Week 8 Lec Flashcards
large intestine absorption struc
microvilli
simple columnar epithelial cells
large intestine secretion struc
abundant Goblet cells
crypts of lieberkuhn
large intestine elimination struc
teniae coli of muscularis externa
sphinctors
colon mucosa
Mucosa
* simple columnar epithelium
* muscularis mucosae
* cellular lamina propria
* NO villi
* simple tubular glands = crypts of Lieberkuhn
* stem cells in bottom of crypts
colon Submucosa type of CT
dense irregular connective tissue
colon muscularis externa
- inner circular smooth muscle
- outer longitudinal smooth muscle = tenia coli
colon serosa
- simple squamous mesothelium
- loose connective tissue
colon epithelium
Enterocytes – simple
columnar epithelia
Goblet cells abundant,
4:1 in colon
Crypts of Lieberkuhn
Lamina propria
Muscularis mucosae
Auerbach’s plexus
located between the inner & outer smooth muscle
between circular and longtiudnal muscle
Colon = large intestine
How does it differ from the small intestine?
- To increase functional surface area:
microvilli only - Goblet cells abundant in epithelium
for lubrication - NO paneth cells
- NO villi
- Crypts of leiberkuhn – simple tubular glands
- Teniae coli of muscularis externa
Anal Canal
distinguishing histological features : upper region
simple columnar epithelium
numerous glands + goblet cells
smooth muscle
Anal Canal
distinguishing histological features : lower region
stratified squamous epithelium
numerous glands
skeletal muscle
Anal Canal
distinguishing histological features : anal columns
vertical fold of mucosa and submucosa
allow stretch
contain rectal arteries and veins
liver bile production function
BILE production
Bile contains cholesterol, bile salts (made from cholesterol == Emulsifies fats in GIT ), phospholipids and bile pigment (haem in erythrocytes=> bilirubin ==give faeces their colour)
liver alcohol metabolism function
ALCOHOL metabolized to acetate + acetaldehyde
excreted in urine, skin, lung
liver aa metabolism function
Amino acids–> ammonia–> urea excreted by kidneys
liver plasma prodteins production function
Production of plasma proteins such as albumin and clotting factors
liver lipids production function
Lipid metabolism (cholesterol, triglycerides and phospholipids)
lipid storage function
Storage of iron, Vit B12, folic acid and glycogen
Portal triad
portal vein
hepatic artery
bile duct
Hepatocytes Surface specializations:
- 2 free surfaces facing sinusoids covered in short microvilli
- Desmosomes & gap junctions between hepatocytes
- Bile canaliculi (1μm diameter) between hepatocytes
Sinusoids epithelium
Endotheium
discontinuous with large fenestrae and
incomplete basement membrane
sinusoids kupffer cells
Phagocytes destroy microorganisms, damaged erythrocytes…
No junctions with the endothelial cells
Rest on the apical surface of the endothelial cells in the
sinusoid lumen
sinusoids stellate cells
Store Vitamin A
Activated in liver disease to secrete collagen –> fibrotic cirrhosis
Space of Disse
- Site of exchange of material between blood & hepatocytes
- Lies between the surface of hepatocytes & endothelial cells
- Hepatocyte microvilli project into this space
- Stellate cells located in space of disse
Plasma that remains in space of disse (lymph) drains away via
canals then lymph vessels in the portal triads to thoracic duct
Space of Disse
Gallbladder function
- Stores, concentrates & adds mucus to BILE
- BILE released in response to fatty foods in duodenum
gall bladder
Folded mucosa
simple columnar epithelium + lamina propria
* Muscularis externa
* Adventitia with elastic fibres & adipocytes
& outer free surface covered with serosa (peritoneum)
* NO muscularis mucosae or submucosa present
Pancreas functions acini
ACINI secretions contain over 20 digestive inactive enzymes
trypsinogens, protease, elastase, lipase…
plus water & electrolytes
pancreas function ducts
Pancreatic DUCTS add bicarbonate ions (alkaline fluid)
pancreas duodenal mucosa function
Enteropeptidases released from DUODENAL MUCOSA
activate the enzymes for digestion
Pancreas Duodenal enteroendocrine cells
release cholecystokinin CCK & secretin into the blood
CKK : enzyme secretion
secretin : water & electrolyte secretion
