Body Basics Chapter 03

Why Learn about Chemistry When Studying Nutrition? Organization Atoms → molecules → compounds → cells → tissues → organs → organ systems Atoms Ion Electrolyte

Levels of Organization in the Body

Why Learn about Chemistry When Studying Nutrition? Element Pure substance of only one type of atom 20 are essential to human health 6 elements account of 99% of body weight Molecule Two or more atoms are joined together Chemical bonds Macromolecules Molecular formula

Understanding Molecular Formulas

How are Cells, Tissues, Organs, & Organ Systems Related? Cytoplasm Organelles Transport mechanisms Passive mechanisms Osmosis Simple diffusion Facilitated diffusion Active mechanisms

Passive Transport Mechanisms

Carrier-Mediated Active Transport

A Typical Cell

How are Cells, Tissues, Organs, & Organ Systems Related? Types of tissue Epithelial Skin and inner lining of organs Connective Supports, connects, and anchors Muscle tissue Skeletal and smooth muscle Neural tissue

How are Cells, Tissues, Organs, & Organ Systems Related? Organs and organ systems More than 40 organs Eleven organ systems Communication systems Nervous system Endocrine system Chemical messengers Homeostasis

Organ Systems and Related Major Functions

What Happens during Digestion? Digestive system Hollow tube from mouth to anus Lumen Organs Transit time 24 to 72 hours Accessory organs Functions Digestion, absorption, elimination

Organs of the Digestive System

What Happens during Digestion? Neural and hormonal signals Peristalsis Wave-like muscular contraction Sphincters One-way valves Mucosa Enzymes Hormones

Peristalsis

Sphincters Regulate the Flow of Food

What Happens during Digestion? Cephalic phase of digestion Before food enters the mouth Mouth Physical digestion Grinding action of teeth Chemical digestion Saliva

What Happens during Digestion? Esophagus Swallowing is in two phases Bolus pushed back to pharynx Voluntary Bolus enters the esophagus Involuntary Peristalsis propels food toward the stomach Gastroesophageal sphincter Gastroesophageal reflux disease (GERD)

Voluntary and Involuntary Phases of Swallowing

Gastroesophageal Reflux Disease (GERD)

What Happens during Digestion? Stomach Functions Mixing food with gastric secretions Temporary food storage Ulcers Gastrin Chyme Gastric emptying Pyloric sphincter

What Happens during Digestion? Small intestine Primary site of chemical digestion & nutrient absorption Duodenum Secretions from gallbladder & pancreas Surface area Villi Specialized epithelial cells Microvilli

Overview of the Small Intestine & Accessory Organs

Absorptive Surface of the Small Intestine

What Happens during Digestion? Pancreas Protects small intestine from acid Gallbladder Storage reservoir for bile Dispersion of large fat globules Gallstones Cause Risk factors

The Pancreas Has an Important Role in Nutrient Digestion

Nutrient Absorption: What Happens after Digestion? Transfer of nutrient from lumen Blood or lymph Bioavailability Influential factors One nutrient influencing another nutrient

Nutrient Absorption and Circulation

Nutrient Absorption: What Happens after Digestion? Large intestine Sphincter between small and large intestine Prevent backward flow into small intestine Prevent premature flow into the colon Absorption of water and electrolytes

Overview of the Large Intestine

Nutrient Absorption: What Happens after Digestion? Large intestine Ideal environment for bacterial growth Microbiota Probiotic versus prebiotic foods Sphincter between rectum & anal canal Feces Intestinal disorders Irritable bowel syndrome (IBS) Inflammatory bowel disease

How Does the Body Circulate Nutrients & Excrete Waste Products? Cardiovascular system Water-soluble nutrients Circulate directly to liver Lymphatic system Lacteal Fat-soluble nutrients Excretion of wastes Excretory organs

What Is Metabolism? Metabolism Sum of chemical processes within a cell to maintain life Energy metabolism Transform stored energy in nutrients into ATP

What Is Metabolism? Metabolic pathways Enzymes Catabolic pathways Assistance of vitamins and minerals Catabolic pathways Breakdown of molecules to release energy Anabolic pathways Use of energy to construct pathways

What Is Metabolism? Metabolic pathways Catabolic pathways Anaerobic Limited energy generation Aerobic Anabolic pathways Example