Digestive System. In one end and out the other.

Transcription

1 Digestive System In one end and out the other.

2 Overview Every cell in the body needs nourishment, yet most cells cannot leave their position in the body and travel to a food source, so the food must be delivered. The digestive system with the help of the circulatory system, is like a gigantic meals on wheels system, serving over 75 trillion customers the nutrients they need. It also has its own quality control and waste disposal system.

3 Functions Ingestion Digestion Mechanical Chemical Absorption Assimilation Elimination

4 3 Types of Movement 1. Chewing and swallowing 2. Peristalsis 3. Segmentation

5 Structures and Locations an overview Oral Cavity Thoracic Cavity Esophagus Abdominal Cavity Stomach Small intestine Duodenum Jejunum ileum

6 Structures an overview (cont.) Abdominopelvic Cavity Large intestine Cecum and veriform appendix Ascending colon Transverse colon Descending colon Sigmoid colon Rectum Anus

7 Structures Oral cavity Fxs Speech Taste Mastication Swallowing

8 Oral Cavity Sxs (cont.) Teeth Fxs Ingestion Mechanical digestion Sxs (2123) 32 permanent teeth 4 groups ( 4 quadrants) Incisors Canines Premolar (bicuspids) molars

9 Oral Cavity Sxs (cont.) Tongue Fxs Ingestion Mechanical digestion Some taste receptors Smooth and skeletal muscle covered by e.t.

10 Oral Cavity Sxs (cont.) Palate Fxs Ingestion Mechanical and some chemical digestion Hard (bony) and soft (m.m. and c.t.) Uvula Elastic cartilage and mm used in speech and guiding food.

11 Oral Cavity Sxs (cont.) Salivary glands Fxs Chemical digestion Moisten food Types Parotid anterior to ear Submandibular inferior middle mandible Sublingual inferior to tongue

12 Salivary glands

13 Deglutition (swallowing)

14 Esophagus Muscular tube lined with moist stratified squamous e.t. About 12 long Lies anterior to the vertebrae and posterior to trachea

15 Wall Sxs Structures in abdominal cavity Mucosa inner layer Submucosa c.t. Muscularis smooth mm 2 layers, circular and longitudinal Serosa outer layer Peritoneum: parietal, visceral, cavity, fluid, mesentery Lumen

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17 Stomach Regions Cardia Fundus Body Pylorus pyloric sphincter at distal end Internal anatomy Rugae longitudinal folds to allow expansion and increase surface area Muscular wall is 3 layers Longitudinal, circular, oblique Fxs Temporary food storage, mixing chamber Minor absorption Chemical and mechanical digestion -- chyme

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19 Small Intestine Components Duodenum final site of chemical digestion Jejunum absorption and assimilation Ileum - absorption and assimilation

20 Small Intestine (cont.) Internal Anatomy Plicae circulares increase surface area Villi increase surface area Microscopic projections on surface of plicae

21 Abdominopelvic cavities Large Intestine Sxs Cecum and veriform appendix A blind sac at the junction of the large and small intestine Colon About 4-5 long Sequence; Ascending transverse descending Sigmoid Rectum and Anal Canal Straight muscular tube Thick muscular layer

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23 Large Intestine (cont.) Fxs Absorption and assimilation of inorganic nutrients and H 2 O Extensive action of microorganisms are involved in the formation of feces Absorption of vitamin B12 and K Defecation (elimination)

24 Fecal Facts FART fecal air by rectal transmission 100 ml of water is lost in feces/day ¾ water, ¼ solid Solid portion consists of: 3% protein, 15% inorganic, 20% fat, 30% bacteria, 30% undigested fiber

25 Accessory Digestive Sxs Pancreas Endocrine and exocrine gland Exocrine portion secrete 20+ digestive enzymes into the duodenum Liver Largest glandular sx in the body Over 500 known fxs to regulate, detoxify, and metabolize products of digestion Gall Bladder Stores bile made in the liver Fxs to emulsify fats and buffer acidic contents in the duodenum

26 Biliary Duct System 1 = hepatic duct 2 = common hepatic duct 3 = Cyctic duct 4 = common bile duct 5 = pancreatic duct

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