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B2 - Organisation - Coggle Diagram
B2 - Organisation
the lungs
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the lungs are like big pink sponges and are protected by the ribcage and are surrounded by the pleural membranes
the air that you breathe in goes through the trachea and this splits into two tubes called bronchi and the bronchi splits into progressively smaller tubes called bronchioles
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Alveoli
the lungs contain millions of little air sacs called alveoli surrounded by a network of blood capillaries and this is where gas exchange happens
the blood passing next to the alveoli returns to the lungs from the rest of the body, so it contains lots of carbon dioxide and very little oxygen.
oxygen diffuses out of the alveolus (high concentration) into the blood (low concentration) - carbon dioxide diffuses out of the blood (low concentration) into the alveolus (high concentration) to be breathed out.
when the blood reaches body cells oxygen is released from the red blood cells (where there's a high concentration) and diffuses into the body cells (where the concentration is low)
at the same time, carbon dioxide diffuses out of the body cells (where there's a high concentration) into the blood (where there's a low concentration and is then carried back to the lungs.
Cell Organisation
cells are the basic building blocks that make up all living organisms and there are specialised cells that carry out a specific function. the process by which cells become specialised is called differentiation and this happens during the development of a multicellular organism.
then these specialised cells form tissues, which form organs, which form organ systems
a tissue is a group of similar cells that work together to carry out a particular function:
1) muscular tissue - which contracts (shortens) to move whatever its attached to
2) glandular tissue - which makes and secretes chemicals like enzymes and hormones
3) epithelial tissue - which covers some parts of the body e.g. the inside of the gut
an organ is a group of different tissues that work together to perform a certain function:
1) muscular tissue - which moves the stomach wall to churn up the food
2) glandular tissue - which makes digestive juices to digest food
3) epithelial tissue - which covers the outside and inside of the stomach
an organ system is a group of organs working together to perform a particular function: for example, the digestive system breaks down and absorbs food and is made up of these organs: 1) glands - which produce digestive juices 2) the stomach and small intestine which digest food 3) the liver, which produces bile 4) the small intestine which absorbs soluble food molecules 5) the large intestine which absorbs water from undigested food leaving faeces
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Enzymes
therefore living things produce enzymes that act as biological catalysts - enzymes reduce the need for high temperatures and we only have enzymes to speed up the useful chemical reactions in the body
a catalyst is a substance which increases the speed of a reaction, without being changed or used up in the reaction
chemical reactions usually involve things either being split apart or joined together and every enzyme has an active site with a unique shape that fits onto the substance involved in a reaction
enzymes are really picky - so for it to work, the substrate has to fit into its active site - this diagram shows the 'lock and key' model 
to calculate the rate of reaction, you do - rate=1000/time
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