Digestion.

• Principles of Organisation cellular level(heart muscle cell) Tissue level(heart muscle tissue), organ level(heart), organ system level(circulatory system), organism level(deer)
• Cells Basic functional and structural units in living organism.
• Tissue a group of cells of similar structure working together to perform a particular function.
• Organs made from a group of different tissues working together to perform a particular function.
• Organ systems made from a group of organs with related functions, working together to perform body functions within the organism.
• Human digestion basics​

  • Digestion is a process in which relatively large, insoluble molecules in food (such as starch, proteins) are broken down into smaller, soluble molecules that can be absorbed into the bloodstream and delivered to cells in the body​ These small soluble molecules (such as glucose and amino acids) are used either to provide cells with energy (via respiration), or with materials with which they can build other molecules to grow, repair and function​
• Insoluble means cant be dissolved in water, it is a solid.
• Soluble means that it can be dissolved in water.
• Mechanical digestion​ Physical breakdown of food into smaller pieces so it can be swallowed. ​

  Examples include; the mouth bites/chews using teeth/tongue/jaws; and the stomach’s muscular walls churn/mix the food around
• Smooth muscle in the stomach is involved mechanical digestion
• Chemical digestion​ is

  • Chemical breakdown of food into smaller pieces like protein, carbohydrates, fats, nucleic acids (these are broken down further) with the help of enzymes, in order for nutrients to be absorbed into the blood and then transported to cells.​ (e.g saliva, acid in the stomach)
• Enzyme is a. biological catalyst that speeds up reactions.
• Chemical digestion

  • The purpose of digestion is to break down large, insoluble molecules into smaller, soluble molecules that can be absorbed into the bloodstream​
  • Large insoluble molecules, such as starch and proteins, are made from chains of smaller molecules which are held together by chemical bonds. These bonds need to be broken​
  • Enzymes are biological catalysts – they speed up chemical reactions without themselves being used up or changed in the reaction​
  • There are three main types of digestive enzymes – carbohydrases, proteases and lipases​
• • Protein digestion takes place in the stomach and small intestine, with proteases made in the stomach (pepsin), pancreas and small intestine​
• Proteases are a group of enzymes that break down proteins into amino acids in the stomach and small intestine
• Protease -> Proteins -> Amino Acids​
• • Carbohydrases break down carbohydrates to simple sugars. Amylase is a carbohydrase which breaks down starch into maltose, which is then broken down into glucose by the enzyme maltase​​
  •  Amylase is made in the salivary glands, the pancreas and the small intestine​
• Carbohydrases -> Carbohydrates -> Simple Sugars​
• Lipase -> Lipids -> Glycerol and Fatty Acids​
• •  Lipases break down lipids (fats) to glycerol and fatty acids.​​
  •  Lipase enzymes are produced in the pancreas and secreted (released) into the duodenum (Small intestine)
• Stages of the digestive system

  • Mouth​

  The Alimentary Canal:​

  • Oesophagus​
  • Stomach​
  • Small Intestine​
  • Large Intestine​
• • Absorption is the movement of small digested food molecules from the digestive system into the blood (glucose and amino acids) and lymph (fatty acids and glycerol)​