The human body is made up of many (millions) of cells. Cells' most basic needs are energy, oxygen and water in which to maintain their (cells) environment in the body. The very first principle of planning diet is that the food selected must first provide energy, water, and essential nutrients. In our bodies, cells work together in unity with each other in order to support the whole. The cells genes, decide the nature of the work to be done, hence the genes are the blueprint that directs the production of enzymes which help to do the cell's work.
Cells are then organised into tissues that perform their specific task. An example can be made of muscle cells which join together to form muscle tissue which can contract and relax. Tissues then group together to form organs like the heart, kidneys etc. in the heart for example, muscle tissues, nerve tissues, connective tissues as well as other types of tissues work together to pump blood.
Body fluids supply the tissues continuosly with the necessary energy, oxygen, water and building materials. The fluids always circulate to pick up fresh supplies and deliver wastes to their point of disposal. The body's main fluids are the blood and the lymph. The blood travels in the arteries, veins and capillaries and also in the chambers (rooms) of the heart. As the blood travels through the cardiovascular (heart) system, it delivers all the necessary materials that cells need and picks up the wastes. The blood picks up oxygen in the lungs and also releases carbon dioxide there. The blood circulates to the lungs and then returns to the heart where it receives a powerful “push” out to all the body tissues.
As it passes through the digestive system, the blood delivers oxygen to the cells there, and picks up most nutrients from the intestine for distribution elsewhere. Lymphatic vessels on the other hand pick up most fats from the intestine and transport them to the blood. All the blood leaving the digestive system is destined to the liver, which then chemically changes the absorbed materials to make them better suited for use by other tissues. Later in passing through the kidneys, the blood is cleaned from wastes which are excreted via urine.
This process simply means that we must drink enough water in order to replace the water lost each day. Cardiovascular fitness is also important. Healthy red blood cells also play an important role in carrying oxygen to all the other cells, enabling them to use fuels for energy. Since red blood cells arise, live and die within four months, the body replaces them constantly, a manufacturing process that requires many essential nutrients from food. Medical science hence concludes that many blood disorders are caused by dietary deficiencies or an imbalance in vitamins or minerals; the blood is very sensitive to malnutrition.
In addition to nutrients, oxygen and wastes, the blood carries chemical messengers called hormones and these are taken from one system of cells to another. Hormones communicate changing conditions that demand responses from the organs of the body. Hormones are released into the blood by the help of glands. Example when the pancreas detects that there's a high concentration of the bloods sugar (glucose), it releases a hormone called insulin. Insulin stimulates muscle and other cells to remove glucose from the blood and store it. When the blood glucose level falls, the pancreas secretes another hormone (glucagon) to which the liver responds by releasing into the blood some of the glucose it stored earlier. Thus normal glucose levels are maintained.
Nutrition affects the hormonal system. People who become extremely thin have an altered hormonal balance that may make them unable to maintain their bones. People who eat high fat diets on the other hand have hormone levels that may make them susceptible to certain cancers. Hormones also affect nutrition, along with the nervous system, they regulate hunger and affect appetite. They carry messages to regulate the digestive system, telling the digestive organs what kinds of food has been eaten as well as how much digestive juice to secrete.
Hormones also regulate the menstrual cycle in women and they affect the appetite change which is often experienced during the cycle and during pregnancy. An altered hormonal state is thought to be partly responsible for the lack of appetite sick people experience. They also regulate the body's reaction to stress, suppressing hunger and the digestion and absorption of nutrients. Thus it is that a person's nutrition plays an important role in their hormonal state.
The body's other major communication system is, the nervous system. With the brain and spinal cord as the central controllers, the nervous system receives and integrates information from the sensory receptors all over the body- sight, hearing, touch smell, taste, and others. Which communicate to the brain the state of both the outer and the inner worlds, including the availability of food and the need to eat. The nervous system also sends instructions to the muscles and glands, telling them what to do.
The nervous system's role in hunger regulation is coordinated by the brain. The sensations of hunger and appetite are perceived by the brain's regulatory work, this goes on deep inside the brain centers without the person's (or cortex's) awareness. Deep inside the brain, the hypothalamus monitors many body conditions including the availability of nutrients and water.
The digestive tract sends messages to the hypothalamus by way of hormones and nerves that signal hunger, which also stimulates the stomach to intensify its contractions and secretions thus making gurgling sounds. When the conscious mind of the cortex becomes conscious of hunger, you decide to eat. However; the cortex can override such signals and allow a person to choose to delay eating despite hunger or to eat when hunger is absent.
The hormonal and nervous systems often work together to respond to physical danger known as the stress response or the fight- or -flight reaction. All the organs of the body respond with amazing speed and depending on the type of stress, e.g. If while walking on bare feet you accidentally step on a thorn, the first impulse would be to jump and scream. The heart races to rush the oxygen to the muscles and the blood pressure rises to deliver efficiently the fuel the muscles need for energy. The liver pours glucose from its stores, while the fat cells release fat. The digestive system shuts down to permit all the body's systems to serve the muscles and nerves.
Our number one enemy in modern society is hence not a “saber tooth tiger prowling outside our homes” but a disease called atheriosclerosis. When years of fat have accumulated in the arteries and stresses that strain the heart occur, combined with sudden high blood pressure, a heart attack follows or a stroke which is dibilitating (weakens the body/organs) and even lethal (causing death). Daily exercise as part of a healthy lifestyle releases piled-up stress and strengthens the heart's defense against atheriosclerosis.
The digestive tract, moves food through its various processing chambers by mechanical means. The mechanical actions include breaking down, mixing by the stomach, adding fluid and moving the tract's contents by peristalsis. After digestion and absorption, wastes are excreted. Chemical digestion begins in the mouth where the food is mixed with an enzyme in the saliva that acts on carbohydrates. Digestion continues in the small intestine, where the liver and gallbladder contribute bile that converts fat and where the pancreas and small intestine donates enzymes that continue digestion so that absorption can occur.
A letter from your digestive tract:
To My Owner,
You and I are so close; I hope that I can speak frankly without offending you. I know that sometimes I do offend, with gurgling noises and belching at quiet times and oh yes, the gas. But please understand that when you chew gum, drink carbonated drinks or eat hastily, you gulp air with each swallow. I can't help making noise as I move the air along my length or release it upward in a noisy belch. And if you eat or drink too fast, I can't help getting hiccups. Please sit and relax while you dine. You will ease my task and we'll both be happier.
When someone offers you a new food, you gobble it away, trusting me to do my job. I try, it would make my life easier and yours less gassy, if you would start with small amounts of new foods especially those high in fiber. The bacteria that break down fiber, produce gas in the process. I can handle just about anything if you introduce it slowly. But please: if you do notice more gas than normal from a specific food, avoid it. If the gas becomes excessive, check with a physician- the problem could be something simple or it could be serious.
When you eat or drink too much, it just burns me up. Overeating causes heartburn because acid juice from my stomach backs up into my esophagus. Acid poses no problem to my healthy stomach, whose walls are coated with thick mucus to protect them. But when my too-full stomach squeezes some of the contents back up into the esophagus, the acid burns its unprotected surface. Oh and those tight jeans you wear constrict my stomach, squeezing the contents upward into the esophagus. Just leaning over or lying down after a meal may allow the acid to escape up the esophagus because the muscular closure separating the two spaces is much looser than other such muscles.
When heartburn is a problem, do me a favour and try to eat smaller meals; drink liquids 30 minutes before a meal and 2 hours after a meal, but never during meals; wear reasonably loose clothing; and relax after eating, but sit up (don't lie down) rather take a walk. Sometimes your food choices irritate me. Specifically chemical irritants in foods such as the “hot” chilli peppers, black peppers (spices), chemicals in coffee, fat, chocolate and alcohol.
By the way, I can tell you've been taking heartburn medicines again. You must have been watching those TV commercials and letting them mislead you. You need to know that antacids are designed only to temporarily relieve pain from conditions such as heartburn and ulcers, while antibiotics and other medications help heal ulcers. But in my case, the antacids trigger my stomach, which is normal, to produce more acid. That's because when my normal stomach acidity is reduced, I respond by producing more acid to restore the normal acid condition. And the ingredients in the antacids can interfere with my ability to absorb nutrients.
Please don't take acid reducers and acid controllers for my sake; these reduce my acid so much that my job of digesting becomes much harder. In fact, the drugs can cause indigestion and diarrhea. Thay can also mask the symptoms of a hernia or an ulcer. A hernia can cause food back up in the esophagus, and so feels like heartburn. Ulcer pain can be temporariy received by acid reducers and controllers. Treating only the symptoms of a hernia or an ulcer can delay its diagnosis and cure, I suggest you acsertain the cause.
When you eat too quickly, I worry about choking. Please take time to cut your food into small pieces, and chew it until it is crushed and moistened with saliva. Also refrain from talking or laughing before swallowing, and never attempt to eat when you are breathing hard. When I'm suffering, you suffer too. When constipation and diarrhea strike, neither of us is having fun. Slow, hard, dry bowel movements can be painful, and failing to have a movement for too long brings on headaches and ill feelings. Listen carefully for my signal that it is time to visit the “little room” and make time for it, even if you are busy. The longer you ignore my signal, the more time the colon has to extract water from the feces, thus hardening them.
Please choose foods that provide enough fiber. Fiber attracts water, creating softer, bulkier stools that stimulate my muscles to contract, pushing the contents along. Fiber helps my muscles to stay fit, too, making elimination easier. Be sure to drink enough water, because dehydration causes the colon to absorb all the water it can get from the feces. And please work out regularly; exercise strengthens not just the muscles of your arms, legs and torso, but those of the colon too. When I have the opposite problem, diarrhea, my system will rob you of water and salts. In diarrhea my intestinal contents have moved too quickly drawing water and minerals from the tissues into the contents. When this happens, please rest a while and drink fluids.
I'm willing to work with you, thank you for listening. I know we'll both benefit from communicating like this, since we're in this together.
Your Digestive Tract