DOUG BIO 1203: Unit 07 | Digestive System

What are the major functions of the digestive system?

To break down food and absorb nutrients efficiently.

What is the process of ingestion?

The process of taking food or liquid into the mouth.

Define propulsion in the context of the digestive system.

Movement of matter through the digestive system.

What is mechanical digestion?

Physical breakdown of food into smaller pieces.

What is chemical digestion?

Hydrolysis of macromolecules into smaller molecules.

What is absorption in the digestive process?

Movement of digested products into lymphatic and circulatory systems.

What does defecation refer to?

Elimination of indigestible substances, wastes, bacteria, and unabsorbed substances.

Differentiate between extracellular and intracellular digestion.

Extracellular digestion occurs outside a cell (in the digestive tract), while intracellular digestion occurs inside a cell (e.g., bacteria digested by white blood cells).

What is the anatomy of the buccal cavity?

Includes teeth, hard palate, tongue, and salivary glands, facilitating mechanical digestion and initial chemical digestion.

What is deglutition?

The process of swallowing food, involving the tongue, oral cavity, pharynx, and esophagus.

What are the stages of deglutition?

Voluntary stage, pharyngeal stage, and esophageal stage.

What is the function of the esophagus?

To transport food to the stomach through peristalsis.

What is peristalsis?

The wave-like muscle contractions that move food through the digestive tract.

What are the main functions of the stomach?

Holding area for food, mechanical digestion, chyme formation, and gastric juice production.

What are the components of gastric juice?

Hydrochloric acid, intrinsic factor, digestive enzymes (like pepsinogen), hormones (like gastrin), and mucus.

What role does hydrochloric acid play in digestion?

It increases stomach acidity, activating protein digestion enzymes.

What is the role of intrinsic factor?

It allows for the absorption of vitamin B12, essential for red blood cell formation.

What is the primary enzyme for protein digestion in the stomach?

Pepsinogen, which is activated to pepsin.

What is the significance of the peritoneum?

It lines the abdominal cavity and covers organs, allowing for movement and reducing friction.

What are the four basic layers of the alimentary canal?

Mucosa, submucosa, muscularis, and serosa.

What is the function of the liver in digestion?

It produces bile, processes nutrients, and detoxifies substances.

What is the function of the pancreas in digestion?

It produces digestive enzymes and bicarbonate to neutralize stomach acid.

What is the primary function of the small intestine?

To complete digestion and absorb nutrients into the bloodstream.

What is the role of the large intestine?

To absorb water and electrolytes, and to prepare waste for elimination.

What are the essential nutritional factors?

Carbohydrates, proteins, lipids, vitamins, and minerals.

What are the end-products of carbohydrate digestion?

Monosaccharides, primarily glucose, which are absorbed into the bloodstream.

What are the end-products of protein digestion?

Amino acids, which are absorbed into the bloodstream.

What are the end-products of lipid digestion?

Fatty acids and glycerol, which are absorbed into the lymphatic system.

What are the end-products of nucleic acid digestion?

Nucleotides, which are further broken down into nitrogenous bases, sugars, and phosphates.

How is the secretion of digestive juices controlled?

Through nervous control (e.g., sight, smell of food) and hormonal control (e.g., gastrin).

What are the two main groups of the digestive system?

Gastrointestinal (GI) tract and accessory digestive organs.

What organs are included in the gastrointestinal (GI) tract?

Mouth, pharynx, esophagus, stomach, small intestine, and large intestine.

Name three accessory digestive organs.

Teeth, tongue, and salivary glands.

What is the function of the peritoneal cavity?

It reduces surface tension and allows for movement of organs within the abdominal cavity.

What is the role of saliva in digestion?

It dissolves and lubricates food to form a bolus and initiates starch digestion.

What is the primary enzyme in saliva that aids in carbohydrate digestion?

Salivary amylase.

What are the three stages of deglutition (swallowing)?

Voluntary stage, pharyngeal stage, and esophageal stage.

What occurs in the stomach during digestion?

Mechanical digestion and chyme formation, along with the secretion of gastric juice.

What are the main components of gastric juice?

Hydrochloric acid, intrinsic factor, digestive enzymes (like pepsinogen), and mucus.

What is the role of hydrochloric acid in the stomach?

It increases acidity to activate protein digestion enzymes.

How does the stomach protect itself from digesting its own tissue?

It produces mucus that lubricates and protects the stomach lining.

What type of digestion occurs in the stomach?

Mechanical digestion through churning and chemical digestion of proteins and lipids.

What happens to salivary amylase in the stomach?

It is inactivated due to the low pH.

What is the function of the lower esophageal sphincter?

It regulates the passage of food into the stomach.

What is the primary function of the stomach?

To serve as a holding area for food and facilitate digestion.

What is chyme?

The semi-liquid mixture of food and gastric juices in the stomach.

What is the role of pepsinogen in the stomach?

It is an inactive enzyme that is activated to pepsin for protein digestion.

What is the significance of the muscularis layer in the GI tract?

It consists of two layers of muscle that facilitate peristalsis.

What is the purpose of the buccal cavity in digestion?

It is involved in mechanical digestion through mastication and initial chemical digestion.

What is the primary function of the salivary glands?

To secrete saliva that aids in digestion and lubricates food.

How does the cephalic phase of digestion begin?

It is triggered by the sight, smell, thought, or initial taste of food.

What is pepsinogen and how is it activated?

Pepsinogen is secreted in inactive form and is activated by low pH to form pepsin.

What role does the mucous barrier play in digestion?

The mucous barrier contains bicarbonate ions that denature pepsin.

What triggers the gastric phase of secretion?

The gastric phase is triggered by stomach distension and changes in pH.

What hormone is primarily involved in the gastric phase of secretion?

Gastrin.

What stimulates the release of gastrin?

Stomach distension, partially digested protein, and high pH.

What actions does gastrin promote?

Stimulates gastric glands to produce gastric juice, increases contraction of the lower esophageal sphincter, increases peristalsis of the stomach, and relaxes the pyloric sphincter.

What is the primary function of the liver in digestion?

The liver produces bile salts, controls blood glucose levels, produces plasma proteins, and detoxifies substances.

What is the hepatic portal system?

The hepatic portal system allows modification of nutrients absorbed from the digestive tract by the liver.

What is the function of bile salts?

Bile salts emulsify fats by breaking large globules into smaller ones.

What are the components of pancreatic juice?

Pancreatic juice contains water, salts, sodium bicarbonate, and digestive enzymes.

What enzymes are involved in carbohydrate digestion?

Pancreatic amylase (starch to maltose) and brush border enzymes (maltase, sucrase, lactase).

What is the role of the small intestine in digestion?

The small intestine is where the bulk of digestion and absorption occurs.

What is segmentation in the small intestine?

Segmentation separates chyme and mixes it, providing time for digestion and absorption.

What hormones are secreted by the small intestine?

Secretin and cholecystokinin.

What triggers the release of secretin?

Acidic chyme entering the duodenum.

What is the function of cholecystokinin?

Stimulates the pancreas to release digestive enzymes and the gallbladder to release bile salts.

What is the primary function of the large intestine?

Absorption of water, minerals, and vitamins; formation of feces.

What is the process of defecation?

Involves the colon, rectum, anal canal, and sphincters, regulated by nerve impulses and muscle contractions.

What is the role of pepsin in protein digestion?

Pepsin breaks down proteins into polypeptides in the stomach.

What enzymes are involved in protein digestion in the small intestine?

Trypsin, chymotrypsin, elastase, and carboxypeptidase.

What is the function of lipases in digestion?

Lipases break down triglycerides into monoglycerides and fatty acids.

What is the primary site of nutrient absorption?

The small intestine, facilitated by increased surface area from villi and microvilli.

What is the importance of the ileocecal valve?

It regulates the flow of material from the small intestine to the large intestine.

What is the significance of the gallbladder?

The gallbladder stores bile salts produced by the liver.

What is the role of intestinal juice?

Intestinal juice contains mucus, bicarbonate, hormones, and enzymes for digestion.

What is the function of brush border enzymes?

Brush border enzymes complete the digestion of carbohydrates and proteins in the small intestine.

What is the role of the diaphragm in defecation?

The diaphragm aids in the pressure changes necessary for defecation.

What is the primary function of the rectum?

The rectum stores feces before defecation.