Discussing the Components of Vitamin D (Research Paper Sample)

Vitamin D
Name
Institution

Introduction
For a human body to function normally, there are numerous nutrients and processes needed to make sure this happens. Most of these processes take place in the stomach. Some of these processes are mechanical and chemical food breakdown, absorption, and excretion. Proteins, carbohydrates, and vitamins are examples of body requirements that undergo the mentioned processes to ensure the body remains healthy. Vitamins play a critical role in ensuring this and, more so, vitamin D.
Vitamin D
Scientifically known as calciferol, vitamin D is a fat-soluble vitamin. It can occur naturally in certain foods such as sardines, shrimp, eggs, salmon, etc., or be produced by the body when exposed to the sun, thus its popular name, the ‘sunshine vitamin’ (Bikle, 2014). This vitamin is of great importance to the body as it helps to build strong bones and teeth by helping in the absorption of calcium and phosphorous, it keeps insulin levels in check, thus preventing diabetes type 1, it helps in brain and nerve system development, it helps the heart and lungs to function well, and it boosts the immune system It is clear how vital vitamin Dis to the body, and its absence can lead to serious health issues.
Vitamin D structure and forms
Vitamin D is a type of lipid existing in various forms, all of which are secosteroidstaking the structural form of steroids except steroids have closed B rings while secosteroids have open B rings (Bikle, 2014).
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Figure 1:vitamin D structure
It exists in the following forms;
* Pre-vitamin D3- Also known as or 7- dehydrocholesterol. It is created by cholesterol and is inactive biologically.
* Vitamin D3- also known as cholecalciferol or inactivated 7- dehydrocholesterol. It is created by the skin when exposed to UV rays.
* Vitamin D2- also known as ergocholecalciferol. It comes from plants.
* 25 hydroxyvitaminD- also known as calcidiol. It comes from hydroxylated D3 in the liver. It inactivates receptors and is used to indicate a vitamin deficiency.
* 1,25dihydroxyvitaminD- it comes from hydroxylated 25-D. It helps in activating the nuclear receptors of vitamin D.
Vitamin D receptors (mVDR, nVDR)
Receptors can be defined as proteins that facilitate the joining of signaling ligands to produce a chemical reaction that leads to cell growth, division, or death. Vitamin D has several receptors, which include mVDR and nVDR.The nVDR activates the nuclear receptors of vitamin D and regulates the creation of its responsive genes. The mVDR activates a non-genomic signal transmission route in specific cells.
Vitamin D signaling pathway
The signaling pathway can be defined as changes caused by a ligand fusing in a receptor leading to a chain of biochemical processes such as cell division, growth, or death. During this process, after one molecule receives the signal, it activates the next molecule, and this process repeats itself until all the molecules are activated.Vitamin D in the form of D2 and D3 is inactive, and it undergoes two signaling hydroxylation processes to become active. Seven dehydrocholesterol from the sun is converted to previtamin D3, and vitamin D2 obtained from food is stored in the liver. They are reacted upon by 25 hydroxylases to form 25 hydroxyvitamin D. The second reaction occurs in the kidneys where 1α-hydroxylase reacts on 25 hydroxyvitamin D to form 1,25 dihydroxyvitamin D.
The role of vitamin D in cell division
This vitamin affects various cellular processes such as apoptosis, differentiation, and proliferation. In the cell cycle, this vitamin is known to stop cell growth at the G0-G1phase. It also decreases cyclin D1 and D3 in breast cancer cells. It also controls the differentiation of many malignant as well as normal cells. For example, 1,25 dihydroxyvitamin D stimulates differentiation of leukemia cells to macrophages and apical membrane formation in human intestines. This vitamin activates apoptosis by blocking anti-apoptotic protein cells (Samuel & Sitrin, 2008).
Signaling pathways in cell division/proliferation
Cell proliferation is aprocess where a cell makes new copies of itself ( Samuel &Sitrin, 2008). This process follows several pathways;
* AKT signaling pathway is a serine kinase that helps pass information between various biological reactions, such as preventing apoptosis.
* TGF-Beta pathway is known as transforming growth factors and they help in the growth of homeostasis and the refurbishment of tissues. This is an immunosuppressor linked to cell inflammation and cancer.
* TNF superfamily pathway is a tumor necrosis factor incharge of normal cell functions such as immune responses, apoptosis, and cell division. They also play a part in foreign body rejection, septic shock, and so on.
Gastrointestinal system
The gastrointestinal system can be described as the digestive path from the mouth to the anus (Adrian, 2020). The digestion begins in the mouth, and then the food is passed down through the esophagus to the stomach, where further digestion occurs. The food is then passed to the intestines, where absorption of nutrients takes place. The remaining waste is passed to the rectum to await excretion through the anus. Saliva, liver, pancreas, and gall bladder produce enzymes that help the tract in food digestion and absorption. The peristaltic movement of muscular walls helps in pushing food down the tract. The tract is also layered with epithelial tissue to protect it from harsh chemicals produced during food digestion.
Stomach anatomy
The stomach comprises four sections: the fundus, cardia, gastric body, and pyloric sections (Adrian, 2020). The cardia is the first section after the esophagus. It is where the ingested food passes through (inflow section). The fundus is located horizontally on the superior side of the cardia, and this where dilation occurs. The gastric body follows next. This is the largest part of the stomach. Most of the digestion takes place in this section. The pyloric section co