Cellular Aging Lecture Flashcards
Define cellular aging
Involves differentiation and maturation
Leads to progressive loss of functional capacity characteristic of senescence and ends in death
Results from progressive accumulation of sublethal injury overtime
What is stress induced autophagy?
During nutrient deprivation, starved cells cannibalize itself and recycle the digest material
Mechanism for cell loss in degenerative diseases
What are some process that can be involved in intracellular accumulations?
Normal substance is produced at normal rate but metabolism is inadequate to remove it
Normal or abnormal endogenous substance accumulates because of genetics or something acquired
Exogenous substance is deposited and accumulates because cell cannot degrade it or transport it
What is dystrophic calcification?
observed in areas of necrosis, atherosclerosis and in aging or damaged heart valves
Causes organ dysfunction and membrane damage
What is metastic calcification?
Due to hypercalcemia
Causes hyperparathyroidism, destruction of bone tissue, renal failure
What are some morphologic changes characteristic of cellular aging?
Irregular or abnormally lobed nuclei
Vaculated mitochondria
Decreased ER
Distorted golgi
What are characteristic changes of aging in organ systems
- Skeletal: loss of bone mass
- Skin- wrinkles and sagging
- Heart/kidney/lungs: reduced reserve capacity
- Brain: loss of neurons
- Body fat: redistribution
- Hormones: change in secretion pattern
What is aging affected by?
Genetics, diet, diseases
Cellular aging is often accompanied by what?
Reduced oxidative phosphorylation
Reduced synthesis of nucleic acids, proteins and other cell components
Decreased capacity for uptake of nutrients and repair damage
What are some altered metabolic function that are characteristic of cellular aging?
Increase DNA damage, decrased chromsomal damage repair, reduced oxidative phosphorylation by mitochondria
decreased capacity for nutrient uptake, abnormal folding, etc
What are the two mechanisms proposed to account for cellular aging
- The Clock: genetically determined clock
- Wear and tear: effects of continuous exposure of exogenous influences
What are the three theories about how cells count the number of divisions?
Cellular clock theory (clock genes)
Neuroendrocrine theory (changing hormone levels)
Immune system susceptibility theory (decline in immune cells)
What are the four theories about how cellular damage affect divisions?
Wear and tear (telomere shortening)
Free radical theory ( oxidative stress)
DNA mismatch accumulation theory (genome error due to DNA mutation/damage)
Cross-linking theory (proteins and DNA develop unwanted attachments
What is the roles of telomeres?
Short, repeated sequences of DNA that ensure complete replication of chromsome ends and protect chromosomal ends from fusion and degrdation
What does telomerase do?
Directs RNA template-dependent DNA synthesis, in which nucleotides are added to one strand at the end of a chromsome
