The Digestive System

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The Digestive System
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3 Functions of the digestive system

• DIGESTION
• ABSORPTION
• ELIMINATION

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Digestion

• Starts in the mouth
• Ends in the anus
• Food can be broken down mechanically (chewing)
  and chemically (with enzymes) to be digested
  (broken down).

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Absorption

• Digested food into the bloodstream through the
  walls of the small intestine.
• Cells burn the energy (sugar, fatty acids, and
  amino acids) in the presence of oxygen to release
  stored energy within the food.

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Absorption

• Cells also use larger proteins to help build
  larger protein molecules needed for growth and
  development.

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Elimination

• The digestive system eliminates materials that
  cannot be used in the body via elimination.
• The large intestine concentrates these solid
  wastes, called FECES, and finally the waste
  passes out of the body through the anus.

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Inside the Oral Cavity

• The gastrointestinal tract (GI tract) begins with
  the oral cavity.
• Oral (or/o pertaining to the mouth)
• The cheeks form the walls of the oval shaped oral
  cavity, and the lips surround the opening of the
  cavity.
• The hard palate form the anterior portion of the
  roof of the mouth.
• The soft palate consists of the muscular membrane
  that lies posterior to it.

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The Oral Cavity
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The Oral Cavity

• Ruage are the bumps on the top of the hard
  palate.

• The uvula is the small tissue projection that
  hangs from the soft palate (hangy ball)
• The uvula helps with the production of the sounds
  of speech.
• The tongue covers the floor of the oral cavity,
  aids in moving the food during mastication
  (chewing) and deglutition (swallowing).

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The Oral Cavity
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The Oral Cavity

• Papillae, small raised bumps on the tongue,
  contains taste buds.
• Sensitive to food chemicals and allow
  discrimination of different tastes as the food
  moves across the tongue.

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Papillae

• Some people think that every bump on their tongue
  is, itself, a taste bud, but that is NOT true. 
• Each papillae has many taste buds within it. 
• In addition, we have taste buds that are not even
  on our tongues. 
• Some taste buds are found in our throats, cheeks,
  and in the roof of our mouths.

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Papillae
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Taste Regions
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Tonsillitis
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The Oral Cavity

• The gums are fleshy tissue that surrounds the
  sockets of the teeth.
• The adult human has 32 teeth (16 permanent teeth
  top/16 bottom arch).

Central incisor (1) Lateral incisor (2) Canine
(3) First premolar (4) Second premolar (5) First
molar (7) Third Molar (wisdom tooth) (8)
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Salivary Glands

• 3 pairs in the oral cavity
• Produce Saliva, that contain digestive enzymes.
• Saliva is released from the parotid gland,
  submandibular gland and sublingual gland on EACH
  side of the mouth.
• Narrow ducts carry saliva into the oral cavity.

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The Oral Cavity

• Together the teeth and saliva breakdown food in
  the oral cavity.

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Components of the Digestive System

• Esophagus
• Stomach
• Small Intestine
• Large Intestine
• Gall bladder
• Liver
• Pancreas

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Esophagus

• the tube that connects your mouth and your stomach

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Esophagus

• Muscular tube
• 9-10 inches from the pharynx to the stomach
• Peristalsis is the involuntary, progressive,
  rhythmic contraction of muscles in the walls of
  the esophagus (and other gastrointestinal organs)
  propelling a bolus (mass of food) toward the
  stomach.

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Food Passage thus far

• Oral cavity (teeth, tongue, saliva)
• Pharynx
• Esophagus
• Stomach

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Stomach

• A stretchy bag that holds your food after you eat
• Helps to break food into smaller pieces so your
  body can use it for energy and nutrition

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Esophagus
Stomach
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The Stomach

• From the esophagus into the stomach
• 3 parts Fundus (upper portion)
• Body (middle section)
• Antrum (lower portion)

FUNDUS
ANTRUM
BODY
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Inside the Stomach

• Folds in the lining of the stomach are called
  rugae.
• The rugae contain digestive glands that produce
  the enzyme pepsin (to begin digestion of
  proteins) and hydrochloric acid.
• Food leaves the stomach in 1 to 4 hrs or longer,
  depending on the type/amount of food eaten.

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Sphincters

• Rings of muscles
• Control the opening and closing of the stomach
• Lower esophageal sphincter (cardiac sphincter)
  relaxes and contracts to move food from the
  esophagus to the stomach.
• Pyloric sphincter allows food to move from the
  stomach to the intestine.

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Small Intestine

• Tube that is 20 feet long.
• Continues to digest food
• Food stays in your small intestine for 4 to 8
  hours

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Small Intestine
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Small Intestine

• 20 feet from the pyloric sphincter to the first
  part of the large intestine.

3 parts of the small intestine 1. DUODENUM 2.
JEJENUM 3. ILEUM
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The Small Intestine

• Lined with VILLI
• Tiny microscopic projections
• Microscopic blood vessels in the villi absorb the
  digested nutrients into the bloodstream and lymph
  vessels.

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Duodenum

• 1 foot long
• Receives food from the stomach
• Bile from the liver
• Bile from the gallbladder
• Pancreatic juice from the pancreas
• Enzymes and bile help digest food before it
  passes to the second part of the small intestine.
  

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Large Intestine

• Tube that is 5 feet long
• Gets waste from small intestine
• Waste stays for 10 to 12 hours

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The Large Intestine

• Receives the fluid waste from digestion (the
  material that is unable to pass into the
  bloodstream).
• It stores the waste until they can be released
  from the body.

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Large Intestine
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Large Intestine

• From the small intestine to the anus
• 6 sections
• The APPENDIX hangs from the large intestine.
• The appendix has no clear function but can become
  inflammed and infected when clogged or blocked.
• Thought to be involved with breakdown of plants
  during primitive life.

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Large Intestine Sections
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The Large Intestine

• Absorbs water within the waste material allowing
  the body to expel solid feces (stools).
• Defecation is the expulsion or passage of feces
  from the body through the anus.
• Diarrhea, or watery stools, results from reduced
  water absorption into the bloodstream through the
  walls of the large intestine.

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Gall Bladder

• Storage tank for bile (a greenish-yellow liquid)
  that helps your body break down and use fats
• Located under your liver
• Shaped like a pear

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Gall Bladder
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Gallbladder

• Pear-shaped sac
• Stores and concentrates bile for a later use.
• After you eat the gallbladder contracts, forcing
  the bile into the cystic duct into the common
  bile duct.

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Liver

• Factory for antibodies and bile
• Stores vitamins and sugars until your body needs
  them

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The Liver

• Produces BILE (a thick, orange-black, sometimes
  greenish fluid).
• Bile contains cholesterol (a fatty substance),
  bile acid, and bile pigments.
• Bilirubin produced from the breakdown of RBCs
  in normal RBC destruction.
• Bilirubin travels to the liver through the
  bloodstream, where it is conjugated with another
  substance and added to bile.

• Bilirubin enters the intestine with bile.
• Bacteria in the colon breakdown bilirubin into
  pigments that gives feces its brown color.
• Bilirubin and bile leave the body in feces.

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Liver
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Other Functions of the Liver

• Maintain proper sugar levels (glucose)
• Manufacture blood proteins (blood clotting)
• Releasing Bilirubin, a pigment in bile
• Remove Poisons (toxins) from the blood.

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Jaundice

• Occurs when bilirubin cant leave the body.
• Causes a yellowish discoloration of the skin,
  whites of the eyes, and mucous membranes.

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Pancreas

• Helps you digest food by breaking down sugars

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Functions

• Digest the food we eat
• Take the nutrients out of your food so your body
  can use it

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Food Passage thus far

• Oral cavity (teeth, tongue, saliva)
• Pharynx
• Esophagus
• Stomach
• Small Intestine (duodenum, jejunum, ileum)
• Large Intestine (6 sections)
• Liver

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Recap..can you remember the food path?
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Food Pathway

• Food Enters the
• Oral Cavity
• Pharynx
• Esophagus
• Stomach
• Duodenum
• Jejunum
• Ileum
• Cecum
• Ascending Colon
• Transverse Colon
• Descending Colon
• Sigmoid Colon
• Rectum
• Anus
• Feces Leaves the body

PANCREAS
LIVER
ENZYMES
BILE
GALLBLADDER
SMALL INTESTINE
LARGE INTESTINE
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Hernia

• A hiatal hernia occurs when the upper part of the
  stomach protrudes upward through the diaphragm.
  This condition can lead to GERD (gastroesophageal
  reflux disease).

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Heartburn

• Has nothing to do with the heart - it is a
  digestive problem
• Heartburn is a pain behind the breast bone, often
  described as burning in quality.
• Acid is present in the stomach to digest food.
  Heartburn occurs when small amounts of this acid
  rise up into the esophagus - the tube which
  carries food from the mouth to the stomach. This
  is called reflux.
• The gullet, unlike the stomach, does not have a
  protective lining. So when it is exposed to the
  acid, it can become inflamed and painful.

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Anorexia

• Lack of appetite (-orexia appetite)
• A sign of malignancy or liver disease.
• It is a loss of appetite caused by emotional
  problems such as anger, anxiety, and fear.
• It is an eating disorder classified as a refusal
  to maintain a minimally normal body weight.
• The individual is intensely afraid of gaining
  weight and has a disturbance in the perception of
  the shape or size of his/her body.
• Predominantly affects adolescent females, and its
  principal symptom is a conscious, relentless
  attempt to diet along with excessive, compulsive
  over activity, such as exercise, running, or
  gymnastics.
• Most postmenarchal females with this disorder are
  amenorrheic.

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Bulimia

• Bulimia Nervosa (bulimia means abnormal increase
  in hunger) is characterized by binge eating
  (uncontrolled indulgence in food) followed by
  purging (eliminating food from the body).
• Individuals maintain normal or nearly normal
  weight because after binging they engage in
  inappropriate purging.
• E.g. self-induced vomiting and the misuse of
  laxatives or enemas.