Digestive System Notes PDF

Digestive System Created @July 18, 2024 8:41 AM Class Biology Diagrams Balanced diet & energy requirements Energy requirements Food groups and their functions Food tests...

Digestive System Created @July 18, 2024 8:41 AM Class Biology Diagrams Balanced diet & energy requirements Energy requirements Food groups and their functions Food tests Alimentary canal Peristalsis Enzymes Calorimeter Visking tubing experiment Diagrams Diagram of alimentary canal(Figure 1) Diagram of small intestine(Figure 2) Diagram of villi(Figure 3) Effect of temperature on enzyme activity and rate of reaction(Figure 4) Effect of pH on enzyme activity and rate of reaction(Figure 5) Bomb calorimeter(Figure 6) Simple calorimeter(Figure 7) Balanced diet & energy requirements Definition of a balanced diet Digestive System 1  A diet containing carbohydrates, lipids, proteins, vitamins, minerals, fibre and water, in the right proportions and amounts Energy requirements Age - typically peaks around 25 years and decreases after Pregnancy - pregnant women require more energy Lifestyle - active lifestyles require more energy Food groups and their functions Function within Where is it Nutrient Summary the body found - Main source of - Made of carbon, hydrogen, short term energy and oxygen within the body - Mainly in the form of - Broken down starch(polymer of glucose), from starch and but may also include fructose, glycogen which lactose, and sucrose Rice are large insoluble - Starch is typically stored Potato molecules into within plant cells and is a large Bread Carbohydrates small soluble insoluble molecule molecules such as - Glycogen is the polymer of glucose and other glucose which is found in simple sugars to animal cells allow for diffusion - Make up 1% of the mass of - Used in the human body respiration to - Starvation may occur from release energy lack of carbohydrates Lipids - Made of oxygen, hydrogen, - Acts as insulation and carbon under the skin and - Consist of glycerol and 3 reducing heat loss fatty acids - Helps protect Meat - Saturated fats are those fats organs from Butter which have no double bonds mechanical Cheese and are more common from damage Eggs animal sources - Used as a long Fish - Unsaturated fats are fats term store of which have double bonds energy - Unsaturated fats are considered to be healthier Digestive System 2  than saturated ones - Make up 10% of the mass of the human body - Lack of lipids may lead to flaky skin / skinny body - Overconsumption of lipids may lead to obesity, high chloesterol(buildup of fats in arteries, leading to chronic hart disease, high blood pressure, etc), and type 2 diabetes - Made typically of carbon, hydrogen, oxygen, nitrogen - Consist of amino acids which are joined together - 2 amino acids contain sulphur - Humans require 20 amino - Present in all acids, and 10 of them can be cells made within the body - Required for Meat - Shape of a protein is muscle growth and Fish Proteins important in carrying out its repair of tissues Eggs function - Needed for Dairy products - Order of amino acids enzymes, DNA, determines the shape of and RNA protein - Protein-deficiency disease common in poorer countries is known as kwashiorkor Makes up 18% of the mass of the body - Approximately 3g in the Used to make human body hemoglobin in red - May cause people to blood cells, Liver become anaemic if there is a Iron allowing them to Eggs deficiency as blood does not bind to and carry Spinach carry enough oxygen(people oxygen around the become pale, dizzy, tired) body Calcium - Approximately 1000g in the ◦ Making teeth and human body bones Digestive System 3  - May cause rickets(soft bones) if there is insufficient Dairy products calcium Fish Bread Vegetables ◦ Making teeth and - Approximately 650g in the bones human body ◦ Used in DNA, - Lack of phosphate may RNA and ATP as Most Phosphorus cause part of the foods hypophosphatemia(leading to backbone of the weakness, trouble breathing, double helix and loss of appetite) structure Approximately 100g in the ◦ Body Salt Sodium human body fluids(blood) Most foods Approximately 100g in the ◦ Body Salt Chlorine human body fluids(blood) Most foods ◦ Making bones Approximately 30g in the Green Magnesium ◦ Found within human body vegetables cells Vitamin A Deficiency may cause night - Improving night blindness and damaged vision Digestive System 4  cornea(xerothalmia) - Aids in maintaining the Fish liver oils, immune system liver, butter, carrots Helps with cellular Yeast extract Vitamin B1 Lack may cause beri-beri respiration Cereals Green Vitamin Helps with cellular vegetables Poor growth, dry skin B2 respiration Eggs Fish Lack of Vitamin B3 may cause Helps with cellular Vitamin B3 pellagra(dry red skin, poor Liver, meat, fish respiration growth, digestive disorders) - Needed to make Discovered as a cure to connective tissue scurvy for sailors - Maintaining Fresh fruit Vitamin C Scurvy causes wounds to fail healthy skin, blood Vegetables to heal and bleeding in the vessels, cartilage gums - Heals wounds Vitamin D Lack of vitamin D may cause - Helps bones to rickets absorb calcium Digestive System 5  and phosphate - Aids to maintain Fish liver oils bones Sunlight - Prevents Type of carbohydrate known constipation by Wholegrain as cellulose(used to make the giving muscles of cereals Dietary fibre cell wall for plants) the gut something Fruit Cellulose cannot be digested to push against Vegetables by humans - Prevents bowel cancer - Required for chemical reactions within the body - Used in plasma and cytoplasm Fruits Water - Works as a Vegetables solvent / transport for reactions and temperature regulation Food tests Steps Result(s) - Blue black if starch is - Place sample on spotting present tile Starch - Orange-brown if there is - Place 2-3 drops of iodine no starch solution onto the sample Glucose - Place sample of meal into - Blue if no glucose is a test tube present - Add 5cm3 of water into - Green or yellow if a little is test tube present - Add 5cm3 of Benedict's - Brick red if a lot is present solution - Mix together - Place test tube into water bath and heat between 80- Digestive System 6  100C - Wait for 5 minutes - Mix sample with biuret - Mixture turns purple solution Protein meaning protein is present - Shake together - Add water into test tube - Add sample to test tube - Milky if lipids are - Add a few drops of Lipids present(they dissolve in ethanol into test tube ethanol) - Shake Alimentary canal Part of the alimentary canal Function - Used for mechanical digestion to break down food into smaller bits called bolus Mouth/tongue - Mixed with salivary amylase to help breakdown starch Salivary gland - Produces and secrets salivary amylase - Transports food from the esophagus to Oesophagus the stomach - Liver produces bile which emulsifies(reduces size of) lipids - This increases surface area of lipids Liver - Lipase enzymes can break it down more easily - Aids to neutralise hydrochloric acid which is acidic - Stomach wall secretes hydrochloric acid which has a pH of about 2 Stomach - Kills bacteria which are taken into the gut - Pepsin breaks proteins down into peptides Gall bladder - Stores bile Pancreas - Produces and secretes enzymes Small intestine(duodenum & ileum) - Absorbs soluble products from digested food as well as water Digestive System 7  - Small villi help increase surface area of small intestine allowing for a higher rate of diffusion - Villus contain a network of capillaries which helps transport it to the circulatory system - Lacteal is present in the middle of villus which lipids enter(lipids are not very soluble so the lacteal breaks it down into three fatty acids and a glyceride) - Amino acids are transported directly into the blood - Epithelium is only one cell thick allowing for higher rate of diffusion - Stores waste material which cannot be digested by the body - Mostly cellulose, water, indigestible Large intestine(colon & rectum) remains - Colon absorbs remaining water - Rectum stores semi-solid waste material known as feces Anus - Expels feces from the body (egestion) Digestive System 8  Diagram of the alimentary canal(Figure 1) Digestive System 9  Diagram of the small intestine(Figure 2) Digestive System 10  Diagram of villi Peristalsis Digestive System 11  Two pairs of muscles work in tandem to push the food along Circular muscles are arranged in rings along the gut Longitudinal muscles are arranged along the length of the gut Waves of muscle contraction help move food along Enzymes Biological catalysts which speed up the rate of reaction by lowering the activation energy in living organisms How do they work? Enzyme is specialised for catalysing one reaction(specific to their substrates) Which substrate it catalyses is dependent on the shape of active site(they are complementary in shape to the substrate) Enzyme and substrate join at the active site forming an enzyme substrate complex, lowering the activation energy required to start the reaction Products are formed which leave the active site Digestive System 12  Enzymes are NOT organisms and are proteins Factors affecting enzymes When increasing temperature up till their optimum temperature - Higher temperature gives molecules of enzyme and substrate more kinetic energy - This increases the the number of collisions between enzymes and substrates - More enzyme substrate complexes are formed Temperature - Increased rate of reaction When increasing temperature past their optimum temperature - Enzymes denature and their active site changes shape - Substrates are unable to fit into the active site - Frequency of successful collisions decreases - Decreased rate of reaction - pH affects structure of enzyme molecule - Changes shape of the active site - Substrates are unable to fit into the active pH site - Frequency of successful collisions decreases - Decreased rate of reaction As the concentration of substrate increases, the frequency of collisions between enzymes and substrates Concentration of substrate increase, meaning more enzyme-substrate complexes are formed and thus the rate of reaction is faster Where enzyme is Enzyme Function Source of enzyme secreted Mouth Salivary amylase Starch → maltose Salivary glands Pancreatic Starch → maltose Pancreas Small intestine Digestive System 13  amylase Wall of small Small intestine Maltase Maltose → glucose intestine Pepsin Proteins → peptides Stomach wall Stomach Trypsin Proteins → peptides Pancreas Small intestine Wall of small Peptidases Peptides → amino acids Small intestine intestine Lipids → glycerol and Lipase Pancreas Small intestine three fatty acids Effect on temperature on enzyme activity and rate of reaction(Figure 4) Digestive System 14  Effect of pH on enzyme activity and rate of reaction(Figure 5) Calorimeter Bomb calorimeter Digestive System 15  Bomb Calorimeter(Figure 6) Simple calorimeter Simple calorimeter(Figure 7) Digestive System 16  Calorimeters measure the energy released from a sample of food by burning it Burning sample of food releases energy which then heats up water Energy released from sample of food is calculated using volume of water, mass of food and change in temperature Advantages of bomb calorimeter Accuracy is improved as energy from food is not lost while transferring food to the needle Little to no heat goes to surroundings Food is completely combusted due to the supply of oxygen allowing for release of all the energy Insulation to ensure little to no heat loss to surroundings from water Visking tubing experiment Visking tubing is partially permeable - starch is too large and insoluble to diffuse through the partially permeable Visking tubing while glucose is small and soluble and can diffuse through it down a concentration gradient Digestive System 17  The experiment above is set up twice - both with amylase and starch mixture, one with boiled amylase(denatured) and one with normal amylase which is able to break the large insoluble starch down into small and soluble glucose in the following way: Starch → maltose → glucose This experiment is a good model of the ileum in the small intestine - only small, soluble molecules can pass through the wall of the small intestine into capillaries. However it does not simulate the villi which help break down lipids Expected results at the Expected results at the Boiling tube START of the experiment END of the experiment Iodine test is orange as there is no starch on the Iodine test is orange as exterior of the Visking there is no starch on the tubing(it is unable to diffuse exterior of the Visking through the partially tubing(it is unable to diffuse permeable membrane as it through the partially is large and insoluble) permeable membrane as it Benedict’s test turns green Normal amylase is large and insoluble) to orange indicating a Benedict’s test is blue as positive result - this shows there is no glucose on the that the amylase has exterior of the Visking broken down the starch into tubing(amylase has not small and soluble glucose broken it down into maltose molecules which can + glucose yet) diffuse through the partially permeable Visking tubing Boiled amylase Iodine test is orange as Iodine test is orange as there is no starch on the there is no starch on the exterior of the Visking exterior of the Visking tubing(it is unable to diffuse tubing(it is unable to diffuse through the partially through the partially permeable membrane as it permeable membrane as it is large and insoluble) is large and insoluble) Benedict’s test is blue as Benedict’s test is blue as there is no glucose on the the starch is not broken exterior of the Visking down into glucose(boiled tubing(amylase has not amylase denatures, broken it down into maltose meaning its active site + glucose yet) changes shape and is Digestive System 18  unable to form enzyme- substrate complexes with starch to break it down into glucose) Digestive System 19