The human body - Action and control

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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.

Digestive Enzymes are made inside cells but then are released into digestive system. They work outside of cells and are therefore called “Extra Cellular Enzymes”. There are thousands of enzymes inside living organisms

*37 degrees is the optimum (best) temperature for enzymes in a human. They work best then. *Graph-rates go up because of collision theory and then go down because the enzymes denature (destroyed by heat – change of shape) Enzymes usually stop working after 45 degrees. Enzymes are sensitive to pH, each enzyme works best at a particular or optimum pH

         *Enzymes can

  • build up lots of small molecules into a large molecule. E.g. turning thousands of glucose molecules into a starch molecule
  • turn one type of molecule into another type
  • break down large molecules into smaller molecules e.g. turning a starch molecule into thousands of glucose molecules

Enzymes that speed up digestion  ~ Trypsin(helps to digest proteins), Amylase(digest starch), Lipase(digest fats)

Trypsin (a form of protease) – is an enzyme that helps to break down proteins to amino acids. The protein is insoluble. Digestion breaks up the protein into amino acids, which are soluble.

Amylase – is an enzyme in saliva that breaks down starch to sugars.

Large Insoluble Molecule                        Enzyme                        Small Soluble Molecule

- carbohydrates                                - carbohydrases                - sugar, starch (made up of glucose)

- protein                                        - proteases                - amino acids

- fat                                        - lipases                        - fatty acids and glycerol

Carbohydrates (made up of sugar molecules) ~ for energy

Proteins (made up of amino acids) ~ growth and repair of cells

Fat (made up of fatty acids and glycerol) ~ as a store of energy and for warmth

- saturated fat from animals

- unsaturated fat from plants

Food Tests

Starch – Iodine (From original color Yellow to Dark Blue)

Simple Sugars – Benedict’s Solution (From original color Blue to Brownish Yellow)

Fat

Protein – Biuret (To Purple)

Digestive Organs

*The gut is a long tube, which runs from the mouth to the anus. (About nine meters long)

Salivary Glands

  • Production of saliva that contains amylase (a form of carbohydrase)
  • Amylase digests starch (a carbohydrate) to sugar
  • Mucus, in the saliva, softens and lubricates food, making it slip easily down the throat (to swallow)

Oesophagus (gullet)                                        * Mucus and cilia keeps the lungs clean

  • Tube connecting the mouth (throat) to the stomach
  • Contains circular muscles, on the walls of gullet that relax and contract. This movement pushes the food down from behind the food. The process of this is called peristalsis

Stomach

  • Has strong muscles
  • Muscles contract and relax to mix food with gastric juice and hydrochloric acid produced by the stomach wall; the acid kills the bacteria in the food
  • Gastric juice contains proteases, for digesting proteins to amino acids
  • After food is finished digesting in the stomach, it is a runny liquid that passes down into the small intestine
  • Has a mucus lining to protect stomach from acids

Liver (not part of the gut)

  • Organ that produces (makes) bile
  • Bile is an alkaline green food that neutralizes acids and emulsifies (breaks) fats from big droplets of fat into small droplets

Gall Bladder

  • Bag-like thing which stores bile
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Pancreas

  • Gland which produces pancreatic juice containing protease, carbohydrase and lipase
  • These enzymes require alkaline conditions to work (with the help of bile neutralising acids)

Small intestine

  • Long tube
  • Millions of villi on walls of small intestine to increase surface area and assist with absorption of molecules and nutrients into the cell wall and the surrounding capillaries *diffusion is the passive movement of particles
  • Digested food is absorbed into the blood here
  • Contains intestinal juice, which has protease, carbohydrase and lipase. These enzymes complete the digestion of food
  • The completion of digestion
  • Where most absorption is taken ...

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