Lecture 4.2 - Food in the Body - NATS1560

NATS1560: Food In The Body Angela Cope [email protected] LEARNING OBJECTIVES To define the main parts of the human digestive system and describe the process of digestion To explain in simple terms the basics of human metabolism To explain in simple terms the role of...

NATS1560: Food In The Body Angela Cope [email protected] LEARNING OBJECTIVES To define the main parts of the human digestive system and describe the process of digestion To explain in simple terms the basics of human metabolism To explain in simple terms the role of enzymes To explain in simple terms the action of insulin and glucagon To define Type 1 and Type 2 diabetes To define the main parts of the urinary system 2 Review: Metabolism: all the physical and chemical processes that take place inside an organism a flow of matter and energy (from food) in, through, and out the body Again, incredibly complex!  Energy exists in different forms that can transform into one another: kinetic energy (motion), thermal energy or heat (motions of molecules), chemical energy FOOD (potential energy of chemical bonds), and others The cells of living organisms are able to extract chemical energy from food molecules through the complex process called cellular respiration ENERGY In cellular respiration, monomers from food molecules are oxidized, producing many ATP (adenosine triphosphate) molecules and heat in the process, and carbon dioxide and water as waste products monomers cellular respiration from food + CO2 + H2O O2 chemic al energy ATP molecules heat The heat keeps the body warm. ATP molecules pack energy and take it to where it is needed for physiological functions and muscle motion The body stores unused food energy as chemical energy in glycogen and fat molecules The body uses its glycogen and fat molecules for energy when 4 food is insufficient WHAT FOOD IS FOR Our body disassembles the molecules of macronutrients into molecular “building blocks” (digestion) molecular building blocks: monosaccharides, amino acids, fatty acids, and glycerol It then uses the molecular building blocks to assemble them into body molecules disassemble them into CO2 and H2O to release energy 5 FOOD IN THE BODY Digestion Absorption Metabolism all the physical and chemical processes occurring in the cells of a living organism Excretion 6 THE BODY’S USE OF FOOD ENERGY Basal metabolism: minimal expenditure of energy needed by the body to stay alive on average, about 2/3 of total energy needs changes with age, highest in 1st year of life, stable between ages 20 and 50, declines after 50 mostly used by brain (20%), and liver, heart, and kidneys (38%), minimal use by body fat Physical and mental activity The “thermic effect of food” (about 10% of the metabolizable energy from food) energy lost as heat during digestion and metabolism a little energy is used to maintain body temperature when environment is too hot or too cold 7 METABOLIC PROCESSES Metabolism: all the chemical reactions by means of which an organism uses food molecules to live maintain basic life functions (heart, lungs, liver, brain, kidneys, etc) build new molecules for its organs, tissues, and other needs keep warm use muscles for deliberate physical activity Metabolic pathways: sequences of reactions leading from absorbed nutrients (substrates) to some final products (other compounds and energy) Specific metabolic pathways are enabled or disabled by specific enzymes 8 ENZYMES Enzymes are biological catalysts they enable or speed up metabolic reactions by lowering the activation energy From “Enzymes” at sciencetechstudy.com 9  THE HUMAN DIGESTIVE SYSTEM Digestive tract Organs that aid organs digestion mouth chews and salivary glands mixes food with saliva secrete the enzyme amylase esophagus moves food down into stomach through liver manufactures peristalsis bile, synthesizes glycogen and blood stomach proteins, stores iron adds hydrochloric and vitamins, etc. acid and enzymes (e.g., pepsin) and churns food into small intestine gallbladder stores chyme (duodenum, jejunum, bile ileum) uses enzymes from pancreas to digest pancreas secretes nutrients, and absorbs the digested enzymes (lipases, proteases, and large intestine molecules through carbohydrases) for (cecum, colon, the villi into blood the small intestine, and rectum) absorbs and lymphatic the hormones, water and minerals, vessels insulin and glucagon houses intestinal that regulate glucose flora (friendly levels in the blood bacteria) that complete digestion, eliminates MOUTH AND STOMACH In the mouth, food is chewed and mixed with saliva Saliva enzymes begin breaking down starch Swallowing triggers peristalsis, which moves food through the esophagus In the stomach, food is churned and mixed with gastric juices, and turned into chyme Gastric acid (hydrochloric acid) unfolds proteins, gastric enzyme (pepsin) clips polypeptides into smaller strands, fats separate from the watery mixture 11 SMALL AND LARGE INTESTINE In small intestine, bile (produced in liver, stored in gallbladder) emulsifies fat Enzymes from pancreas and intestinal cells (proteases, lipases, carbohydrases) digest fats, proteins, and starch and disaccharides Simple sugars, fatty acids and glycerol, amino acid, vitamins, and minerals are absorbed through the villi into bloodstream and lymph In large intestine, colon bacteria ferment some of the fibre Fermentation products, water, and minerals are absorbed Residues (waste products and bacteria) are excreted as feces 12 TEST PRACTICE What organ secretes insulin and glucagon? A) Esophagus B) Stomach C) Pancreas D) Gallbladder TEST PRACTICE: What organ performs Peristalsis? A) Esophagus B) Stomach C) Pancreas D) Gallbladder TEST PRACTICE What organ transforms food into chyme? A) Esophagus B) Stomach C) Pancreas D) Gallbladder TEST PRACTICE What is the liver responsible for? A) Synthesis of glycogen B) Production of bile C) Absorption of water D) Absorption of most nutrients E) A&B TEST PRACTICE What organ transforms food into chyme? A) Esophagus B) Stomach C) Pancreas D) Gallbladder THE LIVER Largest organ in the body converts simple sugars into glycogen converts non- carbohydrates into glucose stores iron and fat-soluble vitamins makes cholesterol and synthesizes amino acids into other lipids proteins for blood converts amino acids into variants removes dead blood cells, wastes, toxins and bacteria from bloodstream filters out toxins, e.g. alcohol HORMONES AND NUTRITION The level of glucose in the bloodstream must remain within a narrow range (70-100 mg/dl) − glucose needed for the central nervous system − too much glucose damages blood vessels The level of glucose in the bloodstream is © Sebastian Kaulitzki regulated by two hormones secreted by the When blood glucose is on the rise, insulin pancreas, insulin and glucagon signals the cells of the body to increase their uptake of all nutrients When blood glucose starts to drop, glucagon signals the liver to start breaking down glycogen, fat, and proteins Diabetes mellitus, type 1: pancreas produces too little insulin Diabetes mellitus, type 2: insulin receptors in cells do not function normally 19 THE URINARY SYSTEM Kidneys − clean the blood filtering out waste products and toxins − regulate the amount of water (therefore, the amount of blood) in the body − heart and hypothalamus send signals through changing levels of antidiuretic hormone (ADH) − regulate the concentration of ions and the pH of the blood Ureters channel urine out of the kidneys into the bladder Bladder holds the urine until built-up pressure sends the signal to urinate Sphincter relaxes to let urine out through the urethra 20 REVIEW: What are the functions of the liver? What hormones regulate the level of glucose in the bloodstream? What are Type 1 and Type 2 diabetes? What are the main organs of the urinary system? What are the functions of the urinary system? 21