Organisation

• What is a tissue?

  A tissue is a group of similar cells that work together to carry out a particular function
• Examples of tissues

  Muscular tissue - contracts to move whatever it's attached to

  Glandular tissue - makes and secretes chemicals like enzymes and hormones

  Epithelial tissue - covers some parts of the human body e.g. the inside of the gut
• What is an organ system?

  An organ system is a group of organs working together to carry out a particular function
• Example of an organ system

  Digestive system - glands (pancreas and salivary glands), stomach, liver, small intestine and large intestine
• Why can enzymes be described as biological catalysts?

  They speed up useful chemical reactions in the body
• Why do enzymes only usually catalyse one reaction?

  Their active site is only complimentary to one type of substrate
• What does it mean when an enzyme is denatured?

  Its active site has changed shape due to intense heat or acidic conditions
• Where is amylase found?

  It's made in the salivary gland and the pancreas and it works in the small intestine
• What is the role of lipases?

  They break down lipids into fatty acids and glycerol
• Where is bile made and stored?

  It's made in the liver and stored in the gall bladder
• What does bile do?

  It emulsifies fats into smaller, more soluble pieces which gives the fat a bigger surface area for lipase to work on. It also neutralises the stomach acid to make the conditions alkaline, therefore the enzymes can work in the small intestine
• What are organs?

  Organs are groups of tissues that work together to perform certain functions
• What are the tissues in the stomach and what do they do?

  Muscular tissue - moves the stomach wall to churn up the food

  Glandular tissue - makes digestive juices to digest food

  Epithelial tissue - covers the inside and outside of the stomach
• What is the name of the substance when a substrate fits into the enzyme's active site?

  Enzyme substrate complex
• What is the name of the substance when the enzyme's active site has turned the substrate into two products?

  Enzyme product complex
• What is the optimum pH for enzymes?

  The pH level that they are most active at. E.g., pepsin has an optimum pH of 2
• What does amylase break down?

  It catalyses the breakdown of starch to maltose
• What do carbohydrases break down?

  Carbohydrates into simple sugars
• What do proteases break down?

  Proteins into amino acids
• Where are proteases found?

  They're made in the stomach (called pepsin here) and the pancreas and found in the small intestine
• Where are lipases found?

  They're made in the pancreas and work in the small intestine
• Name three substances and what they test for

  Benedict's Test - testing for sugars - goes red

  Iodine solution - tests for starch - goes blue-black

  Biuret Test - tests for proteins - goes purple
• What do the salivary glands do?

  They produce amylase in the saliva
• What does the stomach do?

  -It pummels the food with its muscular walls

  -It produces pepsin

  -It produces hydrochloric acid to kill bacteria and give the right pH for pepsin to work
• What does the pancreas do?

  It produces amylase, protease and lipase then releases them into the small intestine
• What does the small intestine do?

  It contains protease, amylase and lipase to complete digestion. Digested food is absorbed into the blood here
• What does the rectum do?

  It stores faeces
• What does the large intestine do?

  It's where excess water is absorbed from the food
• What does the gall bladder do?

  It stores bile before it's released into the small intestine
• What does the liver do?

  It produces bile which neutralises stomach acid and emulsifies fat
• What protects the lungs?

  The ribcage
• What goes down the trachea?

  The air that you breathe in
• What tubes join onto the trachea?

  The bronchi
• What do the bronchi split off into?

  Bronchioles
• What are the small bags at the end of bronchioles called?

  Alveoli
• What happens in an alveolus?

  Gas exchange. The blood passing next to the alveoli contains lots of carbon dioxide and little oxygen. The oxygen diffuses out of the alveoli (high concentration) and into the blood (low concentration) and the carbon dioxide diffuses out of the blood (high concentration) and into the alveoli (low concentration) to be breathed out.
• What surrounds the alveoli?

  Lots of blood capillaries
• What happens when blood reaches body cells?

  Oxygen is released from the red blood cells and diffuses into the body cells. At the same time, carbon dioxide diffuses out of the body cells and into the blood. It's then carried back to the heart
• What makes up the circulatory system?

  The heart, blood vessels and blood
• What happens on the right side of the heart?

  Deoxygenated blood flows in through the vena cava and into the right atrium. The atrium contracts and pushes the blood through the tricuspid valve, into the right ventricle. The valve closes and the ventricle contracts, to push the blood through the right semi-lunar valve. The valve will close and the blood is pushed out of the pulmonary artery to go up to the lungs