Download Digestion

Chapter 7
Structure & Function of Human Body
Digestive System
OBJECT IVES
Students should be able to:
* Describe the primary anatomical features &
physiological actions of systems for
providing energy & for removing waste from body.
* Name common diseases or disorders associated with each
system.
* Describe behaviors &actions for each body system that
promote health & prevent major diseases & disorders.
Digestive System, aka Gastrointestinal (GI) Syst.
• Processes food to use for energy
• takes in & digests:
(to allow absorption)
changes to:
Carbs
Glucose
Proteins
AA’s
Lipids
Fatty Acids
• vits & minerals do not req digestion & are
abs’d directly into caps
• absorbs water
• eliminates undigested food products (waste)
Digestive System
• GI syst =‘s long tube ~ 30 ft long
• Extends from mouth to anus
• both mechanical & chemical digestion to
process food
Mechanical Digestion
• Mechanically, food is chopped, mashed, &
mixed
Chemical Digestion
• Chemically, food broken down by Enzymes
produced c in system or added by other organs.
Enzymes break down food into absorbable
nutrients.
GI Syst. cont
Main parts of tube
include:
• Mouth
• Esophagus
• Stomach
• Small intestines
• Large intestines
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When Food enters Mouth:
its taste triggers saliva glands to secrete enz’s,
which begins breakdown of carbs
teeth chop & grind
tongue mashes food against hard palate, mixing
it with saliva
mouth cools or warms food to body temp.
tongue moves food to
back of throat to be
swallowed
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Esophagus
=‘s strong, muscular tube
Connects pharynx to stomach
Loc’d behind trachea & in front of spinal column
composed of layers of muscle that contract to
move food.
contraction called peristalsis, & is controlled by
Autonomic Nervous System (ANS)
Esophagus, cont.
• Food passes into Stomach thru
Cardiac Sphincter (Lower Esophageal
Sphincter), which prevents
acidic contents of stom from
back flowing into esophagus
Stomach
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=‘s muscular, elastic bag
fits under diaphragm on L side of abd.
is protected by lower ribs
Food remains in stomach for 2- 4 hrs while
muscles contract to mix it c digestive juices
Glands in Stomach release:
• Hydrochloric Acid (HCl) to kill bacteria
• Pepsin (enz) to break down protein
• Mucus to protect stomach wall from acid
Stomach, cont:
• When partially digested food leaves stomach, it
goes thru Pyloric Sphincter to enters small
intestine (Duodenum).
Small Intestine, aka Small Bowel
• Consists of 3 parts: Duodenum, Jejunum, &
Ileum.
• Once food passes into Sm Intest, additional
intestinal juices are added, including:
• bile from liver
• pancreatic juice from pancreas
Small Intestine, aka Small Bowel
• Digestion cont’s, but absorption also begins to
occur thru network of small, finger-like
projections called Villi, line the sm intest.
• Each villus contains network of blood & lymph
cap’s
Villi
Small Intestine, aka Small Bowel
• Lymph system aborbs Fatty Acids
• Cap’s abs Amino acids & Simple Sugars
• Vits & Minerals pass unchanged from small
intestine into blood & lymph.
Small Intestine, aka Small Bowel
• material leaving sm intest norm’ly consists only
of indigestible subs, waste material, & excess
water
• material leaves thru
Ileocecal Valve into
Lg Intestine
Large Intestine, aka Colon, aka Large Bowel
• nutrients & water not abs’d in sm intest are
abs’d here
• large intest contains Bacteria that:
 work on Undigested substances
 make Vit K (nec for blood clotting)
 as well as some B-complex vits
Large Intestine, aka Colon, aka Large Bowel
Appendix:
• Loc’d just below Ileocecal Valve in RLQ abd.
• no known fx
Large Intestine, aka Colon, aka Large Bowel
• Rectum:
last part of Lg Intest
serves as storage & elimination structure
for indigestible substances
GI Accessory Organs
• Liver
• Gallbladder
• Pancreas
Liver
• Loc’d mainly in RUQ, but extends into LUQ
• Loc’d under Diaphragm
Liver
• produces thick, green liquid, called Bile
• Bile breaks down lipids (fat) into fatty acids for
absorption
Other Fx’s Liver
• Maint’s Blood Sugar levels
• Filters out & destroys old RBCs & saves iron to
be used again
• Stores Vits
• makes Prothrombin, nec for Blood Clotting
• filters out harmful toxins (poisons) that have
been swallowed, including alcohol & many
drugs
Gall Bladder
• loc’d on inferior surface liver
• stores bile made by liver until it is needed for
digestion of fats
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Pancreas
Loc’d post. to stomach
excretes pancreatic Enzymes into Duodenum
Panc enz’s help digest proteins & fat
also fx’s as Endocrine Gland, to control BS
Digestive System Animation
Peristalsis Animation
(Gastric Antrum)
Major GI Diseases
Appendicitis
• = inflammation of the appendix
• unknown causes.
• only tx is surgical removal (appendectomy)
Gangrenous Appendix
Normal Appendix
Ascites
• not a disease, but a general term used to
describe abnormal accum of fluid in
peritoneal cavity (space between the layers of
the membrane that lines the abdominal and
pelvic cavities).
• Ex’s of causes: Cirrhosis, Cancer, & advanced
CHF can cause this condition.
Cirrhosis
= gp of chronic diseases that involve scarring
of liver tissue, which dec’s ability of
liver to perform its fx’s
Cholelithiasis & Cholecystitis
Cholelithiasis = stones in gallbladder
Cholecystitis = inflammation of gallbladder.
Laproscopic Cholecystectomy
Colon Cancer
• abnormal growth in large intestines that
damages tissue & can cause blockage of
digestive system.
Constipation
• inability to pass feces thru anus
• causes abd distention & discomfort.
• most common causes are:
 lack of dietary fiber
 inadequate fluids
 certain meds
 lack of exercise
Diarrhea
• passage of freq & watery stools
• can be caused by certain diseases, stress,
meds, & diet
Diverticulosis
• = weakening of colon wall leading to
outpouching (diverticula) in wall
• diverticula can trap digestive material &
become infected
• Diverticulitis = inflam of diverticula
Gastroenteritis
• = inflam mucous membranes (inner) lining
stomach & intestines
• Causes include food poisoning, infection, &
toxins
Gastritis = lining of stomach inflamed & can be
caused by spicy foods & certain meds
Heartburn
• occurs when gastric juices back up thru
cardiac sphincter & irritate lower end of
esophagus, which does not have a
protective mucous membrane like stomach
does to protect it against acidic juices
Hemorrhoids
• = painful, dilated veins in lower rectum or
anus
Hepatitis
• = inflammation of liver caused by a virus or
poison
Pancreatitis
• = inflam of pancreas, can be caused by variety
of factors, including Alcohol or duct
blocked by a stone (choledocholitiasis)
Peritonitis
• = condition in which lining (peritoneum) of the
abdominal cavity becomes inflamed
Ulcer
• = open sore in lining of digestive syst.
• Pain occurs when protective lining is damaged
& acidic juices contact delicate tissues
underneath
• Peptic Ulcer: occurs in stomach or duodenum
• Stomach ulcers aka Gastric Ulcers
Ulcerative Colitis
• severe inflammation of colon c formation of
ulcers & abscesses
(abscess = collection of pus in a cavity)
Age Related Changes GI System
Decrease in:
• peristalsis
• control of external sphincter
• taste & appetite
• saliva production
• liver size, weight, & efficiency
• gastric acid secretion
Increase in:
• gum disease
• constipation
• indigestion
Preventive Measures GI Dis
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Eat an adequate amt fiber
Drink plenty of water
Avoid excessive alcohol.
Avoid large amounts of high-fat foods.
Avoid fad diets & other extreme eating habits.
Avoid pushing hard during bowel movements (avoid
constipation).
• Do not rely on regular use of laxatives.
• Make routine dental appointments for examination
& cleaning of teeth.
• Have flexible sigmoidoscopy or colonoscopy
performed at the age & frequency recommended by
your health care provider.
Question
• Which of the following is considered an agerelated change for the digestive system?
A. Increased liver size
B. Decreased peristalsis
C. Increased appetite
B. Decreased peristalsis