DIGESTIVE SYSTEM

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DIGESTIVE SYSTEM
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THE ALIMENTARY CANAL

• The alimentary canal- is the path that food will
  take from the moment it enters your body until it
  exits.
• AKA- The Gastrointestinal Tract, GI, or Gut!
• Includes the mouth, esophagus, stomach, and small
  and large intestines, and anus.
• An adults DT is about 30 feet long.

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THE ACCESSORY ORGANS

• The Accessory Organs- include the teeth, tongue,
  gallbladder, liver, pancreas, salivary glands.
• The accessory digestive glands produce a variety
  of secretions that contribute to the breakdown of
  foodstuffs.

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The Digestive Process

• The digestive tract can be viewed as a
  disassembly line in which food becomes less
  complex at each step of processing and nutrients
  then become available to the body.
• The six essential activities are
• Ingestion
• Propulsion
• Mechanical digestion
• Chemical digestion
• Absorption
• Defecation

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THE ALIMENTARY CANAL Mucous Membrane

• Mucous membrane,(aka mucosa), lines most of the
  alimentary canal from mouth to anus.
• Formed of surface epithelium and a small amount
  of smooth muscle

• Functions include
• Protection against infectious disease.
• Secretion of mucus, digestive enzymes, and
  hormones
• Absorption of end products of digestion into the
  blood.

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Digestion

• Digestion is the mechanical and chemical
  breakdown of foods into forms that cell membranes
  can absorb.
• Mechanical digestion breaks large pieces into
  smaller ones without altering their chemical
  composition
• Chemical digestion breaks food into simpler
  chemicals

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Mouth

• Mouth- a mucosa-lined cavity, is also called the
  oral cavity, or buccal cavity.
• The mouth receives food and begins digestion by
  mechanically breaking up the solid particles into
  smaller pieces. This is called mastication.
• The mouth is also part of the speech and sensory
  perception.
• The mouth is in all responsible for the following
• To ingest
• Begins mechanical digestion by chewing
• Initiates propulsion by swallowing.

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Tongue
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Tongue

• Tongue- mixes saliva with food and moves it
  toward pharynx.
• The surface of the tongue has rough projections
  called papillae. These can provide friction
  which handles food most other papillae contain
  most of the taste buds.
• The tongue is connected in the midline to the
  floor of the mouth by a membranous fold called
  the frenulum.
• The root of the tongue is anchored to the hyoid
  bone.

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3 Types of Tonsils

• All Tonsils are lymphatic tissue and are there
  for associated with fighting infection.
• Alingual Tonsils, Palatine Tonsils, and
  Pharyngeal Tonsils- (aka Adenoids).
• We will discuss these in more detail during the
  Lymphatic System.

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Palate

• The palate forms the roof of the oral cavity and
  consists of a hard anterior part and a soft
  posterior part.
• The soft palate forms a muscular arch, which
  extends posteriorly and downward as a cone-shaped
  projection called the uvula.

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Saliva

• Saliva- Functions
• Cleanses the mouth
• Dissolves food chemicals so that they can be
  tasted
• Moistens food and aids in compacting it into a
  bolus (which is a lump of chewed food)
• Contains enzymes that begin the chemical
  breakdown of starchy foods.

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Salivary Glands

• There are three pairs of major salivary glands
• Parotid (1) is the largest
• Submandibular (2)
• Sublingual (3) (is the smallest)

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Salivary Glands
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Salivary Glands

• Salivary Glands- produce two types of secretory
  cells mucous and serous.
• The parotid glands contains only serous cells.
• The sublingual gland contains mostly mucous cells
• The submandibular contains both cells

• Serous Cells they produce a digestive enzyme
  called amylase. It begins the chemical
  digestion of complex carbohydrates, such as
  sweet potatoes even before it leaves the mouth.
  
• Mucous Cells- produce mucus which binds food
  particles and acts as a lubricant.

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Salivary Glands

• Saliva is mostly 97 to 99.5 water.

• Mumps, a common childrens disease, is an
  inflammation of the parotid glands caused by the
  mumps virus.

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THE ALIMENTARY CANAL

• Teeth- 20 primary, 32 secondary, hardest
  structures in the body that are not part of the
  skeletal system
• By age 2..most children have ALL of the primary
  teeth.

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PHARYNX

• Swallowing (deglutition), moves food into the
  throat or pharynx.
• A passage way for both food and air.
• It connects the nasal and oral cavities with the
  larynx (where your vocal cords are) and
  esophagus.
• Over 22 muscles groups must work together during
  the process of swallowing in order to close of
  the air passageway and lead food down the
  esophagus.
• A flexible flap of tissue called epiglottis
  reflexively closes over the trachea when we
  swallow to prevent choking.

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Esophagus

• ESOPHAGUS is a straight collapsible tube about 25
  centimeters long.
• Provides passageway for food from the pharynx to
  the stomach
• Waves of muscle contractions called Peristalsis
  forces food down the esophagus.

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Esophagus

• At the end of the esophagus, a muscular ring
  called the lower esophageal sphincter (aka
  cardiac sphincter) allows food to enter the
  stomach and then squeezes shut to keep food or
  fluid from flowing back up into the esophagus.

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Heartburn

• Heartburn is the burning, radiating substernal
  pain that occurs when the acidic gastric juice
  regurgitates into the esophagus.
• Common in one who has eaten or drunk to excess,
  extreme obesity, pregnancy, and running which
  cause stomach contents to splash upward with each
  step.

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Movement of food from the esophagus to the
stomach.
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STOMACH

• Stomach- is a temporary storage tank.
• It lies in the upper left quadrant of the
  peritoneal cavity, nearly hidden by the liver and
  the diaphragm.
• Though relatively fixed at both ends the stomach
  is quite movable. Running horizontal in short
  people and vertical in tall people.

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STOMACH

• The stomach is a j-shaped, pouchlike about 25-30
  cm.

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STOMACH

• Stomach- The stomach is a saclike organ.
• It has walls made of layers of muscle, each
  arranged on a different angle.
• As the food enters the stomach, muscle
  contractions begin to twist, turn, and churn the
  food.
• The twisting, turning, and churning of food in
  the stomach is part of mechanical digestion.

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STOMACH

• The food is churned and mixed with stomach fluids
  until a thick paste called chyme is produced.
• The chyme passes through the stomach into the
  small intestine

• The stomach produces gastric juice and mixes it
  with the food. This gastric juice contains Pepsin
  which is an important enzymes that begin the
  digestion of proteins.
• Proteins are the only substances digested in the
  stomach. Proteins are even then only partially
  digested in the stomach.

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STOMACH

• Glands in the stomach produces about 2.8 liters
  of gastric juices daily.
• Pepsin is by far the most important digestive
  juice, it begins the digestion of nearly all
  types of dietary protein.

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STOMACH

• When empty has the volume of 1/5 of a cup, but it
  can expand to hold 8 cups of food after a large
  meal.

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• A ring of muscle the pyloric sphincter located
  between the stomach and the duodenum of the small
  intestines controls food entry.
• It leaves the stomach and enters the small
  intestines through peristaltic waves.

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• Why does your stomach growl?

• As the peristalis muscles contraction move your
  meal along its digestive path, these contractions
  also help churn food, liquid and different
  digestive juices together, rendering them into a
  gooey mix known as chyme.
• Stomach growling is the result of this process.
  Moving with those solid and liquid chyme
  ingredients are gasses and air. As all these
  ingredients get pushed around and broken down
  into easy-to-absorb bits, pockets of air and gas
  also get squeezed and create the noises we hear.

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Small Intestines

• Small intestine- receives secretions from the
  pancreas and liver completes digestion of
  nutrients, absorbs the products of digestion, and
  transports the residues to the large intestines.
• Tubular organ with many loops and coils that
  fills much of abdominal cavity
• 5.5-6.0 meters long and 5 cm in diameter

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Small Intestines

• Small Intestines is made up of 3 key parts
• The duodenum- The C-shaped first part
• The jejunum- the coiled midsection
• The ileum- the final section that leads to the
  large intestines.

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Small Intestines

• The jejunum and ileum are suspended from the
  posterior abdominal wall by a double-layered fold
  of peritoneum called the Mesentery. The
  mesentery supports the blood vessels, nerves, and
  lymphatic vessels that supply the intestinal
  wall.

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Small Intestines

• A filmy, double fold of peritoneal membrane
  called the Greater Omentum drapes like an apron
  from the stomach over the transverse colon and
  the folds of the small intestine.

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CATS!
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Small Intestines

• The inner wall of the small intestines is covered
  with millions of microscopic, fingerlike
  projections called villi. Nutrients can be
  absorbed into the body through this villi.

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ABSORPTION OF THE SMALL INTESTINE

• Most absorbing organ in the alimentary canal
• Its so effective that only very little amounts
  water and electrolytes reach the large intestine

• Enzymes from the intestinal mucous membrane and
  the pancreas break down and absorb carbohydrates,
  proteins, and fat molecules
• Intestinal villi, projections of mucosa, absorb
  water and electrolytes

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Small Intestines

• The Ileocecal sphincter joins the small
  intestines ileum to the large intestines cecum.
  
• Normally remains closed, however eating a meal
  elicits a gastroileal reflex that increases
  peristalsis in the ileum and relaxes the
  sphincter, forcing the contents of the small
  intestine into the cecum.

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Large Intestines

• 1.5 meters long vs/ the small intestines which is
  6 meters long.
• It is located in the lower abdominal region,
  posterior to the stomach
• It begins on the lower right side of the
  abdominal cavitycrosses obliquely to the left
  and then descends into the pelvis
•  

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Large Intestines

• By the time the food reaches the large intestines
  most of the work of absorbing nutrients is nearly
  finished.
• The large intestines main function is to remove
  water from the undigested matter and form solid
  waste that can be excreted
• Bacteria in the colon help to digest the
  remaining food particles.

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Large Intestines

• Large intestine- consist of the cecum, the colon,
  the rectum, and the anal canal.
• Cecum- a pouch at the beginning of the large
  intestine that joins that small intestine to the
  large intestines.

• The colon is divided into four portionsthe
  ascending, transverse, descending and sigmoid.

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Large Intestines

• The colon extends from the cecum up the right
  side of the abdomen (ascending), across the upper
  abdomen (transverse), and then down the left side
  of the abdomen (descending), then it makes an
  S-shaped curve called the (sigmoid) finally
  connecting to the rectum.

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Large Intestines

• The rectum is where feces are stored until they
  leave the digestive system.
• The anal canal connects the rectum to the anus.

• The anal canal opens to the outside as the anus.
• Guarded by two sphincters. Internal anal
  sphincter (involuntary controlled) External anal
  sphincter (voluntarily controlled)

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ABSORPTION OF THE LARGE INTESTINE

• The large intestine has very little digestive
  function
• It absorbs the left over water and electrolytes

• 90 of the water that enters the large intestine
  is absorbed so that very little sodium and water
  is loss

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Large Intestines
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Appendix

• The appendix- a small hollow, fingerlike pouch.
• Hangs at the end of the cecum.
• Scientist think it is left over from a previous
  time in human evolutionit is no longer necessary
  to the DT

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ESSENTIAL ORGANS THAT ARE NOT PART OF THE DT

• The Liver (located under the rib cage in the
  right upper part of the abdomen).
• The Gallbladder (hidden just below the liver)
• The pancreas (beneath the stomach).
• These are NOT part of the alimentary canal, but
  these are essential to digestion.

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Liver

• Liver- largest internal organ
• Shaped like a wedge
• Lies almost entirely within the rib cage.
• Has 4 lobes
• Is a very vital organ with many important roles.
  Its digestive function is to produce bile for
  export to the duodenum.

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Liver

• Bile- is a fat emulsifier, it breaks up fats into
  tiny particles so that they are more accessible
  to digestive enzymes.

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Gallbladder

• The gallbladder is a thin-walled green muscular
  sac about 10 cm (4 inches) long.
• It stores bile that is not immediately needed.
• Bile is often 10 times more concentrated when it
  leaves the gallbladder than when it entered.
• These enzymes and bile travel through special
  channels called the bile ducts which lead
  directly into the duodenum of the small intestine.

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Pancreas

• Pancreas is a soft tad-pole shaped gland.
• It is an endocrine gland but also plays a role in
  digestion.
• It secretes a digestive juice called pancreatic
  juice

• Produces enzymes that help digest proteins, fats,
  and carbs.
• Also makes a substance that neutralizes stomach
  acid.

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Pancreas

• The cells that produce pancreatic juices release
  them into the pancreatic duct that extends the
  length of the pancreas and joins with the bile
  ducts from the liver and gallbladder and empty
  into the duodenum of small intestines.

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MAJOR MINERALS

• Calcium- helps in the structure of bones,
  essential for nerve impulse conduction, muscle
  fiber contraction, and blood coagulation,
  increases permeability of cell membranes and
  activates certain enzymes.

• Calcium is found in milk, cheese, leafy green
  products.
• An excess can cause kidney stones.
• Not enough calcium can cause stunted growth,
  misshapen bones, and fragile bones.

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MAJOR MINERALS

• Phosphorus- helps in structures of bones and
  teeth, component in nearly all metabolic
  reactions, constituent of nucleic acids, many
  proteins, some enzymes and some vitamins, it also
  occurs in the cell membrane, ATP, and phosphates
  of body fluids.

• Phosphorus is found in meats, cheese, nuts, whole
  grain cereals, milk, legumes
• Not enough phosphorus can cause stunted growth

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MAJOR MINERALS

• Potassium- helps maintain intracellular osmotic
  pressure and regulate pH promotes metabolism
  needed for nerve impulse conduction and muscle
  fiber contraction.

• Potassium is found in avocados, dried apricots,
  meats, nuts, potatoes, and bananas.
• A lack of potassium can cause muscular weakness,
  cardiac abnormalities, and edema.

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MAJOR MINERALS

• Sulfur- essential part of various amino acids,
  thiamine, insulin, biotin, and mucopolysaccharides
  .
• Water soluble sulfur is an oil in it's pure water
  soluble form, it is the flexible bond that holds
  your cells together making your skin look good
  without wrinkles.

• Sulfur is found in meats, milk, eggs, legumes
• A deficiency of water soluble sulfur can lead to
  a variety of conditions ranging from skin
  irritations and rashes to total breakdown of
  cellular regeneration.
• For instance have you ever wondered why your pets
  like to go out and chew on the grass, or scratch
  consistently yet don't have fleas, these are
  signs that your pets are deficient in water
  soluble sulfur. The consistent scratching is an
  attempt to relieve the pain caused by a loss of
  nutritional sulfur which provided the flexible
  bond in the skin tissue and has now resulted in
  dry, brittle skin.

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MAJOR MINERALS

• Sodium- helps maintain osmotic pressure of
  extracellular fluids and regulate water movement
  needed for conduction of nerve impulses and
  contraction of muscle fibers aids in regulation
  of pH and in transport of substances across cell
  membrane

• Sodium is found in table salt, cured ham,
  sauerkraut, cheese, graham crackers.
• An excess of sodium can cause hypertension and
  edema.
• A lack of sodium can cause nausea, muscle cramps,
  and convulsions.

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MAJOR MINERALS

• Chlorine maintain osmotic pressure of
  extracellular fluids, regulate pH, and maintain
  electrolyte balance

• Chlorine can be obtained in table salt, cured
  ham, sauerkraut, cheese, graham crackers
• Too much chlorine causes vomiting
• A deficiency of it causes muscles cramps

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MAJOR MINERALS

• Magnesium is needed in metabolic processes (ATP
  production in mitochondria)
• Found in dairy products, legumes, nuts, leafy
  green vegetables

• If you consume too much magnesium it will cause
  diarrhea
• A lack of it will cause neuromuscular disturbances

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VITAMINS

• Thiamine (B1) needed for oxidation of carbs
• It is found in lean meats, liver ,eggs,
  whole-grain cereals, green vegetables

• A deficiency of vitamin B1 enlarges the heart,
  causes muscular weakness, and beriberi.
• Beriberi is a nervous system ailment. Symptoms
  include severe lethargy and fatigue, together
  with complications affecting the cardiovascular,
  nervous, muscular, and gastrointestinal systems.

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VITAMINS

• Riboflavin (B2) - needed in the oxidation of
  glucose and and fatty acids
• Found in meats, dairy products, whole grain
  cereal, and leafy green veggies

• If you do not get enough B2 you get blurred
  vision and dermatitis

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VITAMINS

• Pantothenic acid
• Also a B vitamin
• Needed for oxidation of carbs and fats
• Found in meats, milk, fruits, vegetables,
  legumes, whole-grain cereal

• A shortage of this vitamin is rare, but it causes
  mental depression, loss of appetite, and muscle
  spasms

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VITAMINS

• Cyanocobalamin (B12) needed for synthesis of
  nucleic acids and for metabolism
• In liver, meat, and cheese, eggs

• A loss of B12 causes pernicious anemia

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VITAMINS

• Folacin- (Folic Acid) Folic acid is a B vitamin.
  It helps the body make healthy new cells.
  Everyone needs folic acid.
• For women who may get pregnant, it is really
  important. When a woman has enough folic acid in
  her body before and during pregnancy, it can
  prevent major birth defects of her baby's brain
  or spine.

• Metabolism of certain amino acids and for
  synthesis of DNA
• Found in leafy green vegetables, legumes, whole
  grain cereals

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VITAMINS

• Ascorbic acid (C) needed for production of
  collagen and metabolism of some amino acids
• Found in citrus fruits, tomatoes, potatoes, leafy
  green vegetables

• An excess of vitamin C exacerbates gout and
  kidney stone formation
• A shortage of it causes scurvy, lowered
  resistance to infection, and wounds heal slower