Digestion-Higher Level PowerPoint Presentation

Slide 1 -

Digestion

Slide 2 -

You are a tube inside a tube… And although there are a few twists and turns along the way… It comes out here: Anything that goes in the top hole (mouth) does not become part of the body until it is absorbed (taken in) in a part called the small intestine. This tube is called the GUT.

Slide 3 -

A closer look at absorption… Food is absorbed (taken in) to the body in the small intestine. The wall of the small intestine has small holes in it. Only small particles can pass through it: starch starch starch starch G G G GUT INSIDE THE BODY (BLOOD) Large particles (e.g. starch) are left in the gut and small particles (e.g. glucose) go through into the blood. G G G BUT large particles can be broken down into small particles. This is called DIGESTION

Slide 4 -

TASK: Copy and complete this diagram underneath Question 8 on your worksheet: starch starch starch starch G G G GUT INSIDE THE BODY (BLOOD) G G G BEFORE ABSORPTION GUT INSIDE THE BODY (BLOOD) AFTER ABSORPTION

Slide 5 -

What is the gut? The gut is a coiled tube where food is broken down (digested) and absorbed into the body. Any waste food is passed out of the body through the anus.

Slide 6 -

Proof! We can demonstrate the need for digestion using a model gut. Visking Tubing has the same small holes in it. If we put a mixture of starch and glucose into it, which one will go through the holes?

Slide 7 -

The Model Gut experiment

Slide 8 -

A journey through the gut For the rest of this topic we will be taking a trip through the gut from the starting hole (mouth) to the ending hole (anus). What are the parts of the gut? What will we see on the way?!

Slide 9 -

Tour map

Slide 10 -

Tour guide Mouth Teeth Amylase enzyme (What are enzymes???) Oesophagus peristalsis Stomach Protease enzyme Enzymes and pH Pancreas Amylase, Protease and Lipase Enzymes Small intestine Amylase, Protease and Lipase Enzymes Absorption Large intestine egestion

Slide 11 -

Tour guide Mouth Teeth Amylase enzyme (What are enzymes???) Oesophagus peristalsis Stomach Protease enzyme Enzymes and pH Pancreas Amylase, Protease and Lipase Enzymes Small intestine Amylase, Protease and Lipase Enzymes Absorption Large intestine egestion

Slide 12 -

Teeth Teeth are needed to tear, rip and chew food to physically break it into smaller pieces. Let’s look at the internal structure of teeth. You will need to cut up a copy of Worksheet 1 now.

Slide 13 -

Teeth The crown is the part of the tooth above the gum line The root is the part of the tooth below the gum line The enamel is the white part you can see covering the crown. Enamel is the hardest substance in the human body It covers the dentine and stops bacteria getting inside the tooth

Slide 14 -

Teeth The crown is the part of the tooth above the gum line The root is the part of the tooth below the gum line The dentine is the major component within the tooth. It is made from softer material than enamel so is easier to decay.

Slide 15 -

Teeth The crown is the part of the tooth above the gum line The root is the part of the tooth below the gum line The pulp contains the nerves and blood vessels of the tooth. It is underneath the dentine. This is the bit which hurts when you have toothache!

Slide 16 -

Teeth The crown is the part of the tooth above the gum line The root is the part of the tooth below the gum line The cementum is found outside the dentine in the root. It cements (holds) the tooth into the jaw bone.

Slide 17 -

Types of teeth There are different types of teeth for different functions: Cutting and chopping food Sharp pointed teeth for cutting and tearing food Crushing and grinding food Grinding and mashing food

Slide 18 -

Experiment Get a mirror and look at your own teeth. Can you identify your incisors, canines, pre molars and molars?

Slide 19 -

Experiment A dentist would write your dental records as I: 2/2 C:1/1 PM:2/2 M:3/3 What do you think this means? What is your dental record? If you do not have a full set of teeth, can you explain why some teeth are missing?

Slide 20 -

Tooth decay What do you think causes tooth decay? Saliva is normally slightly alkaline. When we eat, bacteria in our mouth feed on sugar and turn it into acid. The sugar starts to attack the enamel and wear it away.

Slide 21 -

Tooth decay Decay has started in the enamel NO PAIN Decay has reached the dentine SLIGHT TOOTHACHE Decay reaches the pulp SEVERE TOOTHACHE Decay has spread down to the nerve root EXCRUCIATING PAIN!!

Slide 22 -

Preventing Tooth Decay How can we prevent tooth decay? How well do you brush your teeth?! What sort of foods should you avoid? Design a poster for a Year 7 student explaining what causes tooth decay and how to avoid it.

Slide 23 -

Tour guide Mouth Teeth √ Amylase enzyme (What are enzymes???) Oesophagus peristalsis Stomach Protease enzyme Enzymes and pH Pancreas Amylase, Protease and Lipase Enzymes Small intestine Amylase, Protease and Lipase Enzymes Absorption Large intestine egestion

Slide 24 -

Enzymes Remember : Large particles cannot be absorbed in the small intestine starch starch starch starch G G G GUT INSIDE THE BODY (BLOOD) Large particles (e.g. starch) are left in the gut and small particles (e.g. glucose) go through into the blood. G G G BUT large particles can be broken down into small particles. This is called DIGESTION

Slide 25 -

Enzymes They need to be broken down chemically by ENZYMES. Enzymes are biological catalysts. They speed up chemical reactions in the body. Digestive enzymes speed up the breaking down process by holding the large particle (substrate) in place

Slide 26 -

The enzyme fits over the substrate perfectly – like a key fits a lock. It holds the starch molecule in place as a water molecule breaks the bond between two glucose particles Starch molecule Amylase enzyme

Slide 27 -

This continues until the molecule has been broken down completely

Slide 28 -

Digestive Enzymes There are 3 main types of digestive enzymes: Amylase breaks starch down into glucose. Protease breaks protein down into amino acids. Lipase breaks fats down into fatty acids and glycerol

Slide 29 -

Digestive Enzymes Starch Glucose Protein Amino Acids

Slide 30 -

Digestive Enzymes Glycerol Fatty Acid Fatty Acid Fatty Acid Glycerol Fatty Acid Fatty Acid Fatty Acid Lipase Fat Fatty Acids and Glycerol

Slide 31 -

Enzymes in Industry Enzymes are used in biological washing powders. These enzymes are good for breaking down coloured substances from animals or plants like blood or egg stains. Protease enzymes break down protein based stains Lipase enzymes break down fat based stains like greasy marks.

Slide 32 -

Enzymes in Industry Imagine your favourite shirt has a blood stain on it… The protease enzymes in biological washing powders, break down the Haemoglobin It is stained because blood contains the red protein Haemoglobin These smaller molecules are not coloured and dissolve easily in water. They can be washed away.

Slide 33 -

Enzymes in Industry Enzymes are also used in many other processes in industry e.g. Pectinase to extract juice from fruit Protease to break down the proteins in baby food to make it easier for the baby to digest Cellulases to soften vegetables Amylases to make syrup from starch Research one of these uses for homework

Slide 34 -

What factors affect the rate of reaction of enzymes How do you think you can speed up the rate of an enzymic reaction? (Hint: It’s the same as any other reaction!)

Slide 35 -

Amylase and Starch Investigation Amylase enzyme breaks down starch into glucose. Iodine is the test for starch. If starch is present, iodine turns blue/black. Watch the demonstration of the experiment then answer the questions on your sheet.

Slide 36 -

Apparatus Starch and Iodine Amylase enzyme Water at 37˚C Stopwatch, syringe x 2, thermometer,

Slide 37 -

Method Heat the water in the water bath to 37˚C. Measure out 1cm3 of Starch solution and put it into a test tube. Put 5 drops of Iodine into the starch. It should turn blue/black. Put the test tube into the water bath for 2 minutes. Put 5 drops of Amylase into the starch and start the stopwatch. Stop timing when the blue/black colour disappears.

Slide 38 -

Results It took _____ seconds for the Iodine and starch solution to turn colourless.

Slide 39 -

Conclusion When the starch has been digested into glucose by the amylase the blue/black colour disappears. It took _____ seconds for the amylase to digest the starch.

Slide 40 -

Task Design an experiment to investigate how to speed up the digestion of starch by amylase. Use the basic method in your worksheets but add detail to it. Carry out your investigation safely!

Slide 41 -

Basic method Put into a water bath for 2 minutes.  37˚C or  Different temperatures Add drops of Amylase enzyme. 5 drops or  Different number of drops Start the stopwatch! Don’t forget to write down how you will make it a fair test!!

Slide 42 -

Graph Number of drops Or Temperature Time taken (s) Work out the times taken for each experiment in seconds (remember there are 60 seconds per minute!) and put it in your results table Work out the average time taken for each temperature/number of drops and put it in your results table Plot a graph of your AVERAGE results only.

Slide 43 -

Tour guide Mouth Teeth √ Amylase enzyme (What are enzymes???) Oesophagus peristalsis Stomach Protease enzyme Enzymes and pH Pancreas Amylase, Protease and Lipase Enzymes Small intestine Amylase, Protease and Lipase Enzymes Absorption Large intestine egestion

Slide 44 -

Mouth: What happens Food is crushed and ground up by teeth The salivary glands make saliva which makes the food moist and easy for swallowing Amylase enzyme (in saliva) breaks the carbohydrate starch down into glucose.

Slide 45 -

Tour guide Mouth Teeth √ Amylase enzyme (What are enzymes???) √ Oesophagus peristalsis Stomach Protease enzyme Enzymes and pH Pancreas Amylase, Protease and Lipase Enzymes Small intestine Amylase, Protease and Lipase Enzymes Absorption Large intestine egestion

Slide 46 -

Swallowing and Peristalsis Watch the animations and fill in your worksheet Times GCSE Biology: Digestion: Page 13-14 http://www.hopkins-gi.org/multimedia/database/intro_250_Swallow.swf

Slide 47 -

Tour guide Mouth Teeth √ Amylase enzyme (What are enzymes???) √ Oesophagus Peristalsis √ Stomach Protease enzyme Enzymes and pH Pancreas Amylase, Protease and Lipase Enzymes Small intestine Amylase, Protease and Lipase Enzymes Absorption Large intestine egestion

Slide 48 -

Stomach Stomach muscles contract and relax to mechanically break down the food They also mix the food up with gastric juice and hydrochloric acid The acid kills germs in the food The gastric juice contains the protease enzyme PEPSIN to digest protein into amino acids Food spends about 3-4 hours in here.

Slide 49 -

Enzymes and temperature Enzymes work best at 37˚C

Slide 50 -

Enzymes and pH Enzymes work best at one pH. This pH is different for each different enzyme. If the pH goes too low (more acidic) or too high (more alkaline), the enzyme will not work as effectively. However, changes to pH will NOT denature enzymes.

Slide 51 -

Enzymes and pH

Slide 52 -

Tour guide Mouth Teeth √ Amylase enzyme (What are enzymes???) √ Oesophagus Peristalsis √ Stomach Protease enzyme Enzymes and pH √ Pancreas Amylase, Protease and Lipase Enzymes Small intestine Amylase, Protease and Lipase Enzymes Absorption Large intestine egestion

Slide 53 -

The duodenum The first part of the small intestine is called the duodenum. Food, still mixed with gastric juice is squirted into it from the stomach. The food is now a semi liquid, highly acidic mush. It needs to be neutralised and digestion needs to be continued…

Slide 54 -

Liver

Slide 55 -

Tour guide Mouth Teeth √ Amylase enzyme (What are enzymes???) √ Oesophagus Peristalsis √ Stomach Protease enzyme Enzymes and pH √ Pancreas √ Amylase, Protease and Lipase Enzymes Small intestine Amylase, Protease and Lipase Enzymes Absorption Large intestine egestion

Slide 56 -

The small intestine The small intestine produces 3 enzymes to complete digestion: Amylase breaks starch down into glucose. Protease breaks protein down into amino acids. Lipase breaks fats down into fatty acids and glycerol

Slide 57 -

Enzyme summary

Slide 58 -

Absorption The digested food is ABSORBED through the wall of the small intestine into the blood stream. To do this effectively, the small intestine needs to have a large surface area. This is achieved in the following ways:

Slide 59 -

Absorption 1 The tube is over 6 meters long The inner wall of the tube has bends in it The wall is covered in villi (small finger like structures) Pathway for Food

Slide 60 -

Absorption 2: Villi Absorption takes place through villi. These are small finger like structures that stick out into the small intestine tube. They help to increase the surface area of the small intestine.

Slide 61 -

Absorption 2: Villi

Slide 62 -

Absorption 2: Villi The digested food passes through the wall of the villi (epithelium). Why does the epithelium have to be thin? The glucose and amino acids pass into the blood capillary. From here they go to the liver in the HEPATIC PORTAL VEIN

Slide 63 -

The Liver The liver has many functions. Read about them on page 131 in your text book Answer questions 4 – 7 in full sentences.

Slide 64 -

Absorption 2: Villi The fatty acids and glycerol go into one of these lymphatic vessels in the villus. Lymph is a fluid that is made when the liquid part of blood comes out of blood vessels and washes over the cells. Lymph drains into lymphatic vessels before joining the blood again.

Slide 65 -

Tour guide Mouth Teeth √ Amylase enzyme (What are enzymes???) √ Oesophagus Peristalsis √ Stomach Protease enzyme Enzymes and pH √ Pancreas √ Amylase, Protease and Lipase Enzymes Small intestine Amylase, Protease and Lipase Enzymes Absorption Large intestine egestion

Slide 66 -

Egestion Any indigestible food (e.g. fibre) passes into the large intestine (colon). Water is absorbed back into the body. Where has this water come from? The food becomes a solid waste called faeces. Faeces are stored in the rectum and removed through the anus. This removal is called EGESTION.

Slide 67 -

Thank you for travelling along Alimentary Canal. Have a nice day…

Slide 68 -

This powerpoint was kindly donated to www.worldofteaching.com http://www.worldofteaching.com is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.