The Digestive System

Which organ provides the most number of digestive enzymes to the chemical digestive process? A. stomach B. duodenum C. liver D. pancreas

D.

If HCl was not produced in the stomach, which of the following would NOT happen? A. no further bacterial destruction would occur B. pepsin would be formed from pepsinogen C. salivary amylase would continue to function D. carbohydrate digestion would cease

B.

The wall of the GI tract has four layers of tissue. What is the correct arrangement of these tissues from the OUTERMOST to the INNERMOST layers? A. mucosa, serosa, submucosa, muscularis B. serosa, muscularis, submucosa, mucosa C. mucosa, submucosa, muscularis, serosa D. serosa, submucosa, muscularis, mucosa

B.

What is the correct pathway for the movement of a food particle through the digestive system? A. mouth, pharynx, stomach, esophagus, small intestine, large intestine, rectum, anus B. mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus C. mouth, esophagus, stomach, large intestine, small intestine, rectum, anus D. mouth, esophagus, pharynx, stomach, small intestine, large intestine, anus, rectum

B.

The digestion of lipids would be most affected by which important digestive substance produced by the liver?

Bile

Which of the following is NOT a function of the large intestine? A. vitamin K production B. compaction C. digestion of chyme D. water and salt absorption

C.

Which of the following is NOT a function of the liver? A. detoxify alcohol B. store fat soluble vitamins C. produce pepsinogen D. produce and secrete bile

C.

An individual has a genetic disorder that reduces the amount of amylase produced by the body. The digestion of which biological macromolecule would most likely be affected?

Carbohydrates

Starting with the introduction of food into the mouth and ending with the elimination of waste from the anus, briefly describe the events that take place in each digestive organ. Ensure you include 1. the name of each organ, 2. the biological macromolecule digested, 3. the enzyme(s) involved, 4. the monomer absorbed, and 5. the major site of absorption

Food first enters the mouth through the oral fissure. Once with in the oral cavity, the muscles of the mouth push the food between the teeth so it can be masticated as a part of physical digestion. At this time, salivary amylase in the saliva begins the chemical digestion of starches present while lingual lipase in the saliva does the same for lipids. Once the food has been properly masticated, the tongue presses in into a bolus and pushes it posteriorly into the oropharynx. Once the bolus has reached a good size, the epiglottis tips and the bolus moves around it into the laryngopharynx. The tongue and soft palate then block food from entering the nasal cavity or mouth, breathing ceases, the the upper esophagus widens. The pharyngeal constrictors contract and the bolus moves into the esophagus. Here the bolus stimulates stretch receptors in the esophagus, which causes circular muscles above the bolus to contract and push it down, those below it to relax, and the longitudinal muscles to contract. The lower esophageal sphincter relaxes, and the food passes into the stomach. Once in the stomach, food is chemically digested by enzymes. Salivary amylase continues to digest starches, peptidases act on proteins, and gastric lipase acts on lipids. The stomach then under goes rhythmic contractions that churn the food and mix it with gastric juice to promote its breakup The food is now referred to as chime. The chime is pushed between the atrium and the body of the stomach to further break it down, and once it is small enough it is slowly pushed into the duodenum of the small intestines. Further chemical digestion occurs in the small intestines. Starches are further broken down by pancreatic amylase, and even further broken down by dextrinase, glucomylase, and maltase into glucose which is absorbed. Proteins are broken into amino acids by carboxypeptidase, aminopeptidase, and dipeptidase into amino acids which are then absorbed. Lipids are further digested by pancreatic lipase and absorbed with the aid of micelles in the form of cholesterol, fatty acids, or chime which is absorbed my lymphatic vessels. The chime in the small intestines is being moved through segmentation. Once segmentation decreases, peristalsis begins. At this point, there is primarily only residue left. These contraction processed move the remaining residue towards the cecum. Once the cecum is filled, the ileal papillae closes. The residue in the large intestines is consumed by bacteria and nutrients like vitamin K and B are extracted by them and absorbed by the colon. The colon also reabsorbs water and electrolytes. By this point, the residue has been converted into feces. The feces triggers haustral contractions in the colon and the feces is pushed along by segmentation. Mass movements moves even more feces down the path with even more force. Once the feces is in the rectum, defecation reflexes are triggered that intensify peristalsis, contract the rectum, and relax the internal anal sphincter. The puborectalis muscle and the external anal sphincter allow you hold the feces in until an appropriate time. Once these two muscles are voluntarily relaxed, defecation occurs and the feces exits the body.

Briefly describe the function of HCl in our stomachs, and the process by which it is produced.

HCl's function is to activate pepsin and lingual lipase, break down connective tissues and cell walls in food, converting Fe3+ into Fe2+, and to destroy ingested pathogens. It is produced when CAH catlylizes a reaction between of CO2 and water, which gives us H+, which is then pumped into the lumen of the gastric gland. HCO3- ions produced in the reaction are swapped with Cl- in blood plasma and the Cl- is also sent to the lumen of the gastric gland. Here the two ions meet and form HCl.

Briefly describe the process of peristalsis.

Peristalsis is a wave like contraction that occurs in the small intestines. Once one wave starts, it is followed by another wave that started further along the tract. This allows for the undigested residue remaining in the small intestines to be slowly pushed into the colon.

Years of ingesting a rare toxic chemical resulted in damage to an individual's parietal cells. In which digestive organ did the damage occur? The production of which digestive chemical would be impacted? The digestion of which two (2) biological macromolecules would be affected?

Stomach HCL & Intrinsic Factor Carbohydrates & Lipids

Function of the Gallbladder

Stores and concentrates bile

Function of the large intestines

Turns food residue into excrement for removal

Amylase is responsible for the breakdown of ____.

carbohydrates

The _______ gland is the largest salivary gland.

parotid

Function of the rectum

Removal of feces

Function of parietal cells

Secretes HCl, intrinsic factor, and ghrelin

Function of enzymes of the live

Secretes bile; bile

The majority of digestive enzymes are produced by which two digestive organ?

Small intestines; pancreas

Function of the small intestines

fully digests food and absorbs its nutrients

A very weak sphincter found in the digestive tract is the _________ sphincter. A. pyloric B. gastroesophageal C. ceacal D. external anal

B.

Dietary protein is broken down in the stomach by: A. gastrin B. pepsin C. pancreatic peptidase D. hydrochloric acid

B.

Pepsinogen is produced by the ________ cells. A. enteroendocrine B. chief C. parietal D. gastric

B.

Describe at least three of the functions of the large intestine.

it reabsorbs water and electrolytes from food residue, it absorbs vitamins such as B and K after its gut microbiome synthesizes them, it releases food residue from the body in the form of feces.

The process of taking in food is known as: A. digestion B. absorption C. ingestion D. propulsion

C.

Function of the mouth

Chewing, chemical digestion, taste, swallowing

Which is NOT a constituent of saliva? A. water B. lysosome C. amylase D. pepsin

D.

Function of G-Cells

secrete gastrin

The principle site of nutrient digestion and absorption is the ___________.

small intestine

Protein digestion begins in the _________, whereas carbohydrate digestion begins in the mouth.

stomach

Which of the following is NOT an accessory organ of digestion? A. salivary glands B. liver C. pancreas D. gallbladder E. spleen

E.

Describe the function of microvilli (ie: what is their overall contribution to the digestive process.

Microvilli contain brush boarder enzymes that are essential for digestion such as dextrinase and glucomylase needed for digesting starch or sucrase for digesting sucrose

function of esophagus

Moves food from pharynx to stomach

HCl activates the process that produces ________.

Pepsin

Bile is produced in the _________, stored in the liver ________, and is involved in _______ digestion. A. liver; gall bladder; lipid B. liver; gall bladder; carbohydrate C. gall bladder; liver; lipid D. pancreas; liver; carbohydrate

A.

Chemical digestion of carbohydrates begins in the ________, whereas chemical digestion of proteins begins in the ________. A. oral cavity; stomach B. stomach; jejunum C. oral cavity; duodenum D. stomach; duodenum

A.

Function of mucous cells

Secretes mucous

Function and enzymes of the pancreas

Secretion of pancreatic juice, insulin, and glucagon; Pancreatic amylase, pancreatic lipase, ribonuclease, deoxyribonuclease

The ________ nervous system controls the movement of food through the digestive system. A. somatic B. parasympathetic C. sympathetic D. enteric

D.

Function of the stomach

Partially digests food before it enters small intestines