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The human body - Action and control

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Introduction

MODULE 1- THE HUMAN BODY: ACTION AND CONTROL Movement - Animals slither, crawl, roll, walk, run, jump, swim and fly. They can move all or parts of their body. Plants shoot can bend. Their leaves can turn towards the light and their roots towards water Respiration - produces energy. Energy is released from food during the process of respiration Sensitivity - Living organisms can detect changes in their environment. This is called sensitivity. Animals can listen, smell and watch for signs of danger. They can also touch and taste. Plant shoot are sensitive to the direction of light and gravity Growth - All organisms grow for at least part of their lives. Animals stop growing when they reach their adult size. Plants grow throughout their lives. Reproduction - Only living organisms produce offspring. This is called reproduction. Animals lay eggs or have babies. Plants produce seeds Excretion - Activity produces waste products. Excretion is the removal of waste products from the body Nutrition - Food is needed for energy, growth, repair and replacement of tissues, and to help living things stay healthy and free from disease. Plants make their own food using energy from the sunlight. Animals eat plants or other animals Food is broken down from big, insoluble molecules to smaller, soluble molecules during the process of digestion. The smaller molecules (nutrients) are then absorbed. Vitamin, minerals and water are already small enough to be absorbed. Fibre (vegetable) - soluble, cellulose (fibre) cell wall. Physical digestions - Chewing and Stomach. Food is broken down in the digestive system by enzymes. It is then absorbed into the bloodstream. Enzymes - are proteins that are involved in all chemical processes in living things. Enzymes are biological catalysts. They speed up chemical reactions without being changed themselves. Enzymes are specific in their actions and each enzyme controls a particular reaction. They can be used over and over again. ...read more.

Middle

This allows the lens to shrink and become fatter. -->Far Objects Light rays from far objects do not have to be refracted so much. A thin lens is needed. When the ciliary body relaxes, the ring of ciliary muscles gets larger, pulling the suspensory ligament to stretch. This makes the lens thinner. -->Short Sightedness * Eye ball too long, Fat and short lens (bends light rays too much, it is too fat even when ciliary muscles are relaxing), Image is focused in front of the retina (not touching retina) and image becomes blurred - causes - tiring muscles in the eyes, reading in the dark, too close to tv - correction - wearing glasses with a concave (caves inwards) and diverging ( rays spread out) lens --> Long Sightedness * Eye ball too short, Long and thin lens (doesn't bend light rays enough, is too thin even when ciliary muscles are contracting), Image is focuse behind the retina (passed retina) and image becomes blurred - causes - old age - correction - wearing glasses with a convex (curves outwards) and converging lens (rays focused) lens Nervous System Your nervous system controls your actions and coordinates different parts of your body so that they work together and bring out the right responses.Your nervous system send electrical messgaes along nerves to and from different parts of your body * nerve impulses are messages that nerves carry Sense Organs (receptors) >> *A reflex is an involuntary, immediate, automatic & fast reaction/response - Skin - Touch, Temperature - Ears - Sound (hearing), Balance - Tongue - Taste (chemicals) - Eyes - Light - Nose - Smell (chemicals) Stimuli / (Stimulus - only one of the changes) - are changes that can be detected e.g. hot temperature from fire Receptors - detect the changes e.g. hot temperature on skin Effectors - bring about responses e.g. taking hand away from fire Central Nervous System (CNS) ...read more.

Conclusion

They can damage the brain, heart, kidneys, liver and lungs. Abusers may become unconscious, vomit and then suffocate. <Alcohol> Alcoholic drinks contain alcohol (ethanol), which affects the brain. A small amount may make the drinker feel more relaxed and confident. However, alcohol slows down reactions, lose the ability to judge things and lose the ability to concentrate. The body starts to lose control over coordination, causing dizziness, slurred speech and difficulty in walking. A drunk maybe argumentative and aggressive. Eventually, unconsciousness and even death can occur. Drinking alcohol affects the ability to drive. People who are addicted to alcohol are known as alcoholics. Alcohol abusers affect the brain, heart, liver and stomach * Alcohol poisons the liver resulting in a disease called cirrhosis. <Tobacco> Tobacco smoke contains over 4000 chemicals. Many of them are poisons - Nicotine is an addictive stimulant. It damages the heart, blood vessels and nerves - Carbon Monoxide lowers the ability of blood to carry oxygen - Tar collects in the lungs. It causes cancer Smoking causes heart disease and cancers of the mouth, throat, lungs and bladder. Smoking also causes other lung diseases, such as emphysema and bronchitis. * Stimulants - drugs that speed up the nervous system and brain and make you feel more alert e.g. cocaine, ecstasy, amphetamines, caffeine (tea and coffee), nicotine * Depressants (Sedatives) - are drugs that slow down the nervous system and brain and make you feel sleepy e.g. barbiturates (powerful sedatives which slow the heartbeat and breathing rate), solvents, alcohol * Hallucinogens - are drugs that confuse (illusions) your nervous system and cause hallucinations such as hearing or seeing things that don't exists e.g. LSD (Lysergic Acid Diethylamide) * Painkillers - suppress the parts of the brain that give us the feeling of pain e.g. aspirin, paracetamol, morphine --> paracetamol is useful for treating mild pain, but overdoses of it cause liver damage and death --> morphine is given to ease pain in fatally ill patients, but overdoses of it cause heart failure and death - An analgesic drug reduces pain (another form of painkillers) ...read more.

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