Digestive System

Can you sort out the statements into True and False? Carbohydrates, proteins and fats are all made up of carbon, hydrogen, nitrogen and oxygen. 1 2 Fats are made up of smaller units called amino acids 3 Starch is a large carbohydrate molecule 4 Proteins are made up of one or more glucose molecules 5 Starch molecules can be broken down by amylase. 6 Proteins are important for the growth and repair of cells

Parts of The Alimentary Canal The alimentary canal (or gut) is the tube within the body through which food passes and is processed in various ways mouth oesophagus stomach small intestine large intestine anus

Human digestive system mouth salivary glands oesophagus liver stomach pancreas large intestine small intestine anus

Enzymes They are special proteins that behave as catalysts, i.e., they accelerate each and every chemical reaction in your body; otherwise, those chemical reactions wouldn't take place, or would do at a very slow pace. Enzymes are very specific and each one can catalise only one chemical reaction: for instance, the only thing that salivary amylase can do is breaking the starch into maltose.

Role of the Mouth Teeth assist the mechanical breakdown of food Saliva is mixed with food during chewing Saliva contains the enzyme amylase which starts the digestion of food Salivary gland Saliva contains mucus that keeps the mouth moist and lubricates food for easier swallowing Salivary gland Salivary gland

Muscles of the Alimentary Canal Food has to be kept moving along the alimentary canal whilst being mixed with various juices These actions are brought about by muscles in the walls of the canal over which a person has little or no conscious control

Peristalsis The squeezing action of muscles that is used to move food along the alimentary canal Peristalsis-1 Peristalsis-2

Digestive Enzymes What do the following enzymes breakdown? What do they break the large moleculs down into? Amlyases Lipases Proteases

Sites of production of main digestive juices Site of digestive juice production Main digestive juice produced Mouth Saliva Stomach Gastric juice Liver Bile (breaks down big fat droplets into little fat droplets Pancreas Pancreatic juice Small Intestine Intestinal juice

Digestion and Digestive Juices Saliva GASTRIC JUICE Bile PANCREATIC JUICE INTESTINAL JUICE

Digestion and Digestive Juices SALIVA Salivary amylase Mucus Bile GASTRIC JUICE Hydrochloric acid Pepsin (protease) Rennin Mucus PANCREATIC JUICE Pancreatic lipase Trypsin INTESTINAL JUICE Proteases, Lipases, amylase

In the Mouth… Starch maltose Broken down into glucose later by other amylases Salivary amylase

Types of Teeth 1.Incisor 2. Canine 3. Premolar 4. Molar

Tongue The tongue is a muscle on the floor of the mouth that manipulates food for chewing and swallowing (deglutition). It is the primary organ of taste, as much of the upper surface of the tongue is covered in papillae and taste buds.

Taste regions of tongue

Taste buds of tongue

Swallowing of bolus

Section of stomach

In the stomach Protein peptides Broken down into amino acids later by other proteases pepsin

Chyme The fluid food mass that is produced in the stomach when the bolus undergoes a second digestive stage.

Functions of liver There are many functions of the liver. Some of the most important are: 1.                The production of bile 2.                Detoxifying the body, i.e. breaking down alcohol and drugs 3.                Breaking down excess amino acids to form urea 4.                Converting glucose to glycogen for storage 5.                Converting excess carbohydrates to fats 6.                Storing vitamins 7.                Storing minerals such as Iron, Copper, and Zinc. 8.                Making plasma proteins such as fibrinogen which is used in blood clotting 9.                Making cholesterol which is used to form many hormones 10.           Producing heat for the blood and body

Liver Facts • Weighs about 1 pound Liver Facts • Weighs about 1 pound. • Carries out 1000s of functions per day. • Effects the emotions. • Cleanses the blood. • Helps regulate blood sugar. • Metabolizes fats. • Synthesizes vitamin A. • Breaks down toxic substances. • Stores iron for the body. • Stores glycogen (converted glucose). • Metabolizes carbohydrates. • Metabolizes proteins.

Position of Liver

Bile One of the five digestive juices. It is produced by the liver, stored in the gall-bladder, and it is greenish. It is necessary mostly not to carry digestive enzymes to the duodenum, but to transport bile salts to the duodenum. The bile salts are necessary to help the lipids to "dissolve" in the chyle, forming small droplets, easy to be attacked by the lipases. This process is called emulsification.

Small Intestine

Duodenum Gall bladder Bile Hepatopancreatic duct

Jejunum

Intestinal glands

Composition of Bile Constituent pH Na+ K+ Ca2+ Cl- HCO3- Phosphorus Bile acids fatty acids Bilirubin Phospholipids Cholesterol Proteins

In the pancreas…. Fats fatty acids and glycerol Pancreatic lipase

After all the digestive enzymes have done their work… Glucose Amino acids Fatty acids Glycerol

Finish the sentence…. Something new I learnt today was….. Something I found difficult to understand was… The thing I need to revise from today’s lesson is…