S3) Anatomy of the Abdomen Flashcards

1
Q

State the structure and functions of the mucosal epithelial layer

A
  • Structure: selectively permeable barrier
  • Function: promote absorption, produce hormones and mucus, facilitate transport and digestion of food
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2
Q

State the structure and function of the mucosal lamina propria

A
  • Structure: lots of lymphoid nodules and macrophages
  • Function: produce antibodies (mainly IgA)
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3
Q

State the structure and functions of the muscularis mucosae

A
  • Structure: layers of smooth muscle orientated in different directions

- Function:

I. Keeps epithelium in contact with gut contents

II. Keeps crypt contents dynamic

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4
Q

Describe the structure of the submucosa of the gut

A
  • Contains dense connective tissue, blood vessels, glands, lymphoid tissue
  • Contains submucosal plexus (Meissner’s)
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5
Q

Describe the contents of the inner circular muscle layer

A

Contains myenteric (Auerbach’s) plexus

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6
Q

Describe the structure of the serosa in the gut

A
  • Continuous with mesenteries
  • Contains blood and lymph vessels and adipose tissue
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7
Q

What kind of epithelia is found in the gut?

A
  • Stratified squamous (oesophagus and distal anus)
  • Simple columnar (everything else)
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8
Q

What is an enterocyte?

A

An enterocyte is a simple columnar epithelial cell that absorbs nutrients

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9
Q

The enterocyte is the most predominant cell in the small intestine and lumen.

Describe it structure

A
  • Consists of apical and basolateral membranes
  • Blood vessels/lymphatics lie immediately below cell
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10
Q

How are enterocytes adapted for their absorbative function?

A

Microvilli (collectively termed brush border)

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11
Q

Where are goblet cells found?

A
  • Scattered in between enterocytes
  • Increase in number from duodenum to colon
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12
Q

Describe the structure of the goblet cell

A
  • Narrow base (mucus compresses nucleus to its base)
  • Larger apical size
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13
Q

Goblet cells secrete mucus.

What are the three main functions of mucus?

A

Protects epithelia from:

  • Friction (acts as lubricant)
  • Chemical damage (acidic environment)
  • Bacterial inflammation (forms physical barrier)
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14
Q

Where are gastric surface mucous cells found?

A

Gastric surface mucous cells line gastric mucosa/gastric pits

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15
Q

What do gastric surface mucous cells do?

A

Secrete mucus/HCO3 that forms barrier to stomach acid

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16
Q

How is the gut tube adapted for the increased surface area required for absorption?

A
  • Permanent folds
  • Villi
  • Microvilli
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17
Q

Why does the stomach form temporary folds?

A
  • The stomach needs to be easily expandable
  • Temporary folds form called rugae
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18
Q

Crypts are found in the small intestine and colon.

What type of cells do they contain?

A

Contain specialised cells:

  • Stem cells
  • Paneth cells
  • Enteroendocrine cells
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19
Q

What are stem cells?

A

Stem cells are cells that reside in crypts that constantly divide to replace epithelia

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20
Q

Where are paneth cells found and what do they do?

A
  • Location: base of crypts
  • Function: secrete antibacterial proteins to protect stem cells
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21
Q

How can paneth cells be identified?

A

Paneth cells contain vesicles which stain red

22
Q

Where are enteroendocrine cells found and what do they do?

A
  • Location: deeper in crypts and gastric glands
  • Function: secrete hormones that control the function of the gut e.g gastrin, CCK, secretin
23
Q

Briefly, identify states where crypts are affected by inflammatory bowel disease

A
  • Crypt alteration
  • Cryptitis – inflammation of wall
  • Crypt abscess – neutrophils in lumen
24
Q

Describe the organisation of glandular tissue in the gut

A
  • Organised secretory cells – acini and tubules
  • Connected to a duct
25
Q

Provide 3 examples of exocrine glands in the gut

A
  • Salivary glands
  • Pancreas
  • Brunners glands
26
Q

Differentiate between the secretions of acini and tubules

A
  • Acini secrete serous secretions (+ enzymes)
  • Tubules secrete mucous e.g. Brunner’s glands
27
Q

What type of secretions do salivary glands produce?

A
  • Serous secretions
  • Mucous secretions
28
Q

Describe the pathophysiology of ulceration of the gut

A
  • Erosion through muscularis mucosae
  • Failure of protective mechanisms e.g. mucus production
29
Q

Describe the pathophysiology of Coeliac’s disease

A
  • Inability to tolerate gliadin
  • Damages mucosa
  • Results in poor digestion and malabsorption
30
Q

Identify the 5 layers composing the abdominal wall

A
  • Skin
  • Fascia/fat: superficial and deep
  • Anterolateral muscles
  • Transversalis fascia
  • Peritoneum
31
Q

Identify the 4 anterolateral muscles composing part of the abdominal wall

A
  • External oblique
  • Rectus abdominis
  • Internal oblique
  • Transverse abdominis
32
Q

What is an aponeurosis?

A

An aponeurosis is a thin sheet-like tendon

33
Q

What is the rectus sheath?

A

The rectus sheath is the aponeurosis of the lateral muscles surrounding the rectus abdominis

34
Q

What is the arcuate line of the rectus sheath and why is it significant?

A
  • The arcuate line is the lower limit of the posterior layer of rectus sheath
  • It is the point at which inferior epigastric vessels pierce rectus abdominus, found half way between the umbilicus and pubic crest
35
Q

What is the mesentery?

A

The mesentery is a double fold of peritoneum that attaches certain viscera to the posterior abdominal wall

36
Q

What does the mesentery contain?

A
  • Blood vessels
  • Lymph vessels
  • Nerves
  • Fat
37
Q

Provide two definitions of a peritoneal ligament

A

A peritoneal ligament is:

  • A double fold of peritoneum that connects two viscera together
  • A double fold of peritoneum that connects a viscera to the abdominal wall
38
Q

Provide two examples of peritoneal ligaments that connect 2 viscera together

A
  • Gastrocolic ligament: stomach to transverse colon
  • Gastrosplenic ligament: stomach to spleen
39
Q

Provide two examples of peritoneal ligaments that connect a viscera to the abdominal wall

A
  • Falciform ligament: liver to anterior abdominal wall
  • Triangular ligaments: liver to diaphragm
40
Q

What are omenta?

A

Omenta are double folds of peritoneum

41
Q

Where is the greater omentum found?

A

Greater omentum hangs down off the greater curve of the stomach

42
Q

Where is the lesser omentum found?

A

Lesser omentum connects lesser curve of stomach to liver

43
Q

Identify the 3 purposes of a sphincter

A
  • Divide tube into sections
  • Control movement along the tube
  • Prevent reflux of material
44
Q

Identify 6 sphincters found in the human body

A
  • Upper oesophageal
  • Lower oesophageal
  • Pyloric sphincter
  • Sphincter of Oddi
  • Ileo-caecal (valve)
  • Anal sphincter: internal and external
45
Q

Majority of the sphincters in the body are under autonomic control.

Identify the sphincter which is under somatic control

A

External anal sphincter is under voluntary control

46
Q

Identify 4 consequences of sphincter failure in the GI tract

A
  • Duodenal ulceration
  • Reflux
  • Incontinence
  • Dysphagia
47
Q

Blood supply to the gut comes from three branches of the aorta.

Identify them

A
  • Coeliac trunk
  • Superior mesenteric artery
  • Inferior mesenteric artery
48
Q

Describe the venous drainage of the gut

A

All venous drainage goes to liver via the hepatic portal vein

49
Q

How much fluid should there be in the peritoneal cavity?

A

20 - 25 ml

50
Q

Identify and describe 2 differences between the ileum and jejunum

A
  • Ileum has more lymphoid tissue because it is near the large colon and needs protection from the bacteria
  • Jejunum is more vascular (red) and has a greater surface area as it is the main site of transport and absorption