Digestive System (Alimentary Canal + Digestive Glands + Digestive Process)
The Digestive System. The Digestive System: Function Preparation of food for absorption and use by...
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Transcript of The Digestive System. The Digestive System: Function Preparation of food for absorption and use by...
The Digestive System
The Digestive System: Function
• Preparation of food for absorption and use by the millions of body cells
• Alimentary canal - tube through your body that performs the above function.
The Mouth Structure
• Lips: outer boundary
• Cheeks: mucous membrane lateral boundary
• Hard/soft palate - uvula extends from
• Tongue
Tongue
• Places food during chewing
• Papillae contain taste buds
• Multiple blood vessels under tongue = high absorption of soluble drugs into circulation– Ex. Nitroglycerin pills
for heart attack,– Vitamins
Salivary Glands
• Parotid = largest– Located in front of and
below ear– Produces watery
substance with enzymes
• Submandibular– Located below
mandibular angle– Produces enzymes and
mucus
• Sublingual = smallest– Under floor of mouth– Produces mucous type
of saliva
Salivary Glands: Function
• Begins the break down of food through hydrolysis.
• Carbohydrate digestion begins in the mouth with aid of saliva.
Teeth
• Crown - exposed covered with enamel
• Neck - surrounded by gums (gingiva)
• Root - fits into socket
Teeth Coverings
• Enamel - Hardest substance in body
• Dentin - tissues, nerves, blood vessels
• Cementum - covers dentin
Dentition
• Deciduous Teeth– Baby teeth– Primary teeth
• 20 total– 8 incisors– 4 cuspids– 8 molars
Dentition
• Permanent Teeth– Adult teeth– Secondary teeth
• 32 Total
• 3rd set of molars come in after age 17 (wisdom teeth)
Other Organ Components
• Pharynx– Receives bolus
(rounded mass of food)– Carries bolus to
esophagus
• Esophagus– Collapsible tube that
enters the stomach– Posterior to trachea and
heart– Protected by a thick
layer of mucus
Esophagus Continued
• Food (Bolus) moves through the esophagus and the rest of the alimentary canal by peristalsis - involuntary muscle contractions.
Stomach
• Located below diaphragm and liver
• Enlarges after meals then collapses
• Size of large sausage
Stomach Divisions
• Fundus - large portion at end of esophagus
• Body - central portion
• Pylorus - lower portion near small intestine
Sphincter Muscles
• Guard openings to stomach– Cardiac - esophagus
to stomach– Pyloric - lower
portion of stomach to small intestine.
• Pylorospasm - muscle will not relax to allow passage of bolus = vomiting
Stomach Function
• Food storage
• Secretion of gastric juices
• Churning of food and breakdown into chyme - liquid food.
• Absorption = water, alcohol, and drugs
• Glands of stomach– Gastric - secret gastric juice– Mucus - contains enzymes and
hydrochloric acid.
Small Intestines
• 20 feet long• Divisions
– Duodenum = uppermost area, attaches to stomach.
– Jejunum = middle area
– Ileum = end portion, leads to large intestine.
• All set in place by mesentery (membrane)
Small Intestines Continued
• This is where most digestion occurs.
• Absorption of digestive products.
• Inside surface of small intestines covered with tiny projections called villi.– 1mm projections– Increase surface area by
160x
Large Intestines
• 5-6 feet long• Divisions
– Ascending colon - right side of abdomen
– Transverse colon - horizontally across abdomen and under liver
– Descending colon - left side of abdomen
– Rectum - last 7-8 inches– Anus - contains many
arteries and veins• Hemorrhoids -
enlargement of veins in anal canal.
Large Intestines Continued
• Water/electrolyte absorption
• Forms/stores feces
Large Intestines Continued
• Appendix– Located just behind
cecum– No functional
importance in digestion.
– Appendicitis = inflammation of the appendix
Accessory Organs
• Liver structure– Largest gland in body– Under diaphragm– Able to regenerate
• Liver function– Detoxifies many
substances– Makes and secretes bile– Metabolizes proteins,
fats, and carbs
Accessory Organs
• Gall bladder– Stores bile, increases
its concentration• Bile breaks down fat.
– During digestion, empties bile into small intestines
Accessory Organs
• Pancreas– Secretes digestive
enzymes– Secretes insulin– Secretes glucagon
(raises blood glucose levels)