1.3 - The Digestive Sytem

16 feet

Approximately, how long is the digestive tract?

Alimentary Canal

Other term for gastrointestinal tract?

Serosa → Muscularis externa → Submucosa → Mucosa → Lumen

What is the correct order of the small intestine lumen and its main tunic, from the outermost to innermost layer?

Serosa

What is the outermost tunic of the small intestine?

Muscularis externa

What tunic lies immediately internal to the serosa?

Outer longitudinal → Inner circular

What are the two muscle layers of the muscularis externa, from outermost to innermost?

Submucosa

What tunic lies between the muscularis externa and mucosa?

Mucosa

What is the innermost tunic of the small intestine?

Zymogens

This refers to as proenzymes or inactive form of an enzyme, which must be altered to function as an enzyme (e.g., trypsinogen)

Mouth, Pharynx

What constitute the oral cavity and provides the entryway to the digestive tract?

Mastication

This refers to the process in which food is broken down by chewing by the actions of the teeth, toungue, and jaw muscles. Also called as the “mechanical digestion of the mouth”.

Papillae

These are found as projections on the epithelial surface of the tounge that responds via its nerve endings to saltiness, sweetness, sourness, bitterness, and umami in foods.

Sweet

Which taste is traditionally associated with the tip of the tongue?

Salty

Which taste is traditionally associated with the anterolateral sides of the tongue?

Sour

Which taste is traditionally associated with the posterolateral sides of the tongue?

Bitter

Which taste is traditionally associated with the posterior/base of the tongue?

Parotid, Submaxillary, and Sublingual

What are the 3 sets of salivary glands?

Parotid Gland

What is the largest salivary gland?

Sublingual Gland

What is the smallest salivary gland?

α-amylase

The principal enzyme of saliva that hydrolyzes internal α(1-4) bonds within starch.

Lingual Lipase

This enzyme is produced by the lingual serous glands on the tongue and in the back of the mouth. This hydrolyzes dietary triacylglycerols (triglycerides) primarily after food has been swollowed and also present in the stomach.

Lingual Lipase

What enzyme of the mouth has a diminishing activity as we age and is limited by the coalscing of the fats within the stomach. This enzyme is also most helpful in infants as this enhances the digestion of triacylglycerol in milk.

Antibody IgA

An antibody present in the saliva.

R-protein

Also known as haptocorrin, its function is to enhance Vitamin B₁₂ absorption.

Haptocorrin

What is the other name of R-protein?

6.0 - 7.4

What is the pH range of saliva?

Xerostomia

Clinical term for dry mouth?

Bolus

A rounded mass of chewed food ready to be swallowed is called a?

Epiglottis

What structure closes during swallowing to prevent food from entering the trachea?

Peristalsis

This is a progressibe wavelike motion that moves the bolus through the esophagus into the stomach.

Lower esophageal sphincter (LES)

What sphincter closes after food enters the stomach to prevent gastric contents from refluxing back into the esophagus?

Nitric Oxide (NO) and Vasoactive Intestinal Peptide (VIP)

What substances primarily promote relaxation of the lower esophageal sphincter during swallowing?

Gastrin

What hormone primarily increases lower esophageal sphincter tone, promoting its contraction and closure?

Enteric nervous system

What division of the nervous system is commonly referred to as the “brain of the gut” because it independently regulates many gastrointestinal functions?

Deglutition

The movement of food from the mouth into the stomach is achieved by the act of what?

Pyrosis

Clinical term for heartburn is called as?

Gastroesophageal reflux disease (GERD)

What condition is characterized by repeated episodes of heartburn caused by the reflux of stomach contents into the esophagus?

Cardia

What part of the stomach immediately surrounds the opening of the esophagus into the stomach?

Fundus

What dome-shaped superior portion of the stomach lies above the level of the gastroesophageal junction?

Body

What is the largest central portion of the stomach, located between the fundus and pyloric region that serves as the reservoir for swallowed food ans is the main site for gastric juice?

Antrum

What distal portion of the stomach lies between the body and pyloric canal and helps grind and mix chyme before gastric emptying?

Chyme

What is the semi-fluid mixture of partially digested food and gastric secretions formed in the stomach?

Bolus; Chyme`

Chewed food formed into a soft mass for swallowing is called a _____, while the semi-fluid mixture of partially digested food and gastric secretions in the stomach is called _____.

1. Mucous cells

2. Parietal cells

3. Chief cells

4. G cells

5. ECL cells

6. D cells

What are the major cells of the gastric glands and their respective secretions?

Mucous cell

What gastric gland cell secretes mucus and bicarbonate to help protect the stomach lining?

Parietal cell

What gastric gland cell secretes hydrochloric acid (HCl) and intrinsic factor?

Chief cell

What gastric gland cell secretes pepsinogen and gastric lipase?

G cell

What gastric endocrine cell secretes gastrin?

Enterochromaffin-like (ECL) cell

What gastric endocrine cell secretes histamine, which stimulates acid secretion?

D cell

What gastric endocrine cell secretes somatostatin, which inhibits gastric acid secretion?

Mucus and bicarbonate

What substances are secreted by mucous cells of the gastric glands?

Hydrochloric acid (HCl) and intrinsic factor

What substances are secreted by parietal cells of the gastric glands?

Pepsinogen and gastric lipase

What substances are secreted by chief cells of the gastric glands?

Gastrin

What hormone is secreted by G cells of the stomach?

Histamine

What substance is secreted by enterochromaffin-like (ECL) cells of the stomach?

Somatostatin

What hormone is secreted by D cells of the stomach?

Rugae

Refers to the folds of the stomach’s mucosal lining that allow the stomach to expand when filled with food.