Podcast
Questions and Answers
What is the primary goal of the College of Medicine's mission?
What is the primary goal of the College of Medicine's mission?
Which two layers are formed from the inner cell mass during blastulation?
Which two layers are formed from the inner cell mass during blastulation?
What does gastrulation establish in the embryo?
What does gastrulation establish in the embryo?
Which value emphasizes the importance of ideas, opinions, and diversity in the College of Medicine?
Which value emphasizes the importance of ideas, opinions, and diversity in the College of Medicine?
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What is the role of the epiblast layer in embryonic development?
What is the role of the epiblast layer in embryonic development?
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Which characteristic is fundamental to the role model vision of the College of Medicine?
Which characteristic is fundamental to the role model vision of the College of Medicine?
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Which of the following is NOT one of the college's core values?
Which of the following is NOT one of the college's core values?
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Which process involves the formation of mesoderm and endoderm in embryonic development?
Which process involves the formation of mesoderm and endoderm in embryonic development?
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What is the relationship between epiblast and germ layers?
What is the relationship between epiblast and germ layers?
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Which process leads to the formation of the germ layers?
Which process leads to the formation of the germ layers?
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What type of tissue does the ectoderm primarily give rise to?
What type of tissue does the ectoderm primarily give rise to?
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Which statement accurately describes the derivation of the ectoderm?
Which statement accurately describes the derivation of the ectoderm?
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Which germ layer is not a direct product of the epiblast?
Which germ layer is not a direct product of the epiblast?
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The main function of the ectoderm in embryonic development is to form:
The main function of the ectoderm in embryonic development is to form:
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Which of the following statements about the epiblast is true?
Which of the following statements about the epiblast is true?
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At what stage of development does gastrulation typically occur?
At what stage of development does gastrulation typically occur?
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Study Notes
Introduction to the College of Medicine
- King Faisal University's College of Medicine is presented.
- Academic year 2024-2025 is specified.
Vision and Mission of the College of Medicine
- Vision: To become a role model in medical education, research, and promoting community health within the Kingdom.
- Mission: To provide high-quality and effective medical education for future professionals, producing excellent healthcare through research and collaboration, serving the community.
Development of the GIT
- Dr. Naheed Kausar, Assistant Professor of Anatomy and Biomedical Sciences, College of Medicine at King Faisal University, is mentioned.
First Revelation - Surah Al-Alaq (The Clot)
- The first revelation of the Quran is described.
- It highlights the creation of man from a clinging substance and the instruction of Allah to humankind through writing
Blastula
- A blastula is a ball of cells formed after fertilization.
- Implantation on the uterine wall follows fertilization.
Blastocyst
- Inner cell mass (or embryoblast)
- Epiblast and Hypoblast are two layers
Gastrulation (Formation of Embryonic Mesoderm and Endoderm)
- Gastrulation establishes the three germ layers (endoderm, mesoderm, ectoderm) in the embryo.
- Epiblast is the source for all the germ layers.
A cavity in the epiblast forms the amniotic cavity
- The hypoblast lines up to form the yolk sac.
The mesoderm is not formed in 2 midline areas
- Oropharyngeal and cloacal membranes.
- These areas only contain endoderm and ectoderm layers.
The allantois projects into the connecting stack (umbilical cord's primordium).
- The septum transversum is the primordium of the diaphragm.
The yolk sac's lining
- The yolk sac's lining is made of the endoderm and visceral layer of intra-embryonic mesoderm.
Folding of the embryo
- Foregut, midgut, and hindgut are formed by folding
- The yolk sac is encompassed into the embryo
The vitellointestinal duct
- With further growth, the vitellointestinal duct reduces in size.
Formation of foregut and hindgut
- The foregut and hindgut are now on the ventral aspect of the embryo.
- The oropharyngeal and cloacal membranes close the foregut and hindgut.
The primitive gut's lining
- The primitive gut is lined by endoderm and the visceral layer of the intra-embryonic mesoderm.
- The lining is composed of endoderm and parenchyma
The endoderm lining of the primitive gut.
- Endoderm forms the GIT's (Gastrointestinal Tract) lining epithelium and parenchyma (functional part).
- The surrounding mesoderm forms the GIT wall's muscles, connective tissues, and stroma.
The peritoneal folds & the gut tube.
- The primitive gut tube connects with the ventral and dorsal body wall by peritoneal folds.
- The peritoneal folds are named according to different sections of the gut.
Dorsal layers
- Dorsal layers divide into 3 parts (mesogastrium, mesoduodenum, mesocolon) that extend from the stomach's dorsal border to the dorsal body wall.
- Other layers include dorsal mesentery for small intestine that extend from the small intestine to the dorsal body wall and dorsal mesocolon that extends from the colon to the dorsal body wall.
Transverse section division
- The primitive peritoneal cavity is divided into two parts (right and left halves) by the ventral and dorsal mesogastria
Division of GIT
- The GIT is divided into three parts: foregut, midgut, and hindgut, based on their embryonic origin.
Parts of the foregut
- The lower esophagus, stomach, upper part of the duodenum, liver, spleen, and the majority of the pancreas are components of the foregut.
- The foregut's abdominal part gives rise to the lower end of the esophagus, stomach, upper duodenum, bile duct, liver, gallbladder, bile duct, and pancreas.
- These parts are innervated by the celiac trunk.
Parts of the Midgut
- Right two-thirds of the transverse colon, ascending colon, cecum with appendix, the lower half of the duodenum, and a portion of the pancreas are parts of the midgut.
- The midgut is supplied by branches from the superior mesenteric artery.
Parts of the Hindgut
- The hindgut includes the left one-third of the transverse colon, descending colon, sigmoid colon, rectum, and anal canal.
Esophagus development
- The esophagus and respiratory diverticulum (lung bud) develop from the cranial part of the foregut.
- The 4th week sees the respiratory diverticulum (lung bud) appearing on the ventral wall of the foregut adjacent to the pharyngeal gut.
- The trachea and the esophagus formation parts have wide communication initially, and the tracheoesophageal septum gradually separates the respiratory diverticulum from the dorsal foregut.
Esophagus abnormalities
- The esophagus begins short and then lengthens as the heart and lungs descend.
- Abnormal recanalization leads to atresia (absence of lumen) or stenosis (narrowing of the lumen).
- In most cases (90%), the proximal end of the esophagus is a blind sac, and the distal part is connected to the trachea by a narrow canal just above the bifurcation.
Stomach development
- The stomach develops from the distal tubular part of the foregut during the 4th week.
- The primordial stomach is oriented in the median plane and subsequently expands ventrodorsally.
- The stomach is attached to the ventral and dorsal walls by the ventral and dorsal mesogastrium.
- During weeks 5 and 6, the dorsal border grows faster than the ventral border, creating the greater curvature and lesser curvature of the stomach.
- The stomach rotates 90 degrees clockwise around its longitudinal axis during weeks 5-6, affecting the positions of the lesser and greater curvatures.
- The primordial stomach's original left side becomes the ventral surface and the right side becomes the dorsal surface.
Stomach Anomalies
- Hypertrophic pyloric stenosis is an uncommon stomach anomaly but affects one out of 150 males and one out of 750 females.
- It's marked by thickening of the pylorus and resulting stenosis of the pyloric canal, obstructing food passage.
- The stomach is markedly distended, and projectile vomiting occurs due to the failure of gastric emptying.
Duodenum development
- The duodenum develops from the terminal foregut and the midgut's cephalic part.
- It's located caudal to the liver bud and adopts a C-shaped loop just caudal to the fusiform stomach.
- The duodenum is suspended from the dorsal wall by the dorsal mesoduodenum.
Duodenum abnormalities
- Complete occlusion (atresia) or stenosis (narrowing) of the duodenal lumen are infrequent.
- Non-common anomalies include dilated duodenum.
Liver and Biliary System development
- The liver and biliary system arise as a ventral outgrowth called the hepatic diverticulum from the caudal part of the foregut in the 4th week
- The hepatic diverticulum extends into the septum transversum within the ventral mesogastrium
- The hepatic diverticulum enlarges and divides into two parts: a larger cranial portion (which becomes the liver) and a smaller caudal portion (becoming the gallbladder).
Liver and Gallbladder abnormalities
- Variations in typical liver lobulation, accessory hepatic ducts, or gallbladder duplication are ordinary but not clinically significant exceptions.
- Extrahepatic biliary atresia and intrahepatic biliary duct atresia/hypoplasia are rare but clinically substantial anomalies; they stem from a failure of ductal recanalization.
- These abnormalities pose a 1/15,000 and 1/100,000 live-birth risk.
Pancreas development
- The pancreas develops from two buds, the dorsal bud from the caudal foregut opposite the liver bud and the ventral bud from the cranial midgut near the liver.
- The ventral bud moves to the right, lying caudal and posterior to the dorsal bud, integrating with it.
- The main pancreatic duct (of Wirsung) is formed by the distal dorsal pancreatic duct and ventral parts while the proximal dorsal part develops into the accessory pancreatic duct (of Santorini).
Pancreas abnormalities
- Pancreatic tissue may occur at unusual locations in the body (ectopic pancreas)
- Annular pancreas creates a ring around the duodenum, potentially leading to obstruction due to abnormal growth of the ventral pancreatic bud.
Midgut development
- The midgut stays suspended from the dorsal abdominal wall via a short mesentery and communicates with the yolk sac via the vitelline duct.
- During its whole extent, it's supplied by the superior mesenteric artery.
- The midgut loop rapidly expands and forms the primary intestinal loop.
- The caudal part develops into the distal ileum, cecum, appendix, and proximal two-thirds of the transverse colon.
Midgut loop herniation
- The midgut loop herniates through the umbilicus into the proximal part of the umbilical cord in the 5th week and starts rotating anticlockwise.
- The herniated loop continues to grow and herniate.
- The loop completes a 180-degree rotation in the 10th and a 270-degree rotation by the 11th week.
Midgut Abnormalities
- Rotation problems like nonrotation, reversed rotation, or mixed rotation and volvulus (twisting) can result in midgut anomalies.
- Abnormal returns of the physiological hernia to the abdominal cavity cause midgut anomalies like omphalocele
Hindgut development
- In the eleventh week, the hindgut develops into the descending colon, sigmoid colon, rectum, and upper part of the anal canal.
References
- Detailed books on human development are listed.
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Description
Explore the College of Medicine at King Faisal University, detailing its vision and mission for the academic year 2024-2025. This quiz also covers key topics in medical education, including the development of the GIT and the significance of early Quranic revelations related to human creation.
