MCAT Biology Digestive System Part 2 Flashcards
The anus is derived from the __ during embryogenesis
blastopore
In the small intestine the apical surface of epithelial cells have __ to increase their surface area
Microvilli
The __ system stimulates motility and causes the sphincters to relax (allowing the passage of food through the gut)
Parasympathetic nervous system
The submucosa plexus is found in the submucosa and helps to :
- regulate enzyme secretion
- gut blood flow
- ion/water balance in the lumen
Exocrine glands are composed of special epithelial cells, organized into sacs called__
acini (Singular acinus)
The three GI organs primarily involved in exocrine secretion include __,__, and __
- liver
- gallbladder
- pancreas
Gastric glands secrete ___
acid, and pepsinogen
The __ teeth (front teeth) are for cutting
incisors
The __ teeth (canine teeth) are for tearing
Cuspids
The __ teeth are for grinding
Molars
___ hydrolyzes starch in the mouth breaking it into fragments
Salivary amylase (ptyalin)
Salivary amylase breaks sugars down to dissacharides NOT monosaccharides that only occurs at the__
intestinal brush border
Saliva also contains a small amount of __ for fat digestion
Lingual lipase
Saliva also contains lysozyme which attacks ___
bacterial cell walls ( like in your tears too)
The pharynx contains the openings to two tubes __ and__
trachea and esophagus
The ___ is a cartilage-lined tube at the front of the neck that conveys air to and from the lungs
Trachea
The ___ is a muscular tube behind the trachea which conveys food and drink from the pharynx (throat) to the stomach
Esophagus
During swallowing, solids and liquids are excluded from the trachea by a flat cartilaginous flap called the __
epiglottis
__ is secreted by chief cells in the stomach wall
Pepsin
____prevents passage of food from the stomach into the duodenum
Pyloric sphincter
Stretching or excess acidity in the duodenum inhibits ___
further stomach emptying, by causing the pyloric sphincter to contract
__ is secreted by cells in the stomach wall known as G cells, it stimulates acid and pepsin secretion along with gastric motility
Gastrin
The molecule ___ binds to parietal cells to stimulate acid release
Histamine
Ulcer drugs (Tagamet) and (Zantac) function by blocking the binding of ___ to its receptor on parietal cells, resulting in less gastric acidity
Histamine
Digestion is completed in the __ and ___
duodenum and jejunum
The key feature that allows the small intestine to accomplish absorption is___
large surface area
The surface area of the small intestine results from __ . ___ , and ___
- length
- Villi
3 . Microvilli
What are three important structures of the villus of the small intestine that have big purposes
- Capillaries, absorb dietary monosaccharides and AA’s
- Lacteals, absorb dietary fats
- Peyer’s patches are part of the immune system
The villus of the small intestine contain ___ which absorb dietary monosaccharides and amino acids. They merge to form veins and merge with the large hepatic portal vein
Capillaries
The villus contain small lymphatic vellels called ___ which absorb dietary fats
Lacteals
The lacteals of the small intestin merge to form large lymphatic vessels which transport dietary fats to the ___ which empties into the bloodstream
Thoracic duct
What two ducts empty into the duodenum
- Pancreatic duct delivers exocrine secretions from pancreas
- Common bile duct, which delivers bile
Bile is a green fluid, bile acids are made from ___
cholesterol in the liver and are normally absorbed and recycled
The bile has two functions :
- vehicle for the excretion of waste products by the liver
2. Essential for the digestion of fats
The bile duct and the pancreatic duct empty into the duodenum via the same orifice, known as the __
Sphincter of Oddi
Several different __ are responsible for hydrolyzing polypeptides to di- and tripeptides
Pancreatic proteases
Trypsinogen is converted to trypsin by __ an intestinal enzyme
Enterokinase
___ secreted by the duodenum causes the pancreas to secrete water and bicarbonate (high pH)
Secretin
Gamma cells of the islet of Langerhans secrete ___ inhibiting many digestive processes
Somatostatin
What three hormones have the ability to raise blood glucose levels?
- Glucagon (polypeptide hormone from the pancreas)
- Cortisol (steroid from the adrenal cortex)
- Epinephrine (amino acid derivative from the adrenal medulla)
___stimulates peristalsis in the intestine and inhibits stomach emptying
Cholecystokinin
The exocrine activity of the liver is simple__
it secrtes bile
What are the three ingredients of bile?
- bile salts (anionic form)
- Cholesterol
- Bilirubin (from RBC breakdown)
__ emulsifies large fat particles in the duodenum creating smaller clusters of fat particles called micelles
Bile
A ___ is a large crystal formed from bile made with ingredients in incorrect proportions
Gallstone
CCK and PNS stimulate contraction of the ___
gallbladder wall
The __ in hepatocytes contains enzyme pathways that break down drugs and toxins into less toxic forms
Smooth ER
When the stomach is empty, gastric cells produce the hormone __ to stimulate appetite
Ghrelin (Stimulates appetite)
When the colon is full the jejunum (lower intestine) produces ___ to reduce appetite
Peptide YY reduces appetite
The hormone __ produced by white adipose tissue (fat) is an appetite suppressant that acts as an adipostat, maintaining stable lipid contents in adipose tissue
Leptin
__ is secreted in response to increased triglyceride levels and works to suppress appetite until appropriate levels are restores
Leptin
The effects of leptin, ghrelin, and peptide YY on appetite are primarily mediated by the _____
arcuate nucleus of the hypothalamus
As you swallow the upper esophagel sphincter__
relaxes
Monosaccharides must be taken up into the intestinal epithelial cell by ___
active transport
