Digestive System Overview

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Questions and Answers

What is the primary function of the teeth in the digestive system?

Absorption of nutrients

Mechanical breakdown of food (correct)

Secretion of digestive enzymes

Chemical breakdown of food

At what age do deciduous teeth generally begin to erupt?

At birth

6 months (correct)

1 year

3 months

Which type of teeth is the first to emerge during childhood?

Premolars

Incisors

Canines

Molars (correct)

What substance forms the outermost layer of a tooth's crown?

Enamel Signup and view all the answers

Which of the following structures are NOT considered part of the alimentary tube?

Salivary glands Signup and view all the answers

What is the main role of the salivary glands in the oral cavity?

Secrete saliva for digestion Signup and view all the answers

What type of cells produce enamel?

Ameloblasts Signup and view all the answers

Which part of the alimentary tube is primarily responsible for the absorption of nutrients?

Small intestine Signup and view all the answers

What type of epithelium lines the esophagus?

Stratified squamous epithelium Signup and view all the answers

Which structure is responsible for regulating secretions in the mucosa?

Meissner's plexus Signup and view all the answers

How many layers of smooth muscle are typically found in the external muscle layer of the stomach?

Three Signup and view all the answers

What is the function of the pyloric sphincter?

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

Which layer of the alimentary tube is made up of areolar connective tissue and contains many blood vessels?

Submucosa Signup and view all the answers

Which nerve impulses increase secretions in the alimentary canal?

Parasympathetic impulses Signup and view all the answers

What is the name of the fluid that prevents friction between the peritoneum and mesentery?

Serous fluid Signup and view all the answers

What is the primary role of the stomach in digestion?

To break down food mechanically and chemically Signup and view all the answers

What is the primary function of the tongue in the swallowing process?

To elevate and push food toward the pharynx Signup and view all the answers

Which of the following statements about saliva production is correct?

The sight or smell of food can enhance saliva secretion Signup and view all the answers

What role does the lower esophageal sphincter (LES) play in the digestive process?

It controls the entry of food into the stomach Signup and view all the answers

Which type of muscle primarily composes the tongue?

Skeletal muscle Signup and view all the answers

What constitutes the main structural layers of the alimentary tube?

Mucosa, areolar connective tissue, and smooth muscle Signup and view all the answers

What triggers the increase in saliva secretion during digestion?

Physical presence or sight/smell of food Signup and view all the answers

Which salivary gland is located inferior to the floor of the mouth?

Sublingual glands Signup and view all the answers

What condition may arise from improper functioning of the lower esophageal sphincter?

Gastroesophageal reflux disease (GERD) Signup and view all the answers

Study Notes

Introduction

The digestive system breaks down complex organic nutrients into simple organic and inorganic molecules.
These molecules are absorbed into the blood or lymph for transport to cells.
The digestive system is divided into two parts: the alimentary tube and accessory organs.
The alimentary tube runs from the mouth to the anus, including the oral cavity, pharynx, esophagus, stomach, small intestine, and large intestine.
Digestion occurs in the oral cavity, stomach, and small intestine; most nutrient absorption occurs in the small intestine.
Undigestible material (like cellulose) is eliminated by the large intestine (colon).
Accessory organs include teeth, tongue, salivary glands, liver, gallbladder, and pancreas.

Oral Cavity/ Buccal Cavity

Food enters via the mouth.
Boundaries include the hard and soft palate, and cheeks.
The oral cavity contains teeth, tongue, and salivary glands.

Teeth

Teeth function in chewing (mechanical breakdown).
Deciduous teeth (baby teeth) erupt around 6 months and are replaced by permanent teeth around age 6.
A complete set of permanent teeth has 32 teeth of different types (incisors, canines, premolars, molars).
The tooth crown is visible above the gums; the root is embedded in the jawbone.
The tooth structure includes enamel (outermost layer), dentin, and pulp cavity.
Erosion of enamel and dentin can lead to cavities from bacterial acids.

Tongue

The tongue is made of skeletal muscle innervated by the hypoglossal nerves (cranial nerve 12).
Papillae are small projections on the tongue surface.
The tongue is involved in swallowing, pushing food to the pharynx, and sensing taste.
The tongue has nerve supply from facial and glossopharyngeal nerves.

Salivary Glands

Saliva is produced by three pairs of salivary glands (parotid, submandibular, sublingual).
Saliva secretion is continuous but varies based on factors like food and stress.
Saliva is produced by parasympathetic response of facial and glossopharyngeal nerve, increased by sight/smell of food, and decreased by stress.
Saliva plays a role in moistening food, initiating starch digestion, and cleansing the oral cavity.

Esophagus

The esophagus is a muscular tube that carries food from the pharynx to the stomach.
No digestion takes place in the esophagus.
Peristalsis (wave-like contractions) moves food through the esophagus.
The lower esophageal sphincter (LES) prevents backflow of stomach contents.

Layers of the Alimentary Tube

The alimentary canal has four layers including the innermost mucosa layer, submucosa, muscular and outermost serous layer.
The Mucosa is composed of epithelial tissue, connective tissue and muscle layers.
The mucosa layer of esophagus is stratified squamous epithelium; that of stomach and intestines has simple columnar epithelium.
The muscular layer typically contains inner circular and outer longitudinal smooth muscle, which in the upper third of the esophagus contains striated muscle.
The stomach has three layers to help break up food and mix it with digestive enzymes.

Stomach

The stomach is a sac-like organ in the upper left quadrant of the abdomen.
The stomach is responsible for holding food and initiating chemical digestion by secreting gastric juices.
Both chemical and mechanical digestion begin in the stomach.
The cardiac orifice connects to the esophagus, and the pylorus connects to the small intestine.

Small Intestine

The small intestine is a long, coiled tube connecting the stomach to the large intestine.
The small intestine is responsible for most of the absorption of nutrients.
It includes three sections: duodenum, jejunum and ileum.
The duodenum is the first part of the small intestine, where bile and pancreatic secretions enter.
Sections of the small intestine are specialized for absorption.
The lining of small intestine has villi for absorption and enteroendocrine cells for producing hormones.

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Description

This quiz covers the fundamental aspects of the digestive system, including its structure and function. Learn about the components of the alimentary tube, accessory organs, and the processes of digestion and absorption. Test your knowledge on how nutrients are broken down and transported within the body.