Digestive_System_Anatomy_and_Physiology.pptx

Digestive system and body metabolism
Key points of structure and functions of the digestive or gastro intestinal tract for college presentation.

1. Digestive System Anatomy and Physiology of the Human Digestive System Prepared for: College Nursing Students Topic Overview: Structure, Function, and Physiology of Digestion

2. Introduction • The digestive system is responsible for the mechanical and chemical breakdown of food. • Its main goal is to convert food into nutrients the body can use for energy, growth, and repair. • Composed of the alimentary canal and accessory organs.

3. Major Divisions 1. **Alimentary Canal (GI Tract)** – continuous tube from mouth to anus. 2. **Accessory Organs** – contribute to digestion but food does not pass through them. Examples: teeth, tongue, salivary glands, liver, gallbladder, pancreas.

4. Organs of the Alimentary Canal • Mouth • Pharynx • Esophagus • Stomach • Small Intestine • Large Intestine • Anus

5. The Mouth • Site of ingestion and initial digestion. • **Teeth**: mechanically break down food (mastication). • **Saliva**: produced by salivary glands; contains amylase which begins starch digestion. • **Tongue**: manipulates food, forms bolus, and assists in swallowing.

6. Pharynx and Esophagus • **Pharynx**: connects oral cavity to esophagus; serves as a passage for food and air. • **Esophagus**: muscular tube moving food via **peristalsis** to the stomach. • Upper and lower esophageal sphincters regulate movement and prevent reflux.

7. Stomach Anatomy • J-shaped organ located in the upper left abdominal cavity. • Regions: cardia, fundus, body, and pylorus. • Contains gastric pits with glands that secrete HCl and digestive enzymes. • Mucus protects the stomach lining from acid damage.

8. Stomach Physiology • **Mechanical digestion**: churning mixes food with gastric juices → chyme. • **Chemical digestion**: pepsin breaks down proteins. • Gastric emptying moves chyme into the duodenum through the pyloric sphincter.

9. Small Intestine Anatomy • Long coiled tube (~6 meters) consisting of: 1. Duodenum 2. Jejunum 3. Ileum • Lined with villi and microvilli → increase surface area for absorption.

10. Small Intestine Physiology • **Duodenum**: receives bile and pancreatic juice for digestion. • **Jejunum**: primary site for nutrient absorption. • **Ileum**: absorbs remaining nutrients and bile salts. • Enzymes complete digestion of carbohydrates, proteins, and lipids.

11. Large Intestine Anatomy • Includes cecum, colon (ascending, transverse, descending, sigmoid), rectum, and anus. • Functions: water and electrolyte absorption, feces formation, and bacterial fermentation.

12. Large Intestine Physiology • Absorbs water and salts from undigested material. • Houses gut microbiota that synthesize vitamins (K, B12). • Propels fecal matter toward rectum via peristalsis.

13. Accessory Organs • **Liver**: produces bile that emulsifies fats. • **Gallbladder**: stores and concentrates bile. • **Pancreas**: secretes pancreatic juice containing enzymes and bicarbonate.

14. Physiology of Digestion and Absorption • **Carbohydrates** → monosaccharides (by amylase, maltase, sucrase, lactase) • **Proteins** → amino acids (by pepsin, trypsin, peptidases) • **Lipids** → fatty acids and glycerol (by lipase, aided by bile) • Absorbed nutrients enter the bloodstream or lymphatic system.

15. Summary • Digestive system converts food into usable nutrients. • Involves coordinated action of organs, enzymes, and hormones. • Essential for maintaining homeostasis and supporting body functions.