Generally, hypertrophy occurs when a tissue is under increased physiological demands, or when it is being stimulated by hormones. The loss of hormonal stimulation causes an endocrine organ to shrink HypertrophyAn increase in the size of a tissue or organ occurs when the number or size of cells increases without an increase in the number of cells.Atrophy due to disconnection of innervation of skeletal muscles, e.g., carpal tunnel syndrome-related wasting of thenar muscles.This can be reversed by physical activity. This phenomenon occurs when there is a decrease in functional demand, resulting in muscle atrophy.The process can happen physiologically, such as when the uterus shrinks after birth when hormones that stimulated its growth cease to be produced or pathologically, such as when an organ suffers from inadequate blood supply or nutritional deficiencies.Ītrophy caused by pathology includes the following examples: This adaptation, however, may not be sufficient if the stimulus continues, and the cell could become permanently damaged or die.ĪtrophyIt is the loss of size and/or number of cells in a tissue or organ that causes atrophy. It is usually possible to reverse these adaptive changes by removing the stressor. These adaptations allow them to function and survive better in new environments. Organ weight increases as a result.Īdaptive ChangesCells undergo adaptations in response to external stressors, such as environmental stress. The alteration is reversible, but can be difficult to detect using a light microscope, although it may still be apparent when the whole organ is examined. In the absence of an energy-dependent ion pump in the plasma membrane, cellular swelling is the first sign that a cell has been injured and cannot maintain its internal ionic and fluid balance. Apoptosis is a mode of cell death that involves cell activating enzymes that break down a cell's own DNA, proteins and nuclei. Heterolysis - Inflammatory mediators such as neutrophils release hydrolytic enzymes to disintegrate cells.Īpoptosis - This type of cell death is also called programmed cell death. Some tissues, such as the pancreas and gastric mucosa, undergo autolysis others, such as the heart, liver, and kidney, undergo intermediate to slow autolysis. As a result of degradative enzymes on lethally injured cells, it results in the dissolution of the cells due to the loss of membrane integrity and leakage of cellular contents.Īutolysis (self digestion) - An enzyme released from the lysosomes is responsible for the cell's disintegration. Necrosis - The morphological changes that accompany necrosis are caused by lethally injured cells. Nutritional dearrangementCell injuries can be divided into two categories:.Acquired causesAcquired causes include the following:.As a result of its internal and external environments, cells experience a variety of stresses that cause injury.There are physiological and pathological stresses. Injury: Stress that exceeds the capacity of the cell to adapt.Adaption: An adaptation is a response to a stimulus by modifying morphology and function of a cell.When the cell is under excessive physiological or pathological stress, it may settle into a new steady state:.The process by which cells maintain their steady state is called homeostasis.All organ injuries are caused by molecular or structural changes in the cell.

Pathological hypertrophy definition