WEEK 4: Ageing and death Flashcards
What is aging?
Ageing is simply the process of becoming older and mature; or becoming a senescent.
Why do we Age?
Because of cellular aging.
Ageing is a risk factor for diseases.
Name 3 examples of such diseases.
Ischemic heart diseases
Alzheimer’s diseases
Cancer
What is cellular aging?
Cell ageing is defined as
*Loss of functional capacity
*Progressive decline in proliferative capacity
which ends in cell death.
OR
Progressive decline in cellular function and viability
1. Caused by genetic abnormalities.
- The accumulation of cellular and molecular damage.
- Due to exposure to exogenous influences
Outline factors Contributing to Cell Ageing.
- Genetic factors
- Diet
- Social conditions
- Atherosclerosis
- Diabetes mellitus
- Age-related diseases, e.g., osteoarthritis
State some indicators of Declining Cell Function associated with ageing.
- Decreased oxidative phosphorylation
- Decreased synthesis of
Structural and enzymatic proteins
Cell receptors - Decreased capacity for uptake of nutrients
- Decreased repair of chromosomal damage
State the 4 main mechanisms of cellular ageing.
DNA Damage
Cellular senescence: the cessation of cell division.
Defective protein Homeostasis
Deregulated nutrient sensing
Outline morphologic alterations due to Cell Ageing.
- Irregular and abnormal location of nuclei
- Pleomorphic and vacuolated mitochondria
- Dilated and distorted endoplasmic reticulum
- Distorted Golgi apparatus
State some causes of DNA damage.
*By endogenous agents (ROS)
*By exogenous agents (physical, chemical, Biological)
*Premature Ageing, Werner syndrome, (Defective helicase)
What is cellular senescence?
State 2 causes of cellular senescence.
Cellular senescence is a phenomenon characterized by the cessation of cell division.
- After fixed number of cell division, cell leaves cell cycle, and becomes arrested in terminally Non dividing state.
- Telomere erosion.
What is a telomere?
Where is it found?
Short repeated sequence of DNA.
Found at the end of linear chromosome.
THE THEORIES OF CELL AGEING.
What is the function of telomeres?
Name the enzyme that regulate de novo synthesis of telomeres.
What is the function of telomerase?
- Normally, DNA damage is repaired by DNA repair enzymes. Accumulation of DNA damage due to defective DNA repair mechanisms induces ageing.
- Telomeres are critical for the stabilization of the terminal portion of chromosomes and anchoring them to the nuclear matrix.
De novo synthesis of telomeres is regulated by an enzyme called telomerase.
During somatic cell replication, a small segment of the telomere is not duplicated leading to telomere shortening and loss of DNA, inducing cellular ageing.
Telomerase repairs the shortened tips of chromosomes and maintains their length.
Telomerase activity upregulated telomere length maintained avoids cell ageing.
State the 6 systemic signs of ageing.
- Skin-Wrinkles
- Hair– Grey
- Bones—Reduced mobility
- Brain– Loss of memory
- Eyes—Poor vision
- Ears—Reduced hearing
The terminal events in death are visible in the 3 main systems of the body.
CNS, CVS and Respiratory system.
Outline what happens in each system.
CNS– Pupils dilated unresponsive to light
CVS– Unrecordable BP, No Pulse rate, No heart sounds
Respiratory system– No breath sounds, chest movement
What is Euthanasia?
What is it also known as?
The most controversial bioethical issue, the practice of ending life for reason of mercy.
Euthanasia is a legal painless killing of a patient suffering from an incurable and painful disease to eliminate pain and suffering.
Also known as Mercy Killing.
