Lecture 12 Flashcards
How long is the small intestine?
2.5 to 3 metres long.
What are the 3 parts of the small intestine, from front to back?
Duodenum (first 30cm),
jejenum,
ileum.
What does the duodenum receive from the …stomach?
… pancreas?
…liver and gallbladder?
Chyme.
Enzymes.
Bile.
What function is the duodenum responsible for?
Digestion.
Which regions in the small intestine absorb nutrients, water, vitamins, minerals?
All 3.
What secretes copious amounts of bicarbonate-rich fluid into the stomach?
Crypts of Liberkuhn.
Do the cells in mucosa form villi in the stomach?
Yes.
Do villi have capillaries and lymphatic vessels?
Yes.
What is the total surface area available for digestion and absorption due to villi and microvilli?
300m^2.
What is associated with the brush border (microvilli) in the stomach?
Digestive enzymes (lactase, maltase, sucrase, nucleases, peptidases etc.)
How long is the pancreas, and how much does it weigh?
About 20cm long, weighs 100g.
What do acinar cells make, and where are they found?
Digestive enzymes, bicarbonate.
Found in the pancreas.
Where are digestive enzymes synthesised in the pancreas released?
Duodenum, via secretory duct.
What 4 zymogens are produced in the pancreas?
Chymotrypsin, Trypsin, Carboxypeptidase, Elastase.
What type of cell is an acinar cell?
Exocrine cell.
What 5 active enzymes are secreted by acinar cells in the pancreas?
Pancreatic amylase, lipase, proteases, DNase, RNase.
What do Islets of Langerhans synthesise, and what type of cell are they?
Synthesises hormones to secrete into the blood.
Endocrine cells.
What 3 types of cells are found in the islets of langerhans?
And what is produced by each one of these cells?
β-cells : insulin
α-cells : glucagon
δ-cells : somatostatin.
Where are monosaccharides, amino acids, electrolytes, water transported to in the body from the small intestine?
Transported to blood capillaries of villi, then to liver via mesenteric veins, then hepatic portal vein.
What do bile salts do to fats? And why?
Emulsifies fats into micelles (small droplets). Makes them susceptible to digestion by pancreatic lipase.
What happens to fatty acids and monoglycerides?
Converted into chylomicrons, which enter lymphatic capillary system. This drains into blood via left subclavian vein in neck.
What does the liver make, and where are these products stored?
Bile pigments and bile salts. Stored in gall bladder.
What dos the liver do generally?
Detoxifies absorbed materials, regulates blood composition, and blood glucose levels (glycogen).
How does the liver contribute to blood plasma?
Produces many of the proteins.
What stimulates the conversion of glucose to glycogen?
Insulin.
What stimulates the conversion of glycogen to glucose?
Glucagon.
How would you describe bile salts chemically?
Amphipathic, cholesterol derivatives.
Bile salts are recirculated. What is the pathway?
Ileum, capillaries, hepatic portal vein, liver, common bile duct, duodenum…
How are chylomicrons formed?
Fatty acids and monoglycerides from fat digestion absorbed and synthesised into triglycerides.
These are then packed into chylomicrons by golgi apparatus.
What happens after exocytosis to chylomicrons?
Enter lacteals, then into lymphatic system.
How long is the colon, and where is it located?
Last metre of GI tract.
What 4 parts comprise the colon? (start to end)
Ascending, transverse, descending, sigmoid.
Does digestion and absorption happen in the colon?
No digestion, little absorption.
What happens in the first 3 segments of the colon?
Water absorption and inorganic ions.
What is the storage colon used as?
Storage depot.
How many anal sphincters are there, and what is each called?
2.
Rectum and anus.
At what kind of pH are digestive enzymes in the intestine most active at?
Slightly alkaline pH.
What are the 3 phases in the regulation of gastric secretion? How long does each take?
Cephalic/Reflex phase. (few minutes)
Gastric phase. (few hours)
Intestinal phase. (brief)
What happens in cephalic phase?
Nervous system stimulates salivary and gastric secretions in response to aroma, taste, sight, thought of food.
