Cell Response to Stress & Aging

Cell Response to Stress, Injury, & Aging

• Inadequate nutrition triggers cellular atrophy, facilitating survival with limited resources.
• Cell efficiency: Most cells are capable of remarkable adaptability when faced with increased demands, such as size increase or proliferation.
• Cells can exhibit reversible changes in response to adverse conditions through gene expression modulation.
• Adaptations may involve changes in cell size, number, and differentiation into different cell types.
• If stressors are insurmountable, cells may undergo apoptosis or necrosis, leading to cell death.

Atrophy

• Atrophy refers to a reduction in cell size, impacting the overall size of organs or tissues.
• Advantages of atrophy include decreased oxygen consumption and resource utilization due to smaller and fewer organelles.
• Common types of atrophy include disuse atrophy (muscle cells affected by immobility or casting) and denervation atrophy (loss of nerve stimulation).

Hypertrophy

• Hypertrophy is the increase in organ or tissue size due to heightened demand, primarily observed in muscle tissues like cardiac and skeletal muscles.
• Normal physiological hypertrophy occurs with increased workload, such as from exercise.
• Adaptive hypertrophy is seen when there is a thickening of an organ, e.g., urinary bladder due to outflow obstruction.
• Compensatory hypertrophy can occur, e.g., the enlargement of one kidney following the removal of another.

Hyperplasia and Related Terms

• Hyperplasia involves an increase in cell number, typically in organs capable of mitotic division, excluding muscle cells and neurons.
• Metaplasia is characterized by the reversible transformation from one cell type to another.
• Dysplasia signifies deranged cell growth, resulting in abnormal cell shapes, sizes, and organization.

Hormonal Influence on Atrophy and Hypertrophy

• Hormonal changes can significantly impact tissue and organ size, notably:
  • Decreased estrogen levels, such as during menopause, can lead to breast and reproductive organ atrophy.
  • Testosterone abuse may cause testicular atrophy.

Explore how cells adapt to stress, injury, and aging in this quiz. You'll learn about cellular atrophy, hypertrophy, and the mechanisms behind cell survival and death. Test your knowledge on the changes that cells undergo in response to various conditions.