Lecture 23 Flashcards
What does the large intestine absorb?
Water
What is the function of the large intestine?
To store faeces until defecation
What are the three constituents of the large intestine?
The cecum, colon, and rectum
What are the four components of the colon?
Ascending, transverse, descending, sigmoid
What separates the ascending colon and the transverse colon?
The right colic (hepatic) flexure
What separates the transverse colon and the descending colon?
The left colic (splenic) flexure
What is the location of the ascending and descending colons?
Lateral and retroperitoneal
What is the location of the sigmoid and transverse colon?
Intraperitoneal
What is the cecum?
A blind-ended pouch where the SI and LI connect which houses the appendix and ileocecal valve
What is the function of the ileocecal valve?
To regulate the passage of material into the large intestine
What is the function of the vermiform appendix?
Used as a reserve of large intestinal bacteria
Where is the vermiform appendix?
Attached to the cecum
What is appendicitis?
When the appendix becomes inflamed
What does the large intestine wall need modification for?
To store faeces, expel faeces during defecation, to be lubricated and allow the absorption of water
What are the teniae coli?
Bands of longitudinal muscle around the LI wall
What is the function of the teniae coli?
To contract for motility
What is the haustra?
A series of pouches along the LI wall
What is the function of the haustra?
To store faeces longer
What are omental appendices?
Sacs of fat along the LI wall
What are the layers of the large intestines muscularis?
Inner circular layer and outer longitudinal layer
What is different about the outer longitudinal layer in comparison to the SI?
Contains teniae coli, the three thicker bands of muscle for stronger contractions
What is the composition of the large intestinal musoca?
It lacks villi but has intestinal glands from invaginated mucosa.
What are the cells of the LI mucosa?
Absorptive cells for water and salt and goblet cells for protection and lubrication
What is the rectum?
The last part of the large intestine that stores faeces
What is the anal canal?
The connection between the rectum and anus
What structural change occurs within the anal canal?
Epithelium changes from simple columnar to stratified squamose
Why does the epithelium change to stratified squamose?
For extra protection from abrasions
How many anal sphincters do we have?
Two; internal and external
What is the internal anal sphincter?
Sphincter composed of smooth muscle for involuntary control
What is the external anal sphincter?
Sphincter composed of skeletal muscle for voluntary control
What is the defecation reflex?
When faeces move into rectum, stretch receptors are stimulated. Internal anal sphincter relaxes from a localised reflex and also a longer reflex that goes to spinal cord to make us aware we need to go to the toilet.
What is the function of the liver?
To metabolise products, detoxify blood and produce bile
What is the location of the liver?
A wedge shaped organ in the superior right quadrant of the abdominopelvic cavity, attached to the stomach by the lesser omentum
What is the gallbladder?
A hollow organ below the liver, connected via the cystic duct to the bile duct
What is the function of the gallbladder?
To store and concentrate bile
What can cause problems in the gallbladder?
Gallstones which is calcified bile that can obstruct tubes
How much cardiac output does the liver receive?
~25%
What is the blood supply of the liver?
1/3 from the hepatic artery and 2/3 from the hepatic portal vein
What does the hepatic artery supply the to liver?
Oxygenated blood
What does the hepatic portal vein supply to the liver?
Nutrient-rich, deoxygenated blood from the small intestine to be processed by hepatocytes
Where do the hepatic portal vein, heaptic artery and bile duct travel within?
The lesser omentum
What is the structure of the liver?
Lobes are separated into lobule functional units
What do lobules contain?
Rows of hepatocytes that produce bile and detoxify the blood, liver sinusoidal capillaries between rows and bile canaliculi canals between cells
What is the hepatic portal triad?
A branch of hepatic artery, hepatic portal vein and bile duct
In what direction does blood flow in the liver?
From the branch of the hepatic portal vein at the peripheries of the lobule towards the central vein in the centre of the lobule
What processes the blood that travels through the lobules?
The hepatocytes that also produce bile
Where is bile secreted in the lobules?
It is secreted by the hepatocytes into the canalicular and travels to the bile duct which is situated at the peripheries of the lobules
Where does the central vein drain to?
The hepatic vein which later drains to the inferior vena cava
Where does the bile from the hepatocytes travel after it has entered the bile ducts?
To the gallbladder
What connects the bile duct and the pancreatic duct?
The hepatopancreatic ampulla
