NUTRITION

1. NUTRITION • Food is a source of energy and building materials for heterotrophs. • Energy is needed for daily chemical activities (metabolism)and the building materials needed for growth and the repair of tissues.

2. The tube starts here: You are a tube inside a tube… This tube is called the GUT. THROUGH-GUT. And although there are a few twists and turns along the way… Anything that goes in the top hole (mouth) does not become part of the body until it is absorbed (taken in) in a part called the small intestine. It comes out here:

3. BASIC STRUCTURE AND FUNCTIONof the human digestive system. different parts of the digestive system have different _______________ functions SPECIALISED

4. Cannot make their own food Make their own food Made by photosynthesis or chemosynthesis Have to find their food made by others

5. Examples of heterotrophs paramecium

6. Obviously, a heterotroph!

7. Enzymes • They need to be broken down chemically by ENZYMES. • Enzymes are biological catalysts. They speed up chemical reactions in the body. • Digestive enzymes speed up the breaking down process by holding the large particle (substrate) in place

8. Enzymes (Chemical Digestion) Remember : • Large particles cannot be absorbed in the small intestine INSIDE THE BODY (BLOOD) GUT Large particles (e.g. starch) are left in the gut and small particles (e.g. glucose) go through into the blood. starch starch starch G G G G G G BUT large particles can be broken down into small particles. This is called DIGESTION starch

9. The enzyme fits over the substrate perfectly – like a key fits a lock. Amylase enzyme Starch molecule It holds the starch molecule in place as a water molecule breaks the bond between two glucose particles

10. This continues until the molecule has been broken down completely

11. Digestive Enzymes • There are 3 main types of digestive enzymes: • Carbohydrasesbreaks carbohydratesdown into glucose. • Protease breaks protein down into amino acids. • Lipase breaks fats down into fatty acids and glycerol

12. carbohydrase Protease Digestive Enzymes Glucose Starch Amino Acids Protein

13. Digestive Enzymes Lipase Fatty Acid Glycerol Fatty Acid Glycerol Fatty Acid Fatty Acid Fatty Acid Fatty Acid Fatty Acids and Glycerol Fat

14. Tour guide • Mouth - saliva (contain enzyme) • Teeth • Amylase enzyme (What are enzymes???) • Oesophagus • peristalsis • Stomach – Gastric juice (contain enzyme) • Protease enzyme • Enzymes and pH • Pancreas Pancreatic juice (contain enzyme) • Amylase, Protease and Lipase Enzymes • Small intestine - Intestinal juice(contain enzyme) • Amylase, Protease and Lipase Enzymes • Absorption • Large intestine • egestion

15. 1 4 2 3 5 6 8 9 7 10 11 13 14 12 15

16. Salivary gland

17. There are different types of teeth for different functions: Types of teeth (Mechanical digestion) Sharp pointed teeth for cutting and tearing food DENTAL FORMULA 2.1.2.3. 2.1.2.3 Grinding and mashing food Crushing and grinding food Cutting and chopping food

18. Salivary glands

20. Saliva • Water softens food and moistens food, facilitating chewing (mastication) • Is neutral (or slightly alkaline for enzyme action (pH 8) • Contains enzymecarbohydrase (salivaryamylase) for digesting cooked starch.

21. The lining of the mouth cavity is able to "tell" when food is "ready". The tongue and palate mould the food into a small ball or ____________that is then ready for swallowing. bolus reflex • Swallowing is a __________ action of the tongue, palate, pharynx and glottis.

22. Swallowing & Peristalsis 1 The bolus is pushed downwards by peristalsis ____________ muscles above the bolus contract 3 The tube above the bolus narrows The______________muscles below the bolus relax. circular longitudinal

23. STOMACH

24. Gastric pits Gastric juice contains... protease enzymes which act upon proteins. water enabling easy movement of the food., mucinwhich forms a thick protective layer against the action of the enzymes in gastric juice. hydrochloric acid which provides an acid medium for enzyme action as well as acts as an antiseptic destroying "germs" taken in with the food.

25. GASTRIC PIT

26. ACCESSORY GLANDS

27. Gall bladder liver Common bile duct Hepatico- pancreatic duct pancreas

28. ACCESSORY GLANDS

29. NORMAL LIVER SECTION THROUGH LIVER HEPATIC PORTAL VEIN HEPATIC VEIN

31. Liver Functions 2. Liver detoxifies (makes harmless) harmful substances, such as alcohol (has enzyme alcoholic dehydrogenase). 3. Liver forms and stores fat 6. The liver is able to convert glucose to glycogen that is then stored in the liver (It can also convert glycogen back into glucose when the body needs it). • 5 The liver serves as a storehouse for mineralssuch as iron. 7. Secretes bile • Bile • Waterkeeps the food fluid for easy movement. • Alkaline bile salts neutralize the acid food from the stomach. • Emulsifies fats increasing the surface area for enzyme action. • Bile salts help in the absorption of fat and vitamins A, D, E and K that are fat-soluble. 4. Storage organ for the Vitamins A, D and B12

32. Liver Stomach Gall bladder Duodenum Pancreas Bile

33. duodenum • Like the liver, the pancreas is also an associated gland of the alimentary canal that opens up into the small intestine. It is a large gland that lies in the loop of the ____________________ of the small intestine. It secretes pancreatic juice that is carried by the pancreatic duct. The pancreatic duct joins the common bile duct and forms the hepato-pancreatic duct before it enters the duodenum. • Specialized cells called islets of _____________________, amongst the ordinary cells of the pancreas, secrete the hormones _____________ and ____________ that play an important role in controlling the blood ___________ (sugar) level. Langerhans insulin glucagon glucose

34. Tour guide • Mouth • Teeth √ • Amylase enzyme (What are enzymes???) √ • Oesophagus • Peristalsis √ • Stomach • Protease enzyme • Enzymes and pH √ • Pancreas • Amylase, Protease and Lipase Enzymes • Small intestine • Amylase, Protease and Lipase Enzymes • Absorption • Large intestine • egestion

36. Pancreas • Secretes • Pancreatic juice (containing digestive enzymes) • Hormones: insulin and glucagon

37. Pancreatic juice • Pancreatic juice is important since ... • water keeps the food fluid enabling easy movement of the food. • sodium bicarbonate neutralizes the acid food coming from the stomach so that the enzymes can function efficiently in the small intestine. • it contains the following enzymes o carbohydrasesto digest carbohydrates. o proteases to digest proteins o Lipases to digest lipids/fats

39. The duodenum • The first part of the small intestine is called the duodenum. • Food, still mixed with gastric juice is squirted into it from the stomach. • The food is now a semi liquid, highly acidic mush called chyme. • It needs to be neutralised and digestion needs to be continued…

40. jejenum • The ________________ is a short intermediate tube that follows the duodenum. It leads into the ileum. • The _____________ is the longest part of the small intestine. It runs from the jejunum to the sac-like caecum that is the first part of the large intestine. ileum

41. the ______________ on the outside. • the muscular region, assisting in peristalsis, made up of: • o an outer layer of ___________________ muscles. • o an inner layer of _______________ muscles. • a ______________________ made up of connective tissue with blood vessels, lymph vessels and nerves. • a ______________________ or mucous membrane which is the Innermost layer. It is lined with columnar epithelium with goblet cells that secrete mucous. SEROSA LONGITUDINAL CIRCULAR SUBMUCOSA MUCOSA

42. The small intestine has a large area for digestion and absorption because: • It is very long and folded in the abdomen. • The inner mucosa is folded. • On the surface of the mucosa are millions of microscopic villi

43. Small Intestine wall serosa • the ______________ on the outside. • the muscular region, assisting in peristalsis, made up of: • o an outer layer of ___________________ muscles. • o an inner layer of _______________ muscles. • a ______________________ made up of connective tissue with blood vessels, lymph vessels and nerves. • a ______________________ or mucous membrane which is the Innermost layer. It is lined with columnar epithelium with goblet cells that secrete mucous. longitudinal circular Sub-mucosa mucosa

44. Villi • These are small finger like structures that stick out into the small intestine tube. • They help to increase the surface area of the small intestine.

45. Outer wall Pathway for Food Inner wall Villi

46. VILLI

47. HOW TO DRAW A VILLUS ENLARGED LACTEAL CAPILLARY NETWORK CRYPT OF LIEBERKUHN BRUNNER’S GLAND EFFERENT VESSEL AFFERENT VESSEL TO LYMPHATIC SYSTEM

48. How is the villus well-adapted to the functions of digestion and absorption in the small intestine? • Finger-like, increasing surface area for absorption of nutrients • Villi wave motion mixes food with enzymes. • Crypts of Lieberkuhn secrete digestive enzymes to complete food digestion. • Brunner’s glands and mucous epithelium secrete mucus to aid peristalsis in the movement of food and to protect the intestinal wall.

49. How is the villus well-adapted to the functions of digestion and absorption in the small intestine? • Simple columnar epithelium is thin for short distances for absorbed foods to travel. • The Epithelium also actively absorbs the digested food • Brush border (microvilli) of simple columnar epithelium increases the absorptive surface area. • Capillary network efficiently carries away the absorbed food. • Lacteal carries away the absorbed products of lipid digestion.

50. Simple Columnar Mucous epithelium with micovilli A VENULE B ARTERIOLE C LACTEAL D CAPILLARY NETWORK E CRYPT OF LIEBERKUHN F BRUNNER’S GLAND G EFFERENT VESSEL H AFFERENT VESSEL I