Oxidative stress

Chia sẻ: Nguyen Uyen | Ngày: | Loại File: PDF | Số trang:4

Thêm vào BST

Báo xấu

67
lượt xem 5
download

Download Vui lòng tải xuống để xem tài liệu đầy đủ

To understand oxidative stress, we review mitochondria together. MItochondria Mitochondria consume over 80 percent of the oxygen we breathe and make over 90 percent of the energy our cells need to function. They use the oxygen in the air we breathe to release energy from food. This process transforms food calories into chemical energy, water, and carbon dioxide. The released chemical energy is then stored in the form of adenosine triphosphate (ATP). ATP is the universal currency of energy used by all life on earth. It is like an electrical power source that drives the engines of the cell. This process...

Chủ đề:

Bình luận(0) Đăng nhập để gửi bình luận!

Lưu

Nội dung Text: Oxidative stress

Oxidative stress To understand oxidative stress, we review mitochondria together. MItochondria Mitochondria consume over 80 percent of the oxygen we breathe and make over 90 percent of the energy our cells need to function. They use the oxygen in the air we breathe to release energy from food. This process transforms food calories into chemical energy, water, and carbon dioxide. The released chemical energy is then stored in the form of adenosine triphosphate (ATP). ATP is the universal currency of energy used by all life on earth. It is like an electrical power source that drives the engines of the cell. This process of burning food to make ATP is called oxidative phosphorylation. Only mitochondria can do it. Mitochondria are important in relation to the aging process for two reasons: their role in energy production and, the generation of free radicals. In a healthy state, about 20% of the
oxygen we breathe forms free radicals. In an unhealthy state up to 80% of the oxygen we breath forms free radicals. Oxidative stress Oxidative stress represents an imbalance between the production and manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal redox state of tissues can cause toxic effects through the production of peroxides and free radicals that damage all components of the cell, including proteins, lipids, and DNA. Some reactive oxidative species can even act as messengers through a phenomenon called redox signaling Free radicals: Free radicals are lacking one electron. Having an unpaired electron makes these radicals very unstable, then the radicals will start attacking healthy cells to find one.They take that electron from another molecule, stabilizing themselves, and in doing so, create a new free radical. This new unstable molecule starts the search all over again for another cell to get an electron from. A chain reaction develops causing repeated damage to healthy cells, first attacking the cell membrane and then working its way through to the DNA of the cell. This is the beginning of disease processes which debilitate our bodies with degenerative
conditions, inflamed tissues, compromised immune systems and cancer, just to name a few. Generally, free radicals react with other molecules, damaging them. However some processes such as the killing of bacteria by neutrophil granulocytes is beneficial. Causes of oxidative stress: Common sources of oxidative stress are: toxicity, chr onic inflammation, glycation, stress, excessive exercise, some medications, alcohol, cigarette smoke, and dietary factors such as consumption of refined carbohydrates (white sugar and flour, for a start), bad fat, bad oils, fried oils, and foods cooked at high temperature (fried or barbequed for example). Overeating may be another source of oxidative stress. The more food that is burned within the mitochondria the more free radicals are produced. Oxidative and disease: The effects of oxidative stress depend upon the size of these changes, with a cell being able to overcome small perturbations and regain its original state. However, more severe oxidative stress can cause cell death and even moderate oxidation can trigger apoptosis, while more intense stresses may cause necrosis.
Oxidative stress contributes to tissue injury following irradiation and hyperoxia. It is suspected (though not proven) to be important in neurodegenerative diseases including Lou Gehrig's disease (aka MND or ALS), Parkinson's disease, Alzheimer's disease, and Huntington's disease. Oxidative stress is thought to be linked to certain cardiovascular disease, since oxidation of LDL in the vascular endothelium is a precursor to plaque formation. Oxidative stress also plays a role in the ischemic cascade due to oxygen reperfusion injury following hypoxia. This cascade includes both strokes and heart attacks. Oxidative stress has also been implicated in chronic fatigue syndrome.