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Humans as organisms.

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Humans as organisms Human cells are made from a nucleus, cell membrane and cytoplasm. Sperm cells have a tail so they can swim. Muscle cells are able to contract so that they can become shorter. White blood cells can change shape to destroy bacteria, which can infect your body. A group of cells that have a similar structure and work together make tissue. Tissues group together to build an organ. Different organs group together and make an organ system. Protein produces 'amino acids' when digested. Starch produces 'sugars' when digested. Fat produces 'fatty acids and glycerol' when digested. Type of food Type of enzyme Digestion products Starch Carbohydrase Sugars Fats Lipase Fatty acids and glycerol Protein Protease Amino acids Proteins in the food need to be broken down by enzymes so that they can dissolve into the bloodstream and be carried all around your body. Health drinks such as 'Lucozade' contain sugar because when this is absorbed into the bloodstream, it provides the cells with the energy and nutrients needed. Food needs to be broken down because much food is insoluble and is too big. Only small molecules can pass from your gut into your bloodstream. Mouth - The salivary glands release amylase, which is a Carbohydrase enzyme. Stomach - has gastric juices that the stomach produces. The gastric juices contain protease enzymes and hydrochloric acid. The hydrochloric acid provides the acidic conditions for a protease enzyme called pepsin to work. ...read more.


this is important to have in your diet. It helps prevent constipation and diseases of the intestine, i.e. cancer. Energy comes from Glucose. It is the body's biggest fuel. Oxygen and glucose react together in body cells to release energy. This process is: Aerobic Respiration Equation: Glucose + Oxygen = Carbon Dioxide + Water + energy Sometimes your body cannot get enough oxygen. E.g. - sprinting. Your muscles are working so hard that they become short of Oxygen. This is called: Anaerobic Respiration This produces Lactic acid as a waste product. Equation: Glucose = Lactic acid+ energy Lactic acid that is produced has to be removed. This is done by using oxygen to break down the acid. After exercise, you often keep breathing heavily to take in extra oxygen. This is because during anaerobic respiration, you build up an oxygen debt and when the exercise is over, you have to repay the debt by taking in extra oxygen. Gas exchange tissues are made from millions of tiny air sacs called 'alveoli'. When a person breathes in, the ribs move out and the diaphragm becomes flatter. In the lungs, oxygen passes into the bloodstream and carbon dioxide passes into the air. Movement of air in and out of the lungs is called ventilation The air entering the alveoli contains a high concentration of oxygen. This gas diffuses into the bloodstream and is transported to all body cells. ...read more.


Anaerobic respiration is incomplete breakdown of glucose without oxygen. Anaerobic respiration in yeast is called Fermentation. Lactic acid is produced during vigorous exercise, without enough oxygen. Lactic acid is removed by replacing the oxygen debt, fast and deep breathing. The waste products of respiration are water and carbon dioxide. The oxygen that enables animals to carry out respiration comes from plants photosynthesis. Plants carry out respiration all the time. Plants get glucose from photosynthesis, using energy from the sun. Five sense organs: Skin, tongue, eyes, ears and nose. CNS is an abbreviation for the 'central nervous system' The CND consists of the brain and spinal cord. Three types of neurones: Sensory, Relay and motor neurones. A synapse is a gap between neurones that transmits the nerve impulse. * Sensory neurones are connected to receptors. * Motor neurones are connected to the effector. * The Relay neurone connects the sensory neurone and the motor neurone. * A stimulus is a change in the environment. * Reflex actions protect us from harm The iris controls the amount of light entering it. The hole in the middle of the iris is called the pupil The Retina contains the light sensitive cells. In bright light the pupil gets smaller. In dim light the pupil gets bigger. The Ciliary muscles control the size of the lens. The optic nerve receives nerve impulses from the retina and send them to the brain. When the lens is focusing on near objects it is fat and round. When the lens is focusing on distant objects it is thin and flat. Light enters through the Cornea. ...read more.

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