- 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
- make you more productive.
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.
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)
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
- 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.
Diet and coronary heart disease
Obesity can lead to these following health problems
- - cancer
- cardivascular disease
- type 2 diabetes
Obesity is also linked to
- high blood pressure (hypertension)
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.
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.
- 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.
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.
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.
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.
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.
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.
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.
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.
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.