Chapter 4.1, Problem 1QC

Summary Introduction

To explain: When the irreversible injury of the cell takes place.

Concept introduction: Cellular injury refers to the injury that occurs to the cells and to the extra cellular matrix (ECM). The cellular injury occurs when the cell is unable to maintain adaptive steady state during injurious stimuli. The cellular injury may lead to cell death or may recover from cellular injury. It is mainly of two types, reversible and irreversible. The chemical agents, insufficient amount of oxygen, free radicals, physical and mechanical factors, genetic factors, infectious agents and imbalance nutrition are the injurious stimulus of the cellular injury.

Explanation of Solution

The irreversible cellular injury refers to the cell death, which leads to nuclear changes as well as cellular membrane disruption in the cell. The irregular cellular injury occurs when the sever vacuolization of cellular mitochondria and the continuous Ca²⁺ ion input occur into the cell. In the cell, manually the intracellular calcium ion concentration is very low. There are certain chemicals that lead to increase in cytosolic Ca²⁺ ion concentration. The increasing Ca²⁺ ion level inside the cell damages plasma membrane and the intra-cellular membrane by activating the number of enzymes.

Inside the mitochondria, the cytosolic reactive oxygen species (ROS) in addition to energy leads to the cellular damage. The mitochondrial damage occurs by the increasing cytosolic calcium ion concentration. The mitochondrial damage leads to the loss of membrane potential that causes ATP depletion and cellular death as well as activates another type of cell death called apoptosis.