Digestive system

What does the submucosal plexus regulate?

Digestive secretions and local blood flow.

What does the myenteric plexus regulate?

GI motility and muscular contractions.

What distinguishes a short reflex from a long reflex?

Short: local enteric neurons. Long: involves the CNS.

How does sympathetic activity generally affect digestion?

It inhibits digestive activity.

What is the lamina propria?

Loose connective tissue in the mucosa containing vessels and immune tissue.

What does MALT stand for?

Mucosa-associated lymphatic tissue.

What is the muscularis mucosae?

Thin smooth muscle layers that produce local mucosal movements.

What is adventitia?

Connective tissue covering organs outside the peritoneal cavity.

What is the main function of the myenteric plexus during peristalsis?

Coordinate smooth muscle contractions that propel contents.

Which membrane layer lines the abdominal cavity wall?

Parietal peritoneum.

What stimulates histamine release during gastric acid secretion?

Vagus nerve stimulation.

How does histamine affect parietal cells?

It increases gastric acid secretion.

What is the function of somatostatin in the stomach?

It inhibits gastric acid secretion.

What triggers somatostatin release during the gastric phase?

A very low stomach pH, around 2.

Which gastric secretion phase produces the most acid?

Gastric phase, approximately 50–60%.

What does the H⁺/K⁺ ATPase pump do?

Pumps H⁺ into gastric glands in exchange for K⁺ using ATP.

What is the enterogastric reflex?

An intestinal reflex that slows gastric activity when chyme enters the duodenum.

What is the role of serotonin in gastric motility?

It stimulates stomach contractions in response to distension.

What stimulates the migrating motor complex between meals?

Motilin released during fasting.

What is the function of vasoactive intestinal peptide (VIP)?

Reduces gastric acid secretion and increases intestinal blood flow.

What does gastric inhibitory peptide (GIP) do in these slides?

Weakly inhibits gastric acid secretion.

What happens to gastric emptying when fatty chyme enters the duodenum?

Gastric emptying slows.

How does glucose enter an intestinal enterocyte?

Through sodium-dependent cotransport.

How does fructose enter an intestinal enterocyte?

Through facilitated diffusion.

What powers sodium-dependent glucose absorption?

The Na⁺ gradient maintained by the Na⁺/K⁺ ATPase.

What is the function of micelles in lipid absorption?

They deliver digested lipids to the enterocyte surface.

What happens to bile salts after micelles deliver lipids?

They remain in the lumen and are mainly reabsorbed in the ileum.

How do chylomicrons reach the bloodstream?

Through lacteals, lymphatic vessels, and the thoracic duct.

Why can vitamin D deficiency reduce calcium absorption?

Vitamin D supports intestinal calcium absorption.

Why do osmotic laxatives soften stool?

Unabsorbed solutes retain water in the intestinal lumen.

The submucosa is labeled __________.

B

Why does peritonitis, inflammation of the peritoneal membrane, affect multiple digestive organs?

The peritoneal membrane surrounds many abdominal organs, so inflammation of the membrane will affect multiple organs rapidly.

Why would a disorder of the digestive system disrupt homeostasis?

The digestive system plays a critical role in many physiological processes that contribute to the maintenance of homeostasis, including supplying dietary nutrients, absorbing water, minerals, and vitamins for healthy body tissues, and eliminating wastes.

Many chemotherapy treatments for cancer kill rapidly dividing cells. What happens to a patient's digestive system on this kind of treatment?

Chemotherapy treatments will reduce the ability of the mucosa to maintain its epithelial lining.

Which of the following organs is not part of the gastrointestinal (GI) tract?

pancreas

Which of the following functions is not associated with the digestive system?

Filtration

The layer identified with a question mark is __________.

dentin

Why would decreased saliva lead to tooth decay?

Saliva helps to moisten and cleanse the oral cavity and contains lysozymes and IgA to kill pathogenic bacteria, preventing tooth decay.

Why do chemical warfare agents (nerve gases) that block the enzyme acetylcholinesterase cause drooling in individuals affected by them?

Salivation is stimulated by the release of acetylcholine by the parasympathetic nervous system. If ACh cannot be broken down by acetylcholinesterase, excess salivation will occur.

Certain diseases, such as Parkinson's disease, will weaken the swallowing reflex and decrease the muscularis externa activity in the esophagus. What is one type of complication that can result?

Patients with Parkinson's disease may aspirate their food because the swallowing reflex may not properly trigger the elevation of the larynx.

The most inferior division of the pharynx is the __________.

laryngopharynx

The bolus will still be able to move down the esophagus even if you are upside down because of __________.

peristalsis

The function of lysozyme in saliva is to __________.

perforate bacterial plasma membranes

During the swallowing reflex __________.

the epiglottis closes off the glottis

What symptoms will a patient with pyloric stenosis (a narrowing due to hypertrophy of the pyloric sphincter) have?

Pyloric stenosis may cause a patient to experience excessive vomiting, leading to electrolyte imbalance and malnutrition.

What additional effects will a vagotomy (severing the vagus nerve) have on a patient besides lowering stomach acid secretion?

Stomach acids are needed to activate pepsinogen so lower acid secretion will affect protein digestion in the stomach.

Celiac disease is caused by an allergy to gluten, a protein found naturally in some grains. The disease damages the lumen of the small intestine, specifically the villi and microvilli. Several symptoms associated with celiac disease would be

abdominal bloating and pain, chronic diarrhea due to excess unabsorbed water, and weight loss.

A meal high in protein will cause __________.

increased gastrin release

A patient presents with gastric acid hypersecretion. It can be explained by an increase in the plasma concentration of which of the following?

gastrin

The smell of croissants in a bakery would trigger the __________ phase of gastric secretion.

cephalic

The esophagus empties into the __________ region of the stomach.

cardia

The __________ cells of the stomach produce and secrete hydrochloric acid (HCl).

parietal

What effect would a poison that stimulates the parasympathetic nervous system, by activating the vagus nerve; have on the motility of the stomach?

This poison would increase the motility of the stomach but not affect much of the churning, which is under the control of hormones and enteric nervous system (ENS) neurons.

Most nutrient absorption in the GI tract occurs in the __________.

small intestine

The pattern of slow, rhythmic contractions of the small intestine during fasting is called the __________.

migrating motor complex (MMC)

The largest folds in the small intestine are the __________.

circular folds (plicae circulares)

Why are patients encouraged to take supplements that contain bacteria found in the natural flora when they are on antibiotics?

Antibiotics often destroy the natural flora in the large intestine which can lead to greater infections.

What would happen with the defecation reflex if the spinal cord were damaged?

Defecation would no longer be under voluntary control since the cerebral cortex would not be able to communicate with the external anal sphincter and levator ani muscle.

The voluntary relaxation of the external anal sphincter that triggers defecation is controlled by the __________.

cerebral cortex

Which of the following sphincters is voluntarily controlled?

External anal sphincter

The structures identified with the question mark are the __________.

pancreatic acini

What digestive functions would be affected by the removal of the pancreas from a patient with pancreatic cancer?

Removal of the pancreas would severely impact chemical digestion because the pancreatic juices contain multiple digestive enzymes needed to digest all types of nutrients.

Why would a pharmacist recommend a patient with liver damage to be given a lower dose of medication over a longer period than what the doctor originally prescribed?

Patients with liver disease metabolize drugs slower and they remain in the system longer than individuals with normal liver function.

The gallbladder releases bile directly into the __________

cystic duct

Which of the following hormones stimulates pancreatic secretions?

secretin

Which of the following functions is not associated with the liver?

Stores and concentrates bile

Why might the drug orlistat, which blocks pancreatic lipase, helps an individual lose weight?

Blocking pancreatic lipase will, in turn, block the chemical digestion and absorption of lipids, potentially leading to weight loss.

What will happen to supplemental digestive enzymes in the stomach after they are ingested?

Supplemental digestive enzymes are proteins and will be broken down in the stomach by the acids and pepsin, rendering them useless.

Would bile salts be effective if they were polar molecules instead of amphiphilic molecules?

If bile salts were polar molecules they would be ineffective because they would not be able to interact with lipids.

Most digestive enzymes catalyze __________ reactions.

hydrolysis

Which of the following is paired incorrectly?

pepsin - oligopeptides

Which of the following vitamins is absorbed in the ileum after binding to intrinsic factor?

Vitamin B₁₂

Which of the following enzymes digests proteins?

Pepsin

Before carbohydrates are absorbed, __________ digest disaccharides into monosaccharides.

brush border enzymes

Which digestive processes are missed by a patient who has a feeding tube placed in their stomach?

Patients with feeding tubes placed in their stomachs will not go through mastication and the initial chemical digestion of carbohydrates.

The digestive organs arterial blood supply does not come from the __________.

hepatic portal vein

What creates the mesentery?

Visceral peritoneum

Saliva is produced by all of the following glands except __________.

esophageal glands

Match the components of saliva with their functions.

Breaks down large polysaccharides into smaller polysaccharides

Salivary amylase

Catalyzes the perforation of bacterial plasma membranes

Lysozyme

Binds specific antigens on pathogens and mediates their destruction

Secretory IgA

Functions to neutralize any acid from the stomach that regurgitates into the esophagus

Bicarbonate ions

What is the main job of the pharynx?

Propulsion

The main function of the tongue during digestion is to __________.

help turn food into a bolus and push the bolus posteriorly during swallowing

The crown of a tooth is covered by __________.

enamel

Which of the following functions of the digestive system allows for food and liquids to pass from one organ to the next?

Propulsion

The __________ is the space between the internal surfaces of the lips and cheeks.

vestibule

Which of the following is not part of the alimentary canal?

Pancreas

The three phases of swallowing, in order, are:

voluntary phase, pharyngeal phase, and esophageal phase.

The third set of molars are more commonly known as __________.

wisdom teeth

The layers of the alimentary canal, from innermost to outer layer, are __________.

mucosa, submucosa, muscularis externa, and serosa

Which of the following are basic processes of the digestive system?

Secretion

Absorption

Propulsion

Defecation

The __________ covers the abdominal organs like an apron.

greater omentum

The __________ forms the outer tissue layer of some abdominal organs.

visceral peritoneum

The circular arrangement of muscles around an opening that controls the passage of material through the alimentary canal is known as a __________.

sphincter

Which of the following organs is part of the alimentary canal?

Esophagus

Carbohydrate digestion begins in the __________.

mouth

Motility through the alimentary canal consists of all the following different types except __________.

mastication

What is the first process to occur in the digestive system?

Ingestion

Food does not normally come in contact with the __________, but they are involved in secretion and digestion.

accessory organs

As a bolus moves down the esophagus, its movement into the stomach is regulated by the __________

gastroesophageal sphincter

What separates the oral cavity from the nasal cavity?

Hard palate and soft palate