Session 3 - Anatomy Of The Gastrointestinal System Flashcards

1
Q

What are the four layers of the gut wall?

A

Mucosa (innermost)
Submucosa
External muscle layers
Serosa (outermost)

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2
Q

What layers make up the mucosa of the gut wall?

A

Epithelial layer
Lamina propria
Muscularis mucosae

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3
Q

What does the lamina propria contain?

A

Lots of lymphoid nodules and macrophages. Produce antibodies to protect against bacterial/viral invasion.

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4
Q

What does the submucosa of the gut wall contain?

A

Dense connective tissue, blood vessels, glands, lymphoid tissue, submucosal plexus (Meissner’s)

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5
Q

What is a enterocyte?

A

A simple columnar cell that absorbs. Predominant cell of small and large intestines. Has microvilli.

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6
Q

What do goblet cells secrete?

A

Mucus

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7
Q

Is there a greater number of goblet cells in the duodenum or colon?

A

Colon. Increasing number as you move from the duodenum to the colon.

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8
Q

What does mucus protect epithelium from?

A
Friction (mucus acts as a lubricant)
Chemical damage (acidic environment)
Bacterial inflammation (forms physical barrier)
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9
Q

What do gastric surface mucous cells (foveolar cells) secrete?

A

Mucus/HCO3 that forms barrier to stomach acid

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10
Q

What is the difference between plicae circulares and rugae?

A

Plicae circulares are permanent folds found in the small intestine. Rugae are temporary folds found in the stomach (allow stomach to expand easily).

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11
Q

What specialised cells are found in the crypts of lieberkuhn and what are their functions?

A

Stem cells -constantly divide to replace epithelia
Paneth cells - secrete antibacterial proteins to protect stem cells
Enteroendocrine cells - secrete hormones that control the function of the gut

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12
Q

Where are crypts of lieberkuhn found?

A

Small and large intestine

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13
Q

Where are Brunners glands found?

A

Duodenum

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14
Q

Give examples of exocrine tissues in the gut.

A

Salivary glands
Pancreas
Brunners glands

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15
Q

What causes ulceration of the GI tract?

A

Erosion through the muscularis mucosae due to failure of protective mechanisms. E.g. loss of mucus production

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16
Q

What is coeliac disease?

A

An abnormal immune response to gliadin (protein found in gluten). Mucosa of intestine becomes inflamed and damaged, villi can’t absorb. Results in malabsorption and diarrhoea.

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17
Q

The term inflammatory bowel disease is mainly used to describe what two conditions?

A

Ulcerative colitis

Crohn’s disease

18
Q

What are the layers of the abdominal wall?

A
Skin
Fascia (+ fat)
 - superficial 
 - deep
4 muscles (3 anterolateral muscles)
 - external oblique
 - internal oblique
 - transverse abdominis
 - rectus abdominis
Transversalis fascia
Peritoneum
19
Q

Which abdominal muscles have an aponeurosis?

A

External oblique
Internal oblique
Transverse abdominins

These lateral muscles have aponeuroses that envelope the midline rectus abdominus muscles.

20
Q

What is the rectus sheath?

A

The aponeurosis of the lateral abdominal muscles surrounding the rectus abdominins

21
Q

What is the arcuate line?

A

Horizontal line that marks the lower limit of the posterior layer of the rectus sheath. It is also where the inferior epigastric vessels perforate the rectus abdominis.
Found roughly half way between the umbilicus and pubic crest.

22
Q

What is a mesentery?

A

A double fold of peritoneum that attaches certain viscera to the posterior abdominal wall.

23
Q

Which viscera are attached to the posterior abdominal wall by mesenteries?

A
Jejunum
Ileum
Appendix
Transverse colon
Sigmoid colon
Rectum
24
Q

What do mesenteries contain?

A

Blood vessels
Lymph vessels
Nerves
Fat

25
Q

What is a peritoneal ligament? Give examples.

A

A double fold of peritoneum that connects two viscera together.
E.g.
Gastrocolic ligament - stomach to transverse colon
Gastrosplenic ligament - stomach to spleen

OR

A double fold of peritoneum that connects a viscera to the abdominal wall.
E.g.
Falciform ligament - liver to anterior abdominal wall
Triangular ligaments - liver to diaphragm

26
Q

What is the falciform ligament?

A

Double fold of peritoneum connecting the liver to the anterior abdominal wall.

27
Q

What are the greater and lesser omenta?

A

Double folds of peritoneum:
Greater omentum - hangs down off the greater curve of the stomach
Lesser omentum - connects lesser curve of the stomach to the liver

28
Q

What is the purpose of sphincters in the GI tract?

A

Divide gut into sections
Control movement along the gut
Prevent reflux of material

29
Q

Name all the sphincters of the GI tract in order.

A
Upper oesophageal
Lower oesophageal
Pyloric 
Sphincter of Oddi
Ileo-caecal valve 
Internal anal
External anal
30
Q

Is the external anal sphincter under somatic or autonomic control?

A

Somatic (voluntary)

31
Q

Which branches of the aorta supply the foregut, midgut and hindgut respectively?

A

Coeliac trunk - supplies foregut
Superior mesenteric artery - supplies midgut
Inferior mesenteric artery - supplies hindgut

32
Q

Which viscera make up the foregut?

A
Lower oesophagus  
Stomach
Spleen 
Liver 
Gallbladder 
Pancreas
Proximal duodenum
33
Q

Which viscera make up the midgut?

A
Distal duodenum
Jejunum
Ileum
Appendix
Ascending colon
Caecum
Proximal 2/3 of transverse colon
34
Q

Which viscera make up the hindgut?

A
Distal 1/3 of the transverse colon
Descending colon
Sigmoid colon
Rectum
Upper anal canal
35
Q

All venous drainage from the intestines and stomach will drain to what organ via what vein?

A

Liver via the hepatic portal vein

36
Q

What is pyloric stenosis?

A

Hypertrophy of the pyloric sphincter. Causes gastric obstruction which can lead to projectile vomiting.

37
Q

What is a volvulus?

A

A volvulus is when a loop of intestine twists around itself and the mesentery that supports it, resulting in a bowel obstruction. Symptoms include abdominal pain, abdominal bloating, vomiting, constipation, and bloody stool.

38
Q

Why is a section of bowel involved in a volovulus at risk of ischaemia?

A

Mesentery contains blood vessels supplying the viscera, twisting of the mesentery can cut off these blood vessels leading to ischaemia.

39
Q

Explain why liver cirrhosis leads to ascites.

A

Liver cirrhosis leads to narrowing of blood vessels in the liver, this increases hydrostatic pressure in the hepatic portal vein. Increased hydrostatic pressure means that more fluid moves out of blood vessels into the interstitium and peritoneal cavity.
Also, reduced liver function means less albumin is produced so there is a lower oncotic pressure in blood so more fluid moves out of the blood.

40
Q

What is ascites?

A

The accumulation of fluid in the abdomen/peritoneal cavity. Most commonly caused by portal hypertension due to liver cirrhosis.