Anatomy and physiology Flashcards
Name the 4 layers of the alimentary. canal.
Mucosa, Submucosa, Muscularis externa, serosa (adventitia)
What kind of epithelium is in peritoneum?
Squamous
Name 4 organs described as retroperitoneal
Ascending colon, descending colo, kidneys, pancreas
Name 4 intraperitoneal organs
Transvers colon, sigmoid colon, stomach, spleen
What is the order of the three main arteries supplying alimentary canal from top to bottom?
Celiac trunk, superior mesenteric, inferior mesenteric
What does the celiac trunk supply?
Stomach, SI, Pancreas, Liver - SSPL
What does the superior mesenteric supply?
SI, Cecum, Ascending colon, transverse colon - SCAT
What does the inferior mesenteric supply?
Descending colon, sigmoid colon, rectum - DSR
Where does all lymph of GI tract drain into?
Celiac, superior mesenteric and inferior mesenteric. Cysterna chyli and into thoracic duct.
What week is gastrulation?
Week 3
During gastrulation what layer forms the GIT?
Endoderm
Name organs of the foregut
Stomach, spleen, liver, gall bladder, pancreas, proximal half of duodenum
Name organs of the midgut
Distal half of duodenum to proximal 2/3 of transverse colon
Name organs of the hindgut
Distal 1/3 of transversals colon to rectum
When does the foregut form?
Week 4 (90 degree rotation along longitudinal axis then ant-post rotation)
When does the pancreas and spleen form?
Week 5
Name forgut anomalies
Oesophageal atresia and tracheo-oesophageal fistula, annular pancreas
When does the midgut form?
Week 6 ( elongation, rotation and herniation)
What happens to the intestinal loop during the 10th week?
Moves into abdominal cavity
Name midgut anomalies
Omphalocele, gastroschisis, Meckel’s diverticulum
When does hindgut form?
End of week 7
Name hindgut anomalies
Urorectal fistula, rectoanal fistula, rectovaginal fistula, imperforate anus
Know the quadrants of the abdomen
R. hypochondrium, epigastric, L.hypochondrium, R. lumbar, periumbilical, L. lumbar, R.iliac fossa, hypogastrium, L. iliac fossa
Where is bile produced?
Liver
What forms the triangle of calot?
Cystic artery, cystic duct, common hepatic duct
What plane does the pancreas lie along?
Transpyloric
What is the surface landmark of the spleen?
Left hypochondrium, 9-11 ribs
What parts of the small intestine has a thin wall, less blood vessels and lots of Peyer’s patches?
Ileum
What are the branches of the celiac trunk?
Left gastric, hepatic, splenic
What vertebral levels do the 3 main vessels arise?
Celiac trunk = T12
Sup. mesenteric = L1
Inf. mesenteric = L3
What does the sup. mesenteric, inf. mesenteric and splenic veins join to form?
Hepatic portal vein
Give examples of portocaval shunts
Haemorrhoids, oesophageal varices, caput. medusae
What causes referred pain?
Visceral sensory fibres referred to appropriate dermatome
Describe an example of somatic system involvement in refereed pain
Inflammed gall bladder detected by C3,4 and 5 since. C4 has two areas
What is the PNS supply of abdominal organs?
Vagus
Pelvic splanchnic nerves (S2,3&4)
Whats is the SNS supply of the abdominal organs?
Abdominopelvic splanchnic nerves
Prevertebral sympathetic ganglia
Abdominal aortic plexus
What is Macburney’s point?
Site of max tenderness in acute appendicitis
What are the four F’s associated with gallstones?
Fatty, Fertile, Female and Forty
What are the two layers of the muscularis externa?
Inner circular and outer longitudinal
What is the difference between serosa and adventitia?
Serosa has peritoneum, Adventitia doesn’t
What epithelium is found in oesophagus?
Stratified squamous, non-keratinised
What. epithelium is found in the stomach?
Simple columnar
In which organs are glands found in the submucosa?
Oesophagus and duodenum (Brunner’s glands)
What do glands in the stomach mucosa secrete and by what cells?
Parietal cells = gastric acid
Chief cells = pepsin
Where are Peyer’s patches found?
SI and ileum
What is distinctive in the large intestine?
Deep crypts and no villi
What shows high density (white) in abdominal x-rays?
Bone, stones, metal, NG tubes
What shows low density (black) in abdominal x-rays?
Air, fat, bowel gas
What shows medium density (grey) in abdominal x-rays?
Soft-tissue, liver, spleen, kidneys, psoas
What is an abdominal x-ray good at showing?
Obstruction (NB: if air in rectum then no obstruction)
What is the rule for determining and obstruction on x-ray?
<3cm = SI <6cm = LI <9cm = Caecum
What can cause obstruction in SI?
Cancer, adhesions, IBD strictures, gallstone ileus
What nervous supply and specific cranial nerves cause increased salivation?
Parasympathetic nervous system (VII and IX)
What nervous supply decreases secretion?
Sympathetic nervous system (superior cervical ganglion)
What is the function of the PNS (vagus) in the GI tract?
Increase secretion and motility
What is the function of the SNS (splanchnic nn) in the GI tract?
Decrease secretion and motility
What are the plexuses of the ENS?
Submucosal and myenteric
What two organs are in a series?
Liver and gut
What monomers and bonds form starch and glycogen?
Glucose and a-1, 4-glycosidic bonds
What are the two types of starch?
a-amylase (straight chains) and amylopectin (branched)
What bonds are found in cellulose?
b-1,4- glycosidic bonds
What breaks down and hydrolyses starch and glucose respectively?
a-amylase
What monomers form lactose?
glucose and galactose
What monomers form sucrose?
glucose and fructose
What monomers form maltose?
glucose and glucose
Where are brush border enzymes found?
Start of duodenum
What transporters are required to transport glucose across villi membrane?
SGLT-1, Glut-2, Na-K ATPase
What transporters are required to transport fructose across villi membrane?
glut-5 and glut-2, not Na-K ATPase
What transporters are required to transport AAs and small proteins across villi membrane?
SAAT1 and NA-K ATPase
What transporters are required to transport di- and tripeptides across villi membrane?
PepT1 and H+ pump (NA-H Exchanger)
Lipase breaks down triacylglycerol into what?
Monoglyceride and two FAs
What is emulsification?
Break down of fats into droplets (increase SA)
What is a micelle?
Bile salt + monoglyceride + fatty acids + phospholipids
What vitamins are fat soluble?
A,D,E,K
Where is the 10% of iron absorbed daily ingested?
Duodenal enterocytes (via DMT1 transporter)
What is the only nutrient controlled by the gut?
Iron
Describe hyperaemia
increased ferritin (iron stores) = more iron bound in enterocytes
Describe anaemia
Reduced ferritin = more iron released in blood
What are the components of saliva?
Water, Mucin, A-amylase, Lysozyme, Electrolytes
Describe the saliva produced by the PNS.
Profuse and watery
Describe the saliva produced by the SNS.
Small volume and viscous
What is the function of the antrum of the stomach?
Gastrin, mixing/grinding (chyme)
What releases pepsinogen?
Chief cells
What releases HCl and intrinsic factor?
Parietal cells
Name 3 mechanisms of gastric acid secretion.
Neurocrine, endocrine and paracrine
What is a Zymogen?
An inactive precursor
What does intrinsic factor do?
Absorb vit b12
What are the 2 phases of gastric acid secretion?
Cephalic (sight, smell, taste, gastrin/ACh) and gastric (distension of stomach, peptides in lumen, gastrin/Ach)
What is the function of enterogastrones?
Response to acid, FAs or monglycerides in duodenum
What prevents ulceration?
Gastrin, Histamine and Acetylcholine reduce pH
Prostaglandins switches of adenylate cyclase
What does acid in duodenum trigger?
Long vagal and short ENS reflexes, secretin release to cause HCO3 secretion
What produces peristaltic waves?
Pacemaker cells in longitudinal muscle layer and basal electrical rhythm
What are the main secretions of the pancreas?
Bicarbonate (duct cells) and digestive enzymes (acing cells)
What stimulates bicarbonate secretion from pancreas?
Secretin from acid in duodenum
What stimulates digestive enzyme secretion from pancreas?
CCK from fat/AAs in duodenum
What is the role of the sphincter of odd?
Controls delivery of pancreatic enzymes and bile into duodenum
What is the function of the liver?
Production and secretion of bile
What is the composition of bile?
Bile acids, lecithin, cholesterol, bile pigments, toxic metals, bicarbonate
What are bile pigments?
Breakdown product of Hb
What are bile acids synthesised from?
Cholesterol
What is the role of secretin?
Acid neutralisation
What is the role of CCK?
Fat/AA digestion
What are the two types of intestinal movement?
Segmentation and peristalsis
Motilin…
Increases migrating motility complex during peristalsis
What do villi absorb?
NaCl, monosaccharides, AAs, peptides, fats, vitamins, minerals, water
What do villi crypt cells secrete?
Cl and H20
Where are tenai coli and haustra found?
Large intestine
Describe the physiology of constipation.
NO absorption of toxins from feral material following long periods of retention. Due to distension of rectum.
How does enterotoxigenic bacteria cause secretory diarrhoea?
Increase Cl and H2O secretion from crypts which swamps absorptive capacity of villus cells
What is the treatment of secretory diarrhoea?
Na/glucose solution (drives H2O reabsorption, oral rehydration therapy
What are the optimal conditions for pathogens in GIT?
pH >6 and slow transit time
What happens when the GIT mucous layer barrier is disrupted?
Bacterial cells penetrate causing dysregulated immune response (inflammation)
What are probiotics?
Added live bacteria
What are probiotics?
Food for resident bacteria
What happens when the normal GIT immune response goes wrong?
IBD and Coeliac disease
What are the functions of the liver?
Protein synthesis, metabolism of fat and carbs, detoxification fo drugs and toxins
What hormone is most likely to be deficient after a gastrectomy?
Gastrin
The excess production of which hormone is most likely to cause delayed gastric emptying with normal gastric mucosa?
Cholecystokinin
The pH of gastric acid secretions is found to be 1 in patient X, what mechanism is responsible for this?
Hydrogen/potassium adenosine triphosphatase pumps
