Lecture 23: Large Intestine and Comment on the Liver Flashcards
What does the large intestine consist of?
3
- Cecum
- Colon
- Rectum
What does the cecum connect to?
Small intestine
What can the colon be divided into?
4
- Ascending
- Transverse
- Descending
- Sigmoid
What is the position of the ascending and descending colon?
Retroperitoneal
What is the position of the transverse and sigmoidal colon?
Intraperitoneal
What does the Ileoceal valve do?
Regulate the passage of material into the cecum and prevents back flow into the ileum
What is the appendix?
A reserve of large intestine bacteria population
Where is the appendix located?
In a variety of positions that differs between people
What is inflammation of the appendix called?
Appendicitis
What does a Barium enema enable?
x-ray images to be taken of large intestine to asses function
What are 3 gross structures of the large intestine?
- Teniae Coli
- Haustra
- Omental appendices
What are Teniae Coli?
Bands of longitudinal smooth muscle
What are Haustra?
Series of pouches in the wall of the colon
What are Omental appendices?
Sacs of fat
What are Teniae Coli a modification of?
Muscularis layer
What is the Teniae Coli?
Three bands of longitudinal smooth muscle
What is the function of Teniae Coli?
Produce stronger contractions
What are the 4 layers of the gut tube?
- Mucosa
- Submucosa
- Muscularis
- Adventitia
What is there a lack of in the large intestine?
Villi
What does the mucosa of the gut tube do?
Invaginates to form intestinal glands
What does the mucosa consist of?
- Epithelium
- Lamina propria
- Muscularis mucosae
What does the muscularis mucosa not do?
invaginate
What is the function of the mucosa of the colon?
Water and salt absorption
What do goblet cells produce in the mucosa of the colon?
Mucous for protection and lubrication
What do the anal columns mark?
Where epithelium changes
What is the epithelium before the Anal columns?
Simple columnar
What is the epithelium of the anal canal?
Stratified squamous
What are the 2 anal sphincters?
- Internal anal sphincter
- External anal sphincter
What is the internal anal sphincter made of?
Smooth muscle
What is the external anal sphincter made of?
Skeletal muscle
How is the internal anal sphincter controlled?
Involuntary control
How is the external anal sphincter controlled?
Voluntary control
What happens when feaces move into the rectum?
It stimulates stretch receptors
What happens once the stretch receptors in the rectum are stimulated?
Internal sphincters relax involuntarily
What happens if there is a conscious decision to dedicate?
External/internal sphincters relax
What is the location of the Liver?
Superior right quadrant of abdominopelvic cavity
What is the function of the liver?
Produce bile which is stored in the gall bladder
How much blood does the liver receive?
25% of the cardiac output
How much of the blood supplied to the liver is from the hepatic artery?
1/3 of the total supply
How much of the blood supplied to the liver is from the hepatic portal vein?
2/3 of the total supply
What type of blood is carried by the hepatic portal vein?
Nutrient rich, deoxygenated blood from the small intestine
What is blood from the hepatic portal vein processed by?
Hepatocytes
What do the hepatic portal vein, hepatic artery and bile duct travel within?
The lesser omentum
What is the structure of the liver?
Functional units called lobules
What are lobules of the liver organised into?
Rows of hepatocytes
What do hepatocytes do?
Produce bile
What do hepatocytes surround?
A vein
Where are liver sinusoids found?
Between rows of hepatocytes
Where are bile canaliculi found?
Between hepatocytes
What makes up a portal triad?
- Branch of hepatic artery
- Branch of hepatic portal vein
- A bile duct
What direction does blood flow in the liver?
Towards the central vein
What happens to the blood travelling towards the central vein?
It is processed by hepatocytes, which produce bile
What happens to bile secreted into canaliculi?
Travels to bile duct
What do the central veins drain into?
Hepatic vein which drains into the inferior vena cava
Where does liver bile travel, to be stored?
The gall bladder, where it is stored and concentrated
What does the bile duct ultimately join?
Pancreatic duct at hepatopancreatic ampulla
