How does hypoxia cause depolarization?
Prolonged exposure to hypoxia causes depolarization of the resting Em in PASMCs (59, 97, 196, 198, 205) and reduces the activity and expression of KV channels (59, 97, 177, 196, 198, 235, 240) through a mechanism involving both activation of the transcription factor, HIF-1, and the endothelium-derived factor endothelin …
What causes depolarization of the brain?
Neurons can undergo depolarization in response to a number of stimuli such as heat, chemical, light, electrical or physical stimulus. These stimuli generate a positive potential inside the neurons. When the positive potential becomes greater than the threshold potential, it causes the opening of sodium channels.
What is Excitotoxicity theory?
Excitotoxicity is a phenomenon that describes the toxic actions of excitatory neurotransmitters, primarily glutamate, where the exacerbated or prolonged activation of glutamate receptors starts a cascade of neurotoxicity that ultimately leads to the loss of neuronal function and cell death.
Why does ischemia cause depolarization?
Ischemia leads to cellular depolarization by altering ion chemical gradients and membrane conductance to ions. These changes alter action potential depolarization and repolarization and depress their conduction within the heart, leading to altered ECG wave morphology, intervals, and segments.
What ion is responsible for repolarization?
potassium (K+) ions
Repolarization is a stage of an action potential in which the cell experiences a decrease of voltage due to the efflux of potassium (K+) ions along its electrochemical gradient. This phase occurs after the cell reaches its highest voltage from depolarization.
Is depolarization more negative?
This means that the interior of the cell is negatively charged relative to the outside. Hyperpolarization is when the membrane potential becomes more negative at a particular spot on the neuron’s membrane, while depolarization is when the membrane potential becomes less negative (more positive).
Is aspartame an excitotoxin?
The most common excitotoxins are aspartame (an artificial sweetener) and monosodium glutamate (commonly known as MSG). The way they cause damage to the body, in a nutshell, is these chemical stimulate glutamate receptors.
Is alcohol an excitotoxin?
We further acknowledge that alcohol treatments might potentiate excitotoxic mechanisms promoted by other insults such as brain ischemia/reperfusion (Zhao et al., 2011); additionally, brain damage in the Wernicke-Korsakoff syndrome in alcoholics might include a prominent excitotoxic component, since neurodamage from …
What is anoxic depolarization?
(November 2013) ( Learn how and when to remove this template message) Anoxic depolarization is a progressive and uncontrollable depolarization of neurons during stroke or brain ischemia in which there is an inadequate supply of blood to the brain.
What is an anoxic event?
Anoxic waters, sea water, fresh water or groundwater that are depleted of dissolved oxygen Anoxic event, when the Earth’s oceans become completely depleted of oxygen below the surface levels Euxinic, anoxic conditions in the presence of hydrogen sulfide
What does anoxia mean in geography?
The term anoxia means a total depletion in the level of oxygen, an extreme form of hypoxia or “low oxygen”. The terms anoxia and hypoxia are used in various contexts: Anoxic waters, sea water, fresh water or groundwater that are depleted of dissolved oxygen
What does anoxic water mean?
Anoxic waters. Anoxic waters are areas of sea water, fresh water, or groundwater that are depleted of dissolved oxygen and are a more severe condition of hypoxia. The US Geological Survey defines anoxic groundwater as those with dissolved oxygen concentration of less than 0.5 milligrams per litre.