Telomeres are protective caps at the ends of each chromosome that shorten with each cell division. Telomere attrition eventually leads to cell senescence or apoptosis, which limits cellular lifespan and contributes to aging.

Changes in epigenetic marks - chemical modifications of DNA and histones - that regulate gene expression without altering the DNA sequence. These alterations can affect several processes involved in aging and as a response to environmental factors.

Proteostasis involves the balance of protein synthesis, folding, trafficking, and degradation. Aging is associated with loss of proteostasis, which leads to the accumulation of misfolded or aggregated proteins that can disrupt cellular function. 

Aging affects the pathways that cells use to sense and respond to nutrients, including insulin and IGF-1 signaling, mTOR, AMPK, and sirtuin pathways. These changes can disrupt metabolic processes and contribute to age-related disease.

Mitochondria are the powerhouses of the cell. With age, their dysfunction leads to reduced energy production and increased oxidative stress, which results in cellular damage and aging.

Senescent cells are those that have lost the ability to divide but do not die off, and release chemicals that can cause inflammation. This damages nearby cells and tissue, contributing to aging and age-related diseases.

Stem cells have the ability to repair diseased or damaged tissues. Over time, the number and function of our stem cells declines, which impairs tissue repair and regeneration. This contributes to aging and loss of organ function

Aging is associated with changes in how cells communicate with each other. This includes increased inflammation (“inflammaging”) and changes in hormone levels and other signaling molecules. This can disrupt homeostasis in tissue and organ systems.