Figure 1.
1. Identify the following abdominal wall landmarks on a given diagram:
a) umbilicus
b) anterior superior iliac spine
c) pubic tubercle
d) costal margin
e) xiphoid process
f) position of inguinal ligament and superficial inguinal ring
g) lateral margin of sacrospinalis muscle
h) twelfth rib
2. Describe how McBurney's point is found.
3. Diagram the boundaries of the four quadrants used in examining the anterior abdominal wall, the epigastrium, and the linea alba.
4. List the four major muscles of the abdominal wall and describe their innervation and functions.
5. On a given diagram of the anterior body wall list and/or diagram in their proper quadrants the position of the following organs:
a) liver
b) gallbladder
c) duodenum
d) pancreas
e) right and left kidney
f) right (hepatic) flexure of colon
g) left (splenic) flexure of colon
h) cecum
i) vermiform appendix
j) stomach
k) spleen
l) sigmoid colon
6. List the organs normally palpable through the abdominal wall.
7. Describe and differentiate between an indirect and a direct inguinal hernia.
8. Describe an umbilical hernia and state its usual cause.
9. Describe the esophagus in terms of:
a) position
b) innervation (peristalsis)
c) venous drainage
10. Describe the major features of the stomach:
a) gross anatomical
b) physiological basis of secretions
c) innervation
11. Describe the physiology of the gastric phase of digestion.
12. Describe the physiological basis for the responses of the stomach to:
a) infection
b) ulcer
c) carcinoma
13. Describe the anatomy and physiology of diaphragmatic hernia.
MINICOURSE 1.1
SECTION 1
a) umbilicus
b) anterior superior iliac spin
c) pubic tubercle
d) costal margin
e) xiphoid process
f) position of inguinal ligament and superficial inguinal ring
g) lateral margin of sacrospinalis:
h) twelfth rib
The bony and muscular (and connective tissue) components of the wall present a formidable barrier to your examination of your patient. They will also, if properly used, tell you a great deal about your patient. However, you should not be chagrined at this barrier but should realize that it does perform important functions for the well-being of the body and that it can, in some circumstances, take over impaired functions of other parts of the body. Finally, it has ailments of its own with which you will become familiar.
An indentation in the anterior abdominal wall located approximately at the level of the fourth lumbar vertebrae is the umbilicus (Figure 1). Notice on the flank of the abdomen at the area we call the hips is a slight protrusion (useful for hanging your jeans on) called the anterior superior iliac spine (ASIS). On the inferior aspect of the sternum one should note a small bony projection called the "xiphoid"process. From the xiphoid and proceeding downward and laterally one will note the left and right costal margin. These structures can easily be felt by palpation. The Pubic tubercle is the bony prominence just superior to the genitalia. After locating this tubercle, draw an imaginary line to the ASIS. This line will approximate the location of the inguinal ligament. At the site of attachment of the inguinal ligament to the pubic tubercle one should note the position of the superficial inguinal ring. This area is important because it is frequently the site of inguinal hernias.
The linea alba is a connective tissue raphe in the midline of the anterior abdominal wall. It is the ultimate insertion of the three "flat" muscles. It is avascular and poorly or non-innervated. Therefore it provides the surgeon with a good site to make a large incision in order to enter the abdominal cavity.
Figure 1.
The umbilicus lies in the midline approximately in the middle of the anterior abdominal wall. It generally lies at the level of the body of the fourth lumbar vertebra. It is, however, most unreliable as a landmark since the wall tends to sag in many people.
The main inferior aspects of the anterior wall are the aponeuroses of the external and internal oblique muscles which form a very important structure, the inguinal canal. The aponeurosis of the external oblique forms the anterior wall and floor of the canal, and the internal oblique aponeurosis forms the posterior wall. This canal transmits the spermatic cord. It has two openings, one the superficial ring, to the scrotum, and the second, the deep ring, to the abdominal cavity. The inguinal region is frequently the site of hernias. McBurney's point is frequently selected by the surgeon for an incision in acute appendicitis. Locate the right anterior superior iliac spine and draw a line from it to the umbilicus. Divide this line into thirds. At the junction of the outer and middle thirds is McBurney's point.
As you study the abdominal viscera you should make frequent reference to the intact anterior abdominal wall to make sure you can identify the location of these underlying organs in your patients.
In order to conveniently describe the area of the abdomen where a clinical
finding is made, it is practical to divide the anterior abdominal wall into
four sections called quadrants. This division is easy; draw a vertical and
horizontal line through the umbilicus. The vertical line approximates the
position of the linea alba which is a fibrous band formed by the aponeuroses
of muscles in the abdominal wall. The linea alba extends from the xiphoid to
the pubic symphysis. The epigastric region is bounded superiolaterally by the
costal margin and inferiorly by the horizontal line through the umbilicus.
Another way of describing the epigastric area is to say it is found in both
the Left Upper Quadrant (LUQ) and the Right Upper Quadrant (RUQ).
SECTION 3
Click here for Answers
SECTION 4
Click on the skull for a Radiology study of the
abdomen
By using the following two figures note the size, shape and position of the above-named organs present within the abdomen. It is important at this point that we understand the location of these various structures in relation to one another and their position within the subdivisions (quadrants) of the abdomen.
OBJECTIVE 5 - Answers
LUQ RUQ
Spleen Liver
Tail of pancreas Gallbladder
4th part of duodenum Hepatic flexure
Jejunum Head of pancreas
Splenic flexure Part 1, 2, 3 of duodenum
Left kidney Right kidney
RLQ LLQ
Ileocecal valve Beginning of Sigmoid colon
Ileum Descending colon
Appendix Rectum
Part of Sigmoid colon
Rectum
For effective palpation of the abdominal contents, the patient should assume a relaxed supine position with his head on a pillow, the knees slightly flexed (not necessary, but preferred) and the arms at his sides. If the knees are flexed too much, this will interfere with effective palpation of the lower abdomen.
As you can imagine, this will take a lot of practice. It's worth it, however. Palpation with careful inspection of the patient may elucidate various clinical signs which would be missed in a hastily performed abdominal examination.
Have the patient take deep breaths during palpation. This may enable you to detect enlargements of spleen or more commonly the liver. Another way to more completely examine the patient is to have him cough. The coughing will cause localized pain in either an acute appendicitis or herniation at various sites in the abdominal wall. With hernias, coughing will demonstrate a bulge in the abdominal wall.
The structures in the abdomen which can be palpated are:
A) liver
B) spleen (only if enlarged)
C) kidneys (in thin individual - right more so than left)
D) aorta (thin individual)
E) colon (thin individual)
F) prostate - male
G) uterus - female (is this obvious?)
H) fallopian tubes
I) ovaries
J) pelvic bony structure
K) bladder
EXERCISE 5
4. On the following diagram, locate the following organs
A hernia is an abnormal protrusion of a viscera through a defect in the
anterior (ventral) abdominal wall (Figure 1). Inguinal and umbilical hernias
are the two types you will encounter most often. They occur mainly because
structural defects develop on the abdominal wall sometime during its early
development so that almost all hernias have some congenital basis for their
occurrence. Most commonly, the protruding viscus is a loop of bowel with its
attendant blood supply and luminal contents. A strangulated hernia is one
whose blood supply has been compromised, resulting in necrosis of the bowel
wall. An incarcerated hernia is one that has become so occluded as to be
irreducible. All hernias are surrounded by a hernial sac derived from the
components of that particular part of the abdominal wall where it protrudes.
An inguinal hernia is a protrusion of a loop of bowel through all or part
of the inguinal canal. It may, in severe cases, enter the scrotum or
labium
majus pudendi. It is more common in the male. Depending on its mode of
into the canal, it may be an indirect (oblique) or a direct hernia.
An indirect inguinal hernia enters the inguinal canal through the deep inguinal
ring and proceeds down the canal (Figure 2).
From the anatomy of this region you can see that an indirect hernia
passes lateral to the inferior epigastric artery. Because of this, the
surgeon must know the origin of the hernia before operating. Many times an
old indirect hernia will have straightened out the inguinal canal so that it
may appear to be a direct hernia, which passes medial to the inferior
epigastric artery. The surgeon's incisions are made accordingly. The sac of
an indirect hernia will consist of the coverings of the spermatic cord that
are derived from the abdominal wall as the testes descended into the scrotum.
Since the defect is due to a patent processus vaginalis, this structure will
also form part of the hernia sac.
A direct inguinal hernia lies medial to the inferior epigastric artery
and is due to a defect in the posterior wall of the inguinal canal (Figure 3).
In this case, the aponeurosis of the muscles forming the posterior wall splits
open and allows the bowel to protrude directly into the superficial ring.
This condition, by the way, is rather rare in women. It is usually found in
individuals with weak abdominal muscles, such as in old men, and usually is
seen to occur bilaterally.
An inguinal hernia differs from a femoral hernia in that in the former,
the "bulge" exits through the superficial inguinal ring (Figure 4) it is
superior and medial to the pubic tubercle. The femoral hernia on the other
hand is located below and lateral to the tubercle.
Umbilical hernia is usually a congenital condition due to failure of the
developing gut to properly retract back into the abdominal cavity (Figure 5).
During development, a major portion of the gut tube normally develops outside
the abdominal cavity in the umbilical sac, a part of the umbilical cord.
Normally, as the various levels of the gut tube become identifiable as
jejunum, ileum and colon, the gut completes its rotation and returns to the
abdominal cavity. When it fails to do this, a congenital umbilical hernia
results. It can also be seen in patients with chronic abdominal distention
due to retained fluid (i.e., ascites).
Hernias will be described more completely in one of the clinical
minicourses coming up.
EXERCISE 3
OBJECTIVE 4 - Questions
EXERCISE 6 DISCUSSION
Click here to see answers.
The esophagus is a muscular tube, approximately
10" long, which opens
into an enlarged cavity called the stomach. Not being the most
dynamic
structure in the body, it does carry on an important function, i.e.
transmitting substances (hamburgers, fries and beer) from the
mouth to the
stomach. It begins at the termination of the laryngopharynx which
also
approximates the level of the cricoid cartilage. It passes through the
mediastinum just in front of the vertebral column and just behind
the trachea.
It then penetrates the substance of the diaphragm and terminates in
the upper
portion of the stomach called the cardia.
It is interesting to note that the esophagus has two
types of muscles
within its muscularis layer. In the upper one-third is voluntary
skeletal
(striated) muscle whereas the lower esophagus contains smooth muscle. The
position of these two types is noteworthy because the voluntary
muscle is
under "willful" control, can either "prevent" substances from passing
into the
esophagus or "allow" the substance to enter. In small children,
however, this
"willful" control is not exactly refined and thus they will swallow
marbles,
pennies, springs, etc., etc.
Once the bolus of food has passed the upper one-third,
it enters the area
of the esophagus which is governed by involuntary smooth muscle.
We find that
this smooth muscle will "milk" the bolus down to the stomach. This
milking
action is called peristalsis.
To control the involuntary milking action of the
smooth muscles requires
a complex nerve supply. The upper one-third is supplied by voluntary
nerve
fibers, whereas the lower two-thirds is supplied by sympathetic and
parasympathetic fibers via the vagus and sympathetic nerve trunks,
which join
to form the esophageal plexus (the neural network encircling the
esophagus.
The esophagus is supplied with blood via branches
from the thyroid
artery, thoracic aorta and the left gastric artery. The venous
drainage from
this structure is unique in that it forms one side of what is called
the
"portal-systemic anastomoses." The anastomoses are formed by the
esophageal
veins emptying into systemic veins on the wall of the thorax, as
well as from
the lower esophagus into the left gastric vein, which is a tributarv
of the
hepatic portal system.
In summary, the esophageal functions are as follows:
Digestion and absorption are not functions of the
esophagus.
EXERCISE 7
OBJECTIVE 9 - Questions
As noted in Objective 9, the esophagus empties into the stomach. The
fundus (F) or top of the stomach is located somewhat to the
left of the body's
midline. The body(B) or main portion of the stomach curves
toward the right
and terminates in a smaller, narrowed area called the pyloric (P)
portion. As
seen from the front, the stomach has a left greater curvature(G.C.)
and a
right lesser curvature (L.C.). From the pyloric portion (P),
a small orifice
guarded by a muscular valve, the pyloric sphincter (P.S.) opens into the small
intestine.
The stomach is lined with an extensive mucosal layer, which, when the
stomach is empty, appears as large folds called rugae. As filling of
the
organ occurs, these rugae smooth out so as to help with the distension
process. It has been shown that this mucous layer contains three specialized
cell types called: l) the zymogenic or chief cells which
secrete digestive
enzymes; 2) parietal cells which secrete hydrochloric acid (HCl);
and 3) the
mucous cells which are responsible for the secretion of mucus.
Collectively,
these various secretions are called the gastric juice (a Pavlovian bell
ringer).
When food reaches the stomach, it is stored there for a brief period of
time. The glands in the stomach secrete a protein-splitting enzyme called
pepsin. This enzyme, it should be noted, is first secreted as an inactive
substance called pepsinogen. The parietal cells secrete HCl, which converts
pepsinogen into pepsin. This reaction, which occurs within the lumen of the
stomach, is critical in that if an "active" protease were secreted, the glands
which secrete it, since they are themselves composed of proteins, would be
attacked by the protease. Thus, it can be said that the two principal
secretions of the stomach mucosa are HCl and pepsin. Hydrochloric acid
functions not only in the activation of enzymes, but also in denaturing
proteins and in the killing of bacteria. The killing of bacteria occurs
secondary to the concentration of hydrochloric acid.
The active enzyme called pepsin
causes protein molecules to be split into
shorter protein links called peptones and proteoses. This is essentially the
first step in the process which will ultimately yield amino acids to be
absorbed by the intestine. It should be noted that pepsin is only active in a
low pH less than 3.0 (high hydrogen ion concentration).
The smooth musculature (which is innervated by the autonomic nervous
system) of the stomach is responsible for the peristaltic mixing action of the
stomach. This action, which mixes the food with the gastric secretions,
converts the food into a thin liquid substance called chyme. This substance
is emptied a little at a time through the pyloric valve (sphincter) into the
first part of the small intestine which is called the duodenum.
The important factor controlling the emptying of the stomach is the
chemical composition and the volume of chyme in the duodenum. When the
duodenum contains an acid, hypertonic solution, fats or when it is distended,
a reflex inhibition of gastric motility occurs. The er.terogastric reflex is
initiated by various receptors within the duodenum such as chemoreceptors,
osmoreceptors and pressure receptors. At the time of such emptying of chyme
from the stomach, a hormonal action takes place. The hormones are known as
enterogastrones (secretin and pancreozymin). The presence of fats
in the
duodenum causes certain cells of this structure to begin to produce a hormone
called cholecystokinin which will inhibit gastric activity.
As proteins and starches are digested--the former in the stomach; the
latter from salivary action--the osmolarity of the chyme increases. If this
increase in osmolarity is faster than the rate of absorption, large quantities
of water will enter the intestine via osmosis. Therefore, as the tonicity
increases (hypertonic solutions) in the intestine, the osmoreceptors cause a
slowdown of gastric motility.
Another hormone in the stomach, gastrin, influences stomach action. The
products of protein digestion, as well as distention of the stomach, cause the
mucosa in the pyloric region to release gastrin. This substance is carried
back to the stomach via the circulatory system and causes the secretion of
digestive enzymes and HCl.
With all the digestion that the stomach is doing, it is a shame that it
does not receive more recognition for placing substances in the bloodstream.
Usually, the intestines receive the credit for this, since they have
specialized absorption capabilities such as active transport, which are
lacking in the stomach. But the stomach's action makes it possible for the
intestines to functior_ well.
In summary of the stomach structure and function:
Furthermore, as far as the stomach's functions are concerned:
EXERCISE 8
OBJECTIVES 10, 11 - Ouestions
1. Name labeled parts of the following diagram of the stomach.
2. Describe the chemical control of gastric emptying.
3. What are the two principal secretions of the stomach mucosa and what are
their principal functions?
4. What ionic environment is necessary for pepsin to act?
5. What is gastrin and what part does it play in gastric activity?
Any disturbance in the normal physiology of the stomach will cause it to
respond in one or more of the following ways:
If an infection is present, the G.I. tract will respond by nausea, vomiting,
abdominal pain and diarrhea. Gastric infection is usually denoted by nausea,
vomiting, epigastric discomfort and pain, whereas abdominal pain and
diarrhea are related to the intestinal phase of the infection (either
bacterial, viral, or enterotoxic).
Depending upon the surrounding circumstances, the mucosa and musculature may
respond in any one or more of the ways listed above. The nausea, vomiting,
diarrhea (N,V,D) and cramping abdominal pain caused by enterotoxins are
indicative of a response of hyperactivity by all parts of the gastrointestinal
tract. The N & V part of the response is an attempt by the stomach to expel
the irritating agent. Because of this agent as well as the hyperactivity of
the gut, large amounts of water and electrolytes empty into various lumens
from which they are lost via vomiting and diarrhea. This loss, from the tissue
to the lumen of the G.I. tract may result in: l) tissue dehydration, and 2)
electrolyte imbalance.
The response of the stomach to viral infection is somewhat different Because a
virus will invade cells directly, both mucosal and muscular cells may become
hypoactive. This can cause a period of inactivity which is sensed by the
patient as an ill-defined fullness. This period may be followed by:
l) emptying into duodenum
GRAPHICS HERE!!!
The stomach response to a lesion caused by an ulcer or carcinoma is usually
bleeding and pain. As the lesion increases and invades the mucosa,
underlying vascular beds and nerve endings become exposed to the acid-pepsin
containing gastric juice. This acidic condition is irritatin8 to the sensory
nerves and is interpreted as pain or causes a reflex leading to hypermotility.
As the vascular beds are eroded the gastric juice corrodes the blood vessel
wall. This leads to bleeding into the crater of the ulcer. This bleed will
usually result in:
EXERCISE 9 OBJECTIVE 12 - Questions
EXERCISE 9 DISCUSSION
Click here for answers
Basically, diaphragmatic hernias can either be congenital or "acquired."
The
congenital variety results from a failure of structures to fuse properly.
The "acquired" variety may result from weak musculature or from trauma which
may permit abdominal contents to enter the thoracic area.
The most common congenital diaphragmatic hernia is the hiatal hernia through
the esophageal hiatus. The manifestations of the hiatal hernia are due
mostly to the reflux esophagitis it causes.
You will want to concentrate your study on the two acquired types of
diaphragmatic hernia l) the sliding, and 2) the rolling or paraesophageal
types. The sliding type which occurs most often (75%) is one in which the
esophageal-gastric junction lies inside the thorax (Figure 1).
The rolling or paraesophageal type which occurs 25% of the time shows the
apex of the herniated mass to be some portion of the greater curvature of
the stomach, not the lesser, as seen in Figure 2.
With the presence of the hernia, mucosal inflammation may be found in the
terminal 1 to 5 cm of the esophagus due to the reflux of gastric contents (HCl
and pepsin) into this segment of the esophagus. The early pathological lesions
are edema and vascular engorgement. These may advance to mucosal erosions,
hemorrhage, cellular infiltration and fibrosis.
Now click on the skull to see a barium study of a hiatal hernia in
a five year old boy who also has Barret esophagus (you will learn more
about that in the second half of this course). In the left half of
the figure, the esophagus, hernia, and stomach are clearly seen.
In the right half, the reflux from the stomach into the
esophagus is observed. Ignore the weird texture in the figure. That is
an artifact of the fact that this image was scanned from a printed paper.
Future releases of this course will use the original films.
The pathophysiology of the hernia is as follows:
EXERCISE 10 OBJECTIVE 13 - Questions
EXERCISE 10 DISCUSSION
Click here for answers
You will recall that an ulcer is a crater-like lesion. When this lesion is
exposed to the products of gastric secretion, it is called a peptic ulcer.
These peptic ulcers will develop in the following areas:
It should be noted that no tissue in the body is immune from the effects of
gastric secretion. Ordinarily, the food, chyme, and alkaline secretion of
the duodenum are able to sufficiently neutralize and thus protect the
mucosa. In Section 8 you studied about the interrelationships between HCl
and pepsin and how pepsin is activated by HCl. Recall that it is pepsin that
has the ability to break the peptide bonds of the protein.
Therefore, in the genesis of an ulcer, HCl is important as an activator of
pepsin and the more HCl there is, the more pepsinogen will be converted to
pepsin. This excess pepsin attacks the protein polysaccharide secretions
that are supposed to protect the mucosa, leaving it exposed to direct attack
by the pepsin. Since major components of the cell membrane and intracellular
components are proteins, they are particularly liable to "digestion" by the
gastric secretions.
EXERCISE 11 OBJECTIVES 14, 15 - Questions
2. An inguinal hernia is a protrusion of a loops of bowel through some part of the tinguinal canal and rings.
It is dues to a weakness in the inguinal
region structures of the anterior abdominal wall, and is thought by most to
be a congenital weakness, even though it may not occur until adulthood. The
loop of bowel may slide in and out of the canal or it may be permanently
located there. An indirect indirect inguinal hernia passes first through
the deep inguinal ring to enter the canal. It passes through the canal and
appears at the superficial ring. The canal is only about 1 1/2 inches long.
A direct inguinal hernia occurs when the wall directly behind the superficial
ring is defective and a loop of bowel presents directly in the superficial
ring. A direct inguinal hernia lies to the medial side of the inferior
epigastric artery and an idirect lies to the lateral side of this artery.
3. An umbilical hernia is a loop of bowel that has not been restracted into
the abdomen during the later starges of in utero growth. It will appear
as a large bulge in the umbilical cord of the newborn. It is a congenital
defect.
2. The important factors controlling gastric emptying are the chemica]
composition and amount of chyme in the duodenum. ˙~˙en the duodenum
contains fat, acid or hypertonic solution, or when it is distended,
gastric motility is reflexively inhibited. The reflexes are initiated bv
duodenal chemoreceptors, osmoreceptors and pressure receptors. Reflexes
mediated entirely by nerve fibers are known collectively as the
enterogastric reflex. The hormones are known as enterogastrones
(secretin and pancreozymin). Fat is the most potent stimulus for
inhibition of gastric motility. Unneutralized acid in the duodenum
inhibits the emptying of more acid from the stomach.
As protein and starches are digested, the osmolarity of the chyme rises.
If absorption does not keep pace, large quantities of water enter the
intestine by osmosis. Hypertonic solutions in the intestine reflexively
cause a slowdown of gastric motility to prevent a further accumulation of
the hypertonic solution.
3. Hydrochloric acid and pepsinogen are the principal secretions of the
stomach mucosa.
Functions of HCl:
Function of pepsin:
1. splits protein into amino acids
4. Pepsin is active only in a high hydrogen ion concentration
(low pH).
5. Gastrin is a hormone whose release bv the pyloric mucosa is effected by
protein, alcohol, caffeine and distention of the antrum of the stomach.
It causes the release of additional HCl and digestive enzymes.
1. Sliding - Occurs about 75 of the time. It occurs when the esophageal-
gastric junction lies inside the thorax.
Paraesophageal - also known as the "rolling" type hernia. A portion of the
greater curvature of the stomach extends through the diaphragm or the
herniated portion lies just below the esophageal-gastric junction.
2. Gastroesophageal reflux is the regurgitation of gastric contents in the
esophagus because of the changes in the pressures above and below the
esophageal gastric sphincter due to the hiatal hernia.
OBJECTIVE 6 Questions
1. List the palpable structures in a thin male.
2. List the palpable structures in a thin female.
3. On the following diagram, locate the following structures
a. four parts of the duodenum
b. pancreas (head, body, tail)
c. spleen
d. splenic flexure of colon
e. descending colon
f. sigmoid colon
g. rectum
a. Liver
b. gallbladder
c. stomach
d. ileum
e. appendix
f. ascending colon
g. helpatic flexure
h. transverse colon
i. splenic flexure
OBJ. 7. Describe and differentiate between an indirect and
a direct inguinal hernia.
OBJ. 8. Describe an umbilical hernia and state its usual
cause.
Hernias
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
1. Define the term hernia.
3. What is an umbilical Hernia?
MINICOURSE 1.1
SECTION 7
OBJ. 9. Describe the esophagus in terms of:
1. position
2. innervation (peristalsis)
3. venous drainage
Esophagus
(l) rapid peristalsis
(2) transports nutrients from oral cavity to stomach
1. Where does the esophagus begin, anatomically?
2. What types of muscles are found in the esophagus?
3. Briefly describe the nerve supply to the esophagus.
4. Name a significant feature of the venous drainage of the
esophagus.
OBJ. 10. Describe the major features of the stomach
relative to:
a) Gross anatomy
b) Physiological basis of secretion
c) Innervation
OBJ. 11. Describe the physiology of the gastric phase
of digestion.
Stomach
l) Rugae - large surface; allows for distention of stomach.
2) Chief cells - secrete pepsinogen; as pepsin, digests proteins.
3) Parietal cells - secrete HCl; converts pepsinogen to pepsin. Also
secrete intrinsic Factor which aids vitamin B12 absorption.
4) Mucous cells - secrete mucus; prevents digestion of stomach wall.
5) Smooth musculature - causes peristaltic mixing of food with gastric
juice; forms chyme; innervated by autonomic nervous system.
6) Pyloric sphincter - allows for slow passage of fat-laden chyme.
7) Cholecystokinin - stimulated by presence of fat; inhibits gastric
digestion.
8) Secretion - stimulated by acid in duodenum; inhibits gastric acid
production.
l) little or no absorption into the bloodstream (with the exception of
glucose and some drugs)
2) digestion begins - especially of proteins
3) food is moistened, softened, partially dissolved
4) food is ground by peristalsis
5) food is transformed into semi-liquid mass called chyme
OBJ. 12. Describe the physiological basis for the response of the stomach to:
a) infections
b) ulcer
c) carcinoma
Pathophysiology of the Stomach
l) a period of hypomotility
2) a period of hypermotility
3) undergo strong spasmodic contractions which result in vomiting
4) hypersecretion of gastric juice
5) hyposecretion of gastric juice
2) spasmodic contractions of stomach and diaphragm via the follow reflex arc:
l) irritation of gastric vagal sensory fibers
2) brainstem vomiting center
vagal fibers to stomach phrenic nerve to diaphragm
results in emptying of stomach by vomiting
l) violent stomach reaction, usually vomiting
2) if no vomiting occurs, the blood passes into the small intestine leading to
a bloody stool.
1. Describe the stomach's response to a bacterial infection.
2. Describe the stomach's response to a viral infection.
3. Describe the stomach's response to an ulcer.
SECTION 10
OBJ. 13. Describe the anatomy and physiology of diaphragmatic hernias.
Diaphragmatic Hernias
Figure 1.
Figure 2.
1. List and describe the two types of acquired diaphragmatic hernias.
2. What is meant by gastroesophageal reflux?
MINICOURSE 1.1
SECTION 11
OBJ. 14. Locate on a diagram the most common positions of peptic ulcers.
OBJ. 15. Describe the pathophysiology of peptic ulcers.
Peptic Ulcers
l) lower esophagus
2) in stomach - called gastric ulcers
3) in the first part of the duodenum - called duodenal ulcers
Figure 1.
1. Which three of the following areas are the most common locations of
peptic ulcer?
2. List in sequence the three major pathophysiological stages in peptic
ulcer development.
Click here for answers
End of text material.
Answers to section 1.1.3
External oblique branches of 8th-12th intercostal nerves
Internal oblique iliohypogastric nerves Transverse abdominis
ilioinguinal nerves
Rectus abdominis - branches of 7th-12th intercostal nerves
OBJECTIVE 8 - Answers to Section 1.1.6
1. A hernia is an abnormal protrusion of the gut through the abdominal
wall.
OBJECTIVE 9 Answers to section 1.1.7
1. It begins at the level of the cricoid cartilage which is the
termination of the pharynx.
2. The upper one-third of the esophagus is voluntary skeletal muscle
and the lower two-thirds are involuntary smooth muscle.
3. The upper one-third of the e.cophagus is supplied by voluntary
nerve fibers. The lower two-thirds is supplied by the sympathetic
and parasympathetic fihers from the vagus and sympathetic nerve
trunk.
4. The venous svstem of the esophagus drains into the svstemic
veins on the
wall of the thorax and also, most importantly, inferiorly into the
hepatic portal system. This is one site of what is called the
"portal-systemic anastomoses."
OBJECTIVES 10, 11 - Answers to Section 1.1.8
1. fundus
2. lesser curvature
3. body
4. greater curvature
5. pyloric portion
1. denatures protein
2. activates enzymes
3. kills bacteria
OBJECTIVE 12 - Answers to Section 1.1.9
1. Nausea, vomiting and diarrhea usually occur as part of the stomach's
attempt to expel the irritants. As a result of the hyperactivity of the gut,
there will also be a change in tissue water content and in the electrolytic
balances as water empties into the gut and irritants are expelled.
2. The response to a virus is different from the response to a bacteria
because the viral cells may cause the mucosal and muscular cell to become
hypoactive. The hypoactivity may cause: l) emptying into the duodenum; or 2) a
reflex arc which will result in vomiting.
3. Because the mucosal layer has broken down, the gastric vascular beds are
exposed to the acidic gastric juices. These juices break down the vessel
well causing bleeding. This will cause vomiting or a bloody stool.
OBJECTIVE 13 - Answers to Section 1.1.10
OBJECTIVES 14, 15 - Answers to section 1.1.11
1 1,5,6
2. a. HCL activates excess pepsin.
b. The excess pepsin attacks the protective secretions of the mucosa.
c. The pepsin can then directly attack the mucosa.
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