4 What I want you to do?Make your own life sized poster on the Human Digestive System:Journey of BIG MACromolecules to Smaller molecules.4 Parts to this journey (make sure you have the 4 hand outs and mark schemes)Structure and Function (Group)Digestive Processes (Group)Chemistry of Life (Extension work for group)Digestive Processes (Individual)Textbook: Shuters Top Class Life Sciences, Grade 11 (2012).
5 Let’s get the show on the road! Read over all the instructions first!Make sure you’ve read and understood the mark scheme.
6 Animal NutritionFood gives organisms energy for all cellular functions.Producers/autotrophsConsumers/heterotrophs:HerbivoresCarnivoresOmnivores
7 Part 1: Structure and Function Overview Eyes, Nose and tongueMouth and teethOesophagusStomachSmall Intestine (duodenum, jejunum and ileum)Colon/Large IntestineRectum and anusSalivary glandsLiver and gall bladderPancreasClick movie icon to start Introduction to Digestion Video!
8 Sensing food and the mouth, tongue and teeth All starts with the senses in the body!Mouth:Beginning of the Big Mac’s journeyTongue and teeth inside the mouthTongue tastes food and helps you swallowTeeth break up food into smaller pieces = mechanical digestion/mastication3 pairs of salivary glands that produce saliva:Water, slippery mucin and enzymes (lysozyme and salivary amylase)Helps to form bolus and lubricate it for swallowingSense of taste and smell videoTeeth video
9 Structure: Teeth 4 types: Humans Incisors canines premolars Molars 2:1:2:3Textbook Pg 123 & 131Q1:Which set of teeth belongs to which type of consumer and give reasons why?
10 Passed the pharynx, through the oesophagus Pharynx (throat):Muscular part at the back of mouthOpens to trachea (to the lungs) and oesophagus (to the stomach)Oesophagus:Narrow muscular tubeBolus moves down through contraction and relaxation of muscles in process called = PERISTALSISQ2:Can you think of other examples in the body where peristalsis is used to move things?Textbook Pg 133
11 Into the stomach Large ‘bag’ that receives and holds food. At each end of the stomach there are valves called sphincters that control the movement of food;Cardiac sphincter at the top endpyloric sphincter at the bottom endCells lining the stomach secrete gastric juice.Hydrochloric acid (HCl), low pHMucus, high pHProteases, (pepsinogen)Alcohol, Vit B12 and aspirin are absorbed.Food leaves the stomach as chyme.Stomach video
12 Into the not so… small intestine Soupy chyme enters small intestine.Folded tube (5 -7m long)Lined with columnar epithelial cells3 parts:DuodenumJejunumIleumDuodenum has Brunner’s glands which secrete alkaline rich mucus;Neutralise ChymeProvide right pH for enzymesLubricationDigestion of food is completed so that simple soluble nutrients can be absorbed.Carbohydrates, fats and proteins are digestedMost digested food absorbedSmall intestine video
13 Large intestineLarge intestine/colon stretches like a frame around the small intestine.Main functions:Absorb water, dissolved minerals and vitaminsHelped by over 700 species of bacteria (gut flora)Caecum and appendix are two structures where small intestine joins large intestine;No digestive function but contain tissue from the immune systemVery large in organisms that digest celluloseRectum is short tube at end of large intestine;Stores indigestible remains for short time before being expelledAt the opening end of rectum is anus;Surrounded by sphincter muscles to help control movement of faecesLarge intestine video
14 Associated glands: Salivary Glands and Pancreas 3 salivary glands that secrete saliva.Pancreas that secretes pancreatic juice.Travels down duct into duodenum (exocrine gland)Contains enzymes for breaking down foodCarbohydrases: starch maltoseProteases: proteins amino acidsLipases: lipids fatty acids and glycerolContains alkaline salts for neutralising acidic chymePancreas controls blood sugar levels by secreting hormones insulin and glucagon (endocrine gland).
15 Associated glands: Liver Largest gland and solid organ in the body.Liver has many functions:Secretes bile which is stored in gall bladder.Bile neutralises acidic chymeEmulsifies fats into small dropletsControls release of glucose in blood by convertingglucose glycogen.Controls excessive amino acid concentrations in the body through deamination.Process where amine group is removed from amino acid producing a carbohydrate and urea.Transports both glucose and amino acids if necessary via hepatic vein (vessel from liver to heart) to the heart and then to cells of the body.Store vitamins and minerals (if not needed pass out through urine).Alcohol and drugs are transported via hepatic portal vein (vessel from small intestine or stomach to the liver) to be metabolised.Liver fact pack