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Digestive System

Digestive System. http:// www.youtube.com/watch?v=0gY-zXsUYgs. As heterotrophs we cannot convert carbon therefore we ingest carbon in our food. All of our cells require nutrition for; Growth Repair Maintenance . Humans as Heterotrophs Hetero=another Trophe = nutrition.

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Digestive System

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  1. Digestive System http://www.youtube.com/watch?v=0gY-zXsUYgs

  2. As heterotrophs we cannot convert carbon therefore we ingest carbon in our food. • All of our cells require nutrition for; • Growth • Repair • Maintenance Humans as HeterotrophsHetero=another Trophe= nutrition

  3. Break down of food into nutrients. • Nutrients absorbed in the body. • Transported throughout the circulatory system. Nutrients in the cell can be used as a source of energy OR Used for the synthesis of chemical compounds Functions of the Digestive System

  4. Stages of the Digestive System • Absorption • Egestion • Ingestion • Digestion

  5. Ingestion occurs when food enters the mouth. • It is mechanically broken down by teeth 1. Ingestion

  6. Chewing stimulates the release of saliva from the salivary organs. • Saliva contains a mixtures of water, mucus and enzymes. 1. Ingestion: Cont.

  7. Enzyme that breaks starch down into simple sugars. 1. Ingestion: Amylase

  8. Food that has been chewed and mixed with saliva becomes a bolus. 1. Ingestion: Bolus • The epiglottis, a flap of skin directs food down the esophagus.

  9. When the bolus has entered the esophagus muscle contractions (peristalsis) move it towards the stomach. 1. Ingestion: Peristalsis

  10. Digestion occurs initially in the stomach. • The stomach is J-shaped, it stores food, and has a capacity of 1.5 L 2. Digestion: Stomach

  11. Food enters and exits the stomach through sphincters. • Sphincters are muscles surrounding a tube-like structure • The bolus enters the stomach when the cardiac sphincter relaxes. 2. Digestion: Sphincters

  12. The stomach contains gastric juice secreted by the stomach lining. • Gastric juice contains a mixture of: • HCL (hydrochloric acid) • Enzymes • Mucus 2. Digestion: Gastric Juice

  13. HCL • Breaks down fibres & Bacteria • Mucus • Protect stomach lining from HCL • If stomach lining is destroyed ulcers form. 2. Digestion: Gastric Juice

  14. Heliobacter pylori

  15. The stomach absorbs: • Water • Alcohol • Some medications (Aspirin) 2. Digestion

  16. Chyme travels out of the stomach by the pyloric sphincter into the small intestine. • Chyme is a mixture of: • Water • Digested food • Gastric Juices 2. Digestion:Chyme

  17. After the pyloric sphincter chime enters the duodenum • Duodenum is first 25cm of the small intestine. • 7m in length, 2.5m in diameter. 2. Digestion: Small Intestine

  18. Majority of digestion occurs here. • Secretions from pancreas and duodenum enter via a duct. 2. Digestion: Duodenum

  19. Has four functions in digestion: • Synthesis • Breakdown • Detoxification • Storage 2.Digestion: Liver

  20. Produces bile which breaks down fats. • Bile is stored in the gallbladder Synthesis

  21. Bile is an emulsifier (a compound used to mix immiscible substances) • This allows for the breakdown of fats and for travel through the digestive system. 1. Synthesis: Bile

  22. Gallstones occur when too much bile or concentrated bile is produced in the gallbladder. • The bile will crystalize into gallstones blocking the gallbladder. 1. Synthesis: Gallstones

  23. Process of removing Nitrogen group from Amino Acids to create urea. 2. Breakdown

  24. When there is a blockage of the gallbladder Jaundice can occur (yellowing of the skin). 2. Breakdown: Jaundice

  25. Removes toxins from the body including • Alcohol • Chemicals 3. Detoxification

  26. 4. Storage Vitamins and carbohydrates are stored in the liver.

  27. Increases the pH of chyme from 2.5 to 9 due to the production of sodium bicarbonate. • Secretes enzymes for digestion • Lipase (fats) • Trypsin (proteins) Pancreas

  28. Secretes • Maltase (maltose - > glucose) • Peptidase (protein breakdown) • Duodenum (beginning), Jejunum (middle), Ileum (end). Small Intestine

  29. Carbohydrates -> Glucose (amylase & maltase) • Proteins -> Amino Acids (pepsin & peptidase) • Fats (triglycerides) -> Fatty Acids & Glycerol (bile & lipase) Food & Enzymes

  30. The jejunum and ileum contain villi (finger like projections) which increase the surface area. • The villi help with absorption of • Glucose • Amino Acids • Fatty Acids • Glycerol 3. Absorption

  31. Once nutrient are absorbed through the villi they enter the blood stream and are dispersed throughout the body 3. Absorption

  32. Digestive System

  33. 3. Absorption: Large Intestine Water absorption Bacteria living in colon releasing Vitamin K & B, also absorbed.

  34. Cellulose aids in the ejection of material from the bowels. • Lack of cellulose in the diet can lead to colon cancer. 4. Egestion

  35. The entire process takes 24-36 hours. Digestive System

  36. Homeostasis The ability of the body to regulate according to the fluctuating internal and external environment

  37. Nervous and hormonal system aid digestion before we eat. • Seeing, smelling and tasting food stimulates production of gastric secretions. Digestion & Homeostasis

  38. Swallowing stimulate the production of gastric juices. • Gastrin (hormone) stimulates the release of gastric juice before food arrives. Digestion & Homeostasis Cont.

  39. Speed of Digestion: • Large meals with digest quickly due to strong stomach contractions and faster emptying. • Fatty meals slow down digestion due to a hormone response from the small intestine. Digestion

  40. Receptors in the body sense: • Blood Sugar levels • Body T • Oxygen level • Disruption in homeostasis -> Signal to brain for correction Homeostasis

  41. Blood Sugar • Concentration crucial to well being • Too low body shuts down (coma) • Eating increases blood sugar (glucose) Homeostasis: Blood Sugar

  42. Body releases insulin from pancreas to bring glucose inside cells. • Extra glucose taken by liver cells and convert to glycogen and stored. Homeostasis: Blood Sugar

  43. insulin release (pancreas) cells take up excess glucose, liver makes glycogen food high glucose normal glucose normal glucose low glucose glycogen release as glucose (liver) glucagon release (pancreas) • Decrease in blood sugar pancreas will be activate to release glucagon • Glucagon (hormone) will convert glycogen (in liver), back to glucose, which will be released into the blood. Homeostasis: Blood Sugar

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