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GI > Lecture 2 - anatomy > Flashcards

Lecture 2 - anatomy Flashcards

1
Q

4 layers of the GI tract

A

Mucosa (innermost)
Submucosa
External muscles
Serosa (outermost)

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2
Q

What does the mucosa consist of?

A

Epithelial cells
Lamina propria
Muscularis mucosa

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3
Q

What does the submucosa contain?

A

Connective tissue with:

  • glands
  • arteries
  • veins
  • nerves

Meissner’s plexus

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4
Q

External muscle of the GI tract

A

Outer longitudinal - divided into 3 bands (taeniae coli). Acts as a shuttle and shortens gut
Inner circular - for peristalsis and contains the Auerbach’s plexus

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5
Q

What does the serosa contain?

A

Blood vessels
Adipose tissue
Lymph vessels

Continuous with the mesenteries

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6
Q

Role of the mucosa epithelial layer

A

Selectively permeable barrier - facilitates the transport and digestion of food

  • Promotes absorption via microvilli
  • Produces hormones
  • Produces mucus via goblet cells
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7
Q

Why does the GI tract contain mucus?

A

Decreases friction
Prevents chemical damage
Reduces bacterial invasion

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8
Q

Role of the lamina propria of the GI mucosa

A

Contains lymphoid nodules and macrophages - immune defense

Produces antibodies (IgA) - resistant to proteases which protects against bacterial and immune invasion

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9
Q

Role of the muscularis mucosae of GI mucosa

A

Layers of the smooth muscle orientated in different directions
Motility - prevents stasis which can cause infection
Keeps the epithelium in contact with the gut contents
Dynamic crypt contents

(peptic ulcers breach the muscularis mucosa)

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10
Q

What type of epithelium lines the oesophagus and distal anus

A

Stratified squamous

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11
Q

What type of epithelium lines the stomach and intestines

A

Simple columnar

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12
Q

Adaptations of the enterocyte

A

Enterocytes line the villi
Microvilli - brush border (increases SA)
Crypts
One cell thick

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13
Q

Goblet cells

A

Scattered between the enterocytes
Increasing number form the duodenum to the colon
Secretes mucus

Nucleus at base due to compression by mucus

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14
Q

Foveolar cells

A

Line the gastric mucosa and gastric pits (in stomach)
Secretes:
- mucus
- HCO3-

Secretions form a barrier to stomach acid

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15
Q

Folds of the GI tract

A

Stomach - rugae (temporary)
Small intestines - plicae circulares
Large intestines - haustra

Villi and microvilli

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16
Q

Villi

A

Found in absorptive areas - small intestines

17
Q

Crypts

A

In small and large intestines
Crypts of Lieberkuhn
Contain specialised cells:

  • Stem cells
  • Paneth cells
  • Enteroendocrine cells
18
Q

Stem cells

A

Divide and replicate for epithelium regeneration every 2- 4 days

19
Q

Paneth cells

A

Guard against infection
Protects stem cells (package and export antimicrobial proteins)

[at base of crypt and bright red]

20
Q

Enteroendocrine cells

A

Secrete gut hormones:

  • G cells - gastrin - stimulates gastric acid secretion from parietal cells

I cells - cholecystokinin - Stimates the gall bladder to contract and release bile

  • S cells - secretin - Stimulates the release of HCO3- and water to dilute acid

[deeper in crypts and gastric glands]

21
Q

Describe the glandular tissue of the gut

A

Acini - produce digestive enzymes
Intercalated ducts - transports secretions Interlobular ducts- secrete sodium bicarbonate into the main duct
Tubules

22
Q

Examples of exocrine glandular structures

A

Salivary glands
Pancreas
Brunners glands

23
Q

Secretion volumes per day

A 
Saliva - 1.5 L
Bile - 0.5 L
Gastric secretions - 2L
Pancreatic secretions - 1.5 L
Small intestines - 1.5 L
24
Q

Layers of the abdominal wall from superficial to deep

A

Skin
Fascia
Fat

External oblique
Internal oblique
Transverse abdominis
Rectus abdominis

Transversalis fascia
Peritoneum

25
Q

Rectus sheath

A

The aponeurosis of the external oblique, internal oblique and transversus abdominis that surrounds the rectus abdominis

The superior 3/4 of the rectus abdominis is completely enclosed by the rectus sheath

The inferior 1/4 is only covered anteriorly. Posteriorly it is covered by the transversalis fascia and parietal pertitoneum

26
Q

Peritoneal cavity

A

Seperate from the abdominal cavity

Serous membrane containing peritoneal fluid forming a potential space

Simple squamous

Envelops intraperitoneal viscera (Visceral peritoneum)

Lines the cavity wall - (parietal)

27
Q

Retroperitoneal structures

A 
Suprarenal glands
Aorta and IVC
Duodenum
Pancreas
Ureters and bladder
Colon (ascending and descending)
Kidneys
Esophagus
Rectum
28
Q

Visceral peritoneum

A

Sympathetic and parasympathetic afferents

  • Pain is poorly localised
  • referred
  • dependent on nerve
29
Q

Parietal peritoneum

A

Somatic afferents

- localised pain

30
Q

What does a mesentery contain?

A

Double fold of peritoneum that contains:

  • blood vessels
  • lymph vessels
  • fat
  • nerves
31
Q

Arcuate line

A

Site of transition of the rectal sheath
Lower limit of the posterior layer of the rectal sheath
Half way between the umbilicus and pubic crest

32
Q

What are the two major divisions of the peritoneal cavity?

A

Greater and lesser sacs

33
Q

What is the connection between the greater and lesser sac?

A

The epiploic foramen (Foramen of Winslow)

34
Q

Boundaries of the lesser sac

A

Anterior:

  • quadrate lobe of the liver
  • gastrocolic ligament and stomach
  • lesser omentum

Posterior:

  • pancreas
  • left kidney
35
Q

Cavities within the peritoneum that can collect fluid

A

Rectovisical - between the rectum and bladder
Rectouterine (pouch of Douglas) - between the rectum and uterus
Visicouterine - between the bladder and uterus

36
Q

Symptoms of peritonitis

A
  • feeling of fullness and bloating
  • fever
  • nausea and vomiting
  • loss of appetite
  • diarrhoea
  • thirst
  • low urine output
  • inability to pass stool or gas
  • fatigue
37
Q

How do the splanchnic nerves enter the abdomen

A

Through the diaphragm at the 4th and 5th intercostal space

GI (18 decks)

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