Digestive System Lectures

Flashcards to help review lecture notes about the digestive system.

What are the four key functions of the gastrointestinal tract or digestive system?

Ingestion, Digestion, Absorption, Excretion

What is the roll of the teeth?

Masticate or chew the food up into smaller fragments, and this begins the process of mechanical digestion

What are the three pairs of salivary glands?

Sublingual, submandibular, parotid

What is the epiglottis?

Spoon shaped flap of cartilage that acts like a lid and seals the airway off, so it means that our food is getting directed down into the esophagus and not into the lungs.

What is mechanical digestion?

Purely a physical process and makes this food smaller to increase surface area and mobility so it can pass through the small and large intestine.

What does the chemical digestion involved?

Enzymes, water, acids, and salts, all beginning to break down complex food molecules into their chemical building blocks

What is the adventitia?

the outermost layer of our organs that are not associated with the peritoneal cavity

Name three layers of the GI tract wall excluding the serosa and adventitia.

Muscularis externa, submucosa, mucosa

What is the serosa?

A thin layer of connective tissue covered with a simple squamous epithelium

What does the submucosa contain?

Loose connective tissue, blood vessels, lymphatics, and nerves

What is the mucosa consisted of?

Epithelium, lamina propria, and the muscularis mucosa

Name the two types of receptors within the GI tract.

Mechanoreceptors and chemoreceptors

What are the two types of nerve plexus?

Intrinsic nerve plexus and the extrinsic nerve plexus

What are the four key functions of the gastrointestinal tract or digestive system?

Ingestion, Digestion, Absorption, Excretion

What is the roll of the teeth?

Masticate or chew the food up into smaller fragments, and this begins the process of mechanical digestion

What are the three pairs of salivary glands?

Sublingual, submandibular, parotid

What is the epiglottis?

Spoon shaped flap of cartilage that acts like a lid and seals the airway off, so it means that our food is getting directed down into the esophagus and not into the lungs.

What is mechanical digestion?

Purely a physical process and makes this food smaller to increase surface area and mobility so it can pass through the small and large intestine.

What does the chemical digestion involved?

Enzymes, water, acids, and salts, all beginning to break down complex food molecules into their chemical building blocks

What is the adventitia?

the outermost layer of our organs that are not associated with the peritoneal cavity

Name three layers of the GI tract wall excluding the serosa and adventitia.

Muscularis externa, submucosa, mucosa

What is the serosa?

A thin layer of connective tissue covered with a simple squamous epithelium

What does the submucosa contain?

Loose connective tissue, blood vessels, lymphatics, and nerves

What is the mucosa consisted of?

Epithelium, lamina propria, and the muscularis mucosa

Name the two types of receptors within the GI tract.

Mechanoreceptors and chemoreceptors

What are the two types of nerve plexus?

Intrinsic nerve plexus and the extrinsic nerve plexus

What kind of stimuli activates receptors in the GI tract?

Stimuli include distension, changes in osmolarity and pH of the contents, and the presence of substrates and end products of digestion.

What is another name for the intrinsic nerve plexus?

The intrinsic nerve plexus is also called the enteric nervous system.

What do motor neurons control?

These neurons control smooth muscle and gland activity.

What do sensory neurons do?

These neurons detect mechanical or chemical changes and relay information to other neurons.

What do interneurons do?

These neurons connect sensory and motor neurons within the plexus.

What are extrinsic nerve plexuses?

The extrinsic nerve plexuses work outside the digestive system and are composed of parasympathetic and sympathetic nerves.

How does the sympathetic and parasympathetic nervous system affect GI secretion?

The sympathetic nervous system inhibits GI secretion and motility, whereas the parasympathetic nervous system stimulates them.

Name three major hormones regulate digestion.

Gastrin, Secretin, and Cholecystokinin (CCK)

Where is Gastrin produced?

Stomach

Where is Secretin produced?

Small Intestine

Where is Cholecystokinin produced?

Small Intestine

What does gastrin do?

Stimulates gastric acid secretion and gastric motility

What does secretin do?

Stimulates secretion of bicarbonate-rich pancreatic juice and inhibits gastric acid secretion.

What does cholecystokinin do?

Stimulates secretion of enzyme-rich pancreatic juice and bile release from the gallbladder.

What is the upper GI tract consist of?

The oral cavity, pharynx, and esophagus

How is the oral cavity lined and how is it useful?

It is lined with stratified squamous epithelium, suitable for resisting abrasion during chewing and swallowing.

What is the roll of the tongue?

The tongue manipulates food for chewing, initiates swallowing, and contains taste buds.

What is the roll of the pharynx?

The pharynx serves as a passageway for both air and food.

What is the roll of the esophagus?

The esophagus is a muscular tube that propels food from the pharynx to the stomach using peristalsis.

What does the lower esophageal sphincter do?

The lower esophageal sphincter (LES) prevents stomach contents from refluxing back into the esophagus.

What is the stomach?

A J-shaped organ that stores food, mixes it with gastric secretions, and begins protein digestion.

What do gastric glands produce.

The gastric glands produce gastric juice, which includes HCl, pepsinogen, mucus, and intrinsic factor.

What do parietal cells secrete?

Parietal cells secrete HCl, which activates pepsinogen and kills bacteria.

What do chief cells secrete?

Chief cells secrete pepsinogen, which is converted to pepsin for protein digestion.

What do mucous cells secrete?

Mucous cells secrete mucus, which protects the stomach lining from acid and enzymes.

Describe the muscularis Externa.

The stomach’s muscularis externa has three layers of smooth muscle: longitudinal, circular, and oblique.

How does the stomach empty itself?

The stomach empties chyme into the small intestine through the pyloric sphincter.

What is the small intestine?

The small intestine is the primary site for nutrient absorption and consists of the duodenum, jejunum, and ileum.

What is the roll of the duodenum?

The duodenum receives chyme from the stomach, as well as bile and pancreatic enzymes.

What is the jejunum?

The jejunum is the middle segment and is highly specialized for nutrient absorption.

What is the ileum?

The ileum absorbs vitamin B_12, bile salts, and any remaining nutrients.

What are villi and microvilli?

These increase the surface area for absorption.

What is the Large Intestine?

The large intestine absorbs water and electrolytes, forms and stores feces.

What is the cecum?

The cecum is the first part of the large intestine, connected to the ileum via the ileocecal valve.

What are the different parts of the colon?

The colon consists of the ascending, transverse, descending, and sigmoid regions.

What is the roll of the Rectum?

The rectum stores feces until defecation.

What is the roll of the anal canal?

The anal canal terminates at the anus, which has internal and external sphincter muscles for controlling defecation.

What is the roll of the Pancreas?

The pancreas produces enzymes that digest carbohydrates, fats, and proteins, and it secretes bicarbonate to neutralize stomach acid.

What is the roll of the Liver?

The liver produces bile, which emulsifies fats for digestion and absorption.

The gallbladder stores and concentrates bile produced by the liver and