Organisation

• Cells - the basic building blocks of all living things, they are the smallest unit of life.
• Tissues - groups of cells that work together to carry out a particular function.
• organs - group of tissues that work together to perform a specific function
• Organ systems - groups of organs that work together to perform a specific function.
• Organisms - living things made up of tissues, organs and organ systems
• The three enzymes

  • amylase
  • lipase
  • protease
• How do enzymes work?

  Enzymes have an active site that matches only to one specific substrate (e.g. carbohydrates). This active site is known as complementary, the substrate binds to the active site where the enzyme breaks it down into smaller molecules (e.g. glucose).
• What are enzymes?

  Catalysts
• What do catalyst do?


  Create an alternate pathway with a lower activation energy for a reaction to take place. In terms of digestions they speed up the process of digestions
• What factors affect the rate of enzymes?


  Temperature , pH , the concentration of enzymes
• Mouth, oesophagus, stomach, small intestine, large intestine, rectum
• What organs are part of the digestive system but do not hold the food?


  Liver, pancreas, gallbladder
• The mouth, stomach, and small intestines all have mechanical digestion properties, such as chewing and churning up the food
• Mechanical digestion is when food is physically broken down into smaller pieces by teeth or muscles.
• Chemical digestion is where enzymes break down complex molecules into simpler ones that can be absorbed through cell membranes.
• Enzyme - A biological catalyst which speeds up chemical reactions without being used up itself.
• Activation Energy - The minimum amount of energy needed for a reaction to occur.
• There is also chemical digestions such as the breakdown of food using enzymes.
• Bile is a fluid that is made and released by the liver and stored in the gallbladder. Bile helps with digestion. It breaks down fats into fatty acids, which can be taken into the body by the digestive tract.
• Villi are finger-like projections on the surface of the epithelial cells lining the small intestine. They increase the surface area available for absorption. Each villus contains capillaries and lacteals (lymphatic vessels).
• The large intestine absorbs water from undigested food residues so they become solid faeces. This process is called defaecation.
• Faeces are passed out through the anus at the end of the rectum.
• Amino Acid - An organic compound containing amino (-NH2) and carboxyl (-COOH) groups joined together by a peptide bond. Proteins are polymers of amino acids.
• Carbohydrate - A polymeric molecule consisting of carbon, hydrogen and oxygen atoms. Carbohydrates include sugars, starches and cellulose.
• The stomach secretes hydrochloric acid, which kills bacteria and activates pepsinogen to form pepsin. Pepsin digests protein molecules into smaller peptides.
• Lipase breaks down lipids (fats) into glycerol and fatty acids
• Bile salts emulsify fats, making them more accessible to enzyme action
• Pancreatic juice contains bicarbonate ions that neutralise the acid from the stomach
• Proteases break proteins down into amino acids
• There are 2 types of tumour

  • benign
  • malignant
• Benign tumours grow slowly and do not spread to other parts of the body
• Malignant tumours grow quickly and can invade nearby tissues and organs
• Cancer cells have mutations in their DNA that cause uncontrolled cell division
• The immune system recognises abnormal cells as foreign and destroys them
• The immune system recognises abnormal cells as foreign and destroys them, but sometimes it fails to destroy all of them
• Cells divide rapidly when they need to repair or replace damaged tissue
• Tumour suppressor genes prevent or slow down the growth of tumours by controlling cell division
• If the immune response is weak or absent, then the cancer will continue to divide and form a tumour
• A malignant tumour is one that can spread and is considered cancerous
• Cancerous cells are able to invade other tissues and organs through blood vessels and lymphatic vessels