GI Anatomy & Function Flashcards
The GI tract is made up of what 7 organs?
- Mouth 2. Esophagus 3. Stomach 4. Small intestine 5. Large intestine 6. Liver 7. Pancreas
What happens in the stomach to aid digestion?
- Food is further broken down and converted to CHYME 2. Where protein digestion begins
Where are nutrients absorbed in digestion?
Small intestines
Where are water and electrolytes reabsorbed during digestion?
Large intestine
Which organ produces bile for digestion?
Liver
Where is bile stored until it is needed?
The gallbladder.
Which GI organ plays a major role in glucose storage and release?
Liver
Which pancreatic secretions does the pancreas produce?
Insulin and glucagon.
What is the purpose of VILLI and MICROVILLI in the wall of the small intestine?
To increase its surface area for absorbing nutrients.
Blood flows into the liver via the _______ vein and out of the liver via the __________ vein.
Portal, hepatic Acronym help: IPOH
What are the major functions of the liver?
- Metabolizes Fat, Carbohydrates, and Protein (F, C, P) 2. Stores carbohydrates 3. Produces bile 4. Converts drugs, hormones, and toxins to soluble forms for excretion
What do the endocrine secretions of the pancreas do?
Help regulate blood glucose levels.
What do the exocrine secretions of the pancreas do?
Help digest food in the small intestine.
Insulin consists of _____ and ______ amino acid chains linked by ______.
Alpha, beta, disulfide bonds
What are the 4 primary functions of the GI tract?
- Ingesting food 2. Breaking food down into component parts 3. Absorbing nutrients 4. Excreting wastes
Name all of the organs of the GI tract.
- Mouth 2. Esophagus 3. Stomach 4. Liver 5. Small intestine 6. Large intestine 7. Rectum 8. Anus 9. Gall bladder 10. Pancreas
In what 2 organs does almost all digestion occur?
- Stomach 2. Small intestine
What is the liquid called that is converted from the food mass in the stomach?
Chyme
What happens to chyme after it leaves the stomach?
Passes through the small intestines where nutrients are absorbed.
After leaving the small intestine, what happens next in digestion?
Chyme enters the large intestine where water, electrolytes, and some other substances are reabsorbed.
There are deep folds on the inside wall of the stomach. Why are they there?
They allow the stomach to stretch to a capacity of about 1.5 L.
In the stomach, what substances are secreted by special glands?
- Mucus - protects the stomach wall from itself being digested by stomach acid 2. Pepsinogen - converts to active enzyme pepsin in the presence of HCl and begins process of digesting protein 3. HCl - helps break down food and activates pepsinogen 4. Histamine, Serotonin, and Gastrin, which stimulate HCl production
Where does carbohydrate digestion begin?
In the mouth.
Where does protein digestion begin?
The stomach.
Chyme from the stomach is gradually released into the duodenum through the _________?
Pyloric sphincter
What are the 3 anatomical sections of the small intestine and their lengths?
- Duodenum - 10 inches long 2. Jejunum - 8 feet 3. Ileum - 12 feet
The duodenum contains ducts from the liver that secrete ______ and ________. Pancreatic ducts secrete ____________, which contain _______, __________, ___________.
Bile salts, phospholipids. Pancreatic secretions. Water, enzymes, and electrolytes.
The secretions of the duodenum serve what purpose?
They neutralize stomach acid to create an appropriate environment for the enzymes to function.
Of the three sections of the small intestine, where does most of the digestion and absorption occur?
Jejunum.
On average, how long does it take chyme to pass through the small intestine and get to the large intestine?
5 hours
What are the fingerlike projections called that cover the inner wall of the small intestine?
VILLI, which are in turn covered with even tinier MICROVILLI, which extend from the tops of enterocytes.
Deep _______, __________, and __________ increase the total surface area of the small intestine wall.
Folds, Villi, MICROVILLI
When chyme reaches the small intestine, what is secreted by the intestines?
Incretins gastric inhibitory peptide (GIP) and glucagon like peptide-1 (GLP-1).
What secretes GIP in the intestine?
Cells in the Duodenum.
What secretes GLP-1 in the intestine?
Cells in the ileum and colon.
What is the large intestine also known as?
The colon.
Does the colon contain folds or villi?
No, because all nutrients have been absorbed by this point.
What function does the large intestine serve?
It serves as the area for reabsorbing most of the water and electrolytes secreted earlier in digestion.
Bacteria in the ______________ digest ____________ that the body cannot break down.
Large intestine, carbohydrates.
What are the primary functions of the liver?
- Produces bile that aids in digestion 2. Further metabolizes nutrients into useful substances.
Blood flows into the liver via the __________ vein and out of the liver via the ___________ vein.
Portal, hepatic Acronym help: IPOH
Blood from vessels surrounding the ____________ passes into the ___________ via the ____________ ____________ vein.
Small intestines, liver, hepatic portal.
How many mL of bile does the liver produce each day?
500-1000mL
Bile produced by the liver consists of ________ and _________, among other substances.
bile salts, phospholipids.
Bile is secreted by _________ cells and stored in the ____________ until it is released into the _____________ through the bile duct.
liver, gallbladder, duodenum.
What 3 substances can be metabolized in the liver?
Carbohydrates Fat Protein
What substances are converted to soluble forms for later excretion in the liver?
drugs, hormones, and toxins
Where does the pancreas lie in the body?
horizontally across the upper part of the abdomen, behind the stomach.
The ___________ duct runs the length of the pancreas and merges with the common ________ duct to enter the duodenum.
pancreatic, bile.
The pancreas contains 2 classes of cells with 2 distinctly different functions. What are the 2 classes of cells?
- Pancreatic Acini 2. Islets of Langerhans
The pancreatic acini secrete what 2 substances? Where are they secreted?
- Electrolytes 2. Enzymes into the pancreatic duct.
Describe the exocrine function of the pancreas.
The first function of the pancreas is to help with the digestion of food in the SMALL INTESTINE.
The acini surround what other group of cells?
islets of Langerhans
Pancreatic cells in the islets of Langerhans secrete what 3 hormones?
- Glucagon 2. Insulin 3. Somatostatin Acronym help: G I S
The alpha cells produce __________.
Glucagon. Acronym help: A —> G
The beta cells produce ____________.
Insulin. Acronym help: B —–> I
The delta cells produce ____________.
Somatostatin. Acronym help: D —–> S
Describe the endocrine function of the pancreas.
The endocrine function of the pancreas involves the regulation of blood glucose.
___________ and ____________ have opposite effects on blood glucose. _________ keeps blood glucose from rising too high and ___________ keeps it from falling too low.
Insulin, glucagon. insulin, glucagon.
Describe the function of somatostatin.
Somatostatin inhibits secretion of insulin and glucagon and inhibits gastric motility. It is believed that this effect helps to prolong the time during which nutrients are absorbed into the blood and taken up by tissues.
Somatostatin inhibits secretion of what?
Insulin and glucagon as well as inhibiting gastric motility.
How is insulin made in the body?
It starts as a long protein called PROINSULIN within the beta cell. Proinsulin is broken down in the pancreas into insulin and a c-peptide fragment.