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Questions and Answers
What is hypoxic injury?
What is hypoxic injury?
Lack of oxygen in the tissues leading to altered cell metabolism and function
Which of the following is a cause of hypoxic injury? (Select all that apply)
Which of the following is a cause of hypoxic injury? (Select all that apply)
Reperfusion injury occurs only after the tissue has been hypoxic for 30 minutes.
Reperfusion injury occurs only after the tissue has been hypoxic for 30 minutes.
False
What happens during oxidative stress?
What happens during oxidative stress?
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Free radicals are molecules that have an ______ electron.
Free radicals are molecules that have an ______ electron.
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Which of the following are types of free radicals? (Select all that apply)
Which of the following are types of free radicals? (Select all that apply)
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What is apoptosis?
What is apoptosis?
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Apoptosis activates an inflammatory response.
Apoptosis activates an inflammatory response.
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Study Notes
Hypoxic Injury
- Lack of oxygen in tissues leads to altered cell metabolism and function
- Caused by decreased oxygen content in the blood (hypoxemia), decreased oxygen carrying capacity of blood (anemia), or decreased blood flow to tissues (ischemia)
- Consequences of decreased oxygen delivery to the cell: Anaerobic metabolism, decreased ATP production, and cell death
- During anaerobic metabolism, the body produces lactic acid as a byproduct, which can lead to acidosis and further cell damage.
- Consequences of decreased ATP: Inability to operate sodium-potassium pump, leading to cell swelling and an influx of water. Decreased calcium pump activity, causing intracellular calcium overload, which triggers the activation of destructive enzymes.
Reperfusion Injury
- Occurs when hypoxic tissue is reperfused after prolonged hypoxia (greater than 60 minutes)
- Reperfusion injury has multiple contributors: Formation of reactive oxygen species (ROS) through oxidative stress, release of calcium from the sarcoplasmic reticulum, and the inflammatory response from WBCs.
Free Radical Injury
- Involves molecules with an unpaired electron that causes damage to cells.
- Sources of free radicals include exposure to extreme energy sources, normal metabolic processes, inflammation, and enzymatic metabolism of drugs or chemicals.
- Types of free radicals include reactive oxygen species (ROS) and reactive nitrogen species (RNS).
- Low levels of these radicals are essential for cell metabolism and immune function, while high levels lead to oxidative stress and cell injury.
- Oxidative stress can cause DNA damage, fragmented proteins, and lipid peroxidation.
- Clinical examples include aging and diseases such as cancer, cardiovascular disease, pulmonary disease, neurodegenerative diseases, and ocular disease.
- Molecules that inactivate free radicals include endogenous antioxidant enzymes like superoxide dismutase, catalase, and peroxiredoxins, as well as non-enzymatic antioxidants such as Vitamin A, Vitamin C, Vitamin E, and glutathione.
Cell Death
- Cell death can occur through apoptosis or necrosis. Apoptosis is programmed cell death, while necrosis is uncontrolled cell death.
- Apoptosis is triggered by both extracellular and intracellular signals, with extracellular signals including death ligands, withdrawal of hormones, or exposure to toxic agents.
- Intracellular signals involve a decrease in anti-apoptotic proteins and an increase in pro-apoptotic proteins.
- Mechanisms of apoptosis include nuclear condensation, cell shrinkage, and activation of caspases that break down structural proteins and DNA.
- Apoptotic bodies are ingested by neighboring cells or phagocytes, eliminating inflammation.
- Clinical examples of apoptosis include embryonic development and cancer cell death.
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Description
Explore the mechanisms and consequences of hypoxic injury and reperfusion injury in tissues. This quiz dives into the effects of decreased oxygen delivery, anaerobic metabolism, and how reperfusion can lead to further cellular damage. Understand the physiological responses to oxygen deprivation and restoration.
