Dieting is the practice of ingesting food in a regulated fashion to achieve or maintain a controlled weight. In most cases the goal is weight loss, but some athletes aspire to gain weight (usually in the form of muscle) and diets can also be used to maintain a stable body weight

List of diets

1

• 100-Mile Diet control

A

• Abs Diet
• Alkaline diet
• Atkins diet

B

• Best Bet Diet
• Blood Type diet
• Body for Life
• Breatharian diet
• Buddhist diet

C

• Cabbage soup diet
• The Cambridge Diet
• Candida control diet
• Cretan diet
• CRON-diet

D

• Detox diet
• Diabetic diet
• Diet for a New America by John Robbins
• The Diet Smart Plan
• Dietary Approaches to Stop Hypertension or the DASH Diet
• Dr. Hay diet

F

• The Fat Resistance Diet
• Feingold diet
• Fit for Life diet
• Flexitarian diet
• Food combining diet
• Fruitarian diet

G

• Gerson diet
• Gluten-free, casein-free diet
• Glycemic Index diet
• The Graham Diet
• Grapefruit diet

H

• Hacker's diet
• Halal diet
• Hallelujah diet
• High protein diet

J

• Jenny Craig
• Joel Fuhrman diet
• Junk food diet

K

• Kosher diet

L

• Lacto vegetarianism
• Living foods diet
• Low-carbohydrate diet
• Low-protein diet

M

• Macrobiotic diet
• Master Cleanse
• Mediterranean diet
• Montignac diet

N

• Natural Foods Diet
• Negative calorie diet
• No-Grain Diet

O

• Okinawa diet
• The Optimal Diet
• Organic food diet
• Ornish Diet
• Ovo-lacto vegetarian diet

P

• Paleolithic diet
• Perricone diet
• Pescetarian diet
• Plant-based diet
• Pollotarian diet
• Prison loaf
• Pritikin diet

R

• Rastafarian diet
• Raw foodism
• Rice Diet

S

• Scarsdale Diet
• Sex Diet
• Shangri-La Diet
• Slimming World diet
• Sonoma diet
• South Beach diet
• Stillman diet
• Subway diet

V

• Vegan diet
• Vegetarian diet
• Very low calorie diet

W

• Weigh Down diet
• Weight Watchers
• Western pattern diet

Z

• Zone diet

Here are some general food diary tips to make sure they work for you and are as easy to use as possible:

• Don't change your eating habits while you're keeping your food diary.
• Be honest and write everything down.
• Keep your diary with you at all times
• Use the KISS Principle and keep it simple.
• The nutrition information you record (kilojoules, etc) doesn't need to be accurate to the hundredth percentile, just accurate enough to be helpful.
• Wait until the end of the day to add up your totals.
• Draw up a page that lists the foods you eat most often and refer to it each time you record those foods.
• For the most accurate results, use the nutritional information panel on the packaging of the foods you eat.
• If you are generally satisfied with the day's food intake, give yourself a mental pat on the back and relish the day's accomplishment.
• If you feel disappointed in what you read, remind yourself that it is only one day in a lifetime of thousands of days. Forgive yourself and start over.
• Analyze what you eat and make the necessary changes.
• Start recording today.
• If you need help, visit a registered dietitian or weight loss professional.

What is a food diary?

Put simply, a food diary is used to record what we eat and drink each day.

Typically, a basic food diary is designed to record:
• When we eat and drink
• What we eat and drink
• How much we eat and drink
• How many grams of Protein, Carbohydrates, Fat and Kilojoules or Calories are contained in what we eat and drink

The basic food diary contain on this site also records:
• Our energy (Kilojoule or Calorie) target each day
• What supplements we take and there nutritional value
• How many glasses of water we drink each day
• The number of surplus (more) or deficit (less) Kilojoules or Calories we consume versus our daily target

In addition to a basic food diary we offers the following other free food diaries:
• An emotional eating food diary
• A sugar, salt and fat food diary
• A fibre, calcium and omega-3 food diary
• An iron, magnesium and potassium food diary
• An alcohol, caffeine and cigarette food diary

Each of these food diaries records our total energy intake versus our daily target but also allows us to focus on individual problem areas or areas that we particularly want to modify.

Why use a food diary?

The main reason we should use a food diary is to make positive changes to our diets.

The reasons that a food diary is superior to relying on our memory are that food diaries are far more accurate (little pieces of chocolate aren't forgotten), and are easier to analyse because they contain more information than just what is eaten.

From a weight loss perspective, by recording exactly what and how much we eat and drink each day, we can better understand why we're putting on weight and what needs to be modified in our diet to help us lose weight and/or increase certain nutrients in our diet.

If we ever visit a dietician to get help with our diet, the first thing they will ask us to do is to keep a food diary for a week or two so that they can analyse what we're eating and recommend changes that will help us reach our weight loss goal.

How a food diary can help aid weight loss

Here are some of the great things a food diary can do to help us lose weight:
• Break down our weight loss goals into manageable chunks (daily energy targets)
• Plan future menu and eating patterns
• Record our actual eating patterns
• Record other important "peripheral information"
• Better understand and manage our eating habits and portion sizes
• Break unhealthy and emotional eating
• Take the guess work out of the weight loss equation
• See how balanced our diet is
• Improve our nutrition
• Stay motivated
• Stop unconscious eating
• Provide a hard record of our successes

How to complete the free food diaries

Generally, food diaries are meant to be kept for at least a week or two, but studies have shown that even keeping track of what we eat for a day or two can help us make positive changes to our diets.

Some people keep a food diary indefinitely to help them maintain a healthy weight range once it's helped them achieve their ideal weight.

How long we keep a food diary is going to be a matter of personal choice, the most important thing is to start using one and when we feel that we don't need to anymore, we can stop.

Let's have a look at how to fill out each field contained in each of the food diaries offered on this site (but before we do remember, we don't need to fill out every detail specified in order to get at least some benefit from these food diaries):

Basic Food Diary

Energy Goal: Simply write down your target number of kilojoules or calories for the day.

Date: Write down the relevant date.

Time: Write down the time of each meal (there is an option to record up to six meals per day, including snacks).

Food/Drink Item: Write a description of what you eat and drink at each meal (e.g. Salad Sandwich).

Qty: Write down how many serves of the food/drink item you consume (e.g. 2).

Protein: (Optional) Write down how many grams of protein are contained in what you've consumed - for this information refer to the nutritional information panel printed on the packaging of the food and drink you consume or consult a set of nutritional tables.

Carbs: (Optional) Write down how many grams of carbohydrates are contained in what you've consumed - for this information refer to the nutritional information panel printed on the packaging of the food and drink you consume or consult a set of nutritional tables.

Fat: (Optional) Write down how many grams of fat are contained in what you've consumed - for this information refer to the nutritional information panel printed on the packaging of the food and drink you consume or consult a set of nutritional tables.

KJ / Cals: Write down the total number of kilojoules or calories contained in each food or drink item consumed.

Energy Subtotal:Add up all the kilojoules or calories contained in all the foods and drinks consumed for each meal and write this figure down in the far right column.

Supplements Table: Record all of the information as above for any supplements taken throughout the day.

Total Energy Intake: Add the two energy subtotal numbers together (if relevant) and write the result in the far right column.

Calculation: Write down the total energy intake number in the first field and your energy goal for the day in the second field. Now subtract the second number from the first and the result will equal your surplus (more) or deficit (less) kilojoules or calories for the day.

Water Consumed: Each time you drink a glass of water (200 - 250ml) simply tick one of the boxes provided.

Emotional eating food diary

Use this food diary if you think you are an emotional eater who often eats when not really hungry.

Instead of recording the amount of protein, carbohydrates and fat in the foods and drinks you consume, record where you ate/drank (e.g. home or office), what you were doing at the time (e.g. working, watching TV) and what mood you were in at the time (e.g. happy, depressed).

Sugar, salt and fat food diary

Use this food diary if you think you might be eating too much sugar, salt or fat in your diet.

Instead of recording the amount of protein and carbohydrates in the foods and drinks you consume, record how much sugar and salt as well as fat they contain instead.

Fibre, calcium and omega-3 food diary

Most of us should be consuming more fibre,calcium and omega-3 fatty acids for weight loss and optimal health and this food diary is designed to help us do just that.

Instead of recording the amount of protein, carbohydrates and fat in the foods and drinks you consume, record the fibre, calcium and omega-3 they contain instead.

Iron, magnesium and potassium food diary

Most of us should be consuming more iron, magnesium and potassium for optimal health and this food diary is designed to help us do just that.

Instead of recording the amount of protein, carbohydrates and fat in the foods and drinks you consume, record the amount of iron, magnesium and potassium they contain instead.

Alcohol, caffeine and cigarette food diary

Over consumption of alcohol, caffeine and cigarettes often accompany or form part of our bad eating habits.

Use this food diary if you think that this applies to you and you would like to track your consumption of these 'undesirables' and understand how each is interrelated.

Instead of recording the amount of protein, carbohydrates and fat in the foods and drinks you consume, record your how much alcohol and caffeine they contain and how many cigarettes you smoke.

Good nutrition is one of the keys to good health. This means making sure you regularly eat foods that have a lot of vitamins and minerals in them, such as fruits, vegetables, whole grains and low- or nonfat dairy.

Do I need to change what I eat?

If you answer yes to any of the following questions, you may need to talk about nutrition with your doctor:
• Has your doctor talked with you about a medical problem or a risk factor, such as high blood pressure or high cholesterol?
• Did your doctor tell you that this condition could be improved by better nutrition?
• Do diabetes, cancer, heart disease or osteoporosis run in your family?
• Are you overweight?
• Do you have questions about what kinds of foods you should eat or whether you should take vitamins?
• Do you think that you would benefit from seeing a nutritionist? (A nutritionist is a registered dietitian who specializes in nutrition counseling.)


Won't it be hard to change my eating habits?

Probably, but even very small changes can improve your health considerably. The key is to keep trying to eat the right foods and stay in touch with your doctor and nutritionist, so they know how you are doing. Here are a few suggestions that can improve your eating habits:
• Find the strong points and weak points in your current diet. Do you eat 4 1/2 cups of fruits and vegetables every day? Do you get enough calcium? Do you eat whole-grain, high-fiber foods regularly? If so, you're on the right track! Keep it up. If not, try adding more of these foods to your daily diet.
• Make small, slow changes, instead of trying to make large, fast changes. Small changes will be easier to make and stick with.
• Keep track of your food intake by writing down what you eat and drink every day. This record will help you see if you need to eat more from any food groups (such as fruits, vegetables or dairy products) or if you need to eat less of a good group (such as processed or high-fat foods).
• Think about asking for help from a nutritionist if you haven't already done so, especially if you have a medical problem that requires you to follow a special diet.

Can I trust nutrition information I get from newspapers and magazines?

Nutrition tips and diets from different sources often conflict with each other. You should always check with your doctor first. Also, keep in mind this advice:
• There is no "magic bullet" when it comes to nutrition. Short-term diets may help you lose weight, but they are difficult to keep up and may even be unhealthy in the long run.
• Good nutrition doesn't come in a vitamin pill. Only take a vitamin with your doctor's recommendation, as your body benefits the most from eating healthy, whole foods.
• Eating a variety of foods is best for your body, so try new foods!
• Stories from people who have used a diet program or product, especially in commercials and infomercials, are advertisements. These people are usually paid to endorse what the advertisement is selling. Remember, regained weight or other problems that develop after someone has completed the program are never talked about in those ads.

What changes can I make now in my diet?
Almost everyone can benefit from cutting back on unhealthy fat. If you currently eat a lot of fat, try just one or two of the following changes, or those suggested in our handout on healthier food choices:
• Rather than frying meat, try baking, grilling or broiling. Take the skin off before eating chicken or turkey. Eat fish at least once a week.
• Cut back on extra fat, such as butter or margarine on bread, sour cream on baked potatoes, and salad dressings. Use low-fat or nonfat versions of these condiments.
• Eat plenty of fruits and vegetables both with your meals and as snacks.
• When eating away from home, watch out for "hidden" fats (such as that in salad dressing and desserts) and larger portion sizes.
• Read the nutrition labels on foods before you buy them. If you need help reading the labels, ask your doctor or your nutritionist.
• Drink no- or low-calorie beverages, such as water, unsweetened tea and diet soda.
Balanced nutrition and regular exercise are good for your health, even if your weight never changes. Try to set goals that you have a good chance of reaching, such as making one of the small changes listed above or walking more in your daily life.

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AIDS/HIV
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Autism
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Behcet’s Disease
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Congenital Heart Disease
Creutzfeldt-Jakob Disease
Crohn’s Disease
Cystic Fibrosis
Diabetes
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Emphysema
Epilepsy
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Graft Versus Host Disease
Hepatitis
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Leprosy
Leukemia
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Lymphoma
Malaria
Meningitis
Multiple Sclerosis
Muscular Dystrophy
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Parkinson’s Disease
Photosensitive Epilepsy
PolioPrion Disease
ScoliosisSickle Cell Disease
Spina Bifida
Syphilis
Tay-Sachs

FOOD AND NUTRITION
What is a Nutrition Facts Label?
The Nutrition Facts Label allows you to determine the amount calories and nutrients in one serving of food. The information on the label is important in determining whether you're eating a healthy, balanced diet.

The label, which is included on every packaged food product, lists the amount of:
• Fat
• Total fat
• Saturated fat
• Trans fat
• Cholesterol
• Sodium
• Total carbohydrate
• Dietary fiber
• Sugars
• Protein
• Vitamins and minerals
Here is an example:

What is a serving size?
Serving size is the first thing listed on the label. A serving size is the amount of food that is typically eaten in one serving. It is listed as a general household measurement, such as pieces, cups or ounces (for example, 7 potato chips or 1/2 cup of cereal).

Serving size is an important part of a healthy diet. Eating very large servings, or portions, can contribute to weight gain because as the portion size increases, you're also eating more calories.

Remember, serving sizes may be extremely small (for example, only 7 potato chips or 1 ounce of cake) to make the food seem low-calories or low-fat, so be careful. If you double a serving size, you must also double all the other values on the nutrition label.

What is the Percent Daily Value?
You are supposed to consume a certain amount of fats, carbohydrates (especially fiber), protein and vitamins and minerals each day. You are also supposed to limit certain types of unhealthy ingredients, such as saturated and trans fats. The nutrition label provides a list of percentages (called the Percent Daily Value) that tell you how much of a certain nutrient one serving of food contains, to how much of that nutrient you should consume daily.

One serving of food with 5% or less of the daily value is considered low. One serving of a food with 20% or more of the daily value is considered high.

The Percent Daily Value is based on a daily diet of 2,000 calories. You will need to adjust the percentages if you eat more or less than 2,000 calories per day. For more information on calorie allowances, read our handout on determining calorie needs.

What ingredients should I limit in my diet?
• Saturated fat. Saturated fat can increase your risk of heart disease and high cholesterol. The average adult should consume no more than 20 grams of saturated fat per day.
• Trans fat. Trans fat also increases your risk of heart disease. Ideally, you should get 0 grams of trans fat per day. When you read a nutrition label remember that companies are allowed to list the amount of trans fat as “0 grams” if it contains less than .5 grams of trans fat per serving. This means that your food can contain some trans fat even if the nutrition label says “0 grams” per serving! Always check the ingredient list for trans fat, which will appear as “hydrogenated vegetable oil” or “partially hydrogenated vegetable oil.” Trans fat is usually found in commercially prepared baked goods, fried foods, snack foods and margarine.
• Cholesterol. Limit your total cholesterol intake to less than 300 milligrams per day (and less than 200 milligrams per day if you have heart disease). Read our handout on cholesterol for more information.

What ingredients should I get more of in my diet?
• Fiber. Fiber aids in digestion, as well as lowering your risk of diabetes and heart disease. A food is considered high in fiber if it contains 5 grams of fiber or more per serving. Men age 50 and younger should get at least 38 grams of fiber per day, while women age 50 and younger should consume at least 25 grams of fiber per day. Fiber is found in foods like fruits, vegetables and whole grains. Look for the words “whole grain.”
• Vitamins and Minerals. The nutrition label lists vitamin A, vitamin C, calcium and iron. You should try to get more of these nutrients in your daily diet, as well as other vitamins and minerals that are not listed on the label. You can learn more about vitamins and minerals

Nutrition: How to Make Healthier Food Choices
Why is healthy eating important?
When combined with exercise, a healthy diet can help you lose weight, lower your cholesterol level and improve the way your body functions on a daily basis.

The U.S. Department of Agriculture’s (USDA) Food Guide Pyramid divides food into 6 basic food groups, consisting of
1) grains,
2) fruits,
3) vegetables,
4) meats and beans,
5) diary and
6) fats.

The USDA recommends that an adult daily diet include the following:
• 3 ounces of whole grains, and 6 ounces of grains total
• 2 cups of fruit
• 2 1/2 cups of vegetables
• 3 cups fat-free or low-fat dairy

How does the urinary system work?
Your body takes nutrients from food and uses them to maintain all bodily functions including energy and self-repair. After your body has taken what it needs from the food, waste products are left behind in the blood and in the bowel. The urinary system works with the lungs, skin, and intestines—all of which also excrete wastes—to keep the chemicals and water in your body balanced. Adults eliminate about a quart and a half of urine each day. The amount depends on many factors, especially the amounts of fluid and food a person consumes and how much fluid is lost through sweat and breathing. Certain types of medications can also affect the amount of urine eliminated.



The urinary system removes a type of waste called urea from your blood. Urea is produced when foods containing protein, such as meat, poultry, and certain vegetables, are broken down in the body. Urea is carried in the bloodstream to the kidneys.

The kidneys are bean-shaped organs about the size of your fists. They are near the middle of the back, just below the rib cage. The kidneys remove urea from the blood through tiny filtering units called nephrons. Each nephron consists of a ball formed of small blood capillaries, called a glomerulus, and a small tube called a renal tubule. Urea, together with water and other waste substances, forms the urine as it passes through the nephrons and down the renal tubules of the kidney.

From the kidneys, urine travels down two thin tubes called ureters to the bladder. The ureters are about 8 to 10 inches long. Muscles in the ureter walls constantly tighten and relax to force urine downward away from the kidneys. If urine is allowed to stand still, or back up, a kidney infection can develop. Small amounts of urine are emptied into the bladder from the ureters about every 10 to 15 seconds.

The bladder is a hollow muscular organ shaped like a balloon. It sits in your pelvis and is held in place by ligaments attached to other organs and the pelvic bones. The bladder stores urine until you are ready to go to the bathroom to empty it. It swells into a round shape when it is full and gets smaller when empty. If the urinary system is healthy, the bladder can hold up to 16 ounces (2 cups) of urine comfortably for 2 to 5 hours.

Circular muscles called sphincters help keep urine from leaking. The sphincter muscles close tightly like a rubber band around the opening of the bladder into the urethra, the tube that allows urine to pass outside the body.

Nerves in the bladder tell you when it is time to urinate, or empty your bladder. As the bladder first fills with urine, you may notice a feeling that you need to urinate. The sensation to urinate becomes stronger as the bladder continues to fill and reaches its limit. At that point, nerves from the bladder send a message to the brain that the bladder is full, and your urge to empty your bladder intensifies.

When you urinate, the brain signals the bladder muscles to tighten, squeezing urine out of the bladder. At the same time, the brain signals the sphincter muscles to relax. As these muscles relax, urine exits the bladder through the urethra. When all the signals occur in the correct order, normal urination occurs.

What causes problems in the urinary system?
Problems in the urinary system can be caused by aging, illness, or injury. As you get older, changes in the kidneys’ structure cause them to lose some of their ability to remove wastes from the blood. Also, the muscles in your ureters, bladder, and urethra tend to lose some of their strength. You may have more urinary infections because the bladder muscles do not tighten enough to empty your bladder completely. A decrease in strength of muscles of the sphincters and the pelvis can also cause incontinence, the unwanted leakage of urine. Illness or injury can also prevent the kidneys from filtering the blood completely or block the passage of urine.

How are problems in the urinary system detected?
Urinalysis is a test that studies the content of urine for abnormal substances such as protein or signs of infection. This test involves urinating into a special container and leaving the sample to be studied.

Urodynamic tests evaluate the storage of urine in the bladder and the flow of urine from the bladder through the urethra. Your doctor may want to do a urodynamic test if you are having symptoms that suggest problems with the muscles or nerves of your lower urinary system and pelvis—ureters, bladder, urethra, and sphincter muscles.

Urodynamic tests measure the contraction of the bladder muscle as it fills and empties. The test is done by inserting a small tube called a catheter through your urethra into your bladder to fill it either with water or a gas. Another small tube is inserted into your rectum or vagina to measure the pressure put on your bladder when you strain or cough. Other bladder tests use x-ray dye instead of water so that x-ray pictures can be taken when the bladder fills and empties to detect any abnormalities in the shape and function of the bladder. These tests take about an hour.

What are some disorders of the urinary system?
Disorders of the urinary system range in severity from easy to treat to life threatening.
Benign prostatic hyperplasia (BPH) is a condition in men that affects the prostate gland, which is part of the male reproductive system. The prostate is located at the bottom of the bladder and surrounds the urethra. BPH is an enlargement of the prostate gland that can interfere with urinary function in older men. It causes blockage by squeezing the urethra, which can make it difficult to urinate. Men with BPH frequently have other bladder symptoms including an increase in frequency of bladder emptying both during the day and at night. Most men over age 60 have some BPH, but not all have problems with blockage. There are many different treatment options for BPH.

Painful bladder syndrome/Interstitial cystitis (PBS/IC) is a chronic bladder disorder also known as frequency-urgency-dysuria syndrome. In this disorder, the bladder wall can become inflamed and irritated. The inflammation can lead to scarring and stiffening of the bladder, decreased bladder capacity, pinpoint bleeding, and, in rare cases, ulcers in the bladder lining. The cause of IC is unknown at this time.

Kidney stones is the term commonly used to refer to stones, or calculi, in the urinary system. Stones form in the kidneys and may be found anywhere in the urinary system. They vary in size. Some stones cause great pain while others cause very little. The aim of treatment is to remove the stones, prevent infection, and prevent recurrence. Both nonsurgical and surgical treatments are used. Kidney stones affect men more often than women.

Prostatitis is inflammation of the prostate gland that results in urinary frequency and urgency, burning or painful urination, a condition called dysuria, and pain in the lower back and genital area, among other symptoms. In some cases, prostatitis is caused by bacterial infection and can be treated with antibiotics. But the more common forms of prostatitis are not associated with any known infecting organism. Antibiotics are often ineffective in treating the nonbacterial forms of prostatitis.

Proteinuria is the presence of abnormal amounts of protein in the urine. Healthy kidneys take wastes out of the blood but leave in protein. Protein in the urine does not cause a problem by itself. But it may be a sign that your kidneys are not working properly.

Renal (kidney) failure results when the kidneys are not able to regulate water and chemicals in the body or remove waste products from your blood. Acute renal failure (ARF) is the sudden onset of kidney failure. This condition can be caused by an accident that injures the kidneys, loss of a lot of blood, or some drugs or poisons. ARF may lead to permanent loss of kidney function. But if the kidneys are not seriously damaged, they may recover. Chronic kidney disease (CKD) is the gradual reduction of kidney function that may lead to permanent kidney failure, or end-stage renal disease (ESRD). You may go several years without knowing you have CKD.

Urinary tract infections (UTIs) are caused by bacteria in the urinary tract. Women get UTIs more often than men. UTIs are treated with antibiotics. Drinking lots of fluids also helps by flushing out the bacteria.

The name of the UTI depends on its location in the urinary tract. An infection in the bladder is called cystitis. If the infection is in one or both of the kidneys, the infection is called pyelonephritis. This type of UTI can cause serious damage to the kidneys if it is not adequately treated.

Urinary incontinence, loss of bladder control, is the involuntary passage of urine. There are many causes and types of incontinence, and many treatment options. Treatments range from simple exercises to surgery. Women are affected by urinary incontinence more often than men.

Urinary retention, or bladder-emptying problems, is a common urological problem with many possible causes. Normally, urination can be initiated voluntarily and the bladder empties completely. Urinary retention is the abnormal holding of urine in the bladder. Acute urinary retention is the sudden inability to urinate, causing pain and discomfort. Causes can include an obstruction in the urinary system, stress, or neurologic problems. Chronic urinary retention refers to the persistent presence of urine left in the bladder after incomplete emptying. Common causes of chronic urinary retention are bladder muscle failure, nerve damage, or obstructions in the urinary tract. Treatment for urinary retention depends on the cause.

Who can help me with a urinary problem?
Your primary doctor can help you with some urinary problems. Your pediatrician may be able to treat some of your child’s urinary problems. But some problems may require the attention of a urologist, a doctor who specializes in treating problems of the urinary system and the male reproductive system. A gynecologist is a doctor who specializes in the female reproductive system and may be able to help with some urinary problems. A urogynecologist is a gynecologist who specializes in the female urinary system. A nephrologist specializes in treating diseases of the kidney.

Points to Remember
• Your urinary system filters waste and extra fluid from your blood.
• Problems in the urinary system include kidney failure, urinary tract infections, kidney stones, prostate enlargement, and bladder control problems.
• Health professionals who treat urinary problems include general practitioners (your primary doctor), pediatricians, urologists, gynecologists, urogynecologists, and nephrologists.

The digestive system is made up of the digestive tract—a series of hollow organs joined in a long, twisting tube from the mouth to the anus—and other organs that help the body break down and absorb food (see figure).

Organs that make up the digestive tract are the mouth, esophagus, stomach, small intestine, large intestine—also called the colon—rectum, and anus. Inside these hollow organs is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food. The digestive tract also contains a layer of smooth muscle that helps break down food and move it along the tract.

Two “solid” digestive organs, the liver and the pancreas, produce digestive juices that reach the intestine through small tubes called ducts. The gallbladder stores the liver’s digestive juices until they are needed in the intestine. Parts of the nervous and circulatory systems also play major roles in the digestive system.

Why is digestion important?
When you eat foods—such as bread, meat, and vegetables—they are not in a form that the body can use as nourishment. Food and drink must be changed into smaller molecules of nutrients before they can be absorbed into the blood and carried to cells throughout the body. Digestion is the process by which food and drink are broken down into their smallest parts so the body can use them to build and nourish cells and to provide energy.

How is food digested?
Digestion involves mixing food with digestive juices, moving it through the digestive tract, and breaking down large molecules of food into smaller molecules. Digestion begins in the mouth, when you chew and swallow, and is completed in the small intestine.

Movement of Food Through the System
The large, hollow organs of the digestive tract contain a layer of muscle that enables their walls to move. The movement of organ walls can propel food and liquid through the system and also can mix the contents within each organ. Food moves from one organ to the next through muscle action called peristalsis. Peristalsis looks like an ocean wave traveling through the muscle. The muscle of the organ contracts to create a narrowing and then propels the narrowed portion slowly down the length of the organ. These waves of narrowing push the food and fluid in front of them through each hollow organ.

The first major muscle movement occurs when food or liquid is swallowed. Although you are able to start swallowing by choice, once the swallow begins, it becomes involuntary and proceeds under the control of the nerves.

Swallowed food is pushed into the esophagus, which connects the throat above with the stomach below. At the junction of the esophagus and stomach, there is a ringlike muscle, called the lower esophageal sphincter, closing the passage between the two organs. As food approaches the closed sphincter, the sphincter relaxes and allows the food to pass through to the stomach.

The stomach has three mechanical tasks. First, it stores the swallowed food and liquid. To do this, the muscle of the upper part of the stomach relaxes to accept large volumes of swallowed material. The second job is to mix up the food, liquid, and digestive juice produced by the stomach. The lower part of the stomach mixes these materials by its muscle action. The third task of the stomach is to empty its contents slowly into the small intestine.

Several factors affect emptying of the stomach, including the kind of food and the degree of muscle action of the emptying stomach and the small intestine. Carbohydrates, for example, spend the least amount of time in the stomach, while protein stays in the stomach longer, and fats the longest. As the food dissolves into the juices from the pancreas, liver, and intestine, the contents of the intestine are mixed and pushed forward to allow further digestion.

Finally, the digested nutrients are absorbed through the intestinal walls and transported throughout the body. The waste products of this process include undigested parts of the food, known as fiber, and older cells that have been shed from the mucosa. These materials are pushed into the colon, where they remain until the feces are expelled by a bowel movement.

Production of Digestive Juices
The digestive glands that act first are in the mouth—the salivary glands. Saliva produced by these glands contains an enzyme that begins to digest the starch from food into smaller molecules. An enzyme is a substance that speeds up chemical reactions in the body.
The next set of digestive glands is in the stomach lining. They produce stomach acid and an enzyme that digests protein. A thick mucus layer coats the mucosa and helps keep the acidic digestive juice from dissolving the tissue of the stomach itself. In most people, the stomach mucosa is able to resist the juice, although food and other tissues of the body cannot.

After the stomach empties the food and juice mixture into the small intestine, the juices of two other digestive organs mix with the food. One of these organs, the pancreas, produces a juice that contains a wide array of enzymes to break down the carbohydrate, fat, and protein in food. Other enzymes that are active in the process come from glands in the wall of the intestine.

The second organ, the liver, produces yet another digestive juice—bile. Bile is stored between meals in the gallbladder. At mealtime, it is squeezed out of the gallbladder, through the bile ducts, and into the intestine to mix with the fat in food. The bile acids dissolve fat into the watery contents of the intestine, much like detergents that dissolve grease from a frying pan. After fat is dissolved, it is digested by enzymes from the pancreas and the lining of the intestine.

Absorption and Transport of Nutrients
Most digested molecules of food, as well as water and minerals, are absorbed through the small intestine. The mucosa of the small intestine contains many folds that are covered with tiny fingerlike projections called villi. In turn, the villi are covered with microscopic projections called microvilli. These structures create a vast surface area through which nutrients can be absorbed. Specialized cells allow absorbed materials to cross the mucosa into the blood, where they are carried off in the bloodstream to other parts of the body for storage or further chemical change. This part of the process varies with different types of nutrients.

Carbohydrates. The Dietary Guidelines for Americans 2005 recommend that 45 to 65 percent of total daily calories be from carbohydrates. Foods rich in carbohydrates include bread, potatoes, dried peas and beans, rice, pasta, fruits, and vegetables. Many of these foods contain both starch and fiber.

The digestible carbohydrates—starch and sugar—are broken into simpler molecules by enzymes in the saliva, in juice produced by the pancreas, and in the lining of the small intestine. Starch is digested in two steps. First, an enzyme in the saliva and pancreatic juice breaks the starch into molecules called maltose. Then an enzyme in the lining of the small intestine splits the maltose into glucose molecules that can be absorbed into the blood. Glucose is carried through the bloodstream to the liver, where it is stored or used to provide energy for the work of the body.

Sugars are digested in one step. An enzyme in the lining of the small intestine digests sucrose, also known as table sugar, into glucose and fructose, which are absorbed through the intestine into the blood. Milk contains another type of sugar, lactose, which is changed into absorbable molecules by another enzyme in the intestinal lining.

Fiber is undigestible and moves through the digestive tract without being broken down by enzymes. Many foods contain both soluble and insoluble fiber. Soluble fiber dissolves easily in water and takes on a soft, gel-like texture in the intestines. Insoluble fiber, on the other hand, passes essentially unchanged through the intestines.

Protein. Foods such as meat, eggs, and beans consist of giant molecules of protein that must be digested by enzymes before they can be used to build and repair body tissues. An enzyme in the juice of the stomach starts the digestion of swallowed protein. Then in the small intestine, several enzymes from the pancreatic juice and the lining of the intestine complete the breakdown of huge protein molecules into small molecules called amino acids. These small molecules can be absorbed through the small intestine into the blood and then be carried to all parts of the body to build the walls and other parts of cells.

Fats. Fat molecules are a rich source of energy for the body. The first step in digestion of a fat such as butter is to dissolve it into the watery content of the intestine. The bile acids produced by the liver dissolve fat into tiny droplets and allow pancreatic and intestinal enzymes to break the large fat molecules into smaller ones. Some of these small molecules are fatty acids and cholesterol. The bile acids combine with the fatty acids and cholesterol and help these molecules move into the cells of the mucosa. In these cells the small molecules are formed back into large ones, most of which pass into vessels called lymphatics near the intestine. These small vessels carry the reformed fat to the veins of the chest, and the blood carries the fat to storage depots in different parts of the body.

Vitamins. Another vital part of food that is absorbed through the small intestine are vitamins. The two types of vitamins are classified by the fluid in which they can be dissolved: water-soluble vitamins (all the B vitamins and vitamin C) and fat-soluble vitamins (vitamins A, D, E, and K). Fat-soluble vitamins are stored in the liver and fatty tissue of the body, whereas water-soluble vitamins are not easily stored and excess amounts are flushed out in the urine.

Water and salt. Most of the material absorbed through the small intestine is water in which salt is dissolved. The salt and water come from the food and liquid you swallow and the juices secreted by the many digestive glands.

How is the digestive process controlled?
Hormone Regulators
The major hormones that control the functions of the digestive system are produced and released by cells in the mucosa of the stomach and small intestine. These hormones are released into the blood of the digestive tract, travel back to the heart and through the arteries, and return to the digestive system where they stimulate digestive juices and cause organ movement.
The main hormones that control digestion are gastrin, secretin, and cholecystokinin (CCK):
• Gastrin causes the stomach to produce an acid for dissolving and digesting some foods. Gastrin is also necessary for normal cell growth in the lining of the stomach, small intestine, and colon.
• Secretin causes the pancreas to send out a digestive juice that is rich in bicarbonate. The bicarbonate helps neutralize the acidic stomach contents as they enter the small intestine. Secretin also stimulates the stomach to produce pepsin, an enzyme that digests protein, and stimulates the liver to produce bile.
• CCK causes the pancreas to produce the enzymes of pancreatic juice, and causes the gallbladder to empty. It also promotes normal cell growth of the pancreas.

Additional hormones in the digestive system regulate appetite:
• Ghrelin is produced in the stomach and upper intestine in the absence of food in the digestive system and stimulates appetite.
• Peptide YY is produced in the digestive tract in response to a meal in the system and inhibits appetite.

Both of these hormones work on the brain to help regulate the intake of food for energy. Researchers are studying other hormones that may play a part in inhibiting appetite, including glucagon-like peptide-1 (GPL-1), oxyntomodulin (+ ), and pancreatic polypeptide.

Nerve Regulators
Two types of nerves help control the action of the digestive system.
Extrinsic, or outside, nerves come to the digestive organs from the brain or the spinal cord. They release two chemicals, acetylcholine and adrenaline. Acetylcholine causes the muscle layer of the digestive organs to squeeze with more force and increase the “push” of food and juice through the digestive tract. It also causes the stomach and pancreas to produce more digestive juice. Adrenaline has the opposite effect. It relaxes the muscle of the stomach and intestine and decreases the flow of blood to these organs, slowing or stopping digestion.

The intrinsic, or inside, nerves make up a very dense network embedded in the walls of the esophagus, stomach, small intestine, and colon. The intrinsic nerves are triggered to act when the walls of the hollow organs are stretched by food. They release many different substances that speed up or delay the movement of food and the production of juices by the digestive organs.
Together, nerves, hormones, the blood, and the organs of the digestive system conduct the complex tasks of digesting and absorbing nutrients from the foods and liquids you consume each day.

The lymphatic system is a network of tubes throughout the body that drains fluid (called lymph) from tissues and empties it back into the bloodstream. The main roles of the lymphatic system include managing the fluid levels in the body, filtering out bacteria, and housing types of white blood cells. Lymph is filtered through the spleen, thymus and lymph nodes before being emptied into the blood.



Keeping a balance of fluid
Blood vessels tend to seep fluid into surrounding tissue. The lymphatic system drains off any extra fluid to stop the tissues from puffing up. The feet in particular are prone to puffiness.

Lymphatic vessels
Lymphatic vessels criss-cross the entire body, except for the central nervous system. Some lymphatic vessels have valves (similar to the valves in veins), which stop the lymph from running back the wrong way.

Spleen
The spleen is inside the abdomen, just under the diaphragm. This is one of the filtering organs of the blood. As well as removing microbes, the spleen also destroys old or damaged red blood cells.

Thymus
The thymus is inside the ribcage, just behind the breastbone. This is another filtering organ of the blood, that contains many white blood cells called lymphocytes.

Lymph nodes
Lymph nodes are found at various points around the body, including the throat, armpits, chest, abdomen and groin. All lie close to arteries. Bacteria picked up from the tissues by the lymph are trapped in the lymph node. White blood cells called lymphocytes can then attack and kill the bacteria. This is why your lymph nodes tend to swell if you have an infection. Viruses and cancer cells are also trapped by lymph nodes.

Common problems
Some common problems of the lymphatic system include:
• Glandular fever - symptoms include tender lymph nodes
• Hodgkin’s disease - a type of cancer of the lymphatic system
• Oedema - swelling caused by too much fluid in the tissues
• Tonsillitis - infection of the tonsils in the throat.

Things to remember
• The lymphatic system maintains fluid levels in the body.
• Bacteria and other microbes are taken up by the lymph and delivered to the lymph nodes for destruction.
• The spleen and thymus are organs that filter the blood.

The cardiovascular system is sometimes called the blood-vascular or simply the circulatory system. It consists of the heart, which is a muscular pumping device, and a closed system of vessels called arteries, veins, and capillaries. As the name implies, blood contained in the circulatory system is pumped by the heart around a closed circle or circuit of vessels as it passes again and again through the various "circulations" of the body.



As in the adult, survival of the developing embryo depends on the circulation of blood to maintain homeostasis and a favorable cellular environment. In response to this need, the cardiovascular system makes its appearance early in development and reaches a functional state long before any other major organ system. Incredible as it seems, the primitive heart begins to beat regularly early in the fourth week following fertilization.

The vital role of the cardiovascular system in maintaining homeostasis depends on the continuous and controlled movement of blood through the thousands of miles of capillaries that permeate every tissue and reach every cell in the body. It is in the microscopic capillaries that blood performs its ultimate transport function. Nutrients and other essential materials pass from capillary blood into fluids surrounding the cells as waste products are removed.

Numerous control mechanisms help to regulate and integrate the diverse functions and component parts of the cardiovascular system in order to supply blood to specific body areas according to need. These mechanisms ensure a constant internal environment surrounding each body cell regardless of differing demands for nutrients or production of waste products.