Autophagy is an intracellular catabolic mechanism. In certain stressful situations, lysosomes degrade degenerated, damaged, aged or non-functional cells, organelles and biomolecules such as proteins and nucleic acids to achieve cellular protection and organelles from cell damage. Autophagy is achieved by forming a bilayer membrane structure in the cytoplasm that wraps the material to be removed and transports it to the lysosome for degradation. In multicellular organisms, newly formed autophagic vesicles form autophagic endosomes by fusing with vesicles in different stages of the endocytic lysosomal pathway, such as early endosomes and late endosomes, before fusing with lysosomes, a process known as autophagic vesicle maturation. Abnormalities in autophagosome maturation, which is precisely regulated by cellular trophic state and stress signaling pathways, lead to the accumulation of large amounts of damaged organelles and toxic protein aggregates in cells.

Apoptosis is an autonomous, genetically controlled, orderly death of cells to maintain the stability of the internal environment. Unlike necrosis, apoptosis is not a passive process, but an active one, involving the activation, expression and regulation of a series of genes, and it is not a phenomenon of autologous damage under pathological conditions, but an active death process for better adaptation to the survival environment. Apoptosis is a fundamental biological phenomenon of cells and plays a necessary role in the removal of unwanted or abnormal cells in multicellular organisms. It plays an important role in the evolution of organisms, the stability of the internal environment, and the development of several systems. Apoptosis is not only a specific type of cell death, but also has important biological significance and complex molecular biological mechanisms.

Cell cycle is the entire process of cell division from the completion of one division to the end of the next division and is divided into two phases: interphase and division. Life is a continuous process passed from generation to generation and is therefore a process of constant renewal and starting from scratch. Thus, it is a process of constant renewal and starting from scratch. The life of a cell begins with the division of its parent cell and ends with the formation of its daughter cells, or the death of the cell itself. Usually, the formation of daughter cells is considered to mark the end of cell division. The cell cycle is the process from the formation of daughter cells at one cell division to the formation of daughter cells at the next cell division. During this process, the genetic material of the cell is copied and distributed equally to the two daughter cells.

Epigenetics is the control of gene expression without altering the DNA sequence, including DNA methylation, genomic imprinting, maternal effects, gene silencing, nucleolus dominant, dormant transposon activation, and RNA editing. In contrast to classical genetics, which focuses on the effects of gene sequences on biological functions, epigenetics focuses on the mechanisms by which these "epigenetic phenomena" are established and maintained.

Immunology is an act of self-protection of the body against infection and invasion by foreign enemies and the exclusion of foreign molecules, including dead cells of the aging self. The immune response is divided into specific and non-specific, and the general term antigen and antibody responses refer to specific immune responses, which require the participation of B cells and T cells. Other immune cells such as macrophages and NK cells mediate non-specific immune responses and are part of the body's natural defense system. A proper immune response can clear pathogens and is beneficial to the organism. However, an excessive immune response can be harmful to the organism itself. Inflammation is one of the results of a violent immune response.

Membrane transport proteins, also known as membrane transport proteins, selectively transport small molecules across the plasma membrane that are not freely diffusing. Membrane transport proteins are membrane integral proteins, or large transmembrane molecular complexes, that function to participate in passive or active transport.