viernes, 24 de diciembre de 2010
domingo, 19 de diciembre de 2010
absorption: The process in which nutrients pass into the blood stream, where they can circulate throughout the body; occurs mainly in the small intestine.
amylase : This enzyme helps break down complex starch molecules into simpler sugar molecules.
cecum: The first part of the large intestine, where waste enters from the small intestine.
celiac disease: An immune reaction to a food protein called gluten, which is found in grains.
chemical digestion: Digestion in which large food molecules are broken down into small nutrient molecules. It takes place mainly in the small intestine.
colon: The second part of the large intestine, where excess water is absorbed. After the excess water is absorbed, the remaining solid waste is called feces.
constipation: Having three or less bowel movements each week.
digestion: Process of breaking down food into nutrients.
digestive system: Body system that breaks down food, absorbs nutrients, and gets rid of solid food waste.
duodenum: The first part of the small intestine; site where most chemical digestion occurs.
enzyme: A substance, usually a protein, that speeds up chemical reactions in the body.
esophagus: The narrow tube that carries food from the pharynx to the stomach.
food intolerance: Occurs when the digestive system is unable to break down a certain type of food.
gall bladder: A small, pear-shaped structure below the liver; stores substances from the liver until they are needed by the small intestine.
gastritis: Inflammation of the lining of the stomach.
gastrointestinal (GI) tract: Organ of the digestive system; a long tube that connects the mouth with the anus.
ileum: The third part of the small intestine; covered with villi; the few remaining nutrients are absorbed in the ileum.
jejunum: The second part of the small intestine; where most nutrients are absorbed into the blood; lined with tiny “fingers” called villi.
large intestine: A relatively wide tube that connects the small intestine with the anus where excess water is absorbed from food waste. It consists of three parts: the cecum, colon, and rectum.
mechanical digestion: Digestion in which large chunks of food are broken down into small pieces. It takes place mainly in the mouth and stomach.
peristalsis: Involuntary muscle contractions which push food through the digestive system.
pharynx: Connects the mouth to the rest of the digestive tract; also connects the mouth and nose to the rest of the respiratory system.
rectum: The third part of the large intestine; where feces accumulates. As the rectum fills, the feces become compacted. The feces are stored in the rectum until they are eliminated from the body.
small intestine: The narrow tube between the stomach and large intestine where most chemical digestion and absorption of nutrients take place.
stomach: A saclike organ located between the end of the esophagus and the beginning of the small intestine. In the stomach, food is further digested both mechanically and chemically.
stomach ulcer: A sore in the lining of the stomach.
villi : Contain microscopic blood vessels; nutrients are absorbed into the blood through these tiny vessels; located on the jejunum and the ileum.
The large pouch-shaped cecum marks the beginning of the colon. Attached near the cecum bottom is the vermiform (worm-like) appendix. The appendix contains lymphoid tissue and intercepts pathogenic microorganisms that enter the digestive tract. Sometimes, fecal matter may become trapped in the appendix, resulting in appendicitis (infection and inflammation).
The three parts of the colon absorb water and minerals from the undigested food and compact the remaining material into feces.
Gut flora or intestinal flora consists of microorganisms that live in the intestine, mostly in the colon. The intestinal bacteria of the gut flora prevent the growth of harmful bacteria and synthesize some vitamins and other functions. The composition of the gut flora differs from person to person and depends on age, diet, environment and use of antibiotics.
Defecation is the digestive process final stage: feces (undigested waste products) are carried to the rectum through peristalsis and eliminated through the anus. It has internal and external sphincters.
A first review
A second review
I recommend you see them to improve your knowledge on the digestive system.(The parts that are above the level of this course, you can skip them or try to learn)
domingo, 12 de diciembre de 2010
As shown in Figure, the mucous membrane lining the small intestine is covered with very small, fingerlike projections called villi (singular: villus). Epithelial cells of each villus has thousands of microscopic projections called microvilli (singular: microvillus). Because there are millions of these tiny projections, they greatly increase the surface area for absorption. In fact, villi increase the absorptive surface of the small intestine to the size of a tennis court! This increases the amount of surface area available for the absorption of nutrients.
Each villus has a network of capillaries and fine lymphatic vessels called lacteals close to its surface. The epithelial cells of the villi transport nutrients from the lumen of the intestine into these capillaries (amino acids and carbohydrates) and lacteals (lipids). The absorbed substances are transported via the blood vessels to the liver and different organs of the body. The food that remains undigested and unabsorbed passes into the large intestine.
The small intestine finishes the process of digestion, absorbs the nutrients, and passes the residue on to the large intestine.
The small intestine is made up of three parts: the duodenum, jejunum, and ileum. Each part has different functions.
The duodenum is the first part of the small intestine. It is about 25 cm long. This is where most chemical digestion takes place. In this part the liver and gall bladder release bile and the pancreas secretes pancreatic juice.
The jejunum is the second part of the small intestine. This is where most nutrients are absorbed into the blood. The jejunum is lined with tiny “fingers” called villi. Each one is only about 1 mm long.
The ileum is the third part of the small intestine. Like the jejunum, the ileum is covered with villi. A few remaining nutrients are absorbed in the ileum. From the ileum, any remaining food waste passes into the large intestine.
Chyme emerging from the stomach into the duodenum is very acidic. The gall bladder release alkaline bile and the pancreas a large amount of sodium bicarbonate which neutralize the acidity of the chyme. This is important for digestion, because digestive enzymes in the duodenum require a neutral environment in order to work. The duodenum is protected from acid by a thick layer of mucus
Inside the duodenal tube, chyme is mixed with the bile and pancreatic juice. Bile breaks down fat particles into smaller droplets thus provide a largely increased surface area for the action of the enzyme pancreatic lipase that breaks down fats. Pancreatic juice conteins many enzymes ( lipase, protease,..) that finalize the food digestion process.
Do not worry about understanding every word. The important thing is to understand the overall process and improve your English comprehension .
There are three parts
Food moves through the esophagus due to peristalsis. At the end of the esophagus, a muscle called a sphincter controls the entrance to the stomach. The sphincter opens to let food into the stomach and then closes again to prevent the food from passing back into the esophagus.
The stomach is a saclike organ located between the end of the esophagus and the beginning of the small intestine. In the stomach, food is further digested both mechanically and chemically. Churning movements of the stomach’s thick muscular walls break down food mechanically. The churning movements also mix the food with gastric juice, a fluids secreted by the stomach. These fluids include hydrochloric acid, digestive enzymes and mucus.
• Hydrochloric acid is a strong acid (pH – 2) and gives the stomach a very acidic environment. This helps destroy any bacteria that have entered the stomach in foods or beverages. An acidic environment is also needed for the stomach’s digestive enzymes to work.
• The main digestive enzyme secreted in the stomach is pepsin that breaks down proteins into smaller molecules .
• Mucus secreted by the gastric glands helps protect the stomach lining from the action of gastric juice.
Small molecules like water, alcohol and salts can be absorbed through the lining of the stomach. Most other substances need further digestion in the small intestine before they can be absorbed. The stomach stores the food until the small intestine is ready to receive it. When the small intestine is empty, a sphincter (Pyloric sphincter) opens between the stomach and small intestine. This allows the partially digested food, now called chyme, to enter the small intestine.
sábado, 11 de diciembre de 2010
The salivary glands, inside the mouth, produce saliva that moistens the food and makes it easier to chew. The salivary enzyme is amylase that breaks down complex starch molecules into simpler sugar molecules (chemical digestion).The mouth also plays an important role in mechanical digestion. The teeth help to digest food mechanically by breaking it into smaller pieces.
There are different teeth types with different shapes and functions:
Incisors: These are your front teeth and are used for biting into your food. They are chisel or wedge-shaped. A human adult has 4 incisors in each jaw
Canines: These are pointed and are used for tearing. An adult human has 2 canines in each jaw.
Premolars and molars at the back of the mouth are larger and broader. They grind food into smaller pieces as you chew. An adult human has 4 pre-molars and 6 molars in each jaw. Third molars are often called wisdom teeth; (they developed thousands of years ago when human diets consisted of mostly raw and unprocessed foods that required the extra chewing and grinding power of a third set of molars. Today wisdom teeth are not needed for chewing and, because they can crowd other teeth, are often removed).
A human baby has 20 baby or milk teeth. These start to develop at about 6 months old and last until you are about 5 - 6 years old. A human adult has 32 teeth called permanent teeth. These start to grow when you are about 5 -6 years old. They replace your milk teeth.
Each tooth consists of a crown and one or more roots.
The crown is the functional part that is visible above the gum. The root is the unseen portion that supports and fastens the tooth in the jawbone. The clear outer layer of the crown is the Enamel, the hardest substance in the human body. The outer layer of the roor is cementum, a bonelike substance that anchors the tooth to the jawbone. Directly beneath the outer layer is dentin, a hard, mineral material that is similar to human bone, only stronger. Dentin surrounds and protects the pulp, or core of the tooth. Pulp contains blood vessels, which carry oxygen and nutrients to the tooth, and nerves, which transmit pain and temperature sensations to the brain.
The muscular tongue helps mix the food with saliva and the enzymes it contains.
When you swallow, the lump of chewed food, now called a bolus, passes into the pharynx.
The pharynx serves both the respiratory system and the digestive system. It connects the mouth to the rest of the digestive tract and, also connects the mouth and nose to the rest of the respiratory system. To prevent food or liquid from entering the trachea (windpipe), the epiglottis (a small flap of tissue) closes over the opening of the larynx (voice box) during swalowing (deglutition).
jueves, 9 de diciembre de 2010
In the digestive process we can consider four stages:
Stage 1: Ingestion.
The intake of food into the body trhough the mouth
Stage 2: Digestion .
The transformation of food into nutrients which the body can absorb. There are two types of digestion:
Mechanical digestion is the physical breakdown of chunks of food into smaller pieces. It takes place mainly in the mouth and stomach.
Chemical digestion: is the chemical breakdown of large, complex food molecules into smaller, simpler nutrient molecules that can be absorbed by the blood. It takes place mainly in the small intestine and trhough the action of enzymes.
Enzymes are substances that speed up chemical reactions. Digestive enzymes speed up the reactions of chemical digestion. Digestive enzymes are secreted by glands in the mucous membranes of salivary glands, stomach, small intestine, and pancreas.
The name of a digestive enzyme typically ends with the suffix -ase, which means “enzyme”. The rest of the name refers to the type of food molecules the enzyme helps digest. For example
proteases split proteins into their monomers, the amino acids
lipases split fat into three fatty acids and a glycerol molecule.
amylases split starch into sugars.
In this video you can learn a little more about enzymes It’s in english but you have in the same page the transcrip of the video.
Stage 3: Absorption:
Absorption is the process in which nutrients pass from the digestive system into the blood stream, where they can circulate throughout the body and carry the nutrients to the cells. Absorption occurs mainly in the small intestine
Stage 4: Egestion:
Egestion is the elimination of undigested food that cannot be absorbed and waste products from the digestive system. These products are transformed into faeces, and expelled from the organism through the anus.
It should not be confused with excretion, which is getting rid of waste formed from the chemical reaction of the body, such as in urine, sweat, etc.
miércoles, 8 de diciembre de 2010
Nutrients in the foods you eat are needed by the cells of your body, we eat foods to obtein nutrients. But:
What organs and processes break down the foofs into nutrients that the body can use for fuel?
What organs and processes let the nutrients enter your bloodstream so they can travel to the cells where they are needed?
The basic processes involved are digestion and absorption. The organs involved are the organs of the digestive system.
Organs that make up the digestive system are shown in figure. Most of the organs form the gastrointestinal tract. Other digestive organs are called accessory organs.
Organs of the digestive system.
1. Gastrointestinal Tract
The gastrointestinal (GI) tract is a long tube that connects the mouth with the anus. It is more than 9 meters long in adults. The upper GI tract includes the mouth, pharynx, esophagus, and stomach. The lower GI tract includes the small and large intestines. Food enters the mouth, passes through the upper and lower GI tracts, and then exits the body as feces through the anus.
The organs of the GI tract are covered by two layers of muscles that enable peristalsis. Peristalsis is a rapid, involuntary, wave-like contraction of muscles. It pushes food through the GI tract.
The inside of GI tract is lined with mucous membranes. Mucous membranes can secrete and absorb substances. The ability to secrete and absorb substances is necessary for the functions of the digestive system.
2. Accessory Organs of the Digestive System
They are additional organs that play important roles in digestion. Food does not pass through them, but they make substances needed for digestion. The accessory organs are the salivary glands, the liver and the pancreas.
- The salivary glands are found in and around your mouth and throat. We call the major salivary glands the parotid, submandibular, and sublingual glands.They all secrete saliva into your mouth .
- The liver is a large organ next to the stomach. It produces digestive substances that are carried by tubes,to the small intestine and gall bladder. The gall bladder is a small, pear-shaped structure below the liver. It stores substances (bile) from the liver until they are needed by the small intestine.
- The pancreas is a gland below the stomach. It produces digestive substances that are carried by a duct to the small intestine.
viernes, 26 de noviembre de 2010
Factors that influence nutrient needs
Role of insoluble fiber
Function of macronutrients.
Main examples of nutrients
Essential amino acids.
Energy of nutrients.
Lipids of plant foods.
Problems of obese people.
Source of Vitamin D
Source of saturated and unsaturated fats
Esamples of nutrients in foods
Vitamins with antioxidants
Anorexia and bulimia characteristic
miércoles, 24 de noviembre de 2010
1. Nutrients: Human beings obtain these chemical substances from ingested foods.
2. Triglycerides: lipids in which three fatty acids are bound to a compound called glycerol
3. Cholesterol: lipid that can damage blood vessels if its concentration in the blood are too high
4. Saturated fats: lipids that are found in animal foods and are solid at room temperature.
5. Unsaturated fats: lipids that are found in plant foods and are liquid at room temperature.
6. Fatty acids: they are a component of triglyceride
7. Dehydration: It occurs when a person does not take in enough water to replace the water that is lost
8. Carbohydrates: Group of nutrients where sugars are included
9. Calorie: It is a unit of energy that measures how much energy food provides to the body
10. Polysaccharides Carbohydrates that contain many saccharides like starch
11. Amino acids: Small molecules that are the building blocks of proteins.
12. Antibodies. White blood cells produce these proteins to destroy bacteria.
13. Fiber: It prevents constipation.
14. Glucose : Simple carbohaydrate that circulates in the blood, providing energy to cells throughout the body.
15. Hemoglobin: Protein that transports the oxigen in the red blood cells.
viernes, 19 de noviembre de 2010
In order to get our diet as complete and balance we must consider, mainly, these criteria:
- Food should provide just the right amount of energy for carrying out our activities and for the development of the organism. Any excess or defect in this energy supply will be prejudicial.
- Diet should supply sufficient proteins, vitamins and minerals. Once again, any excess or defect in this energy supply will be prejudicial.
- With regard to the distribution of the foods which provide energy this should be done in accordance with the following table.
Rich in glucids – 55-60% of total number calories
Rich in lipids – 30% of total number calories
Rich in proteins - 15% of total number calories.
There other criteria to bear in mind like eating 22 g of fibre a day from veges and fruits to avoid constipation and not eating more tham 3g of salt a day to avoid the increase of blood presure and circulatory diseases.
Probably the most famous perfect diet is the Mediterranean Diet. It was the diet of many people around the Mediterranean Basin, especially in Spain, Italy and Greece. The original Mediterranean Diet main characteristics were:
- High consumption of virgin olive oil.
- High intake of vegetables and fruits and legumes.
- Consumption of fish, specially oily (or “bluish” one) three o for times a week
- Consumption of milk and derivates, cheese and yogurt (the original cheese was fresh goat cheese).
- Nuts as snacks
The Mediterranean Diet is the best way to prevent many diseases. The most important are the “brain ictus” or stroke (first cause of death in women and second in men) and the “myocardial infarction” or heart attack (the main cause in men), but are many more. It has been proved the important role of the Mediterranean Diet in the prevention of the metabolic syndrome (some health disorders of which the most important are: too much fat around the waist, high blood pressure and/or insulin levels and unbalanced levels of cholesterol.
The Mediterranean Diet is more than a diet. It is a lifelong living style. High activity, Mediterranean nutrition, anti stress attitudes and not much money shaped a culture that was declared Immaterial Human Heritage by UNESCO a few days ago. Nowadays, these circumstances have changed in the mediterranean countries, young people are changing their diet, but many responsible people are still keeping or returning to what is considered to be the healthiest diet in the world.
Fat is the most energy-dense macronutrient, followed by alcohol, protein and carbohydrate. For example, a glass of full-cream milk has about twice the kilocalories as a glass of soft drink or of skimmed milk Dietary fibre or roughage is not usually ascribed an energy value for humans. Vitamins and elements have no energy value.
Energy requirement can be thought of as the amount needed to maintain the basic processes of life at rest, that is, basal metabolism, plus the amount needed for physical activity under a variety of circumstances. Body weight is an important factor in determining how much energy we need, since more energy will be needed to sustain and move a greater body mass. The total amount of food needed each day will vary with age, sex, body size, activity levels, and whether or not you are pregnant or breastfeeding.
There are a Harris Benedict ecuation for calculating basal metabolic rate (BMR):
BMR Men = 66 + (13,7 x W) + (5 x H) - (6,8 x A)
Where W = weigh in kg; H = height in cm ; and A = age in years
You can also get it directly in same websites.(This website uses English units, so you have to remenber: 1 foot = 0,304 meters and lbs/2.2 = kilograms)
Other posibility is to go to a Spanish website. Maybe in this way it will be easier.
One of the easiest ways To calculate your total daily energy expenditure (calories) is with other Harris Benedict Equation that uses your BMR and then applies an activity factor to determine it. The only factor omitted by the Harris Benedict Equation is lean body mass. Remember, leaner bodies need more calories than less leaner ones.
To determine your total daily calorie needs, multiply your BMR by the appropriate activity factor, as follows:
• If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2
• If you are lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375
• If you are moderatetely active (moderate exercise/sports 3-5 days/week) : Calorie-Calculation = BMR x 1.55
• If you are very active (hard exercise/sports 6-7 days a week) : Calorie-Calculation = BMR x 1.725
• If you are extra active (very hard exercise/sports & physical job or 2x training) : Calorie-Calculation = BMR x 1.9
Total Calorie Needs Example
If you are sedentary, multiply your BMR (1745) by 1.2 = 2094. This is the total number of calories you need in order to maintain your current weight.
Once you know the number of calories needed to maintain your weight, you can easily calculate the number of calories you need to eat in order to gain or lose weight:
Calorie Needs to gain weight. If you want to gain body weight, you need to consume more calories than you burn. One pound (0,45 kg) of body weight is roughly equivalent to 3,500 calories, so eating an extra 500 calories per day will cause you to gain one pound a week.
For optimum health, if you increase your calories to gain weight then (health permitting) gradually increase your level of physical exercise in order to maintain or increase your lean body mass. The benefits of exercise on physical and mental health are well documented and shouldn't be ignored.
Calorie Needs to lose weight. There are approximately 3,500 calories in a pound of stored body fat. So, if you create a 3500-calorie deficit through diet, exercise or a combination of both, you will lose one pound of body weight.
martes, 16 de noviembre de 2010
Obesity occurs when the body mass index is 30.0 kg/m2 or greater. Body mass index (BMI) or Quetelet index is a simple way to estimate the percentage of fat in the body. It is calculated by dividing an individual’s weight (in kilograms) by the square of the individual’s height (in meters). For example, a man who weighs 88 kilograms and is 1.7 meters tall has a BMI of:
88 kg ÷ (1.7 m)2 = 30.4 kg/m2.
Compare this BMI with the BMI values in Table below. The man’s BMI is greater than 29.9 kg/m2, so he would be considered obese.
|Weight Status||BMI Value (kg/m2)|
|Underweight||less than 18.4|
|Normal||from 18.5 to 24.9|
|Overweight||from 25 to 29.9|
|Obese||more than 30|
The combination of eating too much and moving too little generally causes obesity. The best way to lose weight and avoid obesity is to eat less and exercise more. However, many factors may play a role in obesity. Several genes have been identified that control appetite and may contribute to some cases of obesity. Also are important the environmental factors such as the availability of high-fat, high-Calorie fast foods and food advertisements.
Anorexia nervosa is characterized by greatly restricted food intake and low body weight (BMI less than 17.5 kg/m2). People with anorexia nervosa usually have a distorted body image. They think they are too fat when they are actually too thin. They have an obsessive fear of gaining weight and voluntarily starve themselves. They may also exercise excessively to help keep their weight low. Females with anorexia nervosa usually stop having menstrual periods. The disorder mainly affects teenage girls and is extremely serious. At least 10 percent of people with anorexia nervosa die from factors related to the disorder.
Bulimia nervosa is characterized by cycles of binge eating followed by purging to eliminate the food from the body. Purging may be achieved through intentional vomiting or excessive use of laxatives. People with this disorder typically have normal weight or weight slightly greater than normal. Repeated purging can lead to dehydration. Excessive vomiting can damage the teeth and organs of the digestive system. Bulimia nervosa occurs most often in teenage girls and young women.
Causes and Treatment
People with eating disorders usually have other mental health problems as well, most commonly depression. Both depression and eating disorders may have the same underlying physiological cause: low levels of the brain chemical serotonin. The process of eating causes serotonin to be released and may lead to a temporary “high.” Eating disorders can be treated with psychiatric therapy or psychological counseling. Medications may also be prescribed.
lunes, 15 de noviembre de 2010
Group 1. Milk and dairy products Milk Group foods like milk (Skimmed, Semi-skimmed and Whole), cheese ( Fresh, Manchego, Roquefort....) and yogurt together provide calcium and other essential nutrients, including protein amd vitamins.
Calcium is essential for strong, healthy teeth and bones. Bone density and strength built during childhood and adolescence needs to last a lifetime. Adequate calcium intake now — provided by 3 servings of milk, cheese, or yogurt — along with regular physical activity, can help prevent the bone-thinning disease, osteoporosis, later in life — as well as help prevent bone fractures during childhood.
Vitamin D helps the body absorb calcium and use it to build strong bones.
Group 2. Meat, poultry and fishThe Meat Group contains foods from both plants and animals. These provide proteins, fundamentall, as well as iron and B vitamins.
Protein helps build strong muscles and build and repair body tissue. Iron is important part hemoglobin of red blood cells to carry oxygen to all parts of the body.B vitamins helps the body use energy.
Foods in the Meat Group include:
• Beef, chicken, pork and fish.
• Dry beans, such as chickpeas, kidney beans, lentils and split peas.
• Nuts or seeds, such as peanuts, almonds and walnuts.
Group 3. Fats and oils.
The fats group contains are a concentrate source of energy. These include animal fats and vegetable oils. Eaten in moderation they provide the lipids we need and essential fatty acids.
Foods in the Fats Group include:
Saturated fats. These are found mainly in animals ( butter, lard) but some in plants (palm and coconut oils).
Unsaturated fats. These are the vegetable oils (olive and sunflower oils) and fish oil that are rich in omega-3s fatty acids.
Group 4. Cereals, pulses, potatoes and sugar.
These provide proteins and glucids.
Grain Group foods provide complex carbohydrates and fiber. Two categories make up the Grain Group — whole grains and refined grains. Refined grains, such as white rice, pasta or white bread, have the bran and germ removed to give them a finer texture and so they don’t have fiber and vitamin B1 in them.
Complex carbohydrates are an important source of energy and fiber helps promote regular digestion and may reduce the risk for certain cancers and heart disease.
Foods in the Grain Group
Foods from wheat, corn and rice in the Grain like all types of breads, pancakes, biscuits and other foods made from flour and grains. All all types of pasta including spaghetti, macaroni and noodles
This group also includes root vegetables such as potatoes and legumes (soy, beans and peas, lentils, chickpeas and beans) to be rich in carbohydrates.
There are also sugars (glucose, sucrose and all alcohols) present in white or brown sugar, sweets, chocolates, sweet pastries or cakes in general, wine, beer and other alcoholic beverages. They bring lots of energy quick.
Group 5. Fruit.
Fruits provide vitamins A and C, potassium and fiber. The amount of these nutrients in each fruit variety varies. For example, strawberries, oranges and grapefruits are excellent sources of vitamin C, while cantaloupe and apricots are excellent sources of vitamin A. All fruits are naturally low in fat.
Foods in the Fruit Group
Any fruit or 100% fruit juice is in the Fruit Group.
Group 6. Vegetables.
These are a source of vitamins A and C and fiber. Each vegetable contains different amounts of these nutrients. Fiber is important because it promotes regular digestion and may reduce the risk for certain cancers and heart disease.
Foods in the Vegetable Group
Any vegetable or 100% vegetable juice (Fresh, frozen or canned)is in the Vegetable Group: Examples include dark green vegetables, starchy vegetables, orange vegetables, and other vegetables, such as, tomatoes, asparagus, brussels sprouts and eggplant.
domingo, 14 de noviembre de 2010
Vitamins and minerals are micronutrients. They do not provide energy. However, they are needed for good health.
Vitamins are substances that the body needs in small amounts to function properly. Humans need 13 different vitamins. Some of them are listed below . They have many roles in the body. For example, Vitamin A helps maintain good vision. Vitamin B9 helps form red blood cells. Vitamin K is needed for blood to clot when you have a cut or other wound.
Vit A Needed for good vision (Carrots, spinach, eggs) - 600 μg (1 μg = 1 x 10-6 g)
Vit D Needed for healthy bones and teeth (Milk, salmon, tuna, eggs) - 5 μg
Vitn K Needed for blood to clot. (Spinach, Brussels sprouts, milk, eggs) - 60 μg
Vit B1 Needed for healthy nerves (Whole wheat, meat, beans, fish - 0.9 mg (1 mg = 1 x 10-3 g)
Vit B9 Needed to make red blood cells. (Liver, peas, dried beans, green leafy vegetables) - 300 μg
Vit B12 Needed for healthy nerves. (Meat, liver, milk, shellfish, eggs) - 1.8 μg
Vit C Needed for growth and repair of tissues. (Oranges, red peppers, broccoli) - 45 mg
Some vitamins are produced in the body. For example, vitamin D is made in the skin when it is exposed to sunlight. Vitamins B12 and K are produced by bacteria that normally live inside the body. Most other vitamins must come from foods.
Not getting enough vitamins can cause health problems. For example, too little vitamin C causes a disease called scurvy. People with scurvy have bleeding gums, nosebleeds, and other symptoms. Getting too much of some vitamins can also cause health problems. The vitamins to watch out for are vitamins A, D, E, and K (fat-soluble vitamins). These vitamins are stored by the body, so they can build up to high levels.
Minerals are chemical elements that are needed for body processes. Minerals that you need in smaller amounts include iodine, iron, and zinc. Minerals have many important roles in the body. For example, calcium and phosphorus are needed for strong bones and teeth. Potassium and sodium are needed for muscles and nerves to work normally.Minerals that you need in relatively large amounts are listed below. (the quantity you need each day (at ages 9–13 years)
Calcium, needed for strong bones and teeth. (Milk, soymilk, green leafy vegetables) - 1,300 mg
Chloride, needed for proper balance of water and salts in body. (Table salt, most packaged foods) - 2.3 g
Magnesium, needed for strong bones. (Whole grains, green leafy vegetables) - nuts 240 mg
Phosphorus, needed for strong bones and teeth. (Meat, poultry, whole grains\ 1,250 mg
Potassium, needed for muscles and nerves to work normally (Meats, grains, bananas, orange juice) - 4.5 g
Sodium, needed for muscles and nerves to work normally. (Table salt, most packaged foods) - 1.5 g
Not getting enough minerals can cause health problems.For example, too little calcium may cause. This is a disease in which bones become soft and break easily. Getting too much of some minerals can also cause health problems. Many people get too much sodium. Sodium is added to most packaged foods. People often add more sodium to their food by using table salt (sodium chloride). Too much sodium causes high blood pressure in some people.
viernes, 12 de noviembre de 2010
where there are tables with the calories of a lot of foods. This webpage is in Spanish so you must traslate the name of the foods to English.
( I suppose you know WodReference).
There are some webpages that will be very useful when you study the different units of this subject. Maybe you already know them:
martes, 9 de noviembre de 2010
Lipids are organic compounds of carbon, hydrogen, and oxygen. They provide the body with energy. One gram of lipids provides nine kilocalories of energy, more than twice the amount provided by carbohydrates or proteins. Lipids have several other functions as well..
The term fat is often used interchangeably with the term lipid, but fats are actually a particular type of lipid, called triglycerides, in which three fatty acids are bound to a compound called glycerol. Fats are important in the body. They are the main form in which the body stores energy. Stored body fat is called adipose tissue.
Fats are classified as either saturated fats or unsaturated fats. This classification is based on the type of fatty acids.
• Saturated fats.They have saturated fatty acids. Their amount in the diet should be kept as low as possible. If consumed in excess, they contribute to high blood levels of cholesterol and triglycerides. Saturated fats are found in animal foods, such as butter and lard. They are solid or semisolid at room temperature.
• Unsaturated fats. They have unsaturated fatty acids. Eaten in appropriate amounts, they may help lower blood levels of cholesterol and triglycerides and decrease the risk of cardiovascular disease. They are found mainly in plant foods, such as olive oil and sunflower oil, and in saltwater fish .They are liquid at room temperature.
The human body can synthesize all but two of the fatty acids it needs: omega-3 fatty acids and omega-6 fatty acids. Both are unsaturated fatty acids. They are called essential fatty acids because they must be present in the diet. They are found in salmon, vegetable oil, flaxseed, eggs, and whole grains.
Unsaturated fatty acids known as trans fatty acids (or trans fats), are manufactured from plant oils and do not occur naturally. They are added to foods to extend their shelf life. Trans fats have properties like saturated fats and may increase risk of cardiovascular disease. They should be avoided in balanced eating.
You may not think of water as a food, but it is a nutrient. Water is essential to life because it is the substance within which all the chemical reactions of life take place. An adult can survive only a few days without water.
Water is lost from the body in exhaled air, sweat, and urine. Dehydration occurs when a person does not take in enough water to replace the water that is lost. Symptoms of dehydration include headaches, low blood pressure, and dizziness. If dehydration continues, it can quickly lead to unconsciousness and even death. When you are very active, particularly in the heat, you can lose a great deal of water in sweat. To avoid dehydration, you should drink extra fluids before, during, and after exercise.
domingo, 7 de noviembre de 2010
Starch (polysaccharide)is a carbohydrate consisting of a large number of glucose units joined together by bonds.
Simple carbohydrates contain just one or two saccharides. They are all sugars. Examples of sugars in the diet include sucrose, which is found in sugar cane, and lactose, which is found in milk. The main function of simple carbohydrates is to provide the body with energy. One gram of carbohydrate provides four kilocalories of energy. Glucose is the sugar that is used most easily by cells for energy. It circulates in the blood, providing energy to cells throughout the body. Glucose is the only source of energy used by the brain.
Complex carbohydrates, called polysaccharides, generally contain many saccharides. They include starches and fiber. Starches are found in plant foods such as vegetables and grains. They are broken down during digestion to form sugars that provide energy. Fiber consists of indigestible polysccharides and other materials such as cellulose. It is present in all plant foods.
Fiber is important because attracts water as it passes through the large intestine. This helps keep waste moist and moving easily through the intestine. Fibre prevents constipation, which is small, hard and dry faeces that are hard to pass.
Proteins are relatively large organic compounds containing carbon, hydrogen, oxygen, and nitrogen. The elements are arranged in small molecules called amino acids. Amino acids are the building blocks of proteins. They bond together to form long chains, called polypeptides. Proteins consist of one or more polypeptides.
Proteins play many vital roles in the body, including:
• Making up the majority of muscle tissue.
• Regulating many body processes.
• Forming antibodies that destroy bacteria and other “foreign invaders.”
• Transporting nutrients and other vital substances in the blood (Haemoglobin transport O 2 in blood).
Dietary proteins are broken down during digestion to provide the amino acids that cells need to make proteins for the body. Twenty different amino acids are needed for this purpose. Nine of these amino acids cannot be synthesized by cells from simple components and must be obtained from foods. They are called essential amino acids because they are essential in the diet.
Proteins that contain all ten essential amino acids are referred to as complete proteins. They are found in animal foods such as milk and meat. Proteins that are missing one or more essential amino acids are referred to as incomplete proteins. They are found in plant foods such as legumes and rice. By eating a variety of different plant foods containing incomplete proteins, you can include all ten essential amino acids in your diet.
One gram of protein provides four kilocalories of energy. This is the same amount of energy that one gram of carbohydrate provides.
Did you ever hear the saying, “You are what you eat”? It’s not just a saying. It’s actually true. What you eat plays an important role in your health. Eating a variety of healthful foods promotes good physical health and provides energy for growth and activity. Many common diseases and their symptoms can be prevented or helped with healthful eating. Knowing what your body needs can help you choose foods to meet those needs.
Nutrients are chemical elements or compounds that the body needs for normal functioning and good health. There are six main classes of nutrients:
The body needs these nutrients for three basic purposes: energy, building materials, and control of body processes.
A steady supply of energy is needed by cells for all body functions. Carbohydrates, and lipids, mainly, provide this energy through the cellular repirationEnergy is measured in units called kilocalories (kcal), commonly referred to as Calories.
Molecules that make up the body are continuously broken down or used up, so they must be replaced. Some nutrients, particularly proteins, provide the building materials for this purpose. Other nutrients—including proteins, vitamins, and minerals—are needed to regulate body processes.
Nutrients can be classified in two groups based on how much of them the body needs:
• Macronutrients are nutrients that the body needs in relatively large amounts. They include carbohydrates, proteins, lipids, and water.
• Micronutrients are nutrients the body needs in relatively small amounts. They include vitamins and minerals.
The exact amount of a macronutrient an individual needs depends on many factors, including gender and age.
The main purpose of this blog is to be a useful tool for the 3rd year students of Biology and Geology in I.E.S. Hernán Pérez del Pulgar of Ciudad Real.
My idea about the blog is to put several posts every week with information about the Unit we are studying . These posts won't be too long in order to make the learning process easier.
I would like you to put comments to the post (please, only to some of them). In this way I’ll be able to consider your comments to improve your marks .
I'll try to do my best, but it's difficult not to make some little mistakes. I'd like to apologise in advance for these.
Maybe some of you are wondering why I have chosen this name for the blog. “Panda’s thumb” was the title of a book of collected essays about evolution by the Harvard paleontologist Stephen Jay Gould. He was a very important evolutionary biologist and historian of science
Just in case you don’t know what evolution is....
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