Lab: Digestive Chemicals Flashcards
Substance on which a catalyst works
Substrate
Biologic catalyst protein in nature
Enzyme
Increases the rate of a chemical reaction without becoming part of the product
Catalyst
Provides a standard of composition for test results
Control
List three characteristics of enzymes
- substrate specific
- temperature specific
- pH specific
The enzymes of the digestive system are classified as hydrolases. What does this mean
Hydrolases breaks down organic food molecules by adding water to the molecular bonds to cleave them
Salivary amylase is produced by what organ
Salivary gland
Site of action for salivary amylase
Oral cavity or mouth
Substrate of salivary amylase is
Starch
Optimal pH of salivary amylase is
6.7-7.0
Trypsin is produced by what organ
Pancreas
Site of action for trypsin is
Small intestine
Substrate of trypsin
Proteins
Optimal pH of trypsin
8.0
Lipase is produced by what organ
Pancreas
Site of action for lipase is
Small intestine
Substrates of lipase are
Fats and proteins
Optimal pH of lipase is
7.4-8.0
The end products of proteins are
Amino acids
The end products of fats are
Fatty acids and glycerol
The end products of carbohydrates are
Simple sugars glucose
How does the substrate for amylase differ from the substrate for lactase
Substrate of amylase is starch polysaccharides and substrate of lactase is disaccharides
How is the substrate for amylase similar to the substrate for lactase
Site of action is small intestine for both carbohydrates
Where does lactose hydrolysis occur for lactase-persistent individuals
Small intestines
Where does lactose hydrolysis occur for lactose-intolerant individuals who have consumed probiotic bacterial microflora
Large intestine
BAPNA
Used to test for protein hydrolysis which was indicated by a yellow color
Lugol’s iodine
Used to test for the presence of starch which was indicated by blue-black color
Litmus
Used to test for the presence of fatty acids which was evidenced by a color change from blue to pink
Benedict’s solution
Used to test for the presence of reducing sugars maltose, sucrose, glucose as indicated by a blue to green or organge color change
What conclusions can you draw when an experimental sample gives both a positive starch test and a positive maltose test after incubation
Starch digestion is partial into maltose
Why was 37 degrees C the optimal incubation temperature
It is body temperature
Trypsin is a protease similar to pepsin the protein digesting enzyme in the stomach. Would trypsin work well in the stomach why
No because the pH for trypsin is slightly basic the pH optimum for pepsin is acidic
What role does bile play in fat digestion
Emulsification of fat by bile increases the surface area for lipase activity
Assume you have been chewing a piece of bread for 5 to 6 minutes how would you expect it’s taste to change during this interval why
The bread would begin to taste sweet because starch is broken down to glucose by amylase
Mechanism of absorption for monosaccharides
Passive transport
Mechanism of absorption for fatty acids and monoglycerides
Active transport
Mechanism of absorption for amino acids
Active transport
Mechanism of absorption for water
Osmosis passive transport
Mechanism of absorption for Na+, Cl-, Ca2+
Na+ Ca2+ active transport. Cl- diffusion
Secretin is produced by
Duodenal mucosa
Target organs and effects of secretin are
- pancreas secretes bicarbonate liquid buffer
2. liver secretes bile
Gastrin is produced by
- Stomach mucosa
2. Duodenum
Target organs and effects of gastrin are
Gastrin acts on the stomach glands to increase their secretory activity
Cholecystokinin is produced by
Intestinal cells of duodenum
Target organs and effects of cholecystokinin
- production of bile by liver and juice mix by pancreas
- gallbladder contraction to release bile
- inhibits gastric secretion
Swallowing or
Deglutition
Two phases of deglutition are
- Buccal phase (voluntary)
2. pharyngeal-esophageal phase (involuntary)
Which phase of deglutition is voluntary
Buccal
What happens during the buccal phase
The tongue is used to push the food into the back of the throat
During swallowing the larynx
Rises to ensure that it’s passageway is covered by the epiglottis so that the ingested substances don’t enter the respiratory passageways
It is possible to swallow water while standing on your head because
The water is carried along the esophagus involuntarily by the process of peristalsis
The gastroesophageal sphincter
The pressure exerted by the foodstuffs on this sphincter causes it to open allowing the foodstuffs to enter the stomach
The two major types of propulsive movement that occur in the small intestine are
Peristaltic and segmental
Segmental movement acts to
Continuously mix the foods and to increase the absorption rate by moving different parts of chyme mass over the intestinal mucosa but it has less of a role in moving foods along the digestive tract
What are the major functions of the mucosa
Major Functions: Secretion, absorption, protection
What are the subdivisions of the mucosa
Surface epithelium, Lamina propria, muscularis mucosa
What are the major functions of the submucosa
Nutrition, Protection
What are the subdivisions of the submucosa
None
What are the major functions of the Muscularis externa
Regulator of GI motility.
What are the subdivisions of the Muscularis externa:
Smooth muscle Inner/Outer Layers
What are the major functions of the serosa or adventitia
Major Functions: Anchors, protects, and reduces friction.
What are the subdivisions of the Serosa or adventitia
Visceral peritoneum, mesothilium, adventita.
The tubelike digestive system canal that extends from the mouth to the anus is known as the _______ canal or the ________ tract.
alimentary; digestive
What transition in epithelial type exists at the gastroesophageal junction.
Squamous cells in the esophagus to columnar cell in the gastral mucosa.
Differentiate the colon from the large intestine.
Large intestine extends from the ileocecal valve to the anus, but colon is part of the large intestine and divided into ascending, descending, and sigmoid colon.
Conduit for both air and food?
Pharynx
Fingerlike extensions of the intestinal mucosa that increase the surface area for absorption.
Villi
Large collections of lymphoid tissue found in the submucosa of the small intestine.
Peyer’s patches
Region containing two sphincters through which feces are expelled from the body?
Anus
Wormlike sac that outpockets from the cecum?
Appendix
The “gullet”; no digestive/absorptive function?
Esophagus
Membrane securing the tongue to the floor of the mouth?
Frenulum
Covers most of the abdominal regions like an apron?
Greater omentum
Bone-supported anterosuperior boundary of the oral cavity?
Hard palate
Valve at the junction of the small and large intestines?
Ileocecal valve
Structure attached to the lesser curvature of the stomach?
Lesser omentum
Valve controlling food movement from the stomach into the duodenum?
Pyloric valve
Folds of the gastric mucosa?
Rugae
Primary region of food and water absorption?
Jejunum
Posterosuperior boundary of the oral cavity?
Soft palate
Initiates protein digestion?
Stomach: pepsin
Produces mucus; found in the submucosa of the small intestine.
Duodenal glands
Produces a product containing amylase that begins the starch breakdown in the mouth.
Salivary glands
Produces many enzymes and an alkaline fluid that is secreted into the duodenum.
Pancreas
Produces bile that it secreted into the duodenum via the bile duct.
Liver
Found in the mucosa of the small intestine; produces intestinal juice.
Intestinal crypts.
What is the role of the gallbladder
The gallbladder holds bile produced in the liver until it is needed for digesting fatty foods in the duodenum of the small intestine.
The pancreas has two major populations of secretory cells - those in the islets and the acinar cells. Which population serves the digestive process?
Acinar cells
What do parietal cells excrete?
hydrochloric acid (HCl) and intrinsic factor.
Where are parietal cells located?
the gastric glands found in the lining of the fundus and cardia of the stomach.
What do chief cells excrete?
pepsin
Where are chief cells located?
deep in the mucosal layer of the stomach lining
What are the 3 salivary glands?
Lingual, Submandibular + Parotid
What are lacteals?
Special lymphatic vessels of the small intestine which absorb digested fatty acids in the form of chylomicrons
