Digestive Study Guide Flashcards
What digestive enzyme is found in saliva?
- Salivary glands secretion will help bind materials
- Secretes SALIVARY AMYLASE to dissolve starches
Outline the path of food through the digestive tract
Oral Cavity
Pharynx
Esophagus
Stomach
Small Intestine
Large Intestine
Anus
Oral cavity
mastication and breakdown of food by salivary enzymes
Esophagus
related to gastric reflux and heart burn
Stomach
3 muscle layers for contraction that churns and mixes food to alter the materials
What cell types are found in the gastric pits?
Surface Mucous cell
Mucous neck cell
Parietal Cell
Chief Cell
G cell
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Surface Mucous Cell
- secretes alkaline fluid containing mucin
- Mucin becomes hydrated, producing mucus layer.
- This mucus layer along with a high rate of cell turnover in the mucosa helps prevent ulceration of the stomach lining upon exposure to both the high acidity of the gastric fluid and gastric enzymes
Mucous Neck Cell
- secretes acidic fluid containing mucin
- the acidic mucin helps maintain the acidic conditions resulting from the secretion of hydrochlorid acid by parietal cells. Also helps protect the stomach from injury
Parietal Cell
Secretes:
- Intrinsic Factor-required for absorption of vitamin B12
- HCL-it forms the H+ and Cl- secreted across the parietal cells surface. Responsible for Low pH of stomach
HCL in stomach
- converts the inactive enzyme pepsinogen into active pepsin and provides the optimal pH environment for pepsin activity
- it kills most microorganisms that enter the stomach (most cannot survive in the extremely low pH)
- It contributes to the breakdown of plant cell wall and animal connective tissue
- it denatures proteins by causing them to unfold, thus facilitating the chemical digestion by enzymes
Chief Cells
Secretes:
- Pepsinogen-inactive form of pepsin. Must be inactive to prevent destruction of the chief cell proteins
- Gastric lipase- role in fat digestion
G- cell
- enteroendocrine cells that secrete gastrin into the blood.
- gastrine stimulates stomach secretions and motility
Liver
-produce and release bile into the duodenum``
Bile
contains largely water, bicarb ions, bile salts, and lecithin
- helps mechanically digest lipids by emulsifying it.
- makes it into tiny droplets
Gall Bladder
- attached to inferior surface of the liver
- stores, concentrates, and releases bile into duodenum
- sphincter valve controls flow of bile into and out of the gallbladder
Pancreas houses which cells
- Duct Cell
- Acinar Cell
Duct cell
produces bicarb to counter acidic chyme
Acinar Cell
secretes amylase, lipase, protease, and nucleases
The secretions of the small intestine
- epithelial cells
- globlet cells
- intestinal glands
Epithelial cells of the small intestine
- microvilli increase the surface area and appear under the microscope as brush border. This is where brush border enzymes are found
- brush border enzymes complete the chemical digestions of most nutrients by getting it to the points where it can be absorbed into the blood
Goblet cells of the small intestine
- Produces mucin forming mucous which protect stomach and aids in movement from one area to the next
- Increase in number from the duodenum to ileum
Intestinal Glands of the small intestine
- Invaginations of mucosa between intestinal villi
- secrete intestinal juice that extends to the base of the mucosa
- composed of unicellular gland cells and enteroendocrine cells
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Unicellular gland cells
- found in intestinal glands of small intestine
- synthesize enteropeptidase- breaks down proteins
Enteroendocrine cells
- found in intestinal glands of small intestine
- release hormones such as CCK and GIP
What enzymes are involved in digestion of carbohydrates, proteins, and lipids
- Pancreatic Amylase
- Pancreatic Lipase
- Pancreatic Protease
Pancreatic Amylase
- produced by the pancreas and secreted into the small intestine
- continues digestion of starch that began in the oral cavity by salivary amylase
- Brush border enzymes complete the breakdown of starch to individual glucose molecules and are responsible for the digestion of disaccharides
Pancreatic Lipase
- bile salts released from the liver and gallbladder emulifsy lipid droplets to form micelles
- pancreatic lipase functions within micelles to digest each triglyceride into a monoglyceride and two free fatty acids
- Monoglycerides and free fatty acids enter an epithelial cell, while bile salts remain in the intestinal lumen to be reabsorbed and recycled
- Triglycerides are reassembled within epithelial cells. Lipids are then wrapped with protein to form a chylomicron. Chylomicrons are packaged within secretory vesicles and then exocytosed from the cells and absorbed into lacteals to enter the lymph.
Pancreatic Protease
- Proteolytic enzymes are released from the pancreas
- Enteropeptidase activates trypsinogin to trypsin, trypsin then activates chymotrypsinogen into chymotrypsin and procarboxypeptidase into carboxypeptidases
- Activated Pancreatic proteolytic enzymes break proteins into peptides and amino acids
- brush border peptidase breaks peptides into single amino acids to be absorbed through epithelial cell into blood
What are three hormones that regulate the digestive system
- Gastrin
- Secretin
- Cholestokinin (CCK)
Gastrin
produced in stomach
- release of gastrin is initiated by food in stomach
- further stimulates contractile activity and HCl, pepsinogen, gastric lipase release
- Stimulates contraction of pyloric sphincter to slow stomach emptying to give gastric juices more time to work
Secretin
Produced in small intestine
- released in response to increased chyme acidity
- causes release of alkaline solution containing bicarb from liver and pancreatic ducts to help neutralize the acidic chyme
- Inhibits gastric secretions and motility- doesn’t want to handle any material. Tells stomach to slow down
Cholestokinin
produced in small intestine
- released in response to fatty chyme
- stimulates smooth muscle in gallbladder to strongly contract and release bile
- Relaxes smooth muscle within hepatopancreatic ampulla
- allows entry of bile and pancreatic juice into small intestine
- inhibits stomach motility and release of gastric secretions
Describe the structure of the small intestine
- Divided into three continuous regions:duodenum, jejunum, and ileum
- Duodenum receives chyme from stomach mixed with accessory organ secretions.
- Chyme is very acidic
- Bicarb from the pancreas helps neutralize the chyme so that enzymes work
- Most chemical digestions and absorption occur here
Describe the functions of the small intestines
- Ingested nutrients spend at least 12 hours here to give them time to be absorbed
- Absorbs most nutrients and large percentage of water and electrolytes
- Vitamins absorbed here
Describe the Villi in the small intestine
- Fingerlike projection of the mucosa
- Larger and most numerous in the jejunum
- helps increase surface area and absorption and secretion
- Contains an arteriole, capillary network, venule, and lacteal
What are the regions of the large intestine
- Cecum
- Vermiform Appendix
- Colon
- Rectum/anal canal
- Tenaie colon
- Omental Appendices
Cecum
chyme entering from ileum
Teniae Colon
thin longitudinal bundles of smooth muscle that bunch into haustra
Omental Appendices
Lobes of fat hanging off external surface of haustra
Function of the Large intestine
- Continous absorption of water, electrolytes, and vitamins
- Bacterial Flora
- breakdown of carbs, proteins, lipids remaining in chyme. Produce vitamin B and vitamin K as well as gas
- Watery chyme compacted into feces and eliminated through anus (defecation).
- Depending on how much time feces spends in large intestine determines its consistency
