7. Human nutrition

• Balanced diet is a diet containing some of each of the different types of nutrients, in a suitable quantity and proportions.
• Ingestion: the taking of substances, e.g. food and drink, into the body through the mouth
• how age, gender and activity affect the dietary needs of humans:

  • Dietary requirements depend on your age, sex and activity;
  • The amount of energy needed is provided by our carbohydrate and fat intake;
  • Generally, males use more energy than females;
  • And Generally the energy demand increases as we get older until we stop growing;
  • Someone doing physical work will use up more energy than an office worker;
  • While children are growing they need more protein per kilogram of body weight than adults do;
  •  Pregnant women need extra nutrients for the development of the fetus.
• disease: obesity

  cause of malnutrition: too much food (fats)

  symptoms and consequences: Heart disease, strokes, diabetes Extra weight can cause problem with joints (knees)
• disease: coronary heart disease

  cause of malnutrition: too much-saturated fat

  symptoms: Fat deposits build up on the inside of arteries making them stiffer and narrower. If on coronary arteries that supply blood, muscles run short of oxygen and don’t work properly. Deposits also cause blood clot and cause heart attack Higher chance of heart disease
• disease: anorexia (starvation)

  cause of malnutrition: too little food (intense fear of gaining weight:

  symptoms and consequences: Weight loss, organ damage, death (depression, loneliness, insecurity)
• disease: constipation

  cause of malnutrition: lack of fibre

  symptoms and consequences: unable to defecate (poop), pain
• Kwashiorkor

  Cause: Wrong proportion of nutrients; too much carbohydrates and lack of protein Effect: Underweight for the age
• Marasmus

  Cause: Not enough protein and energy in the dietEffect: Low body weight and emaciated (abnormally thin or weak)
• Mechanical digestion is the breakdown of food into smaller pieces without chemical change to the food molecules
• Chemical digestion is the breakdown of large, insoluble molecules into small, soluble molecules
• Absorption is the movement of small food molecules and ions through the wall of the intestine into the blood
• Assimilation is the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells
• Egestion is the passing out of food that has not been digested or absorbed, as faeces, through the anus
• vitamin c maintains healthy skin and gums
• lack of vitamin c leads to scurvy deficiency which causes bleeding under skin and bleeding gums
• Vitamin C food sources: citrus fruits, mango, tomato,guava etc.
• vitamin D is made by our skin when exposed to sunlight
• calcium's function is to help form healthy bones and teeth and maintain normal blood clotting
• Vitamin D maintains hard bones and helps to absorb calcium from the small intestine it is found in milk , butter ,cheese, egg yolk, fish liver oil
• lack of vitamin D leads to rickets deficiency which is soft bones that become deformed
• lack of calcium leads to rickets deficiency and brittle bones and teeth.
• low calcium also leads to slow blood clotting
• iron's function is the formation of haemoglobin in red blood cells and can be found in red meat,vegetables,liver,kidney
• lack of iron leads to anaemia deficiency
• anaemia deficiency is when you don't have enough red blood cells so not enough oxygen is delivered to tissue so you have a constant lack of energy
• fibre's function is the cellulose adds bulk to undigested passing through the intestines and maintains peristalsis
• lack of fibre leads to constipation and long term leads to bowel cancer
• fibre is found in vegetables,fruit,whole meal bread
• water's function is the formation of blood and cytoplasm. it is a solvent for the transport of nutrients and the removal of wastes (urine). enzymes only work in the solution.
• lack of water leads to dehydration
• water can be found in drinks, fruit and vegetables
• Diarrhoea is the loss of watery feaces. It happens when not enough water is absorbed from the feaces.
• the treatment of diarrhoea using oral rehydration therapy:Giving a drink containing water with a small amount of salt and sugar dissolved in it, green coconut water, or a drink made from yoghurt and salt
• Cholera is caused by a bacterium
• The cholera bacterium lives and breeds in the small intestine. The bacteria produce toxin (poison) that stimulates the cells lining the intestine to secrete chloride ions in the lumen of small intestine. This increase the concentration of the fluid in the lumen, lowering the water potential. When the water potential becomes lower than the blood flowing through vessels in the walls of the intestine, water moves out of the blood and into the lumen by osmosis. Lots of water in the canal causes diarrhoea.
• alimentary canal region: mouth

  function: Food is ingested here; mechanical digestion by cutting, chewing and grinding of teeth; Saliva added ‐ contains amylase to digest starch.
• alimentary canal region: oesophagus

  function: Boluses of food pass through by peristalsis, from mouth to stomach.
• alimentary canal region: stomach

  function: Gastric juice added‐ contains protease to digest protein and hydrochloric acid to maintain pH 2 and kill bacteria.
• alimentary canal region: duodenum

  function: Receives pancreatic juice containing protease, lipase and amylase. Juice also contains sodium hydrogen carbonate which neutralizes acid from the stomach ‐ giving pH of 8.