SP25_CH4_Body+Basics

Body Basics Chapter 4 Overview

• Focus: Understanding the digestive system's chemistry and physiology.

Learning Objectives

• Discuss fundamentals of chemistry and physiology.

• Identify major organs of the digestive system:

  • Describe primary functions of each organ.

  • Identify accessory organs and their roles in digestion.

• Discuss nutrient digestion processes, absorption, transport, and waste elimination.

• Explore gut microbiota and its role in health.

Levels of Organization in Biological Systems

• Chemical Level:

  • Atoms combine to form molecules; structure determines function.

  • Example: Water molecules and their importance.

• Cellular Level:

  • Cells are basic units of life consisting of organelles that perform specific functions.

  • Formation of tissues from communities of similar cells.

• Tissue Level:

  • Different tissues combine to form organs.

  • Example: Smooth muscle, connective tissue.

• Organ Level:

  • Organs are composed of multiple tissue types working together.

  • Example: Bladder, stomach.

• Organ System Level:

  • Organ systems consist of two or more organs working together.

  • Example: Digestive system, nervous system.

• Organismal Level:

  • All organ systems function collectively to support life.

Nutrition: Chemistry Foundations

• Chemistry:

  • Study of matter's composition and properties.

  • All foods and bodily functions are based on chemicals.

• Human Physiology:

  • Study of body functions and their chemical basis.

  • Principles of chemistry and physiology form the foundation of nutrition.

Metabolism

• Totality of chemical reactions in cells, converting nutrients into energy.

• Anabolic Processes:

  • Build larger molecules from smaller ones (e.g., muscle repair post-weight lifting).

• Catabolic Processes:

  • Break down larger molecules into smaller molecules (e.g., digestion of starch into sugars).

Absorption and Transport of Nutrients

• Small Intestine Absorption:

  • Nutrients absorbed primarily through villi in the small intestine.

  • Water-soluble nutrients enter blood; fat-soluble nutrients form chylomicrons and enter the lymphatic system.

Gut Microbiota

• Large intestine houses diverse bacteria that:

  • Ferment undigested food.

  • Produce vitamins (K, B-12) and gases.

• Gut health is important; imbalances can lead to dysbiosis, influenced by diet, stress, and antibiotics.

Probiotics and Prebiotics

• Probiotics:

  • Beneficial live microbes, available in supplements/foods.

  • May help in gut health and disorders.

• Prebiotics:

  • Dietary fibers that nourish beneficial gut bacteria (e.g., inulin).

Digestive System Overview

• Structure: Gastrointestinal (GI) tract and accessory organs.

• Length: About 9 meters (30 feet), processes food from mouth to anus.

• Digestion begins in the mouth, involving both mechanical (chewing) and chemical (enzymes in saliva) processes.

• Esophagus transports food to the stomach; stomach aids in further digestion through mechanical churning and chemical secretions.

Stomach Functions

• Mechanical Digestion: Churning of food.

• Chemical Digestion: Hydrochloric acid (HCl) and pepsin assist protein breakdown.

• Chyme Formation: Partially digested food mixed with gastric juices.

Small Intestine Functions

• Three sections: Duodenum, Jejunum, Ileum.

• Most digestion and nutrient absorption occur in the duodenum and jejunum, aided by pancreatic and biliary secretions.

• Segmentation: Movement mixes chyme without pushing it forward, enhancing absorption.

Large Intestine Functions

• Limited absorption; primary role is fecal formation.

• Contains gut microbiota that facilitates further digestion.

  • Imbalance can lead to digestive disorders.

Disorders of the Digestive System

• Inflammatory Bowel Disease (IBD): Chronic inflammation, affects nutrient absorption (examples: Ulcerative Colitis, Crohn's Disease).

• Gastroesophageal Reflux Disease (GERD): Acid reflux causing esophageal damage.

• Peptic Ulcers: Sores in stomach/intestine lining due to HCl and infections.

• Irritable Bowel Syndrome (IBS): Non-damaging, characterized by cramps and abnormal bowel function.

• Colorectal Cancer: Requires early detection and treatment options such as surgery, chemotherapy.