S3) Anatomy of the Abdomen Flashcards Preview

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Flashcards in S3) Anatomy of the Abdomen Deck (50)
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State the structure and functions of the mucosal epithelial layer

Structure: selectively permeable barrier

- Function: promote absorption, produce hormones and mucus, facilitate transport and digestion of food


State the structure and function of the mucosal lamina propria

- Structure: lots of lymphoid nodules and macrophages

- Function: produce antibodies (mainly IgA)


State the structure and functions of the muscularis mucosae

Structure: layers of smooth muscle orientated in different directions

- Function:

I. Keeps epithelium in contact with gut contents

II. Keeps crypt contents dynamic 


Describe the structure of the submucosa of the gut

- Contains dense connective tissue, blood vessels, glands, lymphoid tissue

- Contains submucosal plexus (Meissner’s) 


Describe the contents of the inner circular muscle layer

Contains myenteric (Auerbach’s) plexus 


Describe the structure of the serosa in the gut

- Continuous with mesenteries 

- Contains blood and lymph vessels and adipose tissue


What kind of epithelia is found in the gut?

- Stratified squamous (oesophagus and distal anus)

- Simple columnar (everything else)


What is an enterocyte?

An enterocyte is a simple columnar epithelial cell that absorbs nutrients


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

Describe it structure

- Consists of apical and basolateral membranes

- Blood vessels/lymphatics lie immediately below cell



How are enterocytes adapted for their absorbative function?

Microvilli (collectively termed brush border


Where are goblet cells found?

- Scattered in between enterocytes

- Increase in number from duodenum to colon


Describe the structure of the goblet cell

- Narrow base (mucus compresses nucleus to its base)

- Larger apical size


Goblet cells secrete mucus.

What are the three main functions of mucus?

Protects epithelia from:

- Friction (acts as lubricant)

- Chemical damage (acidic environment)

- Bacterial inflammation (forms physical barrier) 


Where are gastric surface mucous cells found?

Gastric surface mucous cells line gastric mucosa/gastric pits


What do gastric surface mucous cells do?

Secrete mucus/HCO3 that forms barrier to stomach acid 


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

- Permanent folds

- Villi

- Microvilli 


Why does the stomach form temporary folds?

- The stomach needs to be easily expandable

- Temporary folds form called rugae 


Crypts are found in the small intestine and colon.

What type of cells do they contain?

Contain specialised cells:

- Stem cells

- Paneth cells

- Enteroendocrine cells 


What are stem cells?

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


Where are paneth cells found and what do they do?

- Location: base of crypts

- Function: secrete antibacterial proteins to protect stem cells


How can paneth cells be identified?

Paneth cells contain vesicles which stain red


Where are enteroendocrine cells found and what do they do?

- Location: deeper in crypts and gastric glands

- Function: secrete hormones that control the function of the gut e.g gastrin, CCK, secretin


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

Crypt alteration

- Cryptitis – inflammation of wall

- Crypt abscess – neutrophils in lumen 


Describe the organisation of glandular tissue in the gut

- Organised secretory cells – acini and tubules

- Connected to a duct 


Provide 3 examples of exocrine glands in the gut

- Salivary glands

- Pancreas

- Brunners glands 


Differentiate between the secretions of acini and tubules

- Acini secrete serous secretions (+ enzymes)

- Tubules secrete mucous e.g. Brunner’s glands


What type of secretions do salivary glands produce?

- Serous secretions 

- Mucous secretions


Describe the pathophysiology of ulceration of the gut

- Erosion through muscularis mucosae

- Failure of protective mechanisms e.g. mucus production 


Describe the pathophysiology of Coeliac's disease

- Inability to tolerate gliadin

- Damages mucosa

- Results in poor digestion and malabsorption 


Identify the 5 layers composing the abdominal wall

- Skin

- Fascia/fat: superficial and deep

- Anterolateral muscles

- Transversalis fascia

- Peritoneum