Lecture 1.1a - Cell injury and cell death 1

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Questions and Answers

What is the primary mechanism of tissue injury in hypersensitivity reactions?

Overly vigorous immune reaction (correct)

Direct damage by toxins

Insufficient oxidative phosphorylation

Immune system's failure to distinguish self from non-self

Which of the following is NOT a possible mechanism of ischaemia-reperfusion injury?

Increased production of oxygen free radicals

Delivery of complement proteins

Increased number of neutrophils

Decreased mitochondrial activity (correct)

What is the primary mechanism by which cells respond to mild changes in environmental conditions?

Reversible injury

Homeostasis (correct)

Cell adaptation

Cell death

What is the primary target of extreme cold (frostbite) in terms of cell injury?

Cell membrane Signup and view all the answers

What is the characteristic of free radicals?

Single unpaired electron in an outer orbit Signup and view all the answers

What is the main factor that determines the degree of cell injury?

All of the above Signup and view all the answers

What is the result of Na+/K+ pump failure in cell injury?

Cell swelling Signup and view all the answers

Which of the following is an example of an autoimmune reaction?

Grave's disease of thyroid Signup and view all the answers

What is a common consequence of hypoxia on cellular respiration?

Reduction in aerobic oxidative respiration Signup and view all the answers

Which of the following is a characteristic of reversible cell injury?

Cytoplasmic blebs Signup and view all the answers

What is the outcome of ischaemia-reperfusion injury?

Worse tissue injury than if blood flow was not restored Signup and view all the answers

Which of the following is a characteristic of irreversible cell injury?

Karyolysis or karyorrhexis Signup and view all the answers

What is the result of reduced pH in cell injury?

Clumped chromatin Signup and view all the answers

Which of the following is a common source of free radicals?

High concentration of oxygen Signup and view all the answers

What is the primary mechanism of cell membrane damage by free radicals?

Lipid peroxidation Signup and view all the answers

What is the consequence of failure of energy-dependent process of maintaining ribosomes in the correct location?

Ribosome separation from the endoplasmic reticulum Signup and view all the answers

What type of stimuli can cause cell injury?

A combination of physical, chemical, and biological agents Signup and view all the answers

What is a consequence of membrane defects in cell injury?

Swelling and rupture of lysosomes Signup and view all the answers

What is a common result of cell injury due to hypoxia?

Cell death or apoptosis Signup and view all the answers

What is a characteristic of the cell injury response?

Part of a continuum Signup and view all the answers

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

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Description

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.