2. - NUTRITION: group of processes by which the
organism gets and transforms the nutrients that
its cells need.
- NUTRIENTS are chemicals present in the
food that the cells need for:
➢Energy: ENERGETIC NUTRIENTS
➢Building and repairing structures (growth, cell renovation): BODY
BUILDING NUTRIENTS
➢Regulating the chemical reactions in the cell (metabolism):
PROTECTIVE or REGULATORY NUTRIENTS
4. Do you agree with it? Why?
Have you ever heard this statement?
5. Types of Nutrients:
1.- Macronutrients (=needed in larger qualities)
1.1.- Carbohydrates:
- mainly ENERGETIC (4kcal/g)
- simple carbohydrates or sugars like sucrose, fructose and glucose
are quickly digested and absorbed: first source of energy for the cells
- complex carbohydrates like starch or glycogen need a longer
digestion: energy store for the cells
- cellulose (fiber) is a complex carbohydrate. It is not energetic
BUT regulatory
- we can get them from fruits and vegetables (sugars), bread, cereals,
rice and pasta (complex)
6. 1.2.- Lipids:
- They have the three functions of nutrients:
- Fats are the most abundant lipids. They are ENERGETIC nutrients
(store energy in the adipose tissue) (9kcal/g)
- Other lipids (eg. cholesterol, phospholipids) are part of the cell
membranes, so they are BODY-BUILDING nutrients (=for growth and
repair).
- Some lipids are vitamins (A, D, E, K) or hormones (steroids), so they
have a REGULATORY function.
- We can get them from oils, butter, cheese...
7. 1.3.- Proteins:
- They are basically BODY-BUILDING nutrients, but they also have some
REGULATORY functions. When the cell has no carbohydrates or lipids, they
can be used to get energy (4kcal/g).
- We get proteins from meat, fish, eggs...
1.4.- Water:
- It is the most abundant component in our body.
- It has REGULATORY functions:
- refrigerates the body (regulates body temperature)
- transports substances
- helps to remove wastes
- is where metabolism happens
- We get water from liquid foods (water, juices, milk), fruits and vegetables...
8. 2.- Micronutrients (=needed in small amounts)
2.1.- Minerals:
- Some have a BODY-BUILDING function: Ca and P form the bones.
- Others have a REGULATORY function:
- Fe forms the hemoglobin.
- Ca, Fe, Mg are needed for several metabolic
reactions to happen
- oligo-elements are minerals that are present in
less than 0.1% in the body, but are essential for its
normal function: Fe, F, I.
- We get them mainly from fruits and vegetables.
9. 2.2.- Vitamins:
- They may be lipids or proteins.
- They have a REGULATORY function.
- Only small quantities are needed in the organism,
but we cannot produce them, so we have to get them
in the diet.
- Some of them are water-soluble: group B and C.
(excess is easily eliminated through urine or sweat)
- Others are fat-soluble: A, D, E, K
(excess accumulates in the liver and may have
damaging effects)
- We get vitamins from fruit and vegetables.
10.
11.
12.
13. Nutrients (mainly carbohydrates and lipids) are the fuel the cell uses to
get energy in the Cellular Respiration that happens in mitochondria.
14. The units we use to measure ENERGY are:
- calorie (cal): amount of energy needed to increase 1ºC the temperature of
1g of water
1Cal=1kcal=1000cal
- joule (j): unit in the IS
1J=0,24cal
1cal=4,18j
Remember which are the most energetic nutrients?
Which of the following meals is more energetic? Does it mean it is healthier?
15. The energy that one person needs a day (Daily Energetic Requirements)
depends on:
The Basal Metabolic Rate (BMR) is the amount of energy that one
person needs while completely at rest. It depends on the person's age,
sex, height and weight.
Why do we need energy while we are resting?
The Physical Activities that the person does.
So we can calculate the energy we need in a day:
DER = BMR+PA
17. What are GMO?
Genetically Modified Organisms are organisms whose genes have been
altered by using genetic engineering techniques in order to get some
characteristic.
Genetically Modified Foods are plants or animals that have incorporated a
gene from a different species, to get a new feature: tastier and bigger
tomatoes, decaffeinated coffee grains, plague-resistant corn, drought-
tolerant crops, etc.
18. These genetically modified tomatoes
contain anti-oxidants that help to
prevent cancer.
http://www.dailymail.co.uk/sciencetech/article-
1080695/Purple-super-tomato-fight-cancer.html
Golden Rice is a transgenic rice enriched
with vitamin A to help prevent blindness
caused by a deficiency in this vitamin.
19. A BALANCED DIET is the diet that allows a person to keep
healthy and do the physical activities he/she usually does.
To achieve this we should choose foods in the right amount
and of the right group.
Diet must provide the calories and nutrients that the
person needs, especially the essential nutrients (proteins,
minerals, vitamins).
Origin of calories: 55-60% of the calories must come from
carbohydrates, 30-35% from fats, and only 5-10-5 from
proteins.
Animal proteins must be less than 40%
More plant oils and oily fish than animal fats (rich in
cholesterol)
Enough fiber to regulate the function of the intestine;
enough water and minerals.
The diet must be as varied and enjoyable as possible.
24. DIGESTION means breaking down the large, insoluble food molecules into small
soluble molecules (nutrients) that can be absorbed into the bloodstream and used
by the cells.
Digestion can be:
MECHANICAL: breaking down food into smaller pieces through physical
processes (chewing in the mouth, churning in the stomach, etc)
CHEMICAL: involves the use of special chemicals called ENZYMES that speed
up the digestion of large molecules into smaller ones.
28. ANATOMY OF THE DIGESTIVE SYSTEM:
- DIGESTIVE TRACT: a long tube (aprox. 9 m long) that goes from the MOUTH to
the ANUS (Mouth-Pharynx-Oesophagus-Stomach-Small Intestine-Large Intestine)
- GLANDS: that produce digestive juices (containing digestive enzymes and other
chemicals) and pour them into the different organs of the digestive tract (Salivary
Glands, Gastric Glands, Pancreas, Liver, Intestinal Glands)
- Some sphincters or valves regulate the movement of the digesting food from one
organ to the next one.
32. DIGESTION STARTS IN THE MOUTH:
- Mechanical Digestion: Chewing
- Chemical Digestion: Salivary Glands (Parotids,
Sublingual, Submaxilary) produce SALIVA, that
contains:
- AMYLASE: digests carbohydrates
- Mucus
- Lysozyme
- Deglutition: bolus goes down from mouth to the
pharynx and oesophagus. This movement is helped by
gravity and peristalsis.
33. DIGESTION IN THE STOMACH:
- Mechanical Digestion: Peristalsis
- Chemical Digestion: Gastric Glands in the inner walls produce GASTRIC
JUICE, that contains:
- PEPSIN: an enzyme that digests proteins
- Hydrochloric Acid (HCl) needed for the pepsin to work
The bolus enters the stomach through the cardia, and
leaves it through the pylorus, that communicates with
the small intestine (duodenum)
34. DIGESTION IN THE SMALL INTESTINE:
- Mechanical Digestion: Peristalsis
- Chemical Digestion: 3 digestive juices act in the small intestine:
- The PANCREAS produces PANCREATIC JUICE and pours it into the
duodenum when the chyme enters it.
- The LIVER produces BILE, and stores it in the GALLBLADDER. Bile
is poured into the duodenum when the chyme arrives.
- The INTESTINAL GLANDS in the small intestine
walls produce INTESTINAL JUICE
35.
36. - The LIVER produces BILE.
- Bile is stored in the GALLBLADDER until the food enters the small intestine. Then it
is poured into the duodenum.
- Bile has NO ENZYMES but it helps digestion by EMULSIFYING the fats (=breaking
them down in small droplets so they are easier to digest)
37. - The PANCREAS produces PANCREATIC
JUICE. This is poured into the duodenum when
the chyme arrives.
- PANCREATIC JUICE contains:
- sodium bicarbonate to neutralize the acidity of the chyme (it comes from the
stomach)
- enzymes to digest proteins, lipids and carbohydrates:
TRYPSIN and CHYMOTRYPSIN are proteases: breaks down proteins into
amino-acids
AMYLASE is a carbohydrase: breaks down starch into glucose
LIPASE breaks down lipids into fatty acids and glycerol
38. - In the SMALL INTESTINE 3 digestive juices finish the
digestion of the nutrients: bile, pancreatic juice, and
INTESTINAL JUICE.
- INTESTINAL JUICE contains enzymes that digest
carbohydrates, lipids and proteins.
- When digestion has finished, all the large molecules in our food are transformed into
smaller molecules:
Water, vitamins and minerals do not need to be digested.
39. AFTER DIGESTION... ABSORPTION
- Digested food molecules have to pass through the wall of the small
intestine into the bloodstream, which carries them to the cells.
To make absorption easier, quicker and
more efficient:
- the small intestine's wall is very thin (only
one-cell thick)
- the inside wall of the small intestine has a
very big surface area thanks to tiny villi,
that contain the capillaries that absorb the
nutrients.
40. And with the undigested part of the food... EGESTION/DEFECATION
- The part of the foods that have not been absorbed in the small intestin, as well as
water, vitamins, minerals... enter the LARGE INTESTINE, where 3 processes
happen:
1) WATER is reabsorbed in the large intestine, going into the blood capillaries.
Minerals and vitamins are also absorbed here.
2) FAECES are formed with undigested food, fiber
and water. Faeces advance through the large intestine
thanks to the contractions of the intestinal walls, and
are finally released through the ANUS. This is called
EGESTION.
3) Some bacteria live in our large intestine
(INTESTINAL FLORA), and produce some vitamins
(K) that we can also absorbe and use.
