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Co-ordination and control of the body

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Biology Coursework 1. Co-ordination and control of the body a. The Nervous System: * Enables you to know what is going on around you. * Lets you react to your surroundings and co-ordinate behaviour. * Carries electrical signals (impulses), travelling 1-120 MetersPS, reaction time is fast! * Every action in your body needs to be co-ordinated, the conditions inside must also be controlled. i. Hormones: Hormones are chemicals which control processes inside the body. They are Chemical Messages. Individual glands make and release (or secrete) them. The hormones are carried around your body and taken to their specific organ. Depending on the hormone, they can be long-lasting and slow or, like adrenalin, can be short-lasting but fast. ii. How the nervous system works A stimulus (change) is detected by cells called receptors. These receptors are clustered together in sense organs, like your eyes and skin. Once this happens, the information is sent as an electrical impulse and carried along neurones. * Neurones are found as bundles of thousands, known as nerves. The impulse travels along the neurone until it reaches the CNS. * The CNS is made up of your brain and spinal cord. ...read more.


iii. How Synapses Work: Nerves do not join up together; they are separated by gaps called synapses. As the impulse reaches the synapse, chemicals are released and end up at the other side at receptor sites. This then trigger an electrical impulse at the other neurone. iv. The reflex arc in detail: 1. A hot object is touched, which triggers stimulation of skin. Object -> Skin 2. Impulse travels along a sensory neurone to the CNS (here it's the spinal cord) Sensory -> CNS 3. The impulse reaches a synapse with a relay neurone. Sensory -> _synapse_ -> relay 4. The chemical released crosses the gap; this triggers another impulse along a relay neurone. Relay ->... 5. It then reaches the gap from relay to motor neurone, another chemical is released. Relay -> Motor 6. This crosses the gap and triggers an impulse to travel along the motor neurone. Motor ->... 7. When it reaches the effector organ, the organ is stimulated in response. Motor -> Effector Stimulus -> Receptor -> Co-ordinator -> Effector -> Response c. The menstrual cycle: * Control of activities of a woman's individual cells. ...read more.


Control of fertility raises ethical issues, and religious problems. Eggs left, stored to be used later may go to waste if the woman dies. d. Controlling conditions Internal conditions, also known as internal environment, change as your body gets ill etc. When this is happening, the body doesn't function properly. The thing keeping all the bodily functions stable is called homeostasis, and involves you nervous system, hormone systems and many organs. ii. Controlling water and ions: You gain water by eating and drinking. You lose water by breathing out and salt as well by sweating. Water and salt is also lost in urine, made in your kidneys. Your kidneys control the amount of salt and water you lose depending on the conditions. The kidneys are controlled by hormones and nerves. iii. Controlling temperature: The body needs to be kept at 37�, if not; the slightest change can cause your enzymes to stop working, shutting your body down. You control this by sweating to cool down, and shivering to warm up. The nervous system is very important for responding to temperature change. iv. Controlling blood sugar: When digesting, sugar passes into the blood. Without control, blood sugar levels would go up and down just after and a while after a meal. This would cause chaos, so hormones in your pancreas keep your blood sugar levels constant. ...read more.

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