HUBS192 Lecture 23 - Large Intestine and Comments on the Liver Flashcards
why is the large intestine called the large intestine?
because the large intestine is large in diameter
is the large intestine or the small intestine longer in length?
the small intestine is longer in length
where is the cecum located?
sits in the right iliac of the hip
what does the large intestine consist of starting from the cecum?
from the cecum –> up the ascending colon –> to the right coli (hepatic) flexure –> across transverse colon –> left colic (splenic) flexure –> down the descending colon –> reaching the sigmoidal colon –> and finally into the rectum
why is the sigmoidal colon S-shaped?
S-shaped because the colon has to come up and over the pelvic brim
what 3 components does the large intestine consist of?
1) cecum
2) colon
3) rectum
what 4 parts can the colon be further divided into?
1) ascending
2) transverse
3) descending
4) sigmoidal
what 3 parts of the large intestine are intraperitoneal?
1) cecum
2) transverse colon
3) sigmoidal colon
what 2 parts of the large intestine are retroperitoneal?
1) ascending colon
2) descending colon
where is the ileocecal valve located?
located between the ileum and the cecum
what is the function of the ileocecal valve?
- regulates the passage of material from the ileum into the cecum
- prevents back flow of faeces and bacteria from the large intestine into the small intestine
what is the appendix?
blind ended tubular structure
where is the appendix located?
variety of locations that extend of from the cecum
what is the vermiform appendix?
worm like appendage
what is the function of the appendix?
recolonise a population of bacteria in the large intestine after an infection by a large reserve of a population of intestinal bacteria
what is essential for the GI system?
bacteria in the microbiome produce vitamins, hormones, supply energy and protect against pathogens
what is the name for the inflammation of the appendix?
appendicitis
what does a barium enema allow?
enables x-ray images to be taken of the large intestine to assess its function
what are the 3 gross structures of the large intestine?
1) teniae coli
2) haustra
3) omental appendices
what are the haustra separated by?
separated by semilunar folds
what are the teniae coli?
3 bands of longitudinal smooth muscle
-modification of the muscularis layer
what are the haustra?
series of pouches in the wall of the colon
what are the omental appendices?
sacs of fat
what is the function of the bands of smooth muscle that compose the teniae coli?
to generate strong contractions to propel and move faecal matter through the intestine
what forms intestinal glands in the large intestine?
invaginated mucosa forms the intestinal glands
-muscularis mucosae does not invaginate
what is relationship between the microvilli of the small and large intestine?
lack of microvilli in the large intestine
what is the function of the mucosa of the colon?
carries out the remaining water and salt absorption
-large number of mucus producing goblet cells
what epithelium is present in the rectum superior to the anal columns?
simple columnar epithelium
what epithelium is present inferior to the anal columns?
stratified squamous epithelium
what marks the boundary where the epithelium changes in the rectum?
the anal columns
what are the 2 anal sphincters?
1) internal anal sphincter
2) external anal sphincter
what is the internal anal sphincter composed of and what control is it under?
smooth muscle under involuntary control
what is the external anal sphincter composed of and what control is it under?
skeletal muscle under voluntary control
what is the defecation reflex?
movement of faeces into the rectum stimulates stretch receptors as it causes destination of the rectum. Then the internal anal sphincter relaxes (involuntarily). Then the conscious decision is made to defect by relaxing the external anal sphincter
what is the location of the liver?
superior right quadrant of the abdominopelvic cavity
what is the main function of the liver?
produces bile
where is bile stored?
stored in the gall bladder
what is percentage of cardiac output the liver receives?
25% of the cardiac output
from where does the liver receive 1/3 of its blood supply?
from the hepatic artery
from where does the liver receive 2/3 of its blood supply?
venous blood from the hepatic portal vein
what are the 2 characteristics of blood from the hepatic portal vein?
1) nutrient rich, deoxygenated blood from the small intestine
2) blood processed by hepatocytes
what 3 structures travel within the lesser omentum?
- lesser omentum connects the lesser curvature of the stomach to the liver
- the hepatic portal vein, the hepatic artery and the bile duct travel within the lesser omentum
what are the functional units of the liver?
lobules
what do lobules contain?
rows and rows of hepatocytes (liver cells) the are orientated around a central vein that runs through the lobule
what structure is between the rows of hepatocytes?
liver sinusoids are between the rows
what structure is between the liver cells (hepatocytes)?
bile canaliculi between the liver cells
-travels on the way though to a bile duct
where is a portal triad located?
at the corner of the liver lobules
what collection of 3 important vessel structures composes the portal triad?
1) branch of hepatic artery
2) branch of hepatic portal vein
3) bile duct
what are the 2 functions of hepatocytes?
1) remove toxins from the blood
2) produce bile
what is the blood flow and direction of bile within the liver?
1) blood flows towards the central vein
2) blood is processed by hepatocytes, which produce bile
3) bile is secreted into the canaliculi which then travels to the bile ducts
what is the venous drainage of the liver?
central veins drain the hepatic vein which drains into the inferior vena cava
what is hepatic portal vein?
carries nutrient rich, de-oxygenated from the intestines to the liver
what is the hepatic vein?
carries deoxygenated from the liver to the inferior vena cava
what is the hepatopancreatic ampulla?
dilated region where the bile duct ultimately joins the pancreatic duct
