Chapter Questions - Digestive System
Name one organ of the alimentary canal found in the thorax. Name three organs located in the abdominal cavity.
The esophagus is found in the thorax; Stomach, small intestine, and large intestine are found within the abdominal cavity
What is the usual site of ingestion?
Ingestion begins in the mouth in a healthy person
Which digestive system activity actually moves nutrients from the outside to the inside of the body?
The process of ABSORPTION moves nutrients into the body.
When sensors in the GI tract are stimulated, they respond via reflexes. What types of digestive activity may be put into motion via the reflexes?
Reflexes associated with the GI tract promote muscle contraction and secretion of digestive juices or hormones
The term "gut brain" does not really mean there is a brain in the digestive system. What does it refers to?
The enteric nervous system or web of neurons closely associated with the digestive organs.
How does the location of the visceral peritoneum differ from that of the parietal peritoneum?
visceral peritoneum is the outermost layer and the parietal peritoneum is the serous membrane covering the walls of the abdominal cavity
Of the following organs which is are retroperitoneal?
What name is given to the venous portion of the splanchnic circulation?
Hepatic Portal Circulation
Name the layers of the Alimentary Canal from the inside out.
Serosa - Mainly fibrous and areolar connective tissue, visceral peritoneum
Muscularis externa- several layers of smooth muscle tissue
Submucosa - Blood vessels, lymphatic vessels, nerves and connective tissue
Mucosa - mucous membrane lining
Jerry has been given a drug that inhibits parasympathetic stimulation of his digestive tract. Should he “eat hearty” or temporarily refrain from eating, and why?
Jerry should temporarily refrain from eating because the parasympathetic system oversees the digestive activities
How does the oral vestibule differ from the oral cavity proper?
The oral vestibule is the region between the cheek and the teeth. The oral cavity proper is the area enclosed by the teeth
Which structure forms the roof of the mouth?
The palate forms the roof of the mouth. The hard palate is the bony area and the soft palate is posterior to the hard palate.
Besides preparing food for swallowing, the tongue has another role. What is it?
The tongue is important for speech and taste.
What is the importance of the serous portion of saliva.
The serous portion of saliva is rich in salivary amylase, an enzyme that chemically breaks down starch, helps hydrate food stuff and protects against microorganisms
Name three antimicrobial substances found in saliva.
antimicrobial substances found in saliva include lysozyme, defensing, and IgA antibodies
Seven-year old Tina ran to her daddy to show him her lower central incisor which she had wiggled until it “fell out.” Is this a primary or permanent tooth? What name is given to teeth that (according to Tina) fall out?
It is a primary tooth that fell out. It is called a deciduous tooth or milk tooth
Which tooth substance is harder than bone? Which tooth region includes nervous tissue and blood vessels?
Enamel is harder than bone. The pulp region includes nervous tissue and blood vessels
Which teeth are “grinders”?
The molars are “grinders”
To which two organ systems does the pharynx belong?
The pharynx is part of the respiratory and digestive system
How is the muscular externa of the esophagus unique in the body?
Muscular externa undergoes a transformation from skeletal muscle to smooth muscle.
What is the functional significance of the epithelial change seen at the esophagus-stomach junction?
The esophagus is a food chute and undergos a good deal of abrasion which stratifies squamous can withstand. The stomach is secretory mucosa.
What role does the tongue play in swallowing?
The tongue mixes the food with saliva, compacts the food into a ball and initiates swallowing
How are the respiratory passages blocked during swallowing?
The ulula and the soft palate rise and cover the naso pharynx and the epiglottis covers the larynx during swallowing.
What structural modification of the stomach wall underlies the stomach’s ability to mechanically break down food?
The stomach has 3 layers of smooth muscle that are responsible for peristalsis .
Two substances secreted by cells of the gastric glands are needed to produce the active protein-digesting enzyme pepsin. What are these substances and which cells secrete them?
The chief cells produce pepsinogen which is the inactive enzyme pepsin. The parietal cesll secrete HC1 needed to activate pepsinogen
Which protective substances or activities make up the so-called mucosal barrier?
The mucosal barrier consists of thick alkaline mucus secreted by mucus cells
Name the three phases of gastric secretion.
The three phases include cephalic phase, the gastric phase, and the intestinal phase
How does the presence of food in the small intestine inhibit gastric secretion and motility?
Food in the small intestines inhibits gastric activity by triggering the enterogastic reflex and the secretion of entergastrones
How does the pH of the venous blood leaving the stomach change during a meal?
Venous blood becomes more alkaline due to the alkaline tide occurring during HC1 secretion
What common advantage do circular folds, villi, and microvilli of the small intestine provide to the digestive process? Which of these modifications cause chime to spiral through the lumen and slows its passage?
These all increase the surface area of the intestines, additionally the circular folds force chime to spiral through the lumen
What are brush border enzymes?
Brush border enzymes are enzymes associated with the microvilli of the small intestines mucosal cells
What is lacteal and what is its function?
A lacteal is a special lymphatic capillary that picks up lymph from the digestive visera
Name three secretory products that help protect the intestinal mucosa from bacteria damage.
IgA, HC1 and defensin help protect the intestinal mucosa from bacteria damage.
What is portal triad?
A portal triad is a region at the corner of the hepatic lobule that contains a branch of the hepatic portal vien, a branch of the hepatic artery and the bile duct
What is the importance of the enterohepatic circulation?
Enterohepatic circulation is an important recycling mechanism for retaining bile salts for fat absorption.
What is the role of the stellate macrophages of the liver?
Macrophages rid the liver of bacteria and dead cells
What do zymogen granules contain?
Zymogen granules contain inactive digestive enzymes
What is the functional difference between pancreatic acini and islets?
Pancreatic acini produce the exocrine products (digestive enzymes and juices) and islets produce hormones namely insulin and glucagon
What is the makeup of the fluids in the pancreatic duct? In the cystic duct? In the bile duct?
Fluid in the pancreatic duct is biocarbinate rich, enzyme rich pancreatic juice. The cystic and bile duct contains bile.
What stimulates CCK release and what are its effects on the digestive process?
CCk is secretes in response to the entry of chime rich protein and fat in the duodenum. It causes the pancreatic acini to secrete digestive enzymes, stimulates the gall bladder to contract, and relaxes the hepatopancreatic sphincter to relax
Distension of the stomach and duodenal walls have different effects on the stomach secretory activity. What are these effects?
Distension of the stomach wall enhances stomach secretory activity. Distension of the duodenum wall reduces stomach secretory activity to give the small intestines time to carry out its digestive and absorptive activities.
Which is more important in moving food along the small intestine – peristalsis or segmentation?
Segmentation is more important for moving food along in the small intestines.
What is MMC and why is it important?
MMC is the migrating motor complex, a pattern of peristalsis seen in the small intestines that moves the last bit of food plus bacteria and debris into the large intestines. It is important to prevent the over growth of bacteria in the small intestines.
What propulsive movements are unique to the large intestine?
Mass movements and haustral contractions are unique the the large intestines. Mass movements are long, slow, powerful contractions that move over large areas of the colon 3 to 4 times a day, forcing the contents toward the rectum. Haustral contractions are a special type of segmentation.
What is the result of stimulation of the stretch receptors in the rectal walls?
Activations of stretch receptors in the rectal wall initiates the defecation reflex
In what ways are enteric bacteria important to our nutrition?
enteric bacteria synthesize B vitamins and some K vitamins the liver needs to synthesize clotting proteins
What type of chemical reaction is the basis of all enzymatic food breakdown?
All food digestion relies on hydrolysis reactions
Maylase is the starch as _____ is to fats.
What is the role of bile salkts int the digestive process? In absorption?
Bile salts emulsify fats so that they can act efficiently by lipase enzymes, and form micelles that aid in fat absorption
From which germ layer does the digestive system mucosa develop?
Endoderm germ layer
How does cystic fibrosis interfere with the digestive process?
The thick viscous mucus clogs pancreatic ducts and prevents the delivery of pancreatic fluid to the duodenum. This inhibits fat digestion and absorption.
Why are colon and stomach cancers so dangerous?
Colon and stomach cancers are very dangerous because they have few early warning signs