Preview

Ischemic Cascade

Good Essays
Open Document
Open Document
574 Words
Grammar
Grammar
Plagiarism
Plagiarism
Writing
Writing
Score
Score
Ischemic Cascade
The ischemic (ischaemic) cascade is a series of biochemical reactions that take place in the brain and other aerobic tissues after seconds to minutes of ischemia (inadequate blood supply).[1] This is typically secondary to stroke, injury, or cardiac arrest due to heart attack. Most ischemic neurons that die do so due to the activation of chemicals produced during and after ischemia.[2] The ischemic cascade usually goes on for two to three hours but can last for days, even after normal blood flow returns.[3]

A cascade is a series of events in which one event triggers the next, in a linear fashion. Thus "ischemic cascade" is actually a misnomer, since in it, events are not always linear: in some cases, they are circular, and sometimes one event can cause or be caused by multiple other events.[4] In addition, cells receiving different amounts of blood may go through different chemical processes. Despite these facts, the ischemic cascade can be generally characterized as follows:

1. Lack of oxygen causes the neuron's normal process for making ATP for energy to fail. 2. The cell switches to anaerobic metabolism, producing lactic acid. 3. ATP-reliant ion transport pumps fail, causing the cell to become depolarized, allowing ions, including calcium (Ca++), to flow into the cell. 4. The ion pumps can no longer transport calcium out of the cell, and intracellular calcium levels get too high. 5. The presence of calcium triggers the release of the excitatory amino acid neurotransmitter glutamate. 6. Glutamate stimulates AMPA receptors and Ca++-permeable NMDA receptors, which open to allow more calcium into cells. 7. Excess calcium entry overexcites cells and causes the generation of harmful chemicals like free radicals, reactive oxygen species and calcium-dependent enzymes such as calpain, endonucleases, ATPases, and phospholipases in a process called excitotoxicity.[5][6] Calcium can also cause the release of more glutamate. 8. As the

You May Also Find These Documents Helpful

  • Good Essays

    unit 10 review

    • 1120 Words
    • 5 Pages

    d. the relationship between excitation at the sarcolemma and release of calcium ions from the sarcoplasmic…

    • 1120 Words
    • 5 Pages
    Good Essays
  • Good Essays

    Ap Biology Muscle Cells

    • 305 Words
    • 2 Pages

    When muscle cells begin to repolarize, first the acetychloine is removed from the receptors on the cells. This in turn causes the receptor mediated Na+ leak channels to close. Voltage gated potassium leak channels open as a result. As K+ ions begin coming into the cytoplasm to repolarize. When the membrane potential reaches a specific level, the voltage gated potassium leak channels close as well. The sodium potassium pump works throughtout this process, by pumping Na+ ions out and K+ ions into the cells (using ATP, by a process called active transport).Ca2+ ions are pumped back into the SR by means of active transport. The membrane potential is then restored to the resting potential of…

    • 305 Words
    • 2 Pages
    Good Essays
  • Satisfactory Essays

    Bio 101 Review Questions

    • 570 Words
    • 3 Pages

    10. Once ATP is converted into ADP + P, it must be ____. b) recharged by chemiosmosis…

    • 570 Words
    • 3 Pages
    Satisfactory Essays
  • Satisfactory Essays

    Joseph's Story

    • 1010 Words
    • 5 Pages

    Oxygen and blood glucose are essential ions that are necessary for the pumping of the heart. Their delivery to the heart will slow down. Carbon dioxide levels will increase -- this causes the Ph levels to drop. Mitochondria will no longer have…

    • 1010 Words
    • 5 Pages
    Satisfactory Essays
  • Powerful Essays

    Nu-545 Unit 1

    • 5488 Words
    • 22 Pages

    “(3) Specific enzymes that drive active pumps that promote concentration of certain ions, particularly potassium (K+), within the cell while keeping concentrations of other ions, for example sodium (Na+), below concentrations found in the extracellular environment…” (McCance &Huether, pg. 12).…

    • 5488 Words
    • 22 Pages
    Powerful Essays
  • Satisfactory Essays

    Sliding Filament Theory

    • 444 Words
    • 2 Pages

    1. Acetylcholine is released by the axon terminal, diffuses to the muscle cell and attaches…

    • 444 Words
    • 2 Pages
    Satisfactory Essays
  • Satisfactory Essays

    Directions: If you are unable to attend a live collaboration session, this activity will allow you to get credit for the Segment 2 Collaboration Project. Fill out the RED sections of this activity sheet.…

    • 765 Words
    • 5 Pages
    Satisfactory Essays
  • Powerful Essays

    Endocrine Lab Report

    • 2134 Words
    • 9 Pages

    Smooth muscle contractions are affected by calcium and potassium ions. Calcium ion influx into the smooth muscle cell initiates a contraction. Potassium ion concentration in the extracellular medium affects the resting membrane potential of the cell, bringing it closer to or farther away from its threshold voltage. Neurotransmitters affect different types of smooth muscle differently, depending on the association of the smooth muscle with excitable cells. In general, acetylcholine increases the muscle cell’s permeability to calcium, while epinephrine decreases the cell’s permeability to calcium.…

    • 2134 Words
    • 9 Pages
    Powerful Essays
  • Satisfactory Essays

    Joseph's Story

    • 473 Words
    • 2 Pages

    B. Assuming Joseph’s heart has stopped, what cellular processes and membrane functions are going to be affected by the loss of oxygen, blood glucose, and waste removal?…

    • 473 Words
    • 2 Pages
    Satisfactory Essays
  • Good Essays

    Muscle Quiz

    • 1313 Words
    • 6 Pages

    • Pump hydrolyzes ATP to pump 3 Na+ ions out of cell and 2 K+ ions into cell.…

    • 1313 Words
    • 6 Pages
    Good Essays
  • Satisfactory Essays

    The solution of salts inside the cell are hypertonic in comparison to that of the blood stream so therefore the salts move through the semipermeable membrane of the cell to the less concentrated blood stream.…

    • 306 Words
    • 2 Pages
    Satisfactory Essays
  • Satisfactory Essays

    Physio 9.0 exercise 6

    • 349 Words
    • 2 Pages

    calcium channels to open. After this point, no additional voltage can cause the channels to open more, or again, prior to…

    • 349 Words
    • 2 Pages
    Satisfactory Essays
  • Satisfactory Essays

    The intrinsic conduction system consists of __autorhythmic____ __cardiac__ cells that initiate and distribute __impulses_____ throughout the heart.…

    • 1283 Words
    • 6 Pages
    Satisfactory Essays
  • Better Essays

    Ischemia- local decrease in blood supply Infarction- death & deterioration of tissue resulting from lack of blood supply.…

    • 1450 Words
    • 5 Pages
    Better Essays
  • Good Essays

    changed; and c , initiating the depolarization of the membrane. Almost as soon as the…

    • 589 Words
    • 3 Pages
    Good Essays