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Ellie's Body Logistics > Sesh 9: The Digestive System and Liver > Flashcards

Sesh 9: The Digestive System and Liver Flashcards

1
Q

The 3 layers that make up the jejunal mucosa are: (in apical to basolateral order)

1.
2.
3.

A
  1. Simple columnar epithelium
  2. Lamina propria
  3. Muscularis mucosae
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2
Q

What are plicae circulares, and what is their function?

A

Circular folds of mucosa and submucosa that project into the lumen of the small intestine.

They increase the surface area of the small intestine, to increase absorption of nutrients.

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3
Q

The inner layer of external muscle of the small intestine is_________, and the outer layer is__________.

A
  1. Circular

2. Longitudinal

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4
Q

Are there goblet cells in the brush border of the small intestine?

A

Yes, but they secrete less mucus than ones found in gastric pits.

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5
Q

A dilated lymphatic vessel supplying an intestinal villus is called a ______?

What is the function of such vessels?

A

A lacteal.

They absorb digested fats in the form of chylomicrons, which eventually enter the blood via the thoracic duct.

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6
Q

The right flexure of the large intestine is termed the _______ flexure, and the left is termed the ________ flexure.

A
  1. Right hepatic flexure

2. Left splenic flexure

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7
Q

What are the intestinal glands called, and what do they secrete.

A

The Crypts of Lierberkuhn secrete lots of mucous (many G cells within them).

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8
Q

What are the 3 main functions of colonic bacteria?

A
  1. Synthesise vitamin K, B12, thiamine and riboflavine.
  2. Breakdown primary bile acids to secondary bile acids.
  3. Convert bilirubin to non-pigmented metabolites.

All of these products can then be readily absorbed.

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9
Q

What are the 4 vitamins colonic bacteria synthesise?

A
  1. K
  2. B12
  3. Thiamine
  4. Riboflavine
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10
Q

Which 3 regions of the GIT are innervated by the somatic nervous system i.e. Under voluntary control?

A
  1. Mouth
  2. Superior third of the oesophagus
  3. External anal sphincter
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11
Q

The 2 autonomic neuronal plexuses of the gut wall are the_________plexus and the ___________plexus.

The_________plexus is found between the submucosa and muscularis externae.

The __________plexus is found between the inner and outer muscle layer.

A
  1. Submucosal
  2. Myenteric
  3. Submucosal
  4. Myenteric
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12
Q

Give 2 examples of substances that act locally, to provide paracrine control over the GIT?

A
  1. Histamine- controls gastric acid production

2. Vasoactive substances- alters GI blood flow

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13
Q

Which gut hormone stimulates gastric acid secretion from the parietal cells of the stomach?

A

Gastrin

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14
Q

What are the 3 main actions of secretin?

A
  1. Increases bicarb secretion from duct cells of pancreas.
  2. Stimulates bile production at the liver.
  3. Inhibits parietal cell secretion of gastric acid.
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15
Q

What stimulates cholecystokinin release from the enteroendocrine cells of the duodenum?

A

Presence of fatty acids or amino acids in the duodenum.

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16
Q

What are the 3 main actions of cholecystokinin?

A
  1. Increases pancreatic secretion of digestive enzymes.
  2. Stimulates gall bladder to contract and thus release bile.
  3. Acts on CCK receptors in the CNS to suppress hunger.
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17
Q

Name the 4 accessory organs of the digestive system.

A
  1. salivary glands
  2. liver
  3. gallbladder
  4. pancreas
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18
Q

Which layer of the gut wall are Peyer’s patches found within?

A

Within the lamina propria (middle layer of mucosa) of the mucosa.

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19
Q

Glands, arteries, veins and nerves run in the ________ layer of the gut wall.

A

Submucosal

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20
Q

What is the function of the muscularis externa?

A

Creates successive peristaltic waves that move contents along the gut lumen.

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21
Q

Give 3 functions of saliva.

A

Any 3 of:

  • Begins digestion of carbs and fat (salivary amylase and lipase)
  • Bacteriostatic function- contains IgA
  • Protects teeth- high calcium
  • Assists swallowing
  • Alkaline to protect mouth from mostly acidic foods
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22
Q

What classification of epithelium lines the oesophagus?

A

Non-keratinised stratified squamous epithelium.

Resists abrasion

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23
Q

What layer lines the outer oesophagus?

A

Adventitia- thin outermost layer of connective tissue, since oesophagus is not intraperitoneal.

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24
Q

Name 3 substances that the gastric mucosa secretes…

A
  1. Acid
  2. Pepsinogens (subsequently converted into pepsins)
  3. Gastrin
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25
Q

What are the names of the longitudinal folds of the gastric mucosa?

A

Rugae.

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26
Q

Which gastric cells do alcohol and aspirin damage?

A

The mucous cells- abundant in gastric pits. They are quickly replaced by mitosis in the isthmus, where stem cells divide and migrate.

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27
Q

Give 2 ways that gastric mucous protects the stomach lining.

A
  1. Contains bircarbonate, which neutrlaises the H+ at the lining.
  2. Mucous is resistant to pepsin degradation, and therefore protects the pepsins secreted by the gastric glands from digesting the stomach lining.
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28
Q

Are gastric glands exocrine or endocrine glands?

A

Both! 🙈

Exocrine function:

  • Parietal cells secrete H+ into the lumen
  • Chief cells secrete pepsinogens
  • There are mucous secreting cells within the gastric pit

Endocrine function:

  • Parietal cells secrete HCO3- into nearby capillaries, which transport the ions to surface mucous cells
  • Enteroendocrine cells at base (G cells) secrete gastrin
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29
Q

Brunner’s glands are in the walls of the __________ and secrete ______________ _______.

A
  1. Duodenum
  2. Bicarbonate-rich
  3. Mucous

(To neutralise the acidic chyme coming from the stomach)

30
Q

Does most active absorption in the small intestine occur proximally or distally?

A

Proximally.

31
Q

Which portion of the small intestine absorbs iron?

A

Duodenum.

32
Q

What are the 3 phases of swallowing?

A
  1. Voluntary phase- separation of bolus and movement into pharynx.
  2. Pharyngeal phase- bolus hits pressure receptors in the palate and anterior pharynx.
    Inhibits respiration.
    Glottis raises and oesophageal sphincters open.
  3. Oesophageal phase- rapid peristaltic waves.
    Lower oesophageal sphincter opens, so bolus can enter stomach.
33
Q

Why are fluids more difficult to swallow than solids?

A

Because if the epiglottis isn’t fully covering the trachea when you swallow, liquids can get through this gap and enter the respiratory tract.

Also, solids stimulate the swallowing reflex much more than liquids, so more likely to get better co-ordination of swallowing.

34
Q

What are the 4 functions of bile?

A
  1. Neutralises acidic chyme
  2. Emulsifies fats for absorption
  3. Bile acids aid absorption of fat soluble vitamins
  4. Elimination of bilirubin
35
Q

Which 3 things prevent colonic bacteria from invading the colonic wall?

A
  1. Tight junctions between epithelial cells
  2. Mucous
  3. Peyer’s patches containing lymphocytes
36
Q

What is dysphagia?

A

Disease of swallowing e.g. Following a stroke

37
Q

What is a symptom of no bile production?

A

Pale and greasy stools💩

38
Q

What attaches the liver to the anterior abdominal wall and diaphragm?

A

The falciform ligament.

39
Q

What is the bare area of the liver?

A

An area of the posterior of

liver that is not covered by peritoneum.

40
Q

What parts of the body does the hepatic portal vein drain and where does it drain in to?

A

All of the digestive tract from the lower oesophagus to the rectum is drained by the hepatic portal vein, which drains into the liver.

41
Q

List the ducts bile passes down from the liver to the duodenum.

A
  1. Right and left hepatic ducts
  2. Common hepatic duct
    (If not needed, from here would go to gall bladder to be concentrated, via cystic duct)
  3. Bile duct
  4. Pancreatic duct
42
Q

Which vessel delivers oxygenated blood to the liver?

A

The hepatic artery.

43
Q

How much bile do we produce per day?

A

1 Litre.

44
Q

The superior mesenteric vein drains which parts of the GIT?

A
  1. Small intestine
  2. Caecum
  3. Ascending colon
  4. Transverse colon
45
Q

Which parts of the GIT does the inferior mesenteric vein drain?

A
  1. Descending colon
  2. Sigmoid colon
  3. Rectum
46
Q

Which organs does the splenic vein drain?

A
  1. Spleen
  2. Pancreas
  3. Stomach
47
Q

Why is the hepatic portal system called a portal system?

A

Because it is composed of 2 capillary systems in series.

48
Q

Name a toxin carried to the liver via the portal system.

What does the liver do with this compound?

A

Ammonia.

Converts to urea (via the urea cycle) to be excreted.

49
Q

What do not travel in the portal vein?

A

Lipids and lipid-soluble vitamins (A, D, E and K)

50
Q

How are lipids absorbed from the GIT?

A
  • Bile acids form micelles with lipids
  • Taken into cells and processed into chylomicrons
  • Chylomicrons are taken up into lacteals to form chyle
  • Lacteals drain into abdominal lymphatics which then drain into the thoracic duct
51
Q

What are the 4 main functions of the liver?

A
  1. Metabolism (anabolism and catabolism)
  2. Storage
  3. Detoxification
  4. Bile production
52
Q

What function does the liver fulfil in the foetus that is doesn’t in adulthood?

A

Haematopoiesis. But this can be revived in adult if bone marrow is failing.

53
Q

After a splenectomy, what can the liver do?

A

Take over the removal of aged red blood cells.

54
Q

What is the exocrine secretion of the liver?

A

Bile- travels down ducts.

55
Q

Name 3 endocrine secretions of the liver.

A
  1. Angiotensinogen
  2. Thrombopoetin
  3. Insulin like growth factor 1 (IGF-1)
56
Q

__% of the liver’s blood supply is from the hepatic artery, and __% is from the portal vein.

A
  1. 25

2. 75

57
Q

Bile produced by hepatocytes flows in the same/opposite direction to the portal venule and hepatic arteriole…

A

Opposite

58
Q

Which vessels make up a portal triad?

A
  1. Bile duct
  2. Hepatic arteriole
  3. Portal venule
59
Q

What tubular spaces take the place of capillaries and venules in the liver?

A

Sinusoids

60
Q

What shape is a liver lobule?

A

Hexagonal.

61
Q

Lymphatics of the liver arise from the ___________, and drain to the liver ________.

A
  1. Periportal space- space of Mall.

2. Hilum

62
Q

The space of Disse is between which 2 components of the liver?

A

Hepatocytes and sinusoids.

63
Q

What are Kupffer cells?

A

Monocyte-derived macrophages in the sinusoid lining of the liver. 80% of body’s tissue macrophages.

64
Q

What are stellate (ito) cells?

A

In the perisinusoidal space-space of Disse.

Contain vacuoles of vitamin A.

65
Q

How are stellate cells involved in liver cirrhosis?

A

They lose their ability to store vit A, and differentiate into myofibroblasts that secrete collagen into the perisinusoidal space, leading to liver fibrosis.
This collagen surrounds and constricts the central vein, leading to portal hypertension.
Blood tries to find other routes to the IVC, so can get varices around base of oesophagus.

66
Q

What feature of sinusoids allows Kupffer cells to respond to inflammation and damage?

A

Their endothelium is fenestrated, allowing the cells to migrate in and out of the space of Disse.

67
Q

Which cells within the liver can ingest pathogens and recycle red blood cells?

A

Kupffer cells.

68
Q

What does the periportal space of Mall surround?

A

The portal triad of the liver.

69
Q

What is the name of the functional unit of the liver?

A

An acinus

70
Q

What is the name of the group of haem-containing isozymes found in the liver?

A

Cytochrome P450s.

Ellie's Body Logistics (13 decks)

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