DIGESTIVE SYSTEM PT.1 OBJECTIVES

What are the different types of digestion?

Ingestion and Propulsion

What is Ingestion?

Bringing food into the digestive tract

What is Propulsion?

Movement of food through the alimentary canal

How are digestion and absorption different but related processes?

Digestion breaks down the materials, and absorption moves them into circulation (Blood or lymph)

What are the different forms of mechanical digestion?

Mastication: Chewing

What is Secretion?

Movement of food through the alimentary canal

What is Elimination?

Digestive wastes exiting the body as feces

List the organs and structures of the digestive tract in order from the mouth to the anus (21 Answers)

Mouth/oral cavity Fauces

Oropharynx

Laryngopharynx Upper esophageal sphincter

Esophagus

Lower esophageal (cardiac) sphincter

Stomach

Pyloric sphincter

Duodenum

Jejunum

Ileum

Ileocecal valve

Ascending colon Hepatic flexure

Transverse colon Splenic flexure

Descending colon

Sigmoid colon Rectum

Anal canal

List the accessory organs of the Digestive System (Four Answers)

Salivary glands

Liver

Gallbladder

Pancreas

Salivary Glands release their secretions into the what?

Mouth

Liver releases its secretions into the what?

Duodenum

Gall Bladder releases its secretions into the what?

Duodenum

Pancreas releases its secretions into the what?

Duodenum

Mouth belongs to which epithelium?

Stratified Squamous

Fauces belong to which epithelium?

Stratified Squamous

Oropharynx belongs to which epithelium?

Stratified Squamous

Laryngopharynx belongs to which epithelium?

Stratified Squamous

Upper Esophageal Sphincter belongs to which epithelium?

Stratified Squamous

Esophagus belongs to which epithelium?

Stratified Squamous

Lower Esophageal Sphincter (Cardiac) belongs to which epithelium?

Stratified Squamous

Anal Canal belongs to which epithelium?

Stratified Squamous

Stomach belongs to which epithelium?

Simple Columnar

Pyloric Sphincter belongs to which epithelium?

Simple Columnar

Duodenum belongs to which epithelium?

Simple Columnar

Jejunum belongs to which epithelium?

Simple Columnar

Ileum belongs to which epithelium?

Simple Columnar

Ileocecal Valve belongs to which epithelium?

Simple Columnar

Ascending Colon belongs to which epithelium?

Simple Columnar

Hepatic Flexure belongs to which epithelium?

Simple Columnar

Transverse Colon belongs to which epithelium?

Simple Columnar

Splenic Flexure belongs to which epithelium?

Simple Columnar

Descending Colon belongs to which epithelium?

Simple Columnar

Sigmoid Colon belongs to which epithelium?

Simple Columnar

Rectum belongs to which epithelium?

Simple Columnar

Simple Columnar Function

Where absorption and secretion take place

Stratified Squamous Function

Thick multi-cell epithelium that provides protection

No absorption and secretion are taking place

Oral Cavity is lined with what epithelium

Stratified Squamous

Teeth Function

Used for mechanical digestion

Tongue Function

Helps move food around for chewing

Forms a bolus to prepare for swallowing

Salivary Glands Function

Produce saliva, which moistens food

Starts the digestion of starches

Helps protect the mouth from infection

Fauces Function

The opening between the oral cavity and the oropharynx, allowing food to pass into the throat

List the Salivary Glands

Parotid, Submandibular, Sublingual

Parotid Gland Location

Anterior to ear

Sublingual Gland Location

Below the tongue

Submandibular Gland Location

Below the jaw

Parotid Gland Innervation

Glossopharyngeal Nerve (CN IX)

Sublingual Gland Innervation

Facial nerve (CN VII)

Submandibular Gland Innervation

Facial nerve (CN VII)

Mucus Cell Function

Lubricates and binds material

Serous Cell Function

Produces salivary amylase and lipase

Has chemical digestion

Has antimicrobial components

Lysozyme Function

Antibacterial

95% Water Function

Dissolves chemicals to enhance taste sensations

What cranial nerves innervate the tongue? (Four Answers)

CN XII (Hypoglossal) 12

CN VII (Facial) 7

CN IX (Glossopharyngeal) 9

CN X (Vagus) 10

Hard Palate Function

Forming the roof of the mouth

Chewing

Helps with mechanical digestion and speech

Soft Palate Function

Closes off the nasal passage during swallowing

Moves during speech to help with sound production

What functions/processes occur in the pharynx?

Propulsion: Moves food from the mouth to the esophagus

What cranial nerve is the primary innervator of the pharynx?

Vagus Nerve (CN X)

Distinguish between the Oropharynx and the Laryngopharynx.

Oropharynx

Location: Behind the oral cavity

Involved in: Swallowing and speech.

Laryngopharynx

Location: Below the oropharynx

Involved in: Only swallowing

List the layers of the digestive tract wall from innermost to outermost. (Four Answers)

Mucosa

Submucosa

Muscularis

Serosa/Adventitia

Mucosa is the

Innermost layer

Mucosa is lined with

Stratified squamous or Simple columnar

Serosa/Adventitia is the

Outermost layer

Describe Submucosa

A Dense connective tissue and Has larger vessels

Serosa is made of

Visceral Peritoneum

Adventitia is made of

Dense Connective Tissue

Esophagus Function

Propels bolus to stomach

Where is the esophagus located relative to the trachea?

Front of the esophagus

Where is the esophagus located relative to the heart?

Front of the esophagus and below the trachea

Where is the esophagus located relative to the diaphragm?

Passes through the esophageal hiatus of the diaphragm

What happens to the muscularis of the esophagus as you move from the superior end to the inferior end of the organ?

Transition from skeletal to smooth

Lower Esophageal Sphincter Function

Prevent the movement of stomach contents back into the esophagus 

What is the esophageal hiatus?

The opening in the diaphragm through which the esophagus passes

Pyloric Sphincter Function

Controls the emptying of the stomach 

What are the major functions of the stomach? (Four Answers)

Mechanical Digestion

Kills pathogens with acidity

Chemical Digestion of Proteins

Denaturing proteins with acids

Is there significant absorption in the stomach?

No, it has minimal absorption

List the cells of the Gastric Glands

Parietal Cells, Chief Cells, Enteroendocrine Cells

Parietal Cells Secretion

HCl and Intrinsic Factor

Parietal Cells Function (Five Answers)

Secrete HCl

Activates pepsinogen

Kills pathogens

Denatures/breaks some bonds

Secreting intrinsic factor to aid in the absorption of Vitamin B12

Chief Cell Secretion

Pepsinogen

Enteroendocrine Cells Secretion

Gastrin

Enteroendocrine Cells Function

Release hormones like gastrin and secretin that help control digestion, absorption, gut movement, and secretions. Gastrin also increases secretion from parietal cells and chief cells, and boosts gastric motility

Pepsin Function

Chemically digests proteins

HCI Function

Activates pepsinogen

Kills pathogens

Denatures/breaks some bonds

What stimulates the production and release of gastric secretions?

An increase in PH stimulates the production and release of gastric secretions

What is the function of the surface mucous cells that line the stomach?

Secretes protective alkaline mucus

Gastric Folds (Rugae) Function

Allow Expansion

Small Intestine Function

Chemical digestion

Absorption

Propulsion

List the features of the small intestine that enhance/improve its function of absorption (Four Answers)

Length, Circular folds, Villi, Microvilli

How does length enhance absorption?

More area for absorption

How do Circular folds enhance absorption?

Increases surface area and slows food for better absorption

How do Villi enhance absorption?

Increases surface area and contains vessels for nutrient transport

How do Microvilli enhance absorption?

Increase surface area and aid in nutrient digestion

What is the difference between Villi and Microvilli?

Villi are large, visible projections, while microvilli are smaller, hair-like structures on the villi that further enhance absorption.

List the regions of the small intestine in the order in which material would pass through them.

Duodenum, Jejunum, Ileum 

Intestinal Crypts Function

Source of new columnar cells and Produce alkaline mucus

Intestinal Crypts Secretion (Four Answers)

Intestinal Juice

Disaccharidases

Peptidase

Mucus

Submucosal Gland in the Duodenum Function

To secrete alkaline mucus that helps neutralize stomach acid

Protect the intestinal lining

Goblet Cells in the Small Intestine Function

Lubricating mucus that protects against acidic chyme 

Absorptive Cells in the Small Intestine Function

Produce intrinsic enzymes for chemical digestion and absorption

Capillaries and Lymph Capillaries in the mucosa of the intestines Function

Absorbed nutrients