The 4 macromolecules of life are all found in the foods that we eat.
Carbohydrates = simple sugars + simple sugars
Carbohydrates are the body's main source of energy. These can be found in sugars and starches.
A carbohydrate molecule is converted into glucose and used to make ATP (energy). Excess glucose that is not used for energy will turn into fat and be stored in the body.
Lipids = Fatty acids + fatty acids
Lipids are concentrated energy sources. They provide twice as much energy as a carbohydrate.
Proteins = amino acids + amino acids
Proteins are the major building block of tissue in the body. Your body is made up of hundreds of different types of proteins such as:
collagen = strength & support in connective tissue
keratin = make hair and skin waterproof
enzymes = speed up chemical reactions
Vegetarians must be careful to monitor their diets because they do not get all of the essential amino acids. Vegetarians must balance out their diets with beans, nuts, and grains which are rich in proteins.
Nucleic Acids = nucleotides (adenine, guanine, thymine, and cytosine) The building blocks of DNA.
All cells contain a nucleus with DNA. The cells that are eaten are recycled within the body.
Vitamins are essential to our diets to help activate enzymes. There are 2 classes of vitamins:
1. fat-soluable = dissolves in fat. Needed in low doses.(vitamins A,D,E, K)
2. water-soluable = dissolves in water and is excreted with urine.(vitamin C and the B vitamins)
Minerals are inorganic compounds for growth and maintenance of body structures. Some examples are calcium, iodine, iron, phosphorous, potassium, and sodium.
Many digestive enzymes are used to help breakdown food so that the blood can absorb the nutrients and transport them to the cells of the body. Food that is not broken down, exit the body as feces. Nutrients that are used up by cells are excreted via the urinary system. So why is urine liquid?
Digestion begins with the addition of saliva and chewing. Both breakdown food. The roof of your mouth has a hard & a soft palateThe uvula are often mistaken for the tonsils. But it prevents food & drink from going up into the nose. The tongue is skeletal muscle. Holding it to the bottom of your mouth is the frenulum.
You have 4 types of adult teeth for mastication (chewing).
Incisors = 8 front teeth to tear food
Canines (cuspids) = 4 sharp teeth used to tear food
Premolars (bicuspids) = 8 flat teeth for grinding
Molars (tricuspids) = 12 back teeth, flat for grinding last 4 are wisdom teeth which grow in at early adulthood. We probably evolved this to replace lost teeth.
Teeth chew bites of food into a ball called a bolus. The bolus is swallowed down the pharynx. Is the epiglottis dilated or contracted? The bolus then proceeds down the esophagus. Why can you stand on your head and still swallow food up into your stomach?
The esophagus has muscles which push food by peristalsis. Food then enters the stomach where hydrochloric acid break down food particles into a liquid called chyme. Throwing up will bring this acid up and out of the body and can eat away at the cells of the pharynx and esophagus. So why doesn‘t the stomach get eroded away by the acid?
The sensation of being full after a meal is the stretchy tissue expanding
The wall of the digestive tract is made of smooth muscle. The wall has 4 layers:
1 mucosa = coats the canal and aids in absorption & secretion
2 submucosa = connective tissue with blood vessels & nerves
3 muscularis = peristalsis contractions to move food
4 serosa = outermost covering. Keeps the intestines anchored to the abdominal cavity
The lumen is the space food travels in.
As chyme leaves the stomach, it enters the duodenum; the beginning of the small intestine.
The jejunum comes next. It contains microvilli which act like millions of little fingers that absorb nutrients from the chyme. Blood vessels absorb the nutrients here.
The last of the small intestine is called the ileum. It exits into the large intestine.
The water from the chyme is reabsorbed and the chyme becomes feces. E.coli grows in the large intestine and makes vitamin K for the body to help make blood.
There are several different enzymes to break down specific types of food:
Amylase is in saliva and breaks down carbohydrates
Amylase is also found in the pancreas to break down starch into maltose
Pepsin is in the stomach and breaks down proteins
3 main enzymes of the intestines that break down carbohydrates:
Sucrase breaks down sucrose (white and brown sugar)
Lactase breaks down lactose a sugar in milk. Some people lack this and are lactose-intolerant.
Maltase further breaks down maltose
In addition to amylase, the pancreas has protease to break down protein. And lipase to digest fats.
Disorders of the mouth
Cavities result from food accumulating in the teeth and feeds acid-secreting bacteria and plaque.
Gingivitis is inflammation & infection of the gums. Proper brushing & flossing will help to rid of bacteria that causes this.
Periodontitis is an infection of the membrane that anchors the tooth into the gums. This can result from gingivitis and lead to tooth loss.
Cancer can result from smoking or chewing tobacco. Cancer can also form on the lips from sun exposure.
Disorders of the Stomach, liver, pancreas, & small intestine
Acid reflux is the HCl in the stomach coming back up the esophagus.
Ulcers can result from acid reflux eating away the cells of the esophagus. There has been a bacteria H. pylori that causes ulcers too.
Gastroenteritis is swelling of the stomach and may swell in the small intestines from bacteria or irritants like acid.
Gall stones (calculi) is when crystals form in the bile from the gall bladder. These crystals can block the bile duct and prevent bile from mixing with the chyme.
Jaundice is the yellowing of skin and eyes from blood absorbing bile.
Hepatitis is the inflammation of the liver from a virus. Hepatitis A can result from contaminated food. Hepatitis B is easily transmittable through body fluids. Symptoms include fatigue, nausea, joint pain, and a loss of appetite.
Cirrhosis of the liver is cancer and can result from years of alcohol abuse.
Diabetes is the imbalance of sugar in the body. Type I or Diabetes Mellitus is the pancreas not producing insulin. Insulin allows cells to absorb sugar. Type II or Diabetes Insipidus is from eating an unhealthy diet of sugary foods. They often urinate 25 - 30 liters a day. They are thirsty, dehydrated, or have an electrolyte imbalance. A strict diet without a lot of sugar must be maintained.
Stomach stapling is shrinking of the stomach to decrease appetite.
Appendicitis is the rupture of the appendix that can let harmful material enter other organs of the body.
Lisa Sasson, of New York University's Department of Nutrition, Food Studies, and Public Health, says you can achieve successful weight loss by choosing the right foods and taking it slowly. The ideal program is a gradual weight loss of one to two pounds per week. How many calories is that? Sasson says multiplying 10 times your current weight will give you an idea of the number of calories you need for slow, proper weight loss, unless you are severely overweight. Someone who weighs 128 pounds should eat no less than 1200 to 1300 calories per day. Below that, your metabolic rate drops, and you lose water rather than fat.
Sasson says the key to weight loss is a balanced approach. Eat when you're hungry and vary what you eat so you don't get bored. Make sure you include foods from all the major food groups. Have three healthy meals and a few planned snacks, and watch your portions. Choose foods that are easy to find and prepare. Fruits, vegetables, and whole grains will fill you up with fewer calories. Eat slowly and stop when you start to feel full. Drink plenty of water throughout the day and with meals. And finally, allow yourself an occasional treat.
Having the right midmorning snack will keep your metabolism humming and your energy levels up, and will help you avoid eating too much at lunch out of extreme hunger. A medium nectarine along with some almonds gives you fiber, protein, a variety of vitamins and minerals, and heart-healthy fat
