20 Questions
What is the primary mechanism of tissue injury in hypersensitivity reactions?
Overly vigorous immune reaction
Which of the following is NOT a possible mechanism of ischaemia-reperfusion injury?
Decreased mitochondrial activity
What is the primary mechanism by which cells respond to mild changes in environmental conditions?
Homeostasis
What is the primary target of extreme cold (frostbite) in terms of cell injury?
Cell membrane
What is the characteristic of free radicals?
Single unpaired electron in an outer orbit
What is the main factor that determines the degree of cell injury?
All of the above
What is the result of Na+/K+ pump failure in cell injury?
Cell swelling
Which of the following is an example of an autoimmune reaction?
Grave's disease of thyroid
What is a common consequence of hypoxia on cellular respiration?
Reduction in aerobic oxidative respiration
Which of the following is a characteristic of reversible cell injury?
Cytoplasmic blebs
What is the outcome of ischaemia-reperfusion injury?
Worse tissue injury than if blood flow was not restored
Which of the following is a characteristic of irreversible cell injury?
Karyolysis or karyorrhexis
What is the result of reduced pH in cell injury?
Clumped chromatin
Which of the following is a common source of free radicals?
High concentration of oxygen
What is the primary mechanism of cell membrane damage by free radicals?
Lipid peroxidation
What is the consequence of failure of energy-dependent process of maintaining ribosomes in the correct location?
Ribosome separation from the endoplasmic reticulum
What type of stimuli can cause cell injury?
A combination of physical, chemical, and biological agents
What is a consequence of membrane defects in cell injury?
Swelling and rupture of lysosomes
What is a common result of cell injury due to hypoxia?
Cell death or apoptosis
What is a characteristic of the cell injury response?
Part of a continuum
Study Notes
Types of Toxins
- Glucose and salt in hypertonic solutions
- High concentration of oxygen
- Poisons
- Pollutants
- Insecticides
- Herbicides
- Asbestos
- Alcohol
- Narcotic drugs
- Medicines
Immune System Damage
- Hypersensitivity reactions: host tissue injury due to an overly vigorous immune reaction
- Autoimmune reactions: immune system fails to distinguish self from non-self
- Examples: urticaria (hives), Grave's disease of thyroid
Other Methods of Cell Injury
- Sequence of events may differ, but outcome is often similar due to limited cell response to injury
- Examples: extreme cold (frostbite) damages membranes initially, free radicals damage membranes
Ischaemia-Reperfusion Injury
- Worse injury than if blood flow was not restored
- Causes: increased oxygen free radicals, increased neutrophils, and complement proteins
- Result: increased inflammation and tissue injury
Free Radicals
- Reactive oxygen species
- Unstable configuration with single unpaired electron
- Examples: OH* (hydroxyl radical), O2*- (superoxide)
- Produced in: chemical and radiation injury, ischaemia-reperfusion injury, cellular ageing, high oxygen concentrations
Cell Injury Response
- Continuum of cell response to injury
- Cell injury: when cells are stressed and can no longer adapt
- Duration of injury affects cell response
- Cell components most susceptible to injury: vary depending on stimulus
- Stimuli that can cause injury: hypoxia, toxins, physical agents, radiation, micro-organisms, immune mechanisms, dietary insufficiency and deficiencies, dietary excess
Hypoxia
- Deficiency of oxygen leading to reduced aerobic oxidative respiration
- Common cause of cell injury and cell death
Cell Injury and Death
- Cells respond to injury with adaptation, injury, or death
- Degree of injury depends on type, severity, and type of tissue
- Reversible injury: cell swelling, cytoplasmic blebs, clumped chromatin, ribosome separation from endoplasmic reticulum
- Irreversible injury: cell membrane damage, nuclear changes, swelling and rupture of lysosomes, membrane defects, myelin figures, lysis of endoplasmic reticulum, amorphous densities in swollen mitochondria
This quiz covers various types of toxins and how the immune system can damage the body's cells through hypersensitivity and autoimmune reactions. Topics include poisons, pollutants, and more.
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