Chapter 25- Digestive system

logical order of digestive processes.

-A zymogen is an inactive or pro-enzyme that is only activated after it has been secreted and had some of its amino acids cleaved. -The chief cells of the stomach secrete pepsinogen into the stomach lumen; which in the presence of HCl becomes pepsin, the active form of the enzyme. -The pancreas produces a number of zymogens that are released in the GI tract at the duodenum including procarboxypeptidase,chymotrypsinogen, and trypsinogen. -After contacting the intestinal enzyme enteropeptidase, trypsinogen is converted into trypsin. -Trypsin then works on converting both chymotrypsinogen and procarboxypeptidase into chymotrypsin and carboxypeptidase, respectively.

Which of the following statements is/are true about gastric motility? Check all that apply.

-The stomach uses the contraction of three layers of muscle to mix, churn, and propel its contents to the duodenum. -When the pyloric sphincter is relaxed, chyme moves from the stomach to the duodenum. -The receptive-relaxation response of the stomach allows it to accommodate more food.

hydrochloric acid

-activates pepsin and lingual lipase -breaks up connective tissues and cell walls of plants -destroys most ingested pathogens -converts iron to an absorbable form

Pepsin

-active form of a zymogen -digests proteins -autocatalytic

Intrinsic factor

-dysfunction could cause pernicious anemia -essential to the absorption of vitamin B12

Which of the following occurs during the gastric phase of gastric secretion?

-gastrin secretion begins -The secretion of hydrochloric acid and pepsin is stimulated. -Gastric activity is stimulated in response to food increasing the pH of the stomach's contents.

Secretin

-secreted in response to chyme's low pH -ultimately protects the intestinal wall from HCL -results in sodium bicarbonate release by the liver and pancreas -helps flush pancreatic enzymes into the duodenum

Cholecysokinin

-secreted in response to fats in the small intestine -eventually leads to the emulsification of lipid globules -relaxes the sphincter of the hepatopancreatic ampulla -strong stimulatory effect on the gallbladder -stimulates the secretion of pancreatic amylase and pancreatic lipase -stimulates bile release into the duodenum

pancreas

-secretes inactive enzymes that when activated will digest proteins -secretes zymogens -secretes enzymes that digest fat -secretes deoxyribonuclease -secretes an enzyme that digests carbohydrates

Mass movements of the colon occur __________ times per day.

1 to 3

Which of the following is a function of the bacterial flora? Check all that apply.

Bacteria digest cellulose. -Bacteria synthesize vitamin K.

How does sucrose change the configuration of sucrase?

By binding to the active site

Which of the following statements is true regarding the absorption of nutrients? Check all that apply.

Carbohydrates are absorbed as monosaccharides. -Micelles are required for lipid absorption.

The carbonic acid ion is joined to a hydrogen ion by the enzyme carbonic anhydrase.

False

The medulla oblongata controls gastric secretion by utilizing the parasympathetic branch of the nervous system and the endocrine system.

False

Match each component of saliva with its appropriate function or characteristic.

Salivary amylase= digests starch Mucus= binds and lubricates the food bolus Lingual lipase= digests fats Electrolytes= salts, phosphate, and bicarbonate Lysozyme= kills bacteria Immunoglobulin A= antibacterial antibody

Which of the following statements is true regarding sucrase?

Sucrase breaks sucrose into glucose and fructose.

Which of the following statements is true regarding the anatomy of the colon and/or small intestine? Check all that apply.

The colon and the small intestine both have intestinal crypts. -The small intestine and the colon both utilize peristalsis to propel contents. -The small intestine and the colon both have circular and longitudinal muscles in the muscularis.

chronological order of digestive processes.

The digestive process begins with the ingestion of foods. -Starting in the mouth, the mechanical and chemical breakdown of food is referred to as the process of digestion. -Once foods are broken down into chemical monomers, the digestive system works to move nutrients from the GI tract into the cells of the body via absorption. -Indigestible residues along with some of the non-reabsorbed secretions of digestive organs, undergo compaction where the fluids are removed and a remaining solid is created. -The final step requires defecation, where the fecal matter resulting from compaction is excreted from the body.

Which of the following statements is true regarding the swallowing reflex? Check all that apply.

The oral phase is voluntary and the phayngoesophageal phase is involuntary. -Four different cranial nerves carry the motor impulses of the reflex.

Distention of the stomach activates a direct stimulatory effect on the gastric glands.

True

In the parietal cell, carbonic acid dissociates into a bicarbonate ion and a hydrogen ion.

True

Sodium-potassium pumps in the ____________________ work to actively transport sodium out of the cell towards the interstitium while cotransporting potassium to the intracellular fluid.

basal membrane

Ion exchange molecules in the plasma membrane of the parietal cells exchange __________ ions going out for __________ ions coming in.

bicarbonate; chloride

In order for digestion to occur, chyme is required to contact the microvilli of the intestinal wall because the __________.

brush border enzymes are not secreted into the lumen

The absorption of ________ from the intestinal lumen occurs directly through secondary active transport.

carbohydrates

In the parietal cells, the enzyme carbonic anhydrase causes a reaction between __________ and __________.

carbon dioxide; water

Enzymes that break down fats and proteins are secreted by _______ cells.

cheif

The luminal diffusion of sodium to the ICF is coupled with glucose and galactose ________________ into the cell.

cotransport

Gastric Lipase

digests fat in the stomach

Which of the following inhibits the secretion of the gastric glands?

duodenal pH of less than two

What are the segments of the small intestine in the order through which food passes?

duodenum, jejunum, ileum

The network of nerves that regulate digestive motility, secretion, and blood flow is called the __________ system.

enteric nervous

The __________ cells are associated with chemical regulation of digestion.

enteroendocrine

Chemical digestion is a series of chemical reactions that break large chunks of food into proteins, carbohydrates, and fats.

false

The term contact digestion refers to the fact that segmentation must occur in order to propel intestinal contents distally within the digestive tract.

false

Mass movements in the colon are stimulated by the presence of __________ in the __________.

food; stomach and chyme; duodenum

Which of the following hormones does not inhibit gastric gland secretions?

gastrin

Blood sugar refers to circulating levels of __________ in the blood.

glucose

Which of the following is a feature that the stomach and the small intestine have in common?

goblet cells

What are the microscopic structural subunits of the liver?

hepatic lobules

Hydrochloric acid is formed when __________.

hydrogen ions and chloride ions join in the duct of the gastric gland

With a declining intracellular concentration of sodium, sodium now diffuses from the _____________________ to the ICF of the epithelium.

intestinal lumen

lipid

lingual lipase, pancreatic lipase, gastric lipase

How often can a sucrase molecule be used to hydrolyze sucrose?

many times

The peristaltic movement of colonic contents triggered by the gastrocolic reflex approximately 1-3 times per day is called __________.

mass movement

The ________ cells are found mostly in the proximal and distal regions of the stomach.

mucous

Where is sucrase found in the human body?

on the microvilli of the small intestine

Which of the following statements is/are true regarding the regulation of digestive secretions? Check all that apply.

pancreatic enzymes are under both neural and hormonal control - via the vagus nerve, acetylcholine stimulates the pancreatic acini

Defecation is stimulated by __________ and __________ reflexes.

parasympathetic; local

The ___________ cells secrete the substance that converts pepsinogen to pepsin as well as a hormone that regulates appetite.

parietal

protein

pepsin, chymotrypsin, carboxypeptidase

Replacing both surface cells as well as glandular cells, the __________ cells divide rapidly.

regenerative

carbohydrate

salivary amylase, maltase, sucrase

Which of the following is a method of motility in the small intestine? Check all that apply.

segmentation, peristalsis, migrating motor complex

gallbladder

stores the substance that breaks globules of fat into droplets -contraction is induced by cholecystokinin

Liver

synthesizes bile -synthesizes bile acids -releases its secretions into the bile canaliculi

Defecation reflexes are stimulated by the presence of feces in the rectum.

true

Mass movements of the colon propel its contents toward the rectum.

true

When two different people consume the same food, it is possible that one receives a different number of calories from that food because of differing bacterial populations in the large intestine.

true