Lecture 23: Large Intestine and Comments on the Liver Flashcards
what are the parts of the large intestine?
cecum
colon (divides into more parts)
rectum
what are the parts of the colon?
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
what part of the large intestine is retroperitoneal?
ascending and descending colon
what part of the large intestine is intraperitoneal?
transverse and sigmoidal colon
what is the ileocecal valve?
between the ileum and cecum
- regulates the passage of material into the cecum
what are the features of the appendix?
- has a reserve of bacteria
- variety of locations
- inflammation is called appendicitis
what is a barium enema?
enables x-ray image to be taken of large intestine to assess function
what structures does the large intestine have?
- teniae coli
- haustra
- omental appendices
what are teniae coli?
- modification of muscularis layer
- three bands of longitudinal smooth muscle
- help with stronger contraction
what are haustra?
series of pouches in the wall of colon
what are omental appendices?
sacs of fat
how are the villi in the large intestine?
lack of villi in large intestine
what does the mucosa do in the large intestine?
invaginates to form intestinal glands
what is the function of the mucosa of the colon?
water and salt absorption
goblet cells in the mucosa produce mucus (protection and lubrication)
what is the epithelia like in the rectum and anus?
anal columns mark boundary where epithelium changes
- before the anal columns it is simple columnar epithelium
- the anal canal has stratified squamous epithelium
what are the sphincters of the anus?
internal anal sphincter
- smooth muscle (involuntary)
external anal sphincter
- skeletal muscle (voluntary)
what is the defacation reflex?
- movement of faeces into the rectum stimulates stretch receptors
- the internal anal sphincter relaxes (involuntary)
- after conscious decision to defecate is made, external anal sphincter relaxes
where is the liver located?
superior right quadrant of abdominopelvic cavity
what is the function of the liver
produce lots of bile
- stored in gall bladder
what is the blood supply of the liver?
- liver receives 25% of cardiac output
- 1/3 of blood supply is from hepatic artery
- the rest is venous blood from hepatic portal vein
- the mesenteric veins contain nutrient rich deoxygenated blood from the small intestine which is processed by hepatocytes
how is the lesser omentum involved in liver blood supply?
hepatic portal vein, hepatic artery and bile duct travel within the lesser omentum
what is the structure of the liver?
- made of functional units called lobules
- rows of hepatocytes produce bile
- liver sinusoids are between rows
- bile canaliculi between cells
- portal triad
what is a portal triad?
- branch of hepatic artery
- branch of hepatic portal vein
- a bile duct
what is blood flow and bile flow like in the liver?
- blood flows towards the central vein
- processed by hepatocytes, which produces bile
- bile is secreted into canaliculi and travels to bile duct
what is the venous drainage in the liver?
central veins drain into the hepatic vein, which drains into inferior vena cava
*note that hepatic vein is different to hepatic portal vein
what does bile do in the liver?
- bile travels to the gall bladder where it is stored and concentrated
- the bile duct joins the pancreatic duct and the hepatopancreatic ampulla
