Untitled Quiz

Chapter 2: Fate of Nutrients in the Human Body

• Digestion is the process of breaking down foodstuffs into smaller, simpler units.
• Digestive processes also require enzymes to accelerate reactions and hormones to control the process.
• The digestive tract (GI tract) anatomically includes the mouth, esophagus, stomach, small intestine, and large intestine.

Chapter 2.1: Digestion

• The digestive system's organs have specific roles in breaking down food.
• Students should be able to explain the functions of digestive organs and describe how carbohydrates, fats, and proteins are digested.

Digestion

• Digestion breaks down foodstuffs into simpler units, requiring enzymes and hormones.
• The GI tract includes: mouth, esophagus, stomach, small intestine, and large intestine.

Human Digestive Systems

• The human digestive system contains organs like the salivary glands, liver, gallbladder, pancreas, small intestine, large intestine, rectum, and anus.
• If food is not digested and absorbed, it remains undigested and isn't used as nutrients.

Digestive Organs

• This section discusses vital parts of the digestive system.

Mouth

• The mouth is the starting point of the digestive tract.
• Chewing breaks food into smaller, easier-to-digest pieces.
• Saliva begins the breakdown process, mixing with food to prepare it for absorption.
• Saliva contains water, salts, mucus, and enzymes.

Esophagus

• The esophagus is located in the throat, near the trachea.
• It receives food from the mouth during swallowing.
• Peristalsis, or muscular contractions, carry food down to the stomach.

Stomach

• The stomach is a hollow organ that temporarily holds food while it's mixed with gastric juice (enzymes, water, and HCl).
• Gastric juice helps break down food into usable forms.
• Cells in the stomach lining secrete strong HCl and powerful enzymes for breakdown.
• Goblet cells create mucus in the stomach.
• The stomach contents, properly processed, are released into the small intestine.

Pancreas

• The pancreas secretes pancreatic juice, containing enzymes and bicarbonate, into the duodenum (first part of the small intestine).
• These enzymes break down proteins, fats, and carbohydrates.
• The pancreas also produces insulin, a hormone that regulates blood sugar levels.

Liver

• The liver is crucial for processing nutrients absorbed from the small intestine.
• It produces bile, aiding in fat digestion.
• The liver acts as the body's chemical "factory," creating various essential compounds.
• It also has a detoxifying role, breaking down harmful chemicals and drugs.

Gallbladder

• The gallbladder stores and concentrates bile.
• It releases bile into the duodenum, aiding in fat absorption and digestion.

Small Intestine

• The small intestine is a 22-foot long muscular tube that breaks down food using enzymes from the pancreas and bile from the liver.
• It has three segments: duodenum, jejunum, and ileum.
• The duodenum breaks down food; the jejunum and ileum absorb nutrients into the blood.
• Peristalsis continues mixing food with secretions.

Large Intestine

• The colon (large intestine) is a 6-foot long muscular tube that connects the small intestine to the rectum.
• It's composed of the cecum, ascending colon, transverse colon, descending colon, and sigmoid colon.
• The appendix is a small tube attached to the cecum.
• The large intestine processes waste, making bowel movements easier.

Carbohydrate Digestion

• Saliva's amylase starts carbohydrate digestion.
• The stomach's acid halts this.
• Pancreatic amylase and disaccharidases further break down carbohydrates.
• Monosaccharides (glucose, fructose, galactose) are absorbed.

Lipid Digestion

• Some fats melt at body temperature, aiding initial digestion.
• Lingual lipase starts fat breakdown in the stomach.
• Bile helps in emulsification.
• Pancreatic and intestinal lipases break down fats further.
• Glycerol, fatty acids, and monoglycerides are absorbed.

Protein Digestion

• Chewing and saliva moisten food, but protein digestion mostly begins in the stomach.
• Hydrochloric acid (HCl) uncoils protein, activating enzymes.
• Pepsin, a stomach enzyme, breaks proteins into polypeptides.
• Pancreatic enzymes in the small intestine further break down polypeptides into tripeptides, dipeptides, and amino acids.
• The small intestine absorbs these smaller components.

Types of Absorption

• Passive absorption (without energy) happens with water, small lipids, and some minerals.
• Facilitated diffusion (with a carrier) is needed for glucose and fructose.
• Active transport (with energy) is crucial for glucose, galactose, amino acids, etc. Phagocytosis/pinocytosis (engulfment) is another absorption method needed for certain materials or antibodies.

Nutrients Absorption

• Explains passive transport (without energy), facilitated diffusion (with carrier), and active transport (with energy).
• Shows how water, small lipids, minerals, specific sugars and certain amino acids are absorbed.

Nutrients Transportation

• A system for delivering nutrients and reabsorbed water from digested food.
• The circulatory system plays a major role in moving absorbed components to the liver or other body parts.
• Explains nutrient transfer from the intestines to the liver, then to other parts of the body.

Protein Absorption & Transportation

• Explains how amino acids, dipeptides and tripeptides are absorbed and carried via capillaries in the villi of the small intestine.

Vitamin Absorption & Transport

• Explains how fat-soluble vitamins are absorbed with fats, and how water-soluble vitamins need active transport or carriers.
• Highlights the absorption of specific vitamins.

Digestion and Absorption Flow of a Sandwich

• Explains how different components of a sandwich (bread, peanut butter, seeds) are digested and absorbed in each part of the digestive tract.

Pause to Ponder Questions

• These are questioning prompts for students about digestion and absorption functions.