Anatomy Flashcards
What are the layers of the gut wall?
Mucosa (innermost)
Submucosa = dense CT, blood vessels, lymphoid tissue, Meissner plexus
External muscle layers = auerbach plexus
Serosa (outermost) = blood/lymph vessels
What are the layers of the mucosa?
Epithelium = facilitate transport, absorption, hormones, mucus
Lamina propria = lymphoid nodes, IgA
Muscularis mucosae = smooth muscle
What epithelia type lines the gut?
Stratified squamous = beginning and end of gut
When secretion/absorption is needed = simple columnar
What is an enterocyte?
Simple columnar cell that has been specialised for absorption
Microvilli = brush border (contains enzymes)
What is a goblet cell?
Scattered between enterocytes
Prod mucus = lubrication, resist acid (HCO3), protection, food source for bacteria
What are foveolar cells?
Line gastric mucosa/pits
Secrete mucus/HCO3
How does the GI tract achieve such a large surface area?
Permanent folds
Villi
Microvilli
Crypts
What happens when the bowel becomes perforated?
Spill into the peritoneal cavity
Highly acidic
Infection
What is the role of stem cells in the GI tract?
Reside in crypts
Constantly divide to replace epithelia
Outline paneth cells
Base of crypts
Secrete anti-bacterial proteins
Describe enteroendocrine cells in the gut
Deep in crypts
Secrete = gastrin, CCK, secretin
Define cryptitis
Inflam of gut wall
Define crypt abscess
Presence of neutrophils in gut lumen
How is exocrine glandular tissue in the gut organised?
Acini = serous secretions and enzymes
Tubules = secrete mucous
E.g. Salivary, pancreas
Define ulceration
Erosion through muscularis mucosae
Outline coeliac disease
Inability to tolerate gliadin
Damages mucosa
What is IBS?
Irritable bowel syndrome
Symptoms = abdo pain, changes in bowel movements, without evidence of underlying disease
What are the layers of the abdominal wall
Skin
Subcutaneous fat
Fascia: Fascia: Superficial/Deep
External oblique
Internal oblique
Transverse abdominis
Rectus abdominis
Transversalis fascia
Peritoneum
What is an aponeurosis?
Thin sheet like tendon
Where = external oblique, internal oblique, transverse abdominis
What is the rectus sheath?
Aponeurosis of lateral muscle surrounding the rectus abdominis
How does the rectus sheath vary?
Arcuate line = half way between naval and pubic symphysis
External oblique always anterior
Above = internal (A and P), transverse (P) around rectus abdominis
Below = internal/transverse only anterior of rectus abdominis
What is mesentery?
Double fold of peritoneum that attaches certain viscera to the posterior abdo wall
Conduit = blood vessels, lymph, nerves, fat
Jejunum, ileum, appendix, transverse colon, sigmoid colon, rectum
Describe what a peritoneal ligament is
Double fold of peritoneum that connects 2 viscera together
Or double fold connecting viscera to anterior abdo wall
What is omenta?
Double fold peritoneum
Greater = down from greater curve of stomach
Lesser = connects lesser curve of stomach to liver
What is the purpose of sphincters?
Divide tube into sections
Control movement along tube
Prevent reflux
Name the sphincters of the Gi tract
Upper oesophageal
Lower oesophageal
Pyloric sphincter
Oddi
Ileo-caecal (valve)
Anal = Internal, External (voluntary)
Outline the blood supply to the Gi tract
Foregut = coeliac trunk
Midgut = superior mesenteric A
Hindgut = inferior mesenteric A
What is the venous drainages of the gut?
All goes to the liver via the portal vein
Where do the linea semilunares lie?
vertically at the lateral edges of the rectus abdominus muscles
What distinguishes sites of high absorption in the GI tract from sites of low absorption?
large surface area
Where is the most common site for peptic ulceration?
duodenum
What are the attachments of the lesser omentum?
liver to the lesser curve of the stomach and proximal duodenum
The portal vein is formed when which 2 veins unite?
superior mesenteric vein and splenic vein
What is the location of the linea alba?
vertical midline from the xiphoid process to pubic symphysis
