Lecture 2b- 17 January 2019 Lecture based largely on chapter 1 of Advanced Nutrition and Human Metabolism by Gropper et al -5th edition-on 2 hour reserve in library plus Chapter 7 of Understanding Normal and Clinical Nutrition-10th edition

Lecture 2ab- 15,17 January 2019 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

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

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

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

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

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

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

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

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

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?  

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

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  

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                         

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                

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                                        

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                          

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               

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

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

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  

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

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

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?  

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 B12                     -chief cells secrete precursors of pepsin used to degrade protein                   

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  

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  

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                

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  

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?               

Next 2 lectures metabolism of carbohydrates not including fibre