Digestive System Overview

This set of flashcards encompasses key concepts regarding the structure and function of the digestive system based on lecture notes, providing a comprehensive review tool for exam preparation.

What are the main components of the digestive system?

The digestive system consists of the digestive tract (alimentary canal) and accessory organs like salivary glands, liver, gallbladder, and pancreas.

What is the function of the digestive tract?

The digestive tract is a tube from mouth to anus responsible for ingestion, digestion, absorption, and elimination.

What are the accessory organs of the digestive system?

Salivary glands, liver, gallbladder, and pancreas.

What is peristalsis?

Peristalsis is a wave-like muscle contraction that moves food through the digestive tract.

What is segmentation?

Segmentation is the contraction of circular muscles in the digestive tract, mixing food contents.

What is the role of the salivary glands?

The salivary glands secrete saliva to moisten food, prevent bacterial infection, and aid in digestion.

What are the three phases of swallowing?

The voluntary phase, pharyngeal phase, and esophageal phase.

What are the primary functions of saliva?

Saliva moistens food, helps form a bolus, and contains enzymes that begin digestion.

At what part of the digestive system does the bolus enter following swallowing?

The bolus enters the oropharynx.

What type of epithelium lines the esophagus?

Stratified squamous epithelium.

What is the mucosa of the esophagus primarily made of?

Stratified squamous epithelium.

What type of epithelium is found in the stomach?

Simple columnar epithelium.

How long is the esophagus?

About 25 cm long.

What are the components of gastric juice?

Hydrochloric acid (HCl), pepsinogen, and intrinsic factor.

What is the role of intrinsic factor?

It is necessary for the absorption of vitamin B12 in the distal ileum.

What stimulates gastric motility?

Gastrin, secreted by G cells, stimulates gastric motility.

What are the phases of acid secretion from the stomach?

Cephalic phase, gastric phase, and intestinal phase.

What is the primary site of nutrient absorption in the digestive system?

The small intestine.

How long does ingested nutrients stay in the small intestine?

At least 12 hours.

What three regions is the small intestine divided into?

Duodenum, jejunum, and ileum.

What is the main function of the pancreas?

To produce pancreatic juice rich in digestive enzymes.

What is bile's primary function?

To emulsify lipids and assist in fat digestion.

What are the components of pancreatic juice?

Water, bicarbonate, and digestive enzymes.

What role do enterocytes play in the small intestine?

Enterocytes are responsible for nutrient absorption.

What are chylomicrons?

Chylomicrons are lipoprotein particles that transport lipids from the intestine to other tissues.

What is the significance of Peyer patches?

Peyer patches are lymphatic nodules that help monitor intestinal bacteria and prevent infection.

What is the role of bile salts in digestion?

Bile salts emulsify fats, making them more accessible for digestion.

What is the function of the gallbladder?

The gallbladder stores and concentrates bile.

What substances does the liver detoxify?

Ammonia and convert it to urea.

What hormones regulate digestion in the digestive organs?

Gastrin, secretin, cholecystokinin, and gastric inhibitory peptide.

What is the role of the ileocecal valve?

It controls the flow of chyme from the small intestine to the large intestine.

What is the primary function of the large intestine?

To absorb water and electrolytes, and to form and store feces.

What are the types of teeth in adults?

2 incisors, 1 canine, 2 premolars, and 3 molars for a total of 32 adult teeth.

What is the structure of the stomach's muscularis externa?

It has three muscle layers: inner oblique, middle circular, and outer longitudinal layers.

What is a haustrum?

Haustra are pouches that form in the large intestine due to the contraction of taeniae coli.

What is the role of the hepatopancreatic sphincter?

It controls the flow of bile and pancreatic juice into the duodenum.

What are the three types of lipoproteins mentioned?

VLDL (very low-density lipoprotein), LDL (low-density lipoprotein), and HDL (high-density lipoprotein).

How does the body absorb fat-soluble vitamins?

Fat-soluble vitamins are absorbed in the small intestine along with lipids in micelles.

What do capillaries in the villi of the small intestine do?

They absorb nutrients into the bloodstream.

What is the function of weak peristalsis in the large intestine?

Weak peristalsis helps facilitate the slow movement of chyme and formation of feces.

What is the primary chemical that stimulates acid secretion in the stomach?

Gastrin.

How are polysaccharides digested in the intestinal lumen?

Polysaccharides are broken down into oligosaccharides and then into disaccharides through enzyme action.

What cells in the pancreas secrete digestive enzymes?

Pancreatic acini (exocrine cells) secrete digestive enzymes.

What does the term 'enteric nervous system' refer to?

The enteric nervous system is a network of neurons that control gut function independently of the CNS.

What is the role of goblet cells in the digestive system?

Goblet cells secrete mucus to lubricate the digestive tract.

How much water is absorbed by the small intestine?

The small intestine absorbs almost all ingested water.

What kind of muscle is found in the esophagus?

The esophagus contains both skeletal and smooth muscle.

What are the main actions of the digestive system?

Ingestion, secretion, digestion, absorption, and elimination.

What is bile composed of?

Bile is composed of bile salts, bilirubin, cholesterol, fats, and electrolytes.

What is the mean length of the small intestine?

Around 6 meters (20 feet) long).

What causes gallstones to form?

Gallstones form from precipitated cholesterol in bile.

What is the function of the submucosa?

It supports the mucosa and contains blood vessels, lymphatics, and nerves.

What makes up the portal triad in the liver?

The portal triad consists of a portal venule, a hepatic arteriole, and a bile duct.

Where does nutrient absorption predominantly occur?

In the jejunum segment of the small intestine.

What is the role of the mesentery?

The mesentery supports and stabilizes the intraperitoneal GI tract organs.