The Alimentary Canal

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The Alimentary Canal

• - the one way passageway for food / nutrients /
  waste

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The Alimentary Canal
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Human Alimentary Canal

• Mouth
• Pharynx
• Esophagus
• Stomach
• Small intestine
• Large intestine

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Mouth

• True digestive organ
• physical chemical digestion
• Salivary Amylase breaks carbohydrates into
  disaccharides/maltose
• contains teeth, tongue, soft hard palate to
  help with physical digestion
• food is ingested

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Salivary Glands

• Accessory Organs
• produce salivary amylase
• sublingual
• submandibular
• parotids

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Pharynxaka. The throat

• True digestive organ
• no physical or chemical digestion occurs here
• hooks in with the respiratory system

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Esophagus

• True digestive organ
• no physical or chemical digestion occurs here
• food considered a bolus - wet ball of chewed food
• PERISTALSIS starts here - wavelike contractions
  of the tube that moves the foodstuff along the
  alimentary canal

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The Alimentary Canal
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Stomach

• Very muscular organ that participates in both
  physical chemical digestion
• true digestive organ
• lined with thick protective mucous
• the enzyme pepsinogen activates in the acid
  conditions in the stomach and becomes pepsin
• pepsin digests the proteins into groups of 2
  amino acids
• cardiac sphincter valve is at the top and the
  pyloric valve is between the stomach small
  intestine
• the bolus is now considered chyme

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The Alimentary Canal
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Small Intestine

• True digestive organ
• chemical digestion is completed here
• contains 3 main portions
• duodenum first 10 cm of small intestine
• jejunum next 2 ½ meters
• ileum last 4 meters
• the role of the small intestine is threefold
• 1. Finish digestion
• 2. Absorb nutrients
• 3. Storage
• contains villi for absorption of nutrients

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Small IntestineEnzyme Action

• Common bile duct hooks into duodenum
• this hooks up to the pancreas and gallbladder
• pancreatic juice bile is secreted is secreted
  through this
• BILE bile salts- emulsifies the fat - breaks
  into smaller droplets
• Pancreatic Juice contains
• sodium bicarbonate / to neutralize the acid from
  the stomach
• lipase / breaks fats into fatty acids glycerol
• trypsinogen in changed into trypsin in the si.
  Environment and digests the dipeptides into
  single amino acids
• pancreatic amylase finishes carbohydrate
  digestion by breaking disaccharides into
  monosacharides

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Villi

• Increases the surface area in the small intestine
  for the maximum nutrient absorption
• monosaccharides amino acids are diffused into
  the capillaries ? bloodstream
• fatty acids glycerol are absorbed by the
  lacteal which hooks into the lymphatic system

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Pancreas

• Accessory digestive organ
• produces pancreatic juice which contains
  pancreatic amylase, sodium bicarbonate,
  trypsinogen and lipase
• located under the stomach

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• LIVER
• produces bile which breaks up the larger fats

• GALLBLADDER
• stores the bile until needed

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The Alimentary Canal
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Large Intestine

• True digestive organ, but digestion is all done
  by now!!!
• The function is to absorb water minerals
• at the junction of the small large intestine is
  the appendix
• there are 5 portions of the large intestine
• ascending colon
• transverse colon
• descending colon
• sigmoid colon
• rectum which ends in the anal sphnicter
• methane in is a normal bi-product and
• in combination with e. coli bacteria produce
• flatulence

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• At this point the waste products are referred to
  as feces
• CONSTIPATION - waste sits in large intestine too
  long and the stool becomes too hard and is
  difficult to evacuate
• DIARRHEA - waste does not sit in the large
  intestine long enough and not enough water is
  absorbed ? producing a watery stool

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The Alimentary Canal
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Hormones of the Digestive System

• GASTRIN -
• cells of the stomach secrete into bloodstream
• triggers cells of stomach to secrete hydrochloric
  acid so pepsinogen converts to pepsin

• SECRETIN -
• when food enters the small intestine
• secreted by the cells of si. Into the bloodstream
• triggers pancreas to make pancreatic juice