A&P Chapter 24

How could you tell if an individual had a functional liver, by observing lipid digestion?

A fully functioning liver should produce bile acids which are required for lipid digestion and absorption. These take the large fat "globs" and turn them into smaller "globs" called emulsification droplets. This certain process only happens through bile acids created by the liver, therefore if this process is happening, an indinvidual has a functioning liver.

What would happen if the duodenum could not secrete bicarbonate?

Bicarbonate is part of the 1500 ml of pancreatic juice that is secreted to the duodenum of the small intestine each day. Without bicarbonate secretion, acids like hydrochloric acid could not be neutralized.

How could you tell by examining their saliva, which side of an individual's ANS was more active?

By the texture and the consistence of the saliva, if it was thin and enzyme rich it would be from the parasympathetic signals triggered by the medulla oblongata. If it was thick and mucus rich it would have had to come from the sympathetic signals.

What is the physiologic significance of the carbonic anhydrase in the stomach epithelium?

Carbonic anhydrase, an enzyme in the parietal cell, catalyzes the reaction between Water and Carbon Dioxide to create Carbonic acid which in turn causes Chloride and Hydrogen ions to diffuse from the parietal cells into the stomach and react together to make hydrochloric acid (stomach acid).

Influence of destroying intestinal brush border enzymes on bodily ATP production.

Decrease, brush border enzymes are located at the end of the small intestine where a lot of absorption takes place. An enzyme called a-dextrinase removes one glucose at a time. While Sucrose, lactase, and maltase break down sucrose, lactose, and maltose into different monomers.

Influence of an autoimmune response towards chief cells on protein digestion.

Decrease. Chief cells secrete the inactive pre-enzyme pepsinogen that is converted to pepsin by HCl and the protease enzyme that helps breakdown proteins. An autoimmune attack against chief cells would result in a decrease of pepsinogen, and thus a decrease in the ability to breakdown proteins to better digest.

Influence of blocking all spinal reflexes on defecation?

Decrease. There are 4 steps in defecation, 1.) stretching of the rectum stimulates stretch receptors that signal the spinal cord. 2.) Spinal reflex from sacral spinal cord stimulates involuntary contraction of the rectum. 3.) Spinal reflex from sacral Spinal cord stimulates involuntary relaxation of the internal anal sphincter. 4.) Stretch signal to the cerebrum allows for voluntary relaxation of external anal sphincter.

Influence of removing epithelial cell tight junctions on the function of the stomach.

Decrease. Tight junctions in the epithelium of the stomach prevent acids from passing between the epithelial cells to the lamina propria. Hydrochloric acid, found in the stomach, would be very destructive to the epithelium if not for these tight junctions. This is one of the ways the stomach is protected from digesting itself.

Influence of blocking trypsinogen production on chymotrypsin production.

Decrease. Trypsinogen is a zymogen. Enterokinase converts tysinogen into trypsin, trypsin converts chrymotrypsinogen into chromotrypsin, an active protease that digests protein.

What is the physiologic significance of haustral contractions?

In the large intestine, haustral contractions are responsible for churning and mixing the remaining contents of the digestive tract. Unlike segmentation contractions of the small intestine which are random, these contractions always occur at the same sites.

Influence of mechanical digestion on the production of organic monomers.

Increase. Digestion is the process of breaking food into monomers. Digestion process could be divided into mechanical and chemical digestion. Mechanical digestion is physical breakdown of food into smaller particles to increase surface area for chemical digestion. Mechanical digestion involves chewing and breaking down food with teeth, and motility of stomach and intestine.

Influence of the presence of food within the stomach on gastric secretion.

Increase. Food and increased pH in the stomach activate G cells. G cells release gastrin which stimulates gastric gland secretion.

Influence of mastication on chemical digestion.

Increase; Mastication, also known as chewing, is one means of mechanical digestion, which is the physical breakdown of food into smaller particles. This increases the surface area which allows for more enzymes to begin breaking the food down further into monomers, which is the process of chemical digestion.

How could you tell if an individual had intrinsic factor, by doing a blood smear?

Intrinsic factor is the only indispensable stomach function, it's essential for the absorption of vitamin B12. Which is required for erythropoiesis. You could tell if someone had intrinsic factor when looking at a blood smear by looking at the number of red blood cells. If the individual is deficient they won't have intrinsic factor and will most likely be anemic. Intrinsic factor is also produced by the parietal cells.

What is the physiological significance of micelles?

Micelles in the body allows for the absorption of molecules that are insoluble in water such as lipids. Micelles can deliver both hydrophilic and hydrophobic agents.

Influence of overly active Brunner's glands on developing a peptic ulcer of the small intestine.

No Change. Brunner's gland secrete bicarbonate which neutralizes stomach acid. Peptic ulcers are formed by the bacteria Helicobacter pylori who infect mucosa and allow hcl and pepsin access. They're are treated with antibiotics.

Influence of pancreatic amylase on protein digestion.

No change, salivary amylase converts starch to oligosaccharides and pancreatic amylase converts oligosaccharides to smaller polysaccharides. Pepsin, trypsin, chymotrypsin, and carboxypeptidase are the ones involved in protein digestion.

How could you tell if a stomach contained parietal cells?

Parietal cells in the stomach secrete 2 things, hydrochloric acid and intrinsic factor, instrinsic factor. Hydrochloric acid isn't really required to break down anything but it breaks up the different molecules, starch and lipids. Intrinsic factor is essential, without it we would develop enemia, because it is used to digest vitamin b12 which is essential for erythropiesis, the creation of blood cells.

How could you tell if an individual's saliva contained amylase?

Salivary amylase's main function is to digest starch. After you chew certain starchy foods, like potatoes or rice, the digestive process begins. It is completed by the enzyme amylase when it enters the digestive tract. If an individual can successfully digest starches (no intolerance/reactions) they in fact have this enzyme.

How could you tell if the small intestine was undergoing segmentation or peristalsis?

Segmentation and peristalsis are 2 types movement of small intestine. Segmentation is random stationary ring-like constrictions form and un-form in order to mix and churn contents, initiated by the presence of food in the stomach, involves circular muscle of muscularis externa. While peristalsis is waves of contraction that begins in duodenum and push the chyme along for 2 hours. Each wave travels a little further towards colon, suppressed by refilling of stomach, involves longitudinal muscle of muscularis externa.

What is the physiological significance of the emetic center of the medulla oblongata?

The emetic center controls the two stages of vomiting, retching and vomiting. During retching, the emetic center sends signals to the lower esophageal sphincter to cause relaxation while simultaneously stimulating contraction of the duodenum and stomach to move chyme back toward the esophagus. During vomiting, the stimulation of the abdominal muscles causes contractions which open the upper esophageal sphincter and the contents of the stomach and some from the duodenum are expelled out through the oral cavity.

How could you tell if you were observing mechanical digestion?

The person would be chewing their food. Mechanical digestion breaks down food into smaller pieces which increases surface area. The increased surface area makes the next stage of chemical digestion more effective. Muscular contractions of the small intestines that move food through them are also part of mechanical digestion.

What is the physiologic of the submucosal plexus?

The submucosal plexus is one of two nerve networks of the enteric nervous system, which controls the digestive system. The submucosal plexus is in charge of the secretions of the mucosa and contractions of muscularis mucosae.

What is the physiological significance of pharyngeal constrictors?

There are 3 pharyngeal constrictors; the superior, middle, and the inferior. The inferior constrictor contributes to the upper esophageal sphincter and prevents air from entering the esophagus.

What's is the physiologic significance of sodium amino acid transport proteins?

There is also a higher concentration gradient of sodium outside the cell in the intestinal lumen. The sodium amino acid transport proteins allows the amino acids to 'piggyback' on sodium concentration gradient going against its own gradient for protein absorption.

What would happen if the lower esophageal sphincter failed?

This would result in gastroesophageal reflux, more commonly known as heartburn. The lower esophageal sphincter prevents stomach contents and acid from entering the esophagus. If it failed, the acid would cause irritation and inflammation of the esophagus which results in the feeling of pain near our heart.

What would happen if an individual could not absorb water in their intestines?

Water balance is maintained in the intestinal tract through absorption. Out of the 9L of water a day, 8L is absorbed by the the small intestine, while 0.9L is absorbed by the large intestine. When unable to absorb the water in their intestines that individual will develop diarrhea, a condition where too much water is left in the feces. One common cause is a bacteria infection that causes the feces to pass too quickly through the intestines for absorption to occur.

How could you tell if an individual's hard and soft palates were normal? by watching them eat?

You could tell if someone had a normal hard and soft palate if that individual was able to simultaneously chew and breath at the same time while eating. The friction ridges of the hard palate act as speed bumps for the food in your mouth while chewing. The uvula of the soft palate acts as a barrier when you are swallowing that prevents food from entering the nasopharynx during deglutition.