organisation

• cells are basic building blocks of life
• a tissue is a group of cells with a similar structure and function working to carry out a specific function
• organs are a group of different tissues, which all work together to perform a specific job
• an organ system is a group of organs with related functions, working together to perform certain functions within the body
• the digestive system is made of the mouth, esophagus, stomach, small intestines, large intestines and anus
• blood is a tissue containing plasma, red blood cells, white blood cells, platelets
• plasma transports chemical substances around the body
• red blood cells contain haemoglobin which binds to oxygen to transport it from lungs to tissues and cells
• red blood cells do not contain a nucleus which means more room for haemoglobin
• red blood cells are very small so they can fit through the capillaries and deliver oxygen to the cells
• red blood cells are shaped like biconcave disk for large surface area so oxgyen can diffuse quickly
• white blood cells protect the body against infections and can change shape to squeeze out of blood vessels into tissues
• platelets are fragments of cells, which collect at wounds and trigger blood clotting
• arteries take blood away from the heart to organs, they have thick walls made of elastic and muscle to resist high blood pressure
• veins take blood from organs to the heart, they have thinner walls and valves to prevent backflow as the pressure is lower
• capillaries join arteries to veins, they have narrow vessels with walls one cell thick to allow substances to be exchanged
• the heart is a double circulatory system
• coronary heart disease is when the coronary arteries, that provide blood to the heart, become blocked with fatty materials resulting in a lack of oxygen being supplied to the heart
• stents keep arteries open to allow blood to flow through
• statins are drugs that decrease levels of LDL chlolesterol
• non-communicable diseases are not infectious
• cardiovascular disease can be caused by a diet containing lots of LDL cholesterol, smoking damaging the arteries wall, exercise
• type 2 diabetes can be caused by obesity
• your liver and brain function can be affected by alcohol, causes liver failure, and damages nerve cells in the brain
• lung disease and lung cancer can be caused by smoking which damages cells in lining of lungs
• cancer is the result of changes in cells that lead to uncontrollabe growth and division which form tumours
• benign tumours are non-cancerous, grow until there is no more room, dont invade other tissues but can be dangerous if causes pressure to an organ
• malignant tumours are cancerous, may split up, can cause secondary tumours, divide more rapidly and have longer life span than other cells
• epidermis covers the outer surfaces for plant protection
• palisade mesophyll is the main site of photosynthesis in the leaf
• spongy mesophyll is the air spaces between the cell which allow gases to diffuse through the leaf
• xylem vessels transport water and minerals through the plant from roots to leaves, and supports the plant
• phloem vessels transports dissolved food materials through the plant
• transpiration is the loss of water from the leaves through the stomata
• factors of transpiration are, increase in temperature, faster air flow, increase in humidity
• role of a guard cell is to open and close the stomata, at night the stomata is closed because CO2 is not needed for photosynthesis so closing stomata reduces water loss
• translocation is when the phloem tissue transports dissolved sugars from the leaves to the rest of the plant
• enzymes are biological catalysts that speed up chemical reactions
• high temperatures and extreme PH make enzymes denature (change shape)
• if an enzyme is denatured the substrate will no longer fit into the active site