CONTENTS
DEVELOPMENT OF THE GI TRACT 1
CONTROL OF FOOD INTAKE 4
INTRO TO FUNCTIONS & CONTROL OF ALIMENTARY TRACT 9
TRANSPORT ALONG & ACROSS THE GI TRACT 12
INTRO TO LIVER FUNCTION 18
THE OESOPHAGUS & DISORDERS OF GLUCOSE 24
REGULATION & DISORDERS OF GASTRIC SECRETION 27
BILE, GALL BLADDER & GALL STONES 30
PANCREATIC EXOCRINE SECRETIONS & ITS CONTROL 33
PHYSIOLOGY: CONSEQUENCES OF FLUID LOSS FROM THE GI TRACT 36
SYMPTOMS OF GI DISEASE: NAUSEA, VOMITING & PAIN 39
GASTROINTESTINAL THE METABOLIC FUNCTION OF THE LIVER 42
SYSTEM IMMUNOLOGICAL FUNCTIONS OF THE ALIMENTARY TRACT 46
PHARMACOLOGICAL BASIS OF TREATMENT OF GI DISORDERS 48
Revision Question Bank Biomedical Science Sem 2
,SGUL HINDU SOCIETY 1
DEVELOPMENT OF THE GI TRACT
1. What is the significance of the gut tube • Organs and glands are produced by budding
formation? from the gut tube
2. Describe primary germ formation? • The primary germ layers are formed during the
process of gastrulation.
• The embryo is a flat disc, comprised of two cell
layers: epiblast and hypoblast. Epiblast cells in
the mid-line of the embryo begin to ingress,
starting from the caudal (tail) end; this is visible
as the primitive streak.
• The ingressing cells differentiate into the
mesoderm (that will become the surrounding
muscles, connective tissue and mesenteries and
blood vessels).
The epiblast gives rise to the ectoderm (neural
crest; it provides innervation to the gut, the
enteric NS).
The hypoblast (and epiblast) gives rise to the
endoderm (with forms the epithelium and the
gut tube and the glands).
• Most genetic abnormalities occur at this time.
3. Briefly describe how the formation of the gut • The gut tube is formed by the folding of sheets
tube occurs of cells in two directions:
- folding towards the midline along the cranial-
caudal axis
- folding towards the yolk sac at the cranial and
caudal ends
4. The gut tube doesn't form as a tube the first • The gut cells will grow to the point where
time round. Describe this phenomenon. there's no lumen, just a solid tube. This is the
point at which the gut needs rearrangement
(scaffolding).
• Recanalization is where some cells die in a
manner that leaves behind a large diameter in
the middle of the tube.
• Sometimes, the middle part of the gut doesn't
recanalize, leading to duodenal atresia (if
duodenal, it's a short-term issue, if jejunal, then
a long-term issue). Soon after birth, babies start
projectile vomiting green vomit (green due to
bile).
5. What are the subdivisions of the gut, and where • FOREGUT: from the pharynx to the Ampulla of
do their boundaries lie? Vater (duodenal papilla)
• MIDGUT: from the duodenal papilla to the
proximal 2/3rds of the transverse colon
• HINDGUT: from the distal 1/3rd of the
transverse colon to the rectum
6. What are the blood supplies to the different • The coeliac artery supplies the foregut.
parts of the gut? • The superior mesenteric artery supplies the
midgut
• The inferior mesenteric artery supplies the
hindgut
,SGUL HINDU SOCIETY 2
7. What is the innervation of the gut? • Sympathetic ganglia develop next to the major
branches of the aorta.
• Post-ganglionic, sympathetic axons unnerved
the same tissues that the arteries supply with
blood.
• - celiac ganglion: foregut
- superior mesenteric ganglion: midgut
- inferior mesenteric ganglion: hindgut
8. Describe the rotation of the stomach? • First, at the level at which the stomach will
form, the tube begins to dilate, forming an
enlarged lumen.
• It makes a 90° turn about the cranio-caudal
(vertical) axis, so the dorsal border grows more
rapidly than the ventral border, which
established the greater curvature of the
stomach
• This means that the anterior part becomes the
right, and the posterior becomes the left
9. What genes determine the position (of the • Homeotic (HOX) genes
structures) along the cranio-caudal axis?
10. What fixes the mature gut in place? • Fusion of the mesenteries with the posterior
abdominal wall fixes the mature gut in place.
11. Describe pyloric stenosis? • It is when there is a gastric outlet obstruction
caused by smooth muscle hypertrophy (ie. the
smooth muscle forming the pyloric sphincter
overgrows).
• It can be spotted in newborns, as they will start
projectile vomiting shortly after feeding (the
vomit will NOT be bile-stained).
12. Describe the formation of the liver, budding • The hepatic diverticulum grows into the
from the gut tube? mesenchyme of the septum transversum. The
cords of the hepatic endoderm, bile drainage
ducts, and blood vessels proliferate, arranged as
sinusoids.
• The liver exceeds the size of the septum
transversum and expands into the ventral
mesentery.
• The remaining ventral mesentery gives rise to:
- the falciform ligament between the liver and
the body wall
- the lesser omentum between the liver and
stomach
13. Describe the formation of the pancreas, • There are two pancreatic buds:
budding from the gut tube? - dorsal, from the duodenal endoderm (induced
by the notochord)
- central, from the hepatic diverticulum
(induced by the hepatic mesoderm)
• As the duodenum rotates, the dorsal and
ventral buds meet and fuse.
14. Describe the development of the intestines? • The mesentery and the gut grow at different
rates, leading to the stereotypical folding of the
gut.
• The abdomen is too small to accommodate this,
so the gut herniates into the umbilical stalk at
6/7 weeks.
• By 10 weeks, the abdomen is bigger, and the
intestines return.
, SGUL HINDU SOCIETY 3
• This part of gut development can lead to
congenital gut disorders.
15. Describe an umbilical hernia? • It is when the intestines return normally, but
the rectus abdominis fails to fuse around the
umbilicus, leading to gut covered in skin.
16. Describe an omphalocele? • It is the failure of the intestinal loops to return
to the abdomen, so it ends up as a hernia
covered in amnion.
• Its causes are unknown, but it is associated with
maternal obesity, alcohol/ tobacco, SSRI use.
17. Describe gastroschisis? • It is a defect in the abdominal (belly) wall, a
failure of the ventral body wall to fuse. This
results in no covering of the gut as it sits outside
the body.
• There is a marked association with young
maternal age, low maternal BMI, and
recreational drugs (especially cocaine).
18. Describe Hirschsprung's disease? • It is where the person has an aganglionic
megacolon.
• It primarily affects the hindgut.
• There is an absence of parasympathetic ganglia,
caused by a lack of neural crest cells.
• There also is a dilatation of sections of the
colon, with a lack of tone and peristalsis,
leading to profound constipation.
• Because of the failure of the development of
enteric ganglia, there is a section of the gut that
is completely absent of ganglia.
19. In anal development, what is the cloaca? • The cloaca is the transient common end of the
digestive and urogenital systems, including the
base of the allantois (urogenital sinus).
• It is covered by the cloacal (proctodeal)
membrane over the ectoderm depression, the
proctodeum.
• It is split by the urorectal septum. This gives rise
to the urogenital membrane and anal
membrane (that perforate at 7-8 weeks)
20. What could cause an imperforate anus? • An imperforate anus can be:
- persistence of the anal membrane
- atresia of the anal canal, rectum or both
DEVELOPMENT OF THE GI TRACT 1
CONTROL OF FOOD INTAKE 4
INTRO TO FUNCTIONS & CONTROL OF ALIMENTARY TRACT 9
TRANSPORT ALONG & ACROSS THE GI TRACT 12
INTRO TO LIVER FUNCTION 18
THE OESOPHAGUS & DISORDERS OF GLUCOSE 24
REGULATION & DISORDERS OF GASTRIC SECRETION 27
BILE, GALL BLADDER & GALL STONES 30
PANCREATIC EXOCRINE SECRETIONS & ITS CONTROL 33
PHYSIOLOGY: CONSEQUENCES OF FLUID LOSS FROM THE GI TRACT 36
SYMPTOMS OF GI DISEASE: NAUSEA, VOMITING & PAIN 39
GASTROINTESTINAL THE METABOLIC FUNCTION OF THE LIVER 42
SYSTEM IMMUNOLOGICAL FUNCTIONS OF THE ALIMENTARY TRACT 46
PHARMACOLOGICAL BASIS OF TREATMENT OF GI DISORDERS 48
Revision Question Bank Biomedical Science Sem 2
,SGUL HINDU SOCIETY 1
DEVELOPMENT OF THE GI TRACT
1. What is the significance of the gut tube • Organs and glands are produced by budding
formation? from the gut tube
2. Describe primary germ formation? • The primary germ layers are formed during the
process of gastrulation.
• The embryo is a flat disc, comprised of two cell
layers: epiblast and hypoblast. Epiblast cells in
the mid-line of the embryo begin to ingress,
starting from the caudal (tail) end; this is visible
as the primitive streak.
• The ingressing cells differentiate into the
mesoderm (that will become the surrounding
muscles, connective tissue and mesenteries and
blood vessels).
The epiblast gives rise to the ectoderm (neural
crest; it provides innervation to the gut, the
enteric NS).
The hypoblast (and epiblast) gives rise to the
endoderm (with forms the epithelium and the
gut tube and the glands).
• Most genetic abnormalities occur at this time.
3. Briefly describe how the formation of the gut • The gut tube is formed by the folding of sheets
tube occurs of cells in two directions:
- folding towards the midline along the cranial-
caudal axis
- folding towards the yolk sac at the cranial and
caudal ends
4. The gut tube doesn't form as a tube the first • The gut cells will grow to the point where
time round. Describe this phenomenon. there's no lumen, just a solid tube. This is the
point at which the gut needs rearrangement
(scaffolding).
• Recanalization is where some cells die in a
manner that leaves behind a large diameter in
the middle of the tube.
• Sometimes, the middle part of the gut doesn't
recanalize, leading to duodenal atresia (if
duodenal, it's a short-term issue, if jejunal, then
a long-term issue). Soon after birth, babies start
projectile vomiting green vomit (green due to
bile).
5. What are the subdivisions of the gut, and where • FOREGUT: from the pharynx to the Ampulla of
do their boundaries lie? Vater (duodenal papilla)
• MIDGUT: from the duodenal papilla to the
proximal 2/3rds of the transverse colon
• HINDGUT: from the distal 1/3rd of the
transverse colon to the rectum
6. What are the blood supplies to the different • The coeliac artery supplies the foregut.
parts of the gut? • The superior mesenteric artery supplies the
midgut
• The inferior mesenteric artery supplies the
hindgut
,SGUL HINDU SOCIETY 2
7. What is the innervation of the gut? • Sympathetic ganglia develop next to the major
branches of the aorta.
• Post-ganglionic, sympathetic axons unnerved
the same tissues that the arteries supply with
blood.
• - celiac ganglion: foregut
- superior mesenteric ganglion: midgut
- inferior mesenteric ganglion: hindgut
8. Describe the rotation of the stomach? • First, at the level at which the stomach will
form, the tube begins to dilate, forming an
enlarged lumen.
• It makes a 90° turn about the cranio-caudal
(vertical) axis, so the dorsal border grows more
rapidly than the ventral border, which
established the greater curvature of the
stomach
• This means that the anterior part becomes the
right, and the posterior becomes the left
9. What genes determine the position (of the • Homeotic (HOX) genes
structures) along the cranio-caudal axis?
10. What fixes the mature gut in place? • Fusion of the mesenteries with the posterior
abdominal wall fixes the mature gut in place.
11. Describe pyloric stenosis? • It is when there is a gastric outlet obstruction
caused by smooth muscle hypertrophy (ie. the
smooth muscle forming the pyloric sphincter
overgrows).
• It can be spotted in newborns, as they will start
projectile vomiting shortly after feeding (the
vomit will NOT be bile-stained).
12. Describe the formation of the liver, budding • The hepatic diverticulum grows into the
from the gut tube? mesenchyme of the septum transversum. The
cords of the hepatic endoderm, bile drainage
ducts, and blood vessels proliferate, arranged as
sinusoids.
• The liver exceeds the size of the septum
transversum and expands into the ventral
mesentery.
• The remaining ventral mesentery gives rise to:
- the falciform ligament between the liver and
the body wall
- the lesser omentum between the liver and
stomach
13. Describe the formation of the pancreas, • There are two pancreatic buds:
budding from the gut tube? - dorsal, from the duodenal endoderm (induced
by the notochord)
- central, from the hepatic diverticulum
(induced by the hepatic mesoderm)
• As the duodenum rotates, the dorsal and
ventral buds meet and fuse.
14. Describe the development of the intestines? • The mesentery and the gut grow at different
rates, leading to the stereotypical folding of the
gut.
• The abdomen is too small to accommodate this,
so the gut herniates into the umbilical stalk at
6/7 weeks.
• By 10 weeks, the abdomen is bigger, and the
intestines return.
, SGUL HINDU SOCIETY 3
• This part of gut development can lead to
congenital gut disorders.
15. Describe an umbilical hernia? • It is when the intestines return normally, but
the rectus abdominis fails to fuse around the
umbilicus, leading to gut covered in skin.
16. Describe an omphalocele? • It is the failure of the intestinal loops to return
to the abdomen, so it ends up as a hernia
covered in amnion.
• Its causes are unknown, but it is associated with
maternal obesity, alcohol/ tobacco, SSRI use.
17. Describe gastroschisis? • It is a defect in the abdominal (belly) wall, a
failure of the ventral body wall to fuse. This
results in no covering of the gut as it sits outside
the body.
• There is a marked association with young
maternal age, low maternal BMI, and
recreational drugs (especially cocaine).
18. Describe Hirschsprung's disease? • It is where the person has an aganglionic
megacolon.
• It primarily affects the hindgut.
• There is an absence of parasympathetic ganglia,
caused by a lack of neural crest cells.
• There also is a dilatation of sections of the
colon, with a lack of tone and peristalsis,
leading to profound constipation.
• Because of the failure of the development of
enteric ganglia, there is a section of the gut that
is completely absent of ganglia.
19. In anal development, what is the cloaca? • The cloaca is the transient common end of the
digestive and urogenital systems, including the
base of the allantois (urogenital sinus).
• It is covered by the cloacal (proctodeal)
membrane over the ectoderm depression, the
proctodeum.
• It is split by the urorectal septum. This gives rise
to the urogenital membrane and anal
membrane (that perforate at 7-8 weeks)
20. What could cause an imperforate anus? • An imperforate anus can be:
- persistence of the anal membrane
- atresia of the anal canal, rectum or both
