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The health of human beings is fundamental in ensuring that their bodies perform all their functions in the right way. Nutrition can be described as the supply of food materials to the body cells to keep them alive as well as how the body uses these nutrients. All human body parts play a specific role in the complex functions of the body. It is, hence, important that we take nutritious and balanced diets to enhance our body health. Food nutrients can be categorized into Macronutrients and micronutrients. The Macronutrients are needed in relatively larger amounts than the micronutrients (Grossi, et al., 2016, p. 214). Good nutrition and a balanced diet is the building block for body muscles, energy, fitness and immunity to diseases. Water is also a major body requirement and should not be substituted for soft drinks or sugary drinks.
Macronutrients provide energy to the human body. The three macronutrients are proteins, fats and carbohydrates which benefit our bodies differently (Mathias, 2016, p. 132). The three are needed in large amounts and assist the human body in maintaining the body functions and enabling the daily life activities. A well-balanced diet of the three macronutrients requires that 55 percent of the plate are carbohydrates, 30 percent are fats and 15 percent are proteins (Denzel, et al., 2016, p. 87).
Carbohydrates are recommended to take up the greater percentage of food intake. They are easily metabolized or rather broken down into glucose in the body and used as the body’s main source of fuel. The glucose is then easily absorbed by the body tissues (Langley-Evans, 2015). This then makes it easy for the other macronutrients to be used in the repair and growth of tissues. Internal body parts that heavily rely on energy from the carbohydrates to function effectively include the brain, kidneys, muscles and the heart. Carbohydrates also aid in the synthesis of a number of amino acids and the metabolisms of fats. Carbohydrates are found in foods rich in starch such as grains, potatoes, some fruits, and milk. It is also available in lesser quantities in foods such as vegetables, nuts, cheese, and seeds. They can have either simple or complex chemical structures, whereby the simple structured are sweet while the complex one’s taste savory (Insel, et al., 2015, p. 343). Fiber is also an indigestible type of carbohydrate which helps in the digestion system and excretion of waste from our bodies. Foods rich in fiber include fruits, vegetables, and whole grains. They decrease the risks of obesity, cholesterol related problems and heart issues (Farooqui, 2015, p. 238).
The recommended fraction of proteins in any meal taken ranges between 10% - 35%. Proteins play a vital role in the making of cells constituting 50 percent of the dry weight. This means that the human body is largely made from proteins. Proteins also help in the production of new tissues, repairing the ailing ones, as well as maintaining the daily body functions. They also make enzymes that catalyze digestion and other activities as well as support the essential hormones that regulate the body activities. In cases where carbohydrates are not available, they can also be used as a source of energy. Proteins are broken down to amino acids. 21 amino acids are needed by the human body and nine of them are essential since they cannot be produced by the body. Proteins containing the nine essential amino acids are categorized as high-quality proteins and can be found in animal products. Those without the nine amino acids are low quality and are found in plant sources such as legumes plants (Moran & Lowe, 2017).
People have a misconception that fat is harmful or always bad in the human body. However, as a matter of fact, fat is important in enhancing a healthy body. It is recommended that a person’s diet should have between 20 to 30% of fat. There are good fats and bad fat. Examples of bad fats include high-fat meats and sweets while good fat includes nuts, avocados and plants extracted oils (Coulston, et al., 2017, p. 76). Fat plays an essential role in keeping the body warm through insulation and cushioning body organs to maintain body temperature. It enhances the growth, development, and maintenance of cell membranes. It also lubricates a person’s joints and muscles keeping them loose and flexible as well as assisting in the absorption of certain fat-soluble vitamins such as vitamins A, D, E, and K (Gropper, et al., 2017, p. 210).
Unlike the macronutrients, these are required in smaller quantities but are still essential to the proper functioning of the body system for good health. Micronutrients are Minerals and vitamins (Denzel, et al., 2016, p. 251). Minerals help in fastening chemical reactions in the body. Sodium, for instance, ensures the proper functioning of cells as well as maintaining water volume outside them. Potassium maintains fluid volume inside the cells. Calcium strengthens bones and teeth.
There is a wide variety of vitamins, categorized as fat soluble and water soluble. Vitamins are important for the functioning, development, and growth of the cell. Fat-soluble vitamins are vitamin A, D, E, and K. water-soluble vitamins are vitamin C, B-1, B-2, B-3, B-5, B-7, B-6, and B-12. Each vitamin plays a different role from the other. Poor or lack of vitamins intake may lead to health problems. Vitamins rich food includes fruits, vegetables, beans, lentils and fortified foods. Vitamin D is produced by the body after basking in the sun for a considerable duration (Mann & Truswell, 2012, p. 45).
All the above nutrients cannot be produced in the body and are crucial for the development of the body as well as prevention of diseases. Nutritional deficiency risks the body to diseases and health problems. This is when the body cannot absorb or get the required amount of nutrients (Fitzgerald, 2014, p. 256). Some of the consequences of nutritional deficiencies include anemia, which is a blood disorder caused by iron deficiency. Deficiency of Vitamin A causes poor eye health and functioning. Lack of iodine affects the production and functioning of thyroid hormones (Insel, et al., 2016, p. 99). Deficiency of vitamin D and calcium causes muscle weakness, weak bones, poor growth or soft bones in children, and also increases the risk of cancer. Deficiency of vitamin B-12 may lead to megaloblastic anemia, and impaired brain functioning. Vitamin B-5 and B-12 improve a person’s immunity and the nervous system. Their deficiency may lead to numbness, and exaggerated reflexes (Farooqui, 2015, p. 85).
Malnutrition is a condition in both children and adults brought about by insufficient intake, absorption and utilization of nutrients in the human body (Langley-Evans, 2015, p. 201). The two major forms of malnutrition are Protein-energy malnutrition and micronutrient deficiency diseases.
This type of malnutrition is brought about by the lack of glucose and proteins in an individual’s food. It is more prevalent in areas affected by hunger and can be lethal if it prolongs. This is because all body parts require chemical energy gotten from both carbohydrates and proteins to function properly (Farooqui, 2015, p. 97). In children, this form of malnutrition can be categorized into three types. The first is acute malnutrition which is characterized by rapid wasting, thinness, and failure to gain weight in the normal way. The second is chronic malnutrition which is characterized by stunted growth or failure to gain height. The third is Acute and chronic malnutrition which is characterized by the child being underweight (Bose, 2013, p. 100). Acute malnutrition in children can lead to diseases such as marasmus, and Kwashiorkor. Abnormalities caused by the protein-energy malnutrition can be reversed through nutritional therapy but if the effects have been prolonged they can lead irreversible body and organs changes (Denzel, et al., 2016). Adults too can develop extreme wasting and oedema but cannot have stunted growth.
Micronutrient deficiency diseases.
This type of malnutrition is brought about by severe lack of vitamins and minerals that are of utmost necessity in the efficiency of various body processes. These nutrients include iron, iodine, vitamin D, selenium, zinc, iodine, folate, calcium, vitamins A, B, C, D. This form of malnutrition is more common and of great concern developing countries. Zinc deficiency leads to sensory perception and poor immunity. Folate deficiency leads to slow growth. Lack of vitamin B-12 causes nerve degeneration and poor red blood cells formation. Deficiency of vitamin A causes poor vision and bone development. Lack of vitamin D causes bone development disorders and rickets. Deficiency of selenium weakens immunity and affects cardiac functions. Finally, deficiency of iron causes anemia and poor brain development (Gropper, et al., 2017, p. 253).
(b) Anatomy and the physiology of the human digestive system
The human digestive system is complex and is uniquely made to convert food ingested into nutrients that can be absorbed by the body cells and organs. The absorbed nutrients are then used for energy, cell growth, and the repairs of damaged tissues and cells. It is consistent with the digestive tract where food passes through as its processed and absorbed into the bloodstream while waste materials are eliminated from the body. It starts at the lips and ends at the anus.
The Mouth and Esophagus
Food is ingested through the mouth and hence this marks the start of the digestion process. It consists of teeth, salivary glands, and the tongue. The mouth also has taste buds that help to give the vital perception of harmful or rotten food. Upon ingestion, food is processed through the process of mastication and mixing it with saliva. The saliva has enzymes called amylase which aid in the breaking down of carbohydrates. Mastication is the breaking down of large food particles to smaller particles which are then lubricated by saliva to form a bolus or a ball of food easy to swallow (Brett, 2015, p. 105). The bolus is then swallowed with the aid of the tongue through the throat to the esophagus. The esophagus is a muscular tube running from the throat to the stomach. It delivers food to the stomach through muscular contractions called peristalsis. At its end, it has a valve called “lower esophageal sphincter” which is a high-pressure zone that restricts the backward flow of food from the stomach.
The stomach is a hollow muscular sack that holds food for several hours as it is mixed with enzymes aiding the food breakdown. It is located between the esophagus and the small intestines. Rhythmical contractions of the stomach muscles aid in the churning of the food particles to even smaller bits that are more digestible in the intestines (Brett, 2015, p. 132). Its walls secrete acids and enzymes that speed up digestion. Enzyme pepsin enables the digestion of proteins. Other enzymes include gelatinase, lipase and gastric amylase alongside gastric acid and hydrochloric acid. The cells located in the stomach are; mucous cells, parietal cells that secrete hydrochloric acid, Chief cells that produce pepsin and G cells that produce gastrin which aids the secretion of HCl acid. The stomach also protects itself from corrosion by the acids through a layer of mucus on its walls (Mason, 2015, p. 87). The stomach than releases the food into the duodenum.
The small intestine
The small intestines are made up of the duodenum, jejunum and the ileum. The small intestines have more enzymes which are produced by the pancreas, bile from the liver and glands located on the intestines walls which further aid the breakdown of proteins and starch (Marieb, 2015). Peristalsis also occurs here, aiding the movement of food as they mixed with the digestive juices. Most of the digestion in the small intestines takes part in the Duodenum while absorption of nutrients into the blood and other cells is handled by the ileum and jejunum (Green, et al., 2014, p. 432). As soon as food passes to the duodenum, pancreatic enzymes are released to digest protein, fat, and starch. Bile is also released from the liver by the gallbladder to help in fat digestion to form absorbable nutrients.
The jejunum and the ileum aid in the absorption of carbohydrates, proteins, and fat into the bloodstream. The jejunum is the middle section and is about 3 to 6 feet. The ileum is the last part and is about 6 feet long This is facilitated by finger-like projections on the small intestine walls called villi and microvilli that provide an increased surface area to maximize absorption (Midthun, 2014, p. 148). 90% of all ingested food nutrients are absorbed in the small intestines. Most water-soluble vitamins are absorbed in the ileum the villi contain numerous tiny capillaries and lymphatic vessels that transport the nutrients to the blood supply, and liver through the hepatic portal vein (Widmaier, et al., 2014, p. 201). In the small intestines, Proteins and peptides are converted into amino acids, lipids are converted to fatty acids and glycerol while Carbohydrates are converted to monosaccharides or simple sugars such as glucose and fructose (Widmaier, et al., 2014). The nutrients in the blood supply are distributed to all body parts while those in the liver are stored or converted into energy. The residue, which is in liquid form is then passed to the large intestines.
The Large Intestine (Colon)
The large intestine is a tube estimated to be 6 feet. It connects the small intestine to the rectum. The colon is made up of the cecum, the ascending colon, transverse, descending colon and rectum. It is shorter and thicker than the small intestine. The colon, being the final section of the tract absorbs water, and vitamins making the residue solid. The water absorption allows the retention of the utilized water in the metabolism as well as absorbing ions dissolved in the water. It also helps in transmitting the remaining indigestible food from the body as feces (Leung, 2014).
The colon is also home to commensal bacteria or rather gut bacteria that aids in the absorption of vitamins. They break down the undigested fibers and polysaccharides to form short-chain fatty acids which are then absorbed through passive diffusion. These bacteria also aid in the formation of vitamin K and Biotin especially when the vitamin intake from the ingested food is low. The mucosa layer of the colon also produces bicarbonates that neutralize acidity hence giving a conducive environment for the production of the fatty acids and other digestive components (Leung, 2014, p. 104). The lymphoid tissues in the large intestines also play a role in the forming of antibodies and cross-reactive antibodies that aid the immunity and prevent infections (Ogden, 2017). The solid feces are then stored in the rectum and eliminated through the anus in a process called defecation. The anal sphincter muscles control the bowel movements by holding or releasing stool.
The energy required for human beings to conduct their daily life activities is derived from the food we consume. From the above analysis, our health is determined by the ratio of the macronutrients, micronutrients and water intake that constitute our diet. All the dietary portions are important and should never be ignored. The deficiency of any dietary requirements can easily lead to diseases, and malnourishment since the body processes and immunity highly depend on nutrients absorbed in our cells and muscles. The digestive system, on the other hand, is a complex tract that enables the ingestion, digestion, and absorption of nutrients in the bloodstream for storage or usage for the normal body functioning. Enzymes, saliva, mucus, and acids constitute some of the main catalysts of digestion while villi and capillaries aid in absorption. The Pancreas, liver and gallbladder can be called accessory organs of the digestive process for their role in the production of enzymes and bile of the While treatment can be an expensive affair, prevention can save us money and time by staying healthy.
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