small intestine Flashcards
(26 cards)
What is the small intestine’s primary function?
The small intestine is the body’s major digestive organ, where usable nutrients are prepared for absorption into the cells of the body.
Villi and Microvilli: These tiny finger-like projections increase the surface area, making absorption more efficient. They increase more points for nutrients to touch
Capillaries and Lacteals:
Capillaries absorb simple sugars (glucose), amino acids (from proteins), and water-soluble vitamins into the bloodstream.
Lacteals (part of the lymphatic system) absorb fats and fat-soluble vitamins (A, D, E, K).
Q: What is the length of the small intestine in a living person?
A: The small intestine is 2 to 4 meters (7 to 13 feet) long in a living person.
Q: From where does the small intestine extend?
A: The small intestine extends from the pyloric sphincter to the large intestine.
Q: What is the position of the initial part of the small intestine?
The first part of the small intestine is located behind a membrane called the peritoneum, which lines the inside of the abdomen.”
Lies. in a retroperitoneal position
Q: How is the small intestine suspended in the abdominal cavity?
A: The small intestine hangs in sausagelike coils in the abdominal cavity, suspended from the posterior abdominal wall by the fan-shaped mesentery.
The mesentery holds the small intestine and parts of the large intestine in place while allowing them to move slightly.
It contains blood vessels, nerves, and lymphatic vessels that supply the intestines.
The fan shape helps provide stability and flexibility for the intestines, ensuring they stay in the correct position while still being able to expand and contract as needed during digestion.
How is the small intestine positioned in the abdominal cavity relative to the large intestine?
A: The large intestine encircles and frames the small intestine in the abdominal cavity.
Q: What are the three subdivisions of the small intestine?
A: The three subdivisions of the small intestine are the duodenum, jejunum, and ileum.
Q: How long is the duodenum, and what percentage of the small intestine’s length does it account for?
A: The duodenum is about 12 finger widths long and accounts for 5% of the small intestine’s length.
Q: What is the length of the jejunum, and what percentage of the small intestine’s length does it account for?
A: The jejunum accounts for nearly 40% of the small intestine’s length.
Q: What is the length of the ileum, and what percentage of the small intestine’s length does it account for?
A: The ileum accounts for almost 60% of the small intestine’s length.
Q: Where does the ileum join the large intestine?
A: The ileum joins the large intestine at the ileocecal valve.
Q: Where does chemical digestion of food begin in the digestive process?
A: Chemical digestion of food begins in earnest in the small intestine
G Chemical digestion begins in the mouth but is limited.
The small intestine is where digestion happens “in earnest” because most enzymes work there, completing the breakdown of food into absorbable nutrients.
The jejunum is where most absorption happen
Q: How does the pyloric sphincter help the small intestine?
A: The pyloric sphincter controls the movement of chyme into the small intestine and prevents the small intestine from being overwhelmed.
Q: What happens in the duodenum during digestion?
A: In the duodenum, enzymes produced by intestinal cells, as well as enzymes from the pancreas, help to complete the chemical breakdown of food.
Amylase → Breaks down starch.
Proteases (trypsin, chymotrypsin) → Break down proteins.
Lipase → Breaks down fats with the help of bile from the liver.
Q: What role does the pancreas play in digestion in the small intestine?
A: The pancreas produces enzymes that are delivered to the duodenum through the pancreatic ducts to aid in chemical digestion.
Q: How does bile contribute to digestion in the small intestine?
Bile, produced by the liver, enters the duodenum through the bile duct and helps in the digestion of fats, allowing the intestines to absorb fat-soluble nutrients.”
Q: What is the hepatopancreatic ampulla, and where is it located?
A: The hepatopancreatic ampulla is the flasklike enlargement formed by the junction of the main pancreatic and bile ducts at the duodenum.
Yes, exactly! The hepatopancreatic ampulla is the space where the pancreatic duct (which carries digestive enzymes from the pancreas) and the common bile duct (which carries bile from the liver and gallbladder) meet. This is also where the chyme (partially digested food) from the stomach enters the duodenum (the first part of the small intestine).
Key Points:
Bile (from the liver) helps with fat digestion.
Pancreatic enzymes (from the pancreas) break down fats, proteins, and carbohydrates.
Chyme from the stomach mixes with these digestive fluids in the duodenum.
Q: How do bile and pancreatic juice enter the duodenum?
A: Bile and pancreatic juice enter the duodenum together through the duodenal papilla.
Q: Where does nearly all nutrient absorption occur in the digestive system?
A: Nearly all nutrient absorption occurs in the small intestine.
Q: What structures in the small intestine increase its absorptive surface area?
A: The small intestine has villi, microvilli, and circular folds that increase its absorptive surface area.
Q: What are villi, and what do they contain?
A: Villi are fingerlike projections of the mucosa with a rich capillary bed and a lymphatic capillary called a lacteal, which absorb nutrients.
Q: What is the function of microvilli in the small intestine?
A: Microvilli are tiny projections of the plasma membrane of mucosal cells that form the “brush border,” bearing enzymes that complete the digestion of proteins and carbohydrates.
What are circular folds (plicae circulares), and what is their role?
Circular folds are deep folds of both mucosa and submucosa that increase surface area and slow down chyme, allowing for more efficient nutrient absorption.
Q: How do circular folds differ from rugae in the stomach?
A: Unlike the rugae in the stomach, circular folds do not disappear when food fills the small intestine; they remain to increase surface area and slow down chyme.
