Food and Health

- Biology module 2

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  • Created by: Lala
  • Created on: 30-03-11 08:26


 - why do we eat? - nutrition comes from the food we eat. - Good food filled with nutrients - well balanced diet; good nutrition will -

  • provide bettee health
  • stronger immune system
  • ill less often
  • learn more effectively
  • stronger
  • make you more productive.
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Balanced diet

A balanced diet is one that contains all nutrients required for health and apporoaite proportions.

  • carbohydrates - main source of energy
  • proteins - essential for growth and repair of muscle and other body tissues
  • fats - essential source of energy important in cell membrane - water proofing - absorbtion of fat - soluable vitimains and other roles.
  • Vitimains - used in chemical processes taking place inside a cell, some water soluable some fat soluable.
  • Minerals inorganic elements occuring in the body that are essential to its normal functions.
  • water - essential body function - used for transporting subtances around body 60% of the human body is water.
  • Fibre or roughage - indigestable part of our food - essential for functioning of the digestive system.
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Aspect of nutrition

- one important aspect of nutrtion is intake

  • 57% carbohydrates (bread, pasta, rice sugar and sweeets)
  • 30% fats (dairy products, oil )
  • 13% protein ( eggs, meat, fish)

Obesity -

malnutrtion caused by unbalanced diet - biggest world wide on = obesity.

- caused by consuming too much energy excess energy fat in the adipose tissues. Obesity is the conditions in which excessive fat depostion impairs health. Health measured by BMI ( body mass index)

BMI = mass kg / height in m

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- obesity is not just a problem of excess fat - the location where the fat is deposited also has an effect - people with extra fat around the middle (apple shaped) know to be more at risk than people with excess fat around their hips and thighs.

A growing problem - MORE PEOPLE BECOME OBESE.

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Diet and coronary heart disease

Obesity can lead to these following health problems

  • - cancer
  • cardivascular disease
  • type 2 diabetes

Obesity is also linked to

  • gallstones
  • ostheoarthitis
  • high blood pressure (hypertension)
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Other components of diet

- overall intake of energy should be balanced to avoid being overweight or underweight.

- components that can cause coronary heart disease - result of a decomposition of fatty substances in the walls of the coronary arteries - the decomposition is known as atheroscleorsis. this narrows the size of the lumen - restricts blood flow to the heart muscles and may cause oxygen starvation.

some components of the diet help to reduce risk of CHD - dietry fibre, moderate alcohol comsumption and eating oily fish appear to be beneficial.

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Excess salt in the diet decreases the water potentional of your blood.

- as more water is held the blood pressure increases leading to hypertension - the condition where the blood pressure and partially the aistolic pressure ( BP when the heart is relaxing during cyce) maintained at a level too high - damaging the inner lining of arteries which is one of the early steps of the process artheroscelerosis.

- Fats (lipids)

essential part of diet - animal fat tends to be saturatedand plant oil tends to be unsaturated. Saturated fats are more harmful than unsaturated fats - polyunsaturated and monosaturated fats such as found in olive oil beneficial to health.

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- no a trglyceride but it has similar properties - hight blood cholestro concentration have been like 45% - 47% of death from cornary heart disese - the concentration of the chlorestrol blood should be maintained.

- Why is there chlorestrol in the blood?

essential to the normal function of the body found in cell membranes and in the skin must be transported around the body - like fats chlorestrol not soulable in water must be converted so it can mix with water 

  • high density lipoprotein (HDL)
  • Low density lipoprotein (LDL)
  • both types released into the blood and can be taken up by cells that have the correct receptor sites.
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High densitry lipoprotein

- produced by combination of unsaturated fats, chlorestrol and protein.

- tends to carry chlorestrol from body tissues back to liver. Liver cells have receptor sites that allowthe HDLs to bind their cells surface membranes.

- in the liver chlorestrol used to make cell metabolism to make bile or is broken down.

- there fore high levels of HDLS ASSOCIATED WITH reducing blood chlorestrol levels- reduce decomposition of artery walls by artherosceleorisis and maybe used to remove the fatty decomposition of atherosclerosis - since HDLs used unsaturated fats these fats are thought to be more beneficial to health than saturated fats.

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Low density lipoprotein

produced by the combination of satrated fats, chlorestrol and protein - tend to carry chloestrol from live to the tissues - tissue cells have receptors sites that allow LDLs to bind to their cell surface membranes - if too much saturated fat and chloestrol is consumed in the diet then the conc of LDLs in blood will rise - high conc of LDLs will decompostion in the artery walls different fats affect the LDLs causes deposition in artery walls - different fats affect the LDL receptors in a number of ways -

  • saturated fats are thought to decrease the activity of the LDL receptors - therefore blood concentration rises less is removed from blood this results in higher conc of LDL in blood and deposited in artery walls.
  • polyunsaturated fats seem to increase the activity of LDL receptors and so decrease the concentration of LDL in the blood.
  • monsaturated fats also seem to help remove LDLs from blood.
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Diet and lipoproteins

we do not eat lipoproteins but out diet depends on it.

  • Eating a lot of unsaturated (animal) fats will increase conc of LDLs in our blood.
  • eating a low fat diet will reduce the overall conc of lipoproteins
  • eating a high proportions of unsaturated fats will increase the proportions of HDLs in the blood.
  • eating polysaturated fats help to reduce the conc OF LDLs in the blood.
  • eating monosaturated fats help to recue the conc of LDLs in the blood.
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Improving food productions

Plants as foods -

plants carry out photosynthesis , in the process plants convert energy in light to stored chemical form.

- they absorb carbon dioxide from the air to make carbohydrates - most plants store energy as startch. - they absorb minerals such as nitrates from the soil and manufacture a range of other biological molecules when they eat and digest plants.

Humans are omnivores - means eating both plants and animals - gain our nutrtion both directly from plants and indirectly by earing herbivores animals the human food chain tends to be short. Increase food production.

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How can we make food production more efficient

  • increase the growth rate of crops
  • increase the size of the yield for each plant
  • reduce losses of crops due to dieseases and pest
  • make harvesting easier by standardising plant size
  • improve plant respinses to fertilisers

in animals it is possible to:

  • improve the rate of growth
  • increase productivy
  • increase resistance to disease.
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Health and Disease

Health - state of mental, physical and social well being - :

  • free from disease
  • normal physical and mental tasks
  • well fed balanced diet
  • happy positive
  • suitably housed
  • intergrated in society

Disease - departure from good health caused my malfunction of the mind or body. Symptons may be physical mental or social.

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Parasites and Pathogens

Parasites are organisms that live in or on another living host - they harm their host. Taking nutrtion from the host. eg head louse. Internal parasites - tapeworms that live in the digestive system.

Pathogens - organisms that cause disease Take nutritionn from host damage in the process.

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Infectious disease eg bacter fungi protoctists vir

Bacteria - belong to the kingdome prokarytae - cells smaller than normal cells reproduce rapidly - right condition every 20mins. Their presense can cause disease damaging cells or releasing toxic waste. eg chlorea tuberculosis.

Fungi - Atheletes foot, ring worm caused by fungus called tinea. Sends out reproductive hyphae grow on the surface of skin to release spores.

Viruses - cold HIV/AIDS invade cells and take over genetic machinery and other organelles of cells bursts and release new viruses.

Protocstia - no. of disease caused by animals like protocistra - cause harm by entering host cells and feeding on contents as they grow feed on contents of red blood cells.

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