  1
  FON 241; Digestion: L. Zienkewicz
 Acidic           0   Battery acid
             Absorption
• The small intestine:
    • Villi- Small intestinal projections
    • Microvilli- Microscopic hairs on the villi
    • Crypts- crevices between the villi

    All of these components make up the
     massive absorptive area of the
     intestine.



               FON 241; Digestion: L. Zienkewicz
              Absorption of Nutrients

Outside                                     Carrier loads                    Carrier loads
cell                                        nutrient on                      nutrient on
                                            outside of cell . . .            outside of cell . . .

Cell
                                                                    Energy
membrane

                                                 . . . and then                 . . . and then
                                                releases it on                  releases it on
                                                inside of cell.                 inside of cell.
Inside      SIMPLE                   FACILITATED                           ACTIVE
cell       DIFFUSION                  DIFFUSION                          TRANSPORT



         Absorption of nutrients into intestinal cells typically
           occurs by simple diffusion or active transport.

                          FON 241; Digestion: L. Zienkewicz
  The Small Intestinal Villi
                    Stomach
                                            Folds with villi on them



Small intestine




           Circular muscles
         Longitudinal muscles



        FON 241; Digestion: L. Zienkewicz
               The Small Intestinal Villi
                               Lymphatic vessel (lacteal)




Capillaries
A villus
Goblet cells




Crypts


Artery
Vein                                                        (cont’d next slide)

Lymphatic
vessel            FON 241; Digestion: L. Zienkewicz
The Small Intestinal Villi
              Microvilli




   FON 241; Digestion: L. Zienkewicz
       Nutrient Transport
• The nutrient crosses the cell and can…
    • 1. Enter the blood stream
          (water soluble)
                or
    • 2. Enter the lymphatic system

    • Water soluble nutrients and smaller fat products
      are released into the bloodstream.
    • Larger fats, fat-soluble vitamins and turned into
      chylomicrons and released into the lymphatic
      system



                FON 241; Digestion: L. Zienkewicz
               The Vascular System
                              Head and
                               upper
                                body



                               Lungs
                                                          Pulmonary vein
Pulmonary artery
                                       Aorta

                                         Left
                                         side
                      Right
                      side         Heart
                                                Hepatic artery
Hepatic vein                                Portal vein
                     Liver
                                     Digestive                    = Arteries
                                     tract                        = Capillaries
                                                                  = Veins
                       Lymph                                      = Lymph vessels

                              Entire body


               FON 241; Digestion: L. Zienkewicz
  The Vascular System
• Blood delivers Oxygen and
  Nutrients to organs and tissues;
  CO2 and waste products are carried
  away by the blood.

• The digestive system supplies
  nutrients to the blood.

• Heart        Arteries                        Capillaries

                  Veins

           FON 241; Digestion: L. Zienkewicz
   The Vascular System
         (cont.)
• Blood leaving the digestive
  system is taken to the liver via
  a vein.
• The liver is the bodies major
  metabolic organ.
• It receives nutrients and other
  products from the digestive
  system; a gatekeeper.

          FON 241; Digestion: L. Zienkewicz
Route of blood from
intestines to heart.
Heart     Arteries                       Capillaries
                                        (in intestines)

Vein      Capillaries                       Veins
          (in liver)


        FON 241; Digestion: L. Zienkewicz
The Lymphatic System:
• A route for fluid from tissue to
  enter the blood.
• Large fats and fat-soluble vitamins
  use the lymph system
• Ultimately end up in the heart
• Once in the blood stream, the
  nutrients can be delivered to cells,
  organs, etc.

            FON 241; Digestion: L. Zienkewicz
Chylomicron: travels via
 the Lymphatic System
                                     Hydrophilic head




                                     Hydrophobic tail
       FON 241; Digestion: L. Zienkewicz
Common GI Problems…
• Choking- improper closing of the
  epiglottis, food lodged in the pharynx,
  etc.
• Vomiting- stomach contents expelled;
  sometimes the contents of the
  duodenum are expelled.
• Diarrhea- frequent loose stools, lack of
  absorption and increased water in the
  intestine; fast motility
• Constipation- inability to defecate

             FON 241; Digestion: L. Zienkewicz
  Common GI Problems
      (cont.)…
• Gas- excessive gas in the GI tract
• Belching-excessive gas in the stomach
• Reflux- relaxation of the lower
  esophageal sphincter, causing stomach
  acid to touch the lining of the esophagus
• Ulcers- erosion of the lining of the GI
  tract
• Diseases of the GI tract………

             FON 241; Digestion: L. Zienkewicz
                    Diverticula in the Colon




                               Diverticula (plural)



         Diverticulum (singular)



Diverticula may develop anywhere along the GI tract,
         but are most common in the colon.
                   FON 241; Digestion: L. Zienkewicz
      In-text Figure
         Page 74




Eat a variety of food to keep your
  gastrointestinal tract happy.
       FON 241; Digestion: L. Zienkewicz

								
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