This website uses cookies to ensure you have the best experience. Learn more

Oxygen, Oxygen Radicals And Oxidative Stress

1081 words - 5 pages

Oxygen supply to the retina

The retina is one of the most metabolically active and high energy demand tissue in the body, which puts it under a persistent demand for a regular supply of oxygen to meet its metabolic needs (1, 2). The major blood supply to the retina is the central retinal artery that is derived from the ophthalmic artery. The ophthalmic artery is branched from the internal carotid artery and goes along the optic nerve (). Oxygen supply to the retina stems from two vascular beds: the choroidal circulation that supplies the outer 1/3 of the retina, and the retinal circulation that supplies the inner 2/3 of the retina (2, 3). The two circulations differ in their vascular ...view middle of the document...

In comparison, during dark adaptation, the photoreceptor region oxygen consumption is substantially increased by about 50% (3), which causes an increase in the oxygen gradient
In summation, there are three high oxygen consumption regions in the retina: The inner segments of the photoreceptor, the outer plexiform layer, and the inner plexiform layer.

The effects of hyperglycemia on intraretinal oxygen profile

Studies have shown no major differences in oxygen profiles in the cat retina during hyperglycemia and normoglycemia (6), where O2 flows down its concentration gradient from the region of the high oxygen tension to the region of the low oxygen tension.

Retinal Oxygen metabolism

The retina has many unique metabolic needs, it has a high oxygen consumption rate to supply ATP that is needed for the high energy demands of the photoreceptor segment, and it depends on glucose to maintain the electrical activity of the retina (7).

The increased levels of glucose due to hyperglycemia alters the electron transport chain in the mitochondria. Hyperglycemia increases the production of the electron donors NADH and FADH2 which increases the proton gradient across the inner mitochondrial membrane inducing membrane potential heterogeneity (2, 8). This sustained gradient leads to the decreased degradation of the electron transport intermediates which increases its concentration leading to the production of superoxide (2). Moreover, the alteration and disruption of the fission and fusion balance in the mitochondria lead to its structural deformation, fragmentation and apoptosis. And the release of cytochrome C, a pro-apoptotic agent (8).
The elevated levels of superoxide production as a result of hyperglycemia can activate and affect four pathways that are suggested to be responsible for retinal microvascular damage and diabetic retinopathy. Super oxide inhibits GAPDH which causes metabolite accumulation. These metabolites are used in the four metabolic pathways that include: The polyol pathway flux, where the major outcome is the decrease of NADPH levels, which is a cofactor needed for the regeneration of reduced glutathione, an important antioxidant (2). Other alteration in the signaling pathway due to increased levels of ROS are the increased advanced glycation end products (AGE), protein kinase C isoforms activation, upregulation of the hexosamine...

Find Another Essay On Oxygen, Oxygen radicals and oxidative stress

Law of Constant Composition Lab: Magnesium and Oxygen

1445 words - 6 pages therefore, oxygen must make up the remaining 28%.According to the theory of J.L. Proust, a compound always has the same percentage composition no matter how it is prepared. For all three of our own individual group’s trials, we obtained the same percentage composition and this satisfies Proust’s theory.This is also accurate with what we have read in the textbook Chemistry 11 on the “Law of Definite Proportions” on pages 147 –

Oxygen is one of the most important and abundant elements on Earth

577 words - 2 pages is similar to combustion, fuel and oxygen are consumed, while heat and energy are generated.When the body is deprived of an adequate oxygen supply, even for a short period, various organs and processes in the body begin to suffer impairment from oxygen deficiency. This condition is known as "hypoxia". It has been shown that any type of stress to the body will bring oxygen deficiency. TOXIC STRESSES (toxic environment), EMOTIONAL STRESS, PHYSICAL

Atmospheric Oxygen, Giant Paleozoic Insects and the Evolution of Aerial Locomotor Performance

2190 words - 9 pages the Paleozoic era. Some are predatory defense and enhanced flight performance. However, the most plausible is the idea that the oxygen increase in the atmosphere caused the increase in body size. Increased oxygen partial pressure caused an increase in diffusive flux in the tracheal system. This led to the adaptation of the bodies of insects, amphibians, and arthropods to the new environment. Carboniferous - is a major

Greenlake, Seattle Report: life formes, dissolved oxygen, coliform, BOD, nitrates and phosphates, etc

1203 words - 5 pages hatch. The daphnia eat small planktons, such as green algae and diatoms, mainly because they are already so small. Daphnia can withstand temperatures up to forty degrees celsius, but after that, their enzymes break down and they die. Daphnia probably affect Green Lake because it is a main diet for many other animals, and if it were to go, it would probably ruin part of the ecosystem, causing a bad chain reaction.Dissolved OxygenDissolved oxygen

The properties of glass explained by the bonding of Silicon and Oxygen

556 words - 2 pages The properties of glass lie within the bonding structure of silicon. Silicon cannot form strong ð bonds with oxygen by using its valency 3p orbitals. This is because of the large nuclear radius of the silicon atom and its orbitals which results in a less effective overlap with the smaller oxygen orbitals. The silicon atoms then form four single bonds to satisfy the octet rule. Therefore, instead of forming a SiO2 covalent molecule, it will form

Understandin How Mammalian Pulmonary and Circulatory Systems Increase The Delivery of Oxygen to Cells

2514 words - 10 pages Male vs. Female Differences in Vital Statistics I. Introduction The respiratory system and circulatory system are both critical to the life of a mammal. The respiratory and circulatory systems depend on each other greatly. An organism needs both systems to be functioning in order to sustain life. Oxygen needs to be exchanged throughout the body, and the respiratory system and circulatory system are the modes of transportation for

Attenuation of insulin resistance, metabolic syndrome and hepatic oxidative stress by resveratrol in fructose-fed rats

592 words - 3 pages diabetic myocardium accounts for more than 80% deaths among diabetics (Amos et al., 1997). The alteration of cardiac muscle in diabetes has led to the recognition of a new cardiac disease termed 'diabetic cardiomyopathy' (DCM) (Kannel et al., 1974). Several etiological factors like hyperglycemia, metabolic abnormalities and redox imbalance (oxidative stress) may affect the diabetic myocardium. Overwhelming effect of all of them leads to cardiac

Explanations of the major elements: oxygen, carbon, hydrogen, nitrogen, calcium, phosphorus, magnesium, potassium, sulfur, sodium, chlorine, iron and zinc

1424 words - 6 pages extracellular and intercellular fluid. It is required for maintenance of pH and osmotic balance.Iron (Fe)This element is an important trace mineral found in ever cell of the body, usually in combination with protein. Depending on the level of iron in the body, it can act as either an antioxidant, or it can stimulate the formation of free radicals. Iron is an essential nutrient because it is a vital part of red blood cells, which carry oxygen to all

Investigating the effect that temperature has on the rate of reaction and therefore the amount of oxygen produced

3269 words - 13 pages Decomposition of hydrogen peroxide2H2O O + 2H2OPlanningAim:Our aim is to investigate the effect that temperature has on the rate of reaction and the amount of oxygen that is produced.Prediction:With reference to my theory, I predict that the initial rate of reaction will increase with the temperature rise up to 50°C where the enzyme used and released by the yeast will become denatured and wont function normally, reducing the initial rate of

Lab Report Using a Chemical Titration to Measure Rate of Conversion of Hydrogen Peroxide to Water and Oxygen

2711 words - 11 pages Lab Report Using a Chemical Titration to Measure Rate of Conversion of Hydrogen Peroxide to Water and Oxygen Overview: In this laboratory you will use a chemical titration to measure and then calculate the rate of conversion of hydrogen peroxide (HO) to water and oxygen using the enzyme catalase. Objectives: Before doing this exercise, you should understand: Ø the general functions and activities of enzymes Ø the relationship between

Theories of aging, including the Telomere theory, oxidative stress and calorie restriction theories in regards to cell senescence

962 words - 4 pages function causing injury (Sharma & Kaur, 2006); this is what is referred to as oxidative stress. Mostly free radicals are derived from oxygen and carry and unpaired electron; these are referred to as reactive oxygen species (ROS). Free radicals injure cellular lipids, proteins and nucleic acids which may result in improper organ function (Sharma & Kaur, 2006).Our bodies do have in-built defences, antioxidants, but these are not completely

Similar Essays

Cells Are Exposed To Reactive Oxygen Species In Oxidative Stress

1095 words - 5 pages 2.1 OXIDATIVE STRESS The term oxidative stress is often used to imply a condition in which cells are exposed to excessive levels of either molecular oxygen or chemical derivatives of oxygen called reactive oxygen species; (Kojda et al., 1999). This occurs when molecules of oxygen are reduced to various subunits such as water, the production of superoxide anion radical, hydrogen peroxide and hydrogen radicals (Geller, D.A., et al. 1993). On the

Free Radicals And Oxidative Stress (In German)

874 words - 3 pages zwei Prozent der Fälle fehlerhaft, dann nämlich, wenn sich zu wenig Elektronen mit Sauerstoff verbinden. Dabei entstehen "freie Radikale", Substanzen, die schon seit Mitte des letzten Jahrhunderts als Schlüsselfaktor für des Alterungsprozesses gesehen wurden, da sie den Körper einem "oxidativen Stress" aussetzen. Freie Radikale, darunter das Superoxid-anion Radikal (1) und das Hydroxidradikal (2), die als

Ventilation And Oxygen Consumption Essay

481 words - 2 pages Ventilation and Oxygen consumptionProcedure:We measured the ventillation metabolism of the fish at two different temperatures: (25 C) and (15 C). For each fish,we prepared a 250 ml jar by filling it half full with water from the aquarium in which the fish was housed.we transfered the fish from its weighing beaker to the jar adding sufficient water to now fill the jar to about 80% of its capacity.We placed the jar in the appropiate water bath. We

Adaptations Of The Placenta And Foetus To Improve Oxygen Availability

1278 words - 5 pages form of oxygen, glucose and other substances whilst excreting waste products such as carbon dioxide. The placenta and foetus feature many adaptations to ensure the most efficient gas exchange and to ensure high oxygen availability to the foetus . Gas exchange across the placental blood-blood barrier is dependent on many factors such as interhaemal barrier thickness, the surface area of exchange and the concentration gradient of the gases, among