Wk 1 - Anatomy: Oesophagus, Stomach and Duodenum Organisation Flashcards

1
Q

What lines the abdominopelvic structures?

A

The peritoneum (serous membrane)

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2
Q

Where is the GI tract in the body?

A

It occupies most of the abdominopelvic cavity

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3
Q

List the abdominal regions and where they are.

A
  1. Right hypochondrium
  2. Epigastric region
  3. Left hypochondrium
  4. Right lumbar
  5. Umbilical region
  6. Left lumbar
  7. Right iliac
  8. Hypogastric
  9. Left iliac
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4
Q

What lines divide the abdominal regions?

A
  • Horizontal lines: Subcostal plane (L3) and Transtubercular (L5)
  • Vertical lines: Right mid-clavicular and Left mid-clavicular
  • Nb another 3rd horizontal plane that is sometimes used to substitute transtubercular plane - transpyloric plane.
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5
Q

What is the transpyloric plane?

A
  • 3rd horizontal plane used instead of transtubercular
  • Located halfway between the suprasternal notch of the manubrium and the upper border of the symphysis pubis at the level of the first lumbar vertebrae, L1
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6
Q

What is the significance of dividing the abdomen into regions?

A

Used in practice to localise the position of a mass or pain, or to describe the location of abdominal viscera

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7
Q

What are the abdominal quadrants?

A
  1. Right upper quadrant
  2. Left upper quadrant
  3. Right lower quadrant
  4. Left lower quadrant
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8
Q

What are the three developmental regions of the gut tube?

A
  1. Foregut - oropharynx to midway to 2nd part of duodenum
  2. Midgut - 2nd part of duodenum to 2/3rd transverse colon
  3. Hindgut - 2/3rds transverse to anal canal
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9
Q

What main aorta branches supply the gut?

A
  1. Coeliac trunk (T12)
  2. Superior mesenteric artery (L1)
  3. Inferior mesenteric artery (L3)
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10
Q

Describe the general lymphatic drainage of the gut.

A
  1. Foregut drains to
    pre-aortic nodes around
    coeliac artery
  2. Midgut drains to
    pre-aortic nodes around
    superior mesenteric artery
  3. Hindgut drains to
    pre-aortic nodes around
    inferior mesenteric artery
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11
Q

Describe the venous drainage of the gut.

A
  • All venous blood drains via the hepatic portal vein
  • Nb there is variation on route of drainage
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12
Q

What is the sympathetic supply of the gut?

A
  • Coeliac ganglia - Foregut
  • Superior mesenteric ganglia - Midgut
  • Inferior mesenteric ganglia - Hindgut
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13
Q

Generally, where does pain refer to from foregut, midgut and hindgut?

A
  • Foregut - epigastric region
  • Midgut - umbilical region
  • Hindgut - hypogastric region
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14
Q

Describe the parasympathetic nerve supply of the gut?

A
  1. Vagus nerve - foregut and midgut
  2. Pelvic splanchnic nerves (S2-S4) - hindgut
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15
Q

Where do preganglionic fibres synapse?

A

In intrinsic ganglia in the walls of viscera (they do not travel with blood!)

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16
Q

What is the enteric nervous system?

A
  • Extensive network of nerve fibres and clusters of ganglia
  • Located in wall of gut tube
  • ENS acts INDEPENDENTLY but is regulated by the ANS
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17
Q

Describe the gut tube wall layers.

A
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18
Q

What embryological layer does the gut form from?

A

The endoderm

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19
Q

By what week do the main organs form?

A

By week 8 (embryonic period)

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20
Q

When is the embryo most at risk of developmental abnormalities?

A

During weeks 3-4 when the trilaminar disc undergoes cephalocaudal folding and lateral folding

21
Q

What suspends the gut tube in the emryo?

A

The gut tube is suspended by mesenteries (double layers of peritoneum)

22
Q

Where do you find the ventral mesentery?

A

Only found in front of foregut, rest of the gut only has dorsal mesentery

23
Q

What glands start the digestion process?

A

Salivary glands

  • Parotid gland (serous)
  • Submandibular gland (mixed/mostly serous)
  • Sublingual gland (mixed/mostly mucous)
24
Q

What’s the difference between serous and mucous secreting glands?

A
  • Serous –> produces watery secretion that contains enzymes (acidic - darker purple on histology dye)
  • Mucous –> produces mucuos, which is a thick, viscous secretion, comprising of mucin (lighter stain as washes out when staining)
25
Q

What are acini?

A

They are rounded exocrine secretory units that make up the salivary glands. They produce the mucous or enzymes. They have striated ducts that open into the oral cavity.

26
Q

Where does the oesophagus start?

A

At the inferior border of the cricoid cartilage

27
Q

How long is the oesophagus?

A

25cm long

28
Q

Describe the route of the oesophagus in the body.

A
  1. Commences at inferior border of cricoid cartilage
  2. Following vertebra anteriorly, posterior to trachea
  3. Continues posterior to left atrium of heart, anterior to aorta at transverse diaphragm
  4. Enters abdominal cavity where it is encircled by right crus of diaphragm
  5. Courses left of midline to enter stomach
29
Q

At which vertebral level does the oesophagus enter the abdominal cavity/transverses the diaphragm?

A

At level T10 (Vena Cava at T8, Aorta at T12)

30
Q

Where are the 4 constrictions of the oesophagus?

A
  1. Cricopharyngeus
  2. Arch of aorta (can see on AP x-ray)
  3. Left main bronchus (can see on lateral x-ray)
  4. Diaphragm

Constrictions not to be confused with tumours.

31
Q

What is the ‘z line’ located between the oesophagus and the stomach?

A

The z line is where there is an abrupt change from oesophageal (stratified squamous) to gastric mucosa (simple columnar - glandular)

32
Q

What type of epithelium lines the oesophagus?

A

Stratified squamous epithelium

33
Q

What is a hernia? List the main types.

A

A hiatus hernia occurs when a part of the stomach protrudes into the chest through the oesophageal hiatus in the diaphragm. There are two main types of hiatal hernias; sliding and rolling:

  • Sliding hiatus hernia – The lower oesophageal sphincter slides superiorly. Reflux is a common complication, as the diaphragm is no longer reinforcing the sphincter.
  • Rolling (aka para-oesophageal) Hiatus Hernia – The lower oesophageal sphincter remains in place, but a part of the stomach herniates into the chest next to it. This type of hiatus hernia is more likely to require surgical correction to prevent strangulation of the herniated pouch.
34
Q

List the main parts of the stomach.

A
  1. Cardia
  2. Fundus (in any organ, this is opposite the outlet)
  3. Body (makes up bulk of stomach)
  4. Pyloric antrum
  5. Pyloric canal (narrowest part just before pylorus)
35
Q

What is the pylorus?

A

Actual stomach sphincter controlling stomach to duodenum

36
Q

Describe the key relations of the stomach.

A
  • Superior: Oesophagus and left dome of the diaphragm
  • Anterior: Diaphragm, greater omentum, anterior abdominal wall, left lobe of liver, gall bladder
  • Posterior: Lesser sac, pancreas, left kidney, left adrenal gland, spleen, splenic artery, transverse mesocolon

Clinical relevance - peptic ulcers + what would they irritate if burst

37
Q

Label the histological section of the stomach.

A
  • Nb large surface of mucous cells because the stomach is acidic so need to mitigate that.
38
Q

What three branches of the ceoliac trunk supply the stomach?

A

Lesser curvature is supplied by:

  1. Left gastric artery
  2. Common hepatic artery
    1. Hepatic artery proper –> right gastric artery

Greater curvature is supplied by:

  1. Common hepatic artery
    1. Gastroduodenal artery –> right gastroepiploic artery
  2. Splenic artery –> left gastroepiploic artery
39
Q

Describe the venous drainage of the stomach.

A
  • The veins of the stomach run parallel to the arteries
  • They all ultimately drain into the hepatic portal vein
  • The right and left gastric veins drain into the hepatic portal vein directly
  • The right gastroepiploic vein drains into the superior mesenteric vein
  • The left gastroepiploic vein drains into the splenic vein
  • Both splenic vein and SMV drain into the hepatic portal
40
Q

Discuss the sympathetic and parasympathetic innervation of the stomach.

A

Sympathetic:

  • T6-9 –> greater splanchnic nerve –> coeliac ganglion –> arterial route
  • Afferent (pain) fibres travel to T6-9

Parasympathetic:

  • Left vagus nerve –> anterior vagal trunk
  • Right vagus nerve –> posterior vagal trunk
  • Afferent (reflex) innervation generally does not reach consciousness

T4 Nipples, T10 Umbilicus – between them 5-9

41
Q

Describe the lymphatic drainage of the stomach.

A
  • Lymph from gastric, pancreaticosplenic, gastroepiploic and pyloric nodes all drain to coeliac nodes
  • Cancer of the stomach usually occurs in the pyloric region, requiring excision of pyloric and gastroepiploic nodes
42
Q

List the four parts of the proximal small intestine (ie duodenum).

A
  1. Superior part; intraperitoneal (A) + retroperitoneal (B); L1
  2. Descending part (C) where foregut becomes midgut
  3. Horizontal part (D)
  4. Ascending part (E) becomes jejunum at duodenojejunal flexure
43
Q

What is the difference between gastric and duodenal ulcer?

A
  • Gastric ulcer – lesion of gastric mucosa
  • Duodenal ulcer – lesion of pyloric or duodenal mucosa
  • Nb both are ‘peptic ulcers’
44
Q

What bacteria is associated with ulcers?

A

Most ulcers associated with Helicobacter pylori

45
Q

Which ulcers are more common?

A

Duodenal ulcer – lesion of pyloric or duodenal mucosa + generally more ‘benign’ than gastric ulcers

46
Q

What are the risks associated with peptic (duodenal) ulcers?

A
  • Inflamed duodenum may become adherent to liver, gallbladder, pancreas
  • If perforated, may erode gastroduodenal a. resulting in severe haemorrhaging –> very uncommon as ulcers usually caught early/before this happens
47
Q

List the three aspects that increase the surface area of the small intestine (absorption capability).

A
  1. Plicae circulares (except for proximal duodenum and terminal ilium)
  2. Villi (project into the lumen)
  3. Microvilli (need electron microscope to see not same as villi)
48
Q

What are Brunner’s glands?

A
  • Glands of the submucosa
  • Unique to duodenum
  • Secrete bicarbonate (HCO3) to neutralise
49
Q

What is the blood supply to the duodenum?

A
  1. Superior pancreaticoduodenal a. – branch of gastroduodenal a. – supplies duodenum proximal to major duodenal papilla (foregut)
  2. Inferior pancreaticoduodenal a. – branch of SMA – supplies duodenum distal to major duodenal papilla (midgut)