15/16 - Nutrition and aging Flashcards
(33 cards)
What are some of the hallmarks of aging? (4/9)
>genomic instability >telomere attrition >mitochondrial dysfunction >cellular senescence >epigenetic alterations >loss of proteostasis >deregulated nutrient sensing >stem cell exhaustion >altered intercellular >communication
What are the 2 consequences of reductions in salivary flow (due to ageing)
Xerostomia = dryness of oral mucosa Dysphagia = impairment of oral function
What is Periodontal disease and what does it cause?
Lesions on the peridontal tissues (tooth supporting structures)
Cause tooth loss
What is Atrophic gastritis and what does absorption problems does it cause?
Reduction in the production of acid, intrinsic factor and pepsin
- limits calcium, iron, folate, vitamin B12 absorption
Give some impacts of the ageing process on GI tract function (6)
- Loss of teeth
- Xerostomia -> Dysphagia
- Atrophic gastritis
- Bacterial overgrowth of small intestine
- Lactose intolerance
- Loss of colon motility
What is the impact of the ageing process on physiological systems? (7)
- Organs lose function • Decline of Immune function • High levels of chronic illnesses • Connective tissues and blood vessels become stiff - Decreased brain neurones - Psychological + cognitive changes - Sensory impairments
What is the impact of ageing on body composition (4)
-Increased body fat, sarcopenic obesity
• Decreased muscle and lean tissue
• Decreased production of hormones
• Bone mineral density declines
What is the Hayflick limit?
a set number of divisions, at which point the cell enters the senescent stage and is permanently arrested in the G1 phase of the cycle
What is senescence?
capacity of the stem cells to regenerate tissues and
restore tissue function becomes outstripped
Cell Senescence is associated with permanent arrest of cells at the ___ stage of the mammalian cell cycle.
Cell Senescence is associated with permanent arrest of cells at the G1/S stage of the mammalian cell cycle.
What are the 3 mechanisms of cellular senescence?
- Oxidative senscence
- Telomere shortening
- INK4a/ARF(p14) axis
What two drivers of cellular ageing act on the P53 enzyme?
DNA damage (oxidative senescence) Telomere shortening
What happens in ageing which increase oxidative damage to cells, activating P53?
- Increased ROS
- Decreased antioxidant capacity
- Decreased cell capacity to repair damage to DNA
What is P53 and what is its role in the cell cycle?
- A transcription factor
- Activated as a result of cell cycle abnormalities or DNA damage
- Causes senescence or apoptosis
What does P53 activate in order to inhibit the cell cycle?
P21 (cyclin-dependent kinase inhibitor 1)
What is the sequence of events that allows P53 to cause apoptosis?
P53 -> Bax -Cytochrome C release from mitochondria \+ APAF1 (apoptotic peptidase activating factor 1) -> Activation of caspase 9 -> Activation of caspase 3-7 Apoptosis
What is the repeating sequence of bases on the telomere?
What happens every time the cell divides?
What does this cause senescence or apoptosis?
> TTAGGG
Telomeres shortern with each divide as DNA polymerase is unable to copy the ends.
Telomerase can replace some.. but not all
Critical levels = p53 activation
Other than telomere shortening, what other 3 events can activate p53?
> DNA damage
Hypoxia
Hyperproliferative signals
What are the 2 locus at chromosome 9p21 which encode two distinct
proteins known to have a pro-ageing influence?
INK4a and ARF
What is the role of INK4A and how does it contribute to the physical signs of ageing?
Inhibitor of cell cycle - arrest in the G1 phase
Promotes accumulation of senescent cells within tissues
and apposes regen of tissues by stem cells
What is the role of ARF
induces G1 and G2 arrest in the cell cycle as it stabilizes p53
How does caloric restriction increase lifespan?
> Reduce ROS production
Reduce body mass
Insulin, thyroid and sex hormone are reduced
Reduces inflammatory processes, and therefore oxidative processes
Upregulates repair system
Decreases DNA damage
What can cause protein deficiency in the elderly?
> Finances > Poor appetite > Avoidance of fat intake > Trauma > Difficulty chewing > High needs
What are some results of protein deficiency in the elderly
> Suppressed immunity
Slow wound healing
Loss of muscle mass
e.c.t
