Session 3 - Setting the scene - anatomy Flashcards
What are the 4 layers of the intestines?
(inner to outer)
- Mucosa
- Submucosa
- External muscle layers
- Serosa
What are the layers of the mucosa?
- Epithelial layer
- Lamina propria
- Muscularis mucosae
What is the function of the epithelium?
- Selectiveley permeable barrier
- Absorption + transport
- Produce hormones
- Produce mucus
What is the function of lamina propria?
Contains lots of lymphoid nodules / macrophages.
- Produces antibodies (mainly IgA) to protect against pathogens.
What is the function of the muscularis mucosae?
Layers of smooth muscle, different directions.
Keeps epithelium in contact with gut contents, and crypt contents dynamic.
What are the layers and functions of the submucosa?
Dense connective tissue, blood vessels, glands, lymphoid tissue.
Contains meissner’s plexus.
- Inner circular muscle
(myenteric (Auerbach’s) plecus) - Outer longitudinal muscle
- Serosa (blood + lymph + adipose, continuous with mesenteries)
Generally what is the epithelia of the gut, from mouth to anus?
- Stratified squamous in MOUTH and ANUS
- Everywhere esle is SIMPLE COLUMNAR
What is an enterocyte? Name a main feature.
Simple columnar epithelial cell, which absorbs.
Has microvilli.
What are goblet cells?
Cells which secrete mucus in the GI (increase from duodenum to colon).
Why is mucus important in the tract?
- Prevents friction (lubricate)
- Protects from chemicals (acid)
- Barrier against bacteria
Which cells protect the stomach from the highly acid environment?
Gastric surface mucosa cells (foveolar cells)
Secrete mucus + HCO3, to protect stomach
Which factors give the intestines a large surface area?
Folds
Villi
Microvilli
How does the stomach allow for expansion?
Rugae - temporary folds, can expand
Where are krypts of lieberkuhn found, what do they do?
Small and Large intestine. Specialised cells: - Stem cells - Paneth cells (protect - antibacterial proteins) - Enteroendocrine cells
What do enteroendocrine cells do?
Secrete gut controlling hormones:
- Gastrin
- Cholecystokinin
- Secretin
Which cells protect the duodenum from acidic stomach chyme?
Brunner’s cells
- Secrete alkaline fluid containing mucin.
What is the difference between acini and tubules in secretion?
Acini tend to secrete serous (+enzymes) secretions.
Tubules tend to secrete mucus. (e.g. brunner’s)
What is an ulcer?
A lesion that erodes through the muscularis mucosae.
What are the outer layers of the abdominal wall?
- Skin
- Fascia/ fat (superficial/deep)
- 3x muscle layers
- Transversalis fasica
- Peritoneum
What are the three anterolateral muscles in the abdominal wall?
- External oblique
- Internal oblique
- Rectus abdominis
(the lateral muscles have aponeurosis that envelops the midline rectus abdominus muscles) (abs)
What is the arcuate line?
The lower limit of the posterior layer of rectus sheath.
Point at which inferior epigastric vessels pierce the rectus abdominus.
(1/2 way between umbilicus and pubic crest)
What is a mesentery?
A double fold of peritoneum, that attaches certain abdominal viscera to the posterior abdominal wall.
What is contained in mesenteries?
- Blood vessels
- Lymph vessels
- Nerves
- Fat
What is a peritoneal ligament?
A double fold of peritoneum that connects two viscera together.
OR
a viscera to the abdominal wall.
