biological science - the digestive system
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BIOLOGICAL SCIENCE
“DIGESTIVE
SYSTEM”
Prepared by: Ms. Jonna Karla C. Bien, RN
• Gastrointestinal System
• Function-physical and chemical breakdown of food
• Includes alimentary canal and accessory organs
• Accessory organs: Salivary glands, tongue, teeth, liver, gallbladder, and pancreas
Alimentary canal
• Mouth- physical and
chemical breakdown.
• Mastication-the act of
chewing
• Saliva contains
enzyme amylase to
break down
carbohydrates
• Pharynx- contains opening to trachea as well. Epiglottis covers opening of trachea.
• Esophagus-muscular tube dorsal to trachea
• Relies on a rhythmic wave-like motion called peristalsis
Esophagus- transverse view
• Sphincter-a circular
muscle that constricts
a passage or closes a
natural orifice
(opening)
• Cardiac sphincter
• Pyloric sphincter
• Food sits in stomach
for 1-4 hours. Gastric
juices contain
hydrochloric acid-
activates pepsin, kills
bacteria.
• Small intestine: not so
small! 20ft x 1’’
• Duodenum- 1st 10
inches. Bile and
pancreatic juice enter
here
• Jejunum- next 8 ft.
• Ileum- final 12 ft.
When food leaves
small intestine,
digestion is complete
• Small intestine has
lots of enzymes:
peptidases
• maltase, sucrase,
lactase, amylase.
• Lipase
• Bile
Digested food is
absorbed into the
bloodstream.
• Large intestine- 5 ft x
2’’. Separated from
small intestine by
ileocecal valve
• Final absorption of
water, storage of
indigestible material,
absorption of vitamins
B and K by bacteria.
• Colon connects to
rectum- anal canal
opens to the anus
(final opening). Fecal
material is expelled.
What about the accessory organs:
Liver, gall bladder and pancreas • Liver- largest gland in
your body
• Secretes bile-
emulsifies fat, makes
them water soluble.
• Stores glucose in the
form of glycogen
• Makes clotting
proteins
• Detoxifies blood
• Gall bladder- stores
and concentrates bile
• Pancreas- produces
insulin, pancreatic
juices amylase and
lipase. Insulin
regulates the uptake
of glucose by the cells
Diseases • Appendicitis
• Cholecystitis- gall bladder
• Cirrhosis- destruction of liver cells
• Diarrhea
• Diverticulitis
• Gasteroenteritis
• Hernia
• Pancreatitis
• Liver transplant
• Ulcer
• Colitis
• Bariatric surgery
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