Digestive System Lecture 2

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the function of the digestive system?

To eliminate nutrients from the body

To change complex molecules into simple molecules (correct)

To store food in the stomach

To absorb nutrients into the blood

What is another name for the digestive tract?

Gastro-intestinal tract (correct)

Alimentary tract (correct)

Nutrient tube

Digestive cavity

What is the first stage of digestion?

Mastication

Ingestion (correct)

Secretion

Motility

What is the role of mastication in digestion?

To chew food into smaller pieces Signup and view all the answers

What is the function of the salivary glands in the oral cavity?

To produce lubricating mucus Signup and view all the answers

What is the border of the vestibule of the mouth?

Lips and cheeks anteriorly and laterally Signup and view all the answers

What is the final stage of digestion?

Elimination of indigestible components Signup and view all the answers

What is the part of the oral cavity that lies outside the teeth and gums?

Vestibule of the mouth Signup and view all the answers

What is the main function of the salivary glands?

To aid in digestion and lubrication Signup and view all the answers

What is the number of teeth an adult has with a complete set?

32 Signup and view all the answers

What is the function of the papillae on the tongue?

To provide sensation of taste Signup and view all the answers

What is the name of the groove that separates the papillary and tonsillar areas of the lingual surface of the tongue?

Sulcus terminalis Signup and view all the answers

What is the percentage of water in saliva?

99.4% Signup and view all the answers

What is the function of the tongue in the oral cavity?

To aid in chewing, speech, taste, and swallowing Signup and view all the answers

What is the location of the parotid glands?

Below and in front of the ears Signup and view all the answers

What is the percentage of saliva produced by the minor salivary glands?

10% Signup and view all the answers

What is the function of hydrochloric acid in the stomach?

To soften the connective tissue in meat and destroy foreign organisms Signup and view all the answers

What is pepsin?

A protein-digesting enzyme Signup and view all the answers

What is the name of the mixture of gastric juice and food that leaves the stomach to enter the small intestine?

Chyme Signup and view all the answers

What is the longest part of the digestive tract?

Small intestine Signup and view all the answers

What is the function of the jejunum?

Absorption of sugars, fatty acids, and amino acids Signup and view all the answers

What is the function of the ileum?

Absorption of vitamin B12 and reabsorption of conjugated bile salts Signup and view all the answers

What is the purpose of villi in the small intestine?

To increase the surface area for digestion Signup and view all the answers

What is the diameter of the large intestine?

6.5 cm Signup and view all the answers

What is the function of the esophagus?

To carry food into the stomach Signup and view all the answers

Where is the stomach located in the abdominal cavity?

Upper left quadrant Signup and view all the answers

What is the name of the muscular ring that separates the esophagus from the stomach?

Lower esophagus sphincter Signup and view all the answers

What is the purpose of the rugae in the stomach?

To permit expansion of the lining without tearing Signup and view all the answers

What is the name of the space in the diaphragm that the esophagus passes through?

Esophageal hiatus Signup and view all the answers

What is the function of the pyloric sphincter?

To regulate the flow of food into the small intestine Signup and view all the answers

What is the volume of the stomach when it is empty?

50 ml Signup and view all the answers

What is the name of the muscular tube that connects the oral cavity to the pharynx?

Oropharynx Signup and view all the answers

Study Notes

Digestive System Overview

The digestive system is a muscular tube that extends through the body, composed of several parts: oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine.
Also known as the alimentary tract or gastro-intestinal (GI) tract due to the importance of the stomach and intestine in digestion.
Function: to change complex organic nutrient molecules into simple organic and inorganic molecules for absorption into the blood or lymph.

Stages of Digestion

Ingestion: introduction of food and liquid into the oral cavity.
Mastication: chewing, which divides solid food into digestible pieces.
Motility: muscular movements of materials through the tract.
Secretion: lubricating and protective mucus, digestive enzymes, acidic and alkaline fluids, and bile.
Hormone release: local control of motility and secretion.
Chemical digestion: enzymatic degradation of large macromolecules into smaller molecules and their subunits.
Absorption: of small molecules and water into the blood and lymph.
Elimination: indigestible, unabsorbed components of food.

Oral Cavity

Consists of teeth, tongue, and openings of salivary glands.
Two parts: vestibule of the mouth (outside teeth and gums) and mouth cavity proper (inside teeth and gums).
Teeth: 20 primary teeth in children, 32 permanent teeth in adults; incisors (cutting) and molars (grinding) teeth.

Tongue

Mass of striated muscle covered by mucosa, allowing high mobility.
Functions: chewing, speech, taste, and swallowing.
Two surfaces: smooth ventral surface and irregular dorsal surface with papillae and lingual tonsils.

Salivary Glands

Exocrine glands producing saliva with digestive, lubricating, and protective functions.
Collectively produce 1-1.5 L of saliva per day, composed of 99.4% water, ions, and enzymes.
Two types: minor salivary glands (10% of saliva) and major salivary glands (three pairs: parotid, submandibular, and sublingual).

Pharynx and Esophagus

Pharynx: connects oral cavity to esophagus; divided into oropharynx, laryngopharynx, and nasopharynx.
Esophagus: muscular tube, 25 cm long, carrying food into the stomach; no additional digestive processes occur here.

Stomach

Muscular sac, 50 ml in empty state, expanding to 1.5 L after a meal.
Located in the upper left quadrant of the abdominal cavity.
Rugae (folds) in the mucosa allow for expansion without tearing.
Two ends guarded by muscular rings or sphincters: lower esophagus sphincter (LES) and pyloric sphincter.
Gastric juice: mixture of hydrochloric acid (HCl) and pepsin, produced by special cells in the stomach lining.

Small Intestine

Longest part of the digestive tract, 6m long, but narrow in diameter (2.5 cm).
Divided into three parts: duodenum (first 25 cm), jejunum (2.5 m), and ileum (3.5 m).
Functions: breaks down food, absorbs nutrients, and allows food to pass from the stomach into the small intestine.
Villi (tiny finger-like projections) increase the surface area for absorption.

Large Intestine

About 6.5 cm in diameter and 1.5 m long.
Outer longitudinal muscle fibers form three separate bands on the surface.
Functions: absorption of water, electrolytes, and vitamins, and storage of feces.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers the basics of the digestive system, including its composition, parts, and functions. Learn about the oral cavity, pharynx, esophagus, stomach, and intestines.