1. Lecture 2- 19 September 2013 Lecture based largely on chapter 1 of Advanced Nutrition and Human Metabolism by Gropper et al -5 th edition-on 2 hour reserve in library plus Chapter 7 of Understanding Normal and Clinical Nutrition-9 th edition

2. Lecture 2- 19 September 2012 Main components of this lecture are: a) overview of metabolism b) the cell and how it works in metabolism c) digestion and how it contributes to metabolism

3. Outline of lecture 2 a) Overview of Metabolism -definition -catabolism -anabolism -metabolic regulation - why is regulation necessary?

4. Metabolism cannot take place without the cell b) The cell -required as a location to house some metabolism and to produce components for metabolism no matter where such metabolism occurs -specific aspects of metabolism occur at specific points in the cell -must know where metabolism occurs to understand what is happening and why

5. The cell - cell components -plasma membrane -cytoplasmic matrix -mitochondrion -nucleus -endoplasmic reticulum -golgi apparatus -lysosomes and peroxisomes

6. The cell -cellular proteins -receptors and intracellular signalling -transport proteins -catalytic proteins

7. The cell -apoptosis -programmed cell death -cellular enzymes that take the cell offline- implications for disease

8. c) digestion and how it contributes to metabolism -cells are essential for digestion -overview of the structure of the digestive tract -structures of upper gastrointestinal tract -structures of lower gastrointestinal tract and accessory organs

9. -coordination and regulation of digestive processes -regulatory peptides -neural regulation

10. -the process of digestion-secretions and enzymes required for nutrient digestion -oral cavity -esophagus -stomach -small intestine -colon or large intestine

11. More detailed comments a) Overview of Metabolism -metabolism definition-sum total of all chemical reactions that occur in living cells - however the focus of this course in on metabolism as it relates to nutrition -consequently energy metabolism and its regulation will be the focus of this course -energy metabolism - how the body obtains and uses energy-yielding nutrients after they are absorbed

12. Energy metabolism -eg glucose from carbohydrates, glycerol and fatty acids from fat digestion and amino acids from proteins - is this really representative of energy metabolism? -catabolism-energy-producing reactions that occur as the result of breakdown of energy yielding nutrients-eg glucose from carbohydrates, glycerol and fatty acids from fat digestion and amino acids from protein

13. Energy metabolism -anabolism-energy-using reactions that may be used to build carbohydrates, lipids, proteins and participates in the synthesis of a wide variety of molecules in the body.-eg-glycogen synthesis from glucose, triglyceride synthesis from fatty acids and glycerol, protein synthesis from amino acids.

14. Energy metabolism -metabolic regulation -what is metabolic regulation?-orderly control of metabolic processes so that molecules are available for use when they are needed, in the form they are needed, where they are needed, and in the quantities they are needed Catabolic rate =anabolic rate in healthy persons- can you think of 2 exceptions to this equality?

15. Energy metabolism why is regulation necessary? molecules would not be available for use when they are needed, in the form they are needed, and where they are needed and in the quantities that are needed. Catabolic rate = metabolic rate -note that vitamins, minerals and water assist in the regulation of energy metabolism. Water and vitamins are metabolised as the result of the metabolism of energy yielding nutrients. Such metabolic results will not be the focus of this course. Metabolism cannot take place without the cell

16. b) The cell -required as a location to house some metabolism and to produce components for metabolism no matter where such metabolism occurs -specific aspects of metabolism occur at specific points in the cell -must know where metabolism occurs to understand what is happening and why

17. Cell components -plasma membrane -give cell shape and separate it from extracellular environment -protection for cellular contents -allows for cellular stimulation, nourishment and excretion of cellular wastes -bag for cell contents -membrane proteins act as pumps, gates, receptors, energy transducers and enzymes -made up of lipids, proteins and carbohydrates

18. Cell components -cytoplasmic matrix or cytoplasm or cytoplast -has microtrabecular lattice and fluid environment -site of glycolysis, hexose monophosphate shunt, glycogenesis and glycogenolysis, and fatty acid synthesis

19. Cell components -mitochondrion(mitochondria) -generation of most of adenosine triphosphate (metabolic energy) -oxidative metabolism(catabolism) of carbohydrate, lipids and proteins

20. Cell components -nucleus -contains DNA-the brains of the operation -DNA initiates and regulates most cellular activities

21. Cell components -endoplasmic reticulum-network of membranous channels in cytoplast -rough-has ribosomes - protein synthesis -smooth-no ribosomes -lipid synthesis -golgi apparatus-trafficking and sorting of proteins

22. Cell components -lysosomes-digestion of lipids, proteins and polysaccharides within the cell -peroxisomes-fatty acid oxidation and amino acid catabolism

23. Cell components -cellular proteins -receptors and intracellular signalling eg insulin docks to its receptor and sets up a series of intracellular signalling processes by which glucose is transported into the cell.

24. Cell components -cellular proteins -transport proteins-regulate flow of nutrients into and out of cell -can be carriers, pumps or pores

25. Cell components -cellular proteins -catalytic proteins -enzymes that result in reactions taking place more easily in the body -are all enzymes contained in cells?

26. The cell -apoptosis -programmed cell death- certain enzymes take the cell offline-implications for metabolism and health?- why not just have cells live on forever and reproduce forever?

27. c) Digestion and how it contributes to metabolism -cells are essential for digestion- impossible to have and regulate digestion and therefore all other metabolic processes without cells- -note the use of cells-plural-why?

28. Overview of the structure of the digestive tract -structures of upper gastrointestinal tract -oral cavity- mouth and pharynx -esophagus -stomach

29. Overview of the structure of the digestive tract -structures of lower gastrointestinal (gi) tract and accessory organs lower gi tract -small intestine -large intestine accessory organs -liver -pancreas -gall bladder

30. Coordination and regulation of digestive processes -regulatory peptides -gastrin-stimulates release of HCl -cholecystokinin -stimulates release of pancreatic juices and enzymes -stimulates bile release from gall bladder

31. Coordination and regulation of digestive processes -regulatory peptides -secretin-stimulates release of pancreatic juices -inhibits gut motility-why is this important in conjunction with stimulation of release of pancreatic juices

32. Coordination and regulation of digestive processes -regulatory peptides -gastric inhibitory polypeptide -inhibits gastric secretions and motility -somatostatin -inhibits release of gastrin, gastric inhibitory peptide, secretin and vasoactive intestinal peptide

33. Coordination and regulation of digestive processes -regulatory peptides -motilin -causes contraction of smooth muscle in intestinal wall -vasoactive intestinal peptide -stimulates intestinal secretions -relaxes most gi sphincters -inhibits gastric acid secretion -stimulates pancreatic bicarbonate secretion into the small intestine

34. Coordination and regulation of digestive processes -regulatory peptides -gastrin releasing peptide -stimulates release of HCl, gastrin and CCK -neurotensin -may mediate gastric emptying, intestinal motility and gastric acid secretion after fat ingestion

35. Coordination and regulation of digestive processes -regulatory peptides -substance P-increases blood flow to gi tract, inhibits acid secretion, inhibits small intestine motility

36. Coordination and regulation of digestive processes -neural regulation enteric nervous system-nervous system of gastrointestinal tract

37. Coordination and regulation of digestive processes -neural regulation What is a plexus? -myenteric plexus controls peristaltic activity and/or gastrointestinal motility -submucosal plexus controls mainly gastrointestinal secretions and local blood flow

38. Coordination and regulation of digestive processes -neural and hormonal regulation why have both?

39. The process of digestion-secretions and enzymes required for nutrient digestion -oral cavity -teeth-function in digestion -saliva -alpha amylase -starch -linguinal lipase -triglycerides -mucins -lubricate food

40. The process of digestion-secretions and enzymes required for nutrient digestion -esophagus -peristalsis -lower esophageal sphincter -regulates entry of food into stomach why have sphincters at all?

41. The process of digestion-secretions and enzymes required for nutrient digestion -stomach -parietal cells secrete HCl and intrinsic factor -intrinsic factor essential to absorption of vitamin B 12 -chief cells secrete precursors of pepsin used to degrade protein

42. The process of digestion-secretions and enzymes required for nutrient digestion -stomach -endocrine cells secrete hormones related to digestion eg gastrin -pyloric valve -controls dumping in duodenum

43. The process of digestion-secretions and enzymes required for nutrient digestion -small intestine -involvement of liver, gall bladder and pancreas -lipases -proteases -carbohydrases -absorption which ultimately leads to transport within the body- significance for metabolism? -ileocecal valve-controls dumping into colon

44. The process of digestion-secretions and enzymes required for nutrient digestion -colon or large intestine -water retention-why not let the kidney worry solely about this? -bacterial digestion of certain nutrients undigested prior to colon -primarily dealing with carbohydrate and to some extent proteins and amino acids

45. The process of digestion-secretions and enzymes required for nutrient digestion -colon or large intestine -short chain fatty acid absorption 2-4 carbon fatty acids produced by bacterial fermentation of carbohydrate used for energy in the body

46. The process of digestion-secretions and enzymes required for nutrient digestion -colon or large intestine -vitamin K(some bacterial production) and biotin absorption -sodium, chloride and potassium absorption- again why not let the kidney worry solely about ion retention?

47. Next day metabolism of carbohydrates not including fibre