Peptic Ulcers - Mount Carmel Academy
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Transcript Peptic Ulcers - Mount Carmel Academy
Chapter 14 – Part 5
The Digestive System
Digestive Activities of the Mouth
1. Mechanical Breakdown
Food is physically broken down by chewing
2. Chemical Digestion – Begins
carbohydrate digestion
Food is mixed with saliva
Breaking of starch into maltose by salivary
amylase
Activities of the Pharynx and
Esophagus
These organs have
no digestive function
Serve as
passageways to the
stomach
Food propulsion
only
Deglutition (Swallowing)
Deglutition – Swallowing
Complicated process that includes
the coordinated efforts of the tongue,
soft palate, pharynx, and esophagus
It has two phases:
1. Buccal Phase
2. Pharyngeal-Esophageal Phase
Deglutition (Swallowing)
Buccal Phase
Voluntary
Occurs in the mouth
Food is formed into a bolus (food mass)
The bolus is forced into the pharynx by the
tongue
Deglutition (Swallowing)
Pharyngeal-esophageal phase
Involuntary transport of the bolus through
the pharynx and esophagus
All passageways except to the stomach are
blocked
Tongue blocks off the mouth
Soft palate (uvula) blocks the
nasopharynx
Epiglottis blocks the larynx
Deglutition (Swallowing)
Pharyngeal-esophogeal phase (cont.)
Peristalsis moves the bolus toward the
stomach
When food reaches the end of the
esophagus, it presses against the
cardioesophageal sphincter, causing it to
open, and the food enters the stomach
Deglutition (Swallowing)
Food Breakdown in the Stomach
Secretion of gastric juice
Regulated by neural and hormonal
factors
Under normal conditions, 2-3 liters are
produced each day
Sight, smell, and taste of food increase
the secretion of gastric juice
Presence of food or falling pH causes
the release of the hormone gastrin
Food Breakdown in the Stomach
Gastrin causes the stomach glands to
produce:
1. Protein-digesting enzymes
(pepsinogens)
2. Mucus
3. Hydrochloric acid
Acid Environment in the Stomach
Hydrocholoric acid makes the stomach
contents very acidic
The extremely acidic environment is
necessary because it:
1. Activates pepsinogen to pepsin for
protein digestion
2. Provides a hostile environment for
microorganisms
Heartburn
Heartburn – Pain caused
when gastric juice backs up
into the esophagus when the
cardioesophageal sphincter fails to close
tightly
The esophagus has little mucus protection
(unlike the stomach)
If uncorrected, it can cause inflammation of
the esophagus (esophagitis) and even an
ulceration to the esophagus
What are Peptic Ulcers?
Peptic Ulcers – Craterlike
erosion in the mucosa of any
part of the GI tract that is
exposed to the secretions of the stomach
Affects 1 out of every 8 Americans
Most occur in the pyloric part of the stomach
(gastric ulcers) or the first part of the
duodenum (duodenal ulcers)
Develop most frequently between the ages of
50-70 years
Peptic Ulcers: Symptoms
After developing, they tend to recur healing, then flaring up periodically - for
the rest of one’s life if not treated
Produce a gnawing or burning pain in
the abdomen that appears 1-3 hours
after a meal and is relieved by eating
Other symptoms: loss of appetite,
burping, nausea, and vomiting
Peptic Ulcers: Cause
Cause remains incompletely understood
A stressful lifestyle does seem to aggravate
existing ulcers
Recent studies indicate that many ulcers
are actually caused by a strain of acidresistant bacteria (Helicobacter pylori)
Peptic Ulcers: Treatment
1. First step is to avoid smoking,
alcohol, ibuprofen, and aspirin (all
aggravate ulcers)
2. Antacid drugs to neutralize the stomach
acids
3. Triple drug therapy to promote healing
and prevent reccurence
Digestion and Absorption in the
Stomach
Other than the beginning of protein
digestion, little chemical digestion occurs
in the stomach
Protein digestion enzymes
1. Pepsin – an active protein digesting
enzyme
2. Rennin – works on digesting milk protein
Virtually no absorption occurs in the
stomach (Exception: alcohol and aspirin)
Food Propulsion in the Stomach
Food must first be well mixed
Rippling peristalsis occurs in the lower
stomach
Propulsion in the Stomach
The pylorus meters out chyme into the
small intestine (30 ml at a time)
The stomach empties in four to six
hours
Vomiting
Vomiting – Essentially a reverse
peristalsis occurring in the stomach
Accompanied by contraction of the
abdominal muscles and the diaphragm,
which increases the pressure on the
abdominal organs
Caused by:
1. Local irritation of the stomach such as
food poisoning
2. Disturbances of the equilibrium
apparatus of the inner ear
Digestion in the Small Intestine
Food entering the small
intestine is only partially
digested
Carbohydrate and
protein digestion have
been started
Virtually no fats have been digested up to
this point
By the time food reaches the end of the
small intestine, chemical digestion is
complete and nearly all food absorption has
occurred
Enzymes of the Small Intestine
1. Brush border enzymes
Break double sugars into
simple sugars
Complete some protein
digestion
2. Enzyme-rich pancreatic
juice (play the major
digestive function)
Small Intestine: Pancreatic Enzymes
Pancreatic enzymes play the major
digestive function:
1. Help complete the digestion of starch
2. Carry out about half of all protein
digestion
3. Totally responsible for fat digestion
4. Digest nucleic acids
5. Alkaline content neutralizes acidic
chyme coming in from the stomach
Absorption in the Small Intestine
Water is absorbed along the length of the
small intestine
Absorption of the end products of
digestion along the length of the small
intestine
Most substances are absorbed by active
transport through cell membranes
Lipids are absorbed by diffusion
Substances are then transported in the
blood to the liver by the hepatic portal vein
Absorption in the Small Intestine
At the end of the small intestine (ileum),
all that remains is:
Some water
Indigestible food materials
Large amounts of bacteria
Propulsion in the Small Intestine
Peristalsis is the major
means of moving food
Segmental movements
Mix chyme with
digestive juices
Aid in propelling food
Food Breakdown and Absorption in
the Large Intestine
No digestive enzymes are produced
Resident bacteria digest remaining nutrients
Make some vitamins (Vitamin K and B)
Release gases (methane and hydrogen
sulfide) that contribute to the odor of feces
The only absorption: Remaining water,
vitamin K, and vitamin B
Remaining materials are eliminated via
feces
Food Breakdown and Absorption in
the Large Intestine
Feces – The more or less solid product
delivered to the rectum
Contains:
Undigested food
residues
Mucus
Millions of bacteria
Just enough water to allow their smooth
passage
Food Breakdown and Absorption in
the Large Intestine
About 500 ml of gas (flatus) is produced
each day
Much more gas is produced when
certain carbohydrate-rich foods (such
as beans) are eaten
Propulsion in the Large Intestine
Two major types of propulsive
movements occurring in the large
intestine:
1. Sluggish peristalsis
2. Mass movements – Long, slow-moving,
but powerful contractile waves that move
over large areas of the colon
Occurs three to four times per day
Forces the contents towards the rectum
Propulsion in the Large Intestine
When feces are forced into the rectum
by mass movements and its wall is
stretched, a defecation reflex is initiated
Internal anal sphincter is relaxed
Defecation occurs with relaxation of the
voluntary (external) anal sphincter
As feces are forced through the anal canal,
you have time to make a decision as to
whether the external voluntary sphincter
should remain open or be constricted to stop
the passage of feces
Diarrhea
Diarrhea – Watery stools
Results from any condition
that rushes food residue
through the large intestine
before that organ has had time to absorb
the water
Some Causes: Irritation of the colon by
bacteria
Prolonged diarrhea may result in
dehydration (lose fluids and ions)
Constipation
Constipation - Hard stool
Too much water is absorbed
(food remains in the large
intestine for too long)
Stool becomes difficult to pass
May result from:
Lack of fiber in the diet
Poor bowel habits (“failing to heed the
call”)
Laxative abuse