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HUMAN ANATOMY - 8

HUMAN ANATOMY - 8. Digestive system. Primery Purpose of Digestive System. B reak ing down nutrients to the degree to be absorb ed, distributed and used by the body. Scince, dealing with digestive system is call gastro-enterology. Functions of digerstive system.

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HUMAN ANATOMY - 8

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  1. HUMAN ANATOMY - 8 Digestive system

  2. Primery Purpose of Digestive System • Breaking down nutrients to the degree tobe absorbed, distributed and usedby the body. • Scince, dealing with digestive system is call gastro-enterology.

  3. Functions of digerstive system • Digestion - mechanical & chemical • Absorbtion - uptake of digested nutrients into blood vessels within the wall of digestive tract • Elimination – of waste substances out of the body

  4. Basic anatomy of digestive system(p.955, fig. 25.1) The system consists of 2 major subdivisions • Digestive tract : mouth – pharynx – esophagus – stomach – small intestine – large intestine • Accessory organs: salivary glands, liver, pancreas

  5. Mouth (pp.958-959) • Teeth & tongue provied with mechanical digestion • Salivary glands (parotid is the largest) provide with chemical digestion • Salivary amylase digest carbs and salivary lipase starts digest fats

  6. Pharynx & esophagus • Pharynx is muscular funnel, connecting mouth with esophagus. • Esophagus is 30 cm muscular tube, which passes thorax, penetrates diaphagm and enters stomach. • Stomach is J-shaped muscular organ, which spreads from esophagus to small intestine.

  7. Stomach (p.966, fig. 25.12) • Apart from mechanical digestion, stomach provides with chemical digestion of the following enzymes • Pepsin – digests proteins • Gatric Lipase – digests 10-15% of fats • Stomach secrets also hydrocloric acid, which activates these enzymes . • Stomach secrets Intrinsic factor, which binds vit.B12 for its further absorbtion in small intestine (without vit.B12 hemoglobin can’t be synthesized, and anemia develops)

  8. Functions of hydrochloric acid • Activates gastric enzymes • Destroys connective tissues • Converts ferric ions into absorbable ferrous (Fe2+) ions for hemoglobin synthesis • Destroys many pathogens

  9. Small intestine (p.980, fig.25.24) • Consists of 3 parts • Duodenum (lat. “12”) 25 cm length, gets bile & pancreatic content • Jejunum (lat. “empty”)– 1.5 m length, major part of digestion & absorbtion • Ileum (lat. “twisted”)– 2.5 length, has thinner walls, rich in lymphatic nodes.

  10. Large intestine (p.991, fig. 25.31) • It consists of the following parts: • Ascending colon • Transverse colon • Descending colon • Sigmoid colon • Rectum • It function to reabsorb water & NaCl and form feces

  11. Accessory organs • Liver (p.975) • Pancreas (p.977)

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