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NUFS 356 > L18 Physiology of Aging > Flashcards

L18 Physiology of Aging Flashcards

1
Q

When does aging begin?

A

After developmental stage

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2
Q

What is an accelerated ager, normal ager, and a super ager?

A

accelerated ager biological age is higher than the chronological age.
normal ager: biological age matches the chronological age
super ager: body ages very slow

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3
Q

What are the DRI age groups for over 50?

A

51 - 70

>70 years

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4
Q

What are the characteristics of aging?

A
  • molecular and cellular changes
  • a decrease in regeneration capacity
  • changes in tissue, organ and system functions
  • a decline in the ability to respond to stress and environmental stimuli (less likely to return to homeostasis)
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5
Q

What are the theories of aging?

A
  • evolutionary
  • genetic and protein dysfunction
  • free radical damage
  • cell senescence
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6
Q

One of the causes of aging is damage done to genetics. What are the 4 primary hallmarks of aging due to genetic damage?

A

genomic instability
telomere attrition
epigenetic alterations
loss of proteostasis

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7
Q

What causes genomic instability?

A
  • genetic damage from exogenous and endogenous sources that reduce DNA repair mechanisms. Damaged DNA accumulate.
  • some of these exogenous and endogenous sources are free radical reactive oxygen species (ROS). For example superoxide (O2-), and hydrogen peroxide (H202). They are generated mainly in the mitochondria and damage proteins, lipids, and DNA.
  • there are some antioxidant enzymes that neutralize ROS. For example, superoxide dismutase, catalase, glutathione, and peroxidase (some require specific nutrients from the diet).
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8
Q

What are some nutrients and minerals that are important in antioxidant function?
*increasing the expression of genes producing antioxidants in some animals has resuted in longer life

A

copper
zinc
manganese

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9
Q

What is telomere attrition, one of the damages to DNA that causes aging?

A
  • telomeres are a chromosomal part of the DNA that is easily damaged
  • it is the loss of length in the telomere and the repeated repication of the shortening strand which leads to impaired cellular replication
  • telomerase repairs the damage
  • cancer cells have high telomerase so too much can be problematic
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10
Q

What is an epigenetic modification, one of the damages to DNA that causes aging?

A
  • they occur throughout the lifespan from numerous methods (histone modification, DNA methylations, ect.)
  • it is an adaptive response in gene expression
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11
Q

How does the dysregulation of protein homeostasis contribute to aging?

A
  • proper protein folding is important for proper protein function
  • aging is associated with a loss of the repair mechanisms and accuulation of misfolded and unfolded proteins
  • mechanisms for protein folding: lysosome autophagy, ubiquitome-proteasome pathway, heat shock protein mediated folding
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12
Q

What are 3 of the body’s responses to cell damage related to the aging process?

A
  1. deregulation of nutrient sensing
  2. mitochondiral dysfunction
  3. cellular senescence
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13
Q

Explain the deregulation of nutrient sensing, the body’s response to cell damage

A
  • damage to cells can cause a downregulation of nutrient sensing pathways that use anabolic pathways for functioning ??
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14
Q

Explain mitochondrial dysfunction, one of the body’s responses to cell damage?

A
  • the mitochondiral turnover rate is reduced which leads to an increase in cell damage (ie. there is an increase in ROS causing damage, oxidative damage to proteins, changes in lipid membranes, telomere attrition, destabilization of respiratory chain complexes)
  • endurance training and dietary restrictions are known to reduce mitochondrial damage
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15
Q

Explain cellular senescence, one of the body’s reponses to cell damage.

A
  • cell senescence is when the cells stop replicating. This process prevents the replication of damaged cells and triggers the removal of damaged cells by an immune response.
  • can be naturally caused by aging, telomere attrition, and DNA damage
  • This is a positive function in the young but in the old, there is an accumulation of senescent cells or a decrease in clearance of senescent cells causing inflammation, and decreases tissue function, stem cell exhaustion, ect, and ultimately aging.
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16
Q

One of the effects of cellular senscence is stem cell exhaustion. What does this effect in the body?

A

anemia, myelodydisplasia, osteoperosis, decreased fracture repair, decreased repair of muscle fibres, and decreased intestinal function.

17
Q

What are some oral, vision, olfactory, dental changes that occur with aging?

A
  • teeth become ore brittle
  • changes in tooth and mouth mucosal tissue structure
  • reduced saliva
  • reduced function of sensory cells (sight, smell, touch, taste)
  • all of these can impact food intake
18
Q

What are some gastrointestinal changes that occur with aging?

A
  • there is slower motility which delays stomach emptying
  • in the stomach, there are some changes that can affect digestion and absorption of nutrients. For example, decreased nitric oxide, increased stretch, and atrophic gastritis.
  • reduced absorption of nutrients in the small intestine
  • liver decreases in size and decreases blood flow which results in lower detoxification ability
  • impacts satiety and nutrient needs
19
Q

What are some skeletal and muscle changes that occur with aging?

A
  • There is a decrease in size and number of muscle fibres (type 2 more than type 1)
  • reduced innervation
  • lowered muscel strength (upper body more than lower body)
  • sarcopenia nd disability
20
Q

What are some bone changes that occur with aging?

A
  • resorption is greater than formation
  • osteoclasts have greater function than osteoblasts
  • loss of mineral density and protein, as well as changes in mineral crystal properties
  • accumulation of microfractures
  • can result in a loss of height and increased risk of microfractures
21
Q

What are some cardiovascular and pulmonary changes that occur with aging?

A
  • decreased muscle fibres and hypertrophy
  • lower heart rate and maximal output
  • increased vascular resistance
  • reduction in lung function and VO2 max
  • loss of diaphram and inter-rib muscle strength, changes in chest wall
  • alterations in ability to perfom activity
22
Q

What are some renal changes that occur with aging?

A
  • there is a reduced number of nephrons, slowed filtration rate, and decreased blood flow
  • the kidneys usually maintain normal function but they are slow to rspond to sudden changes
  • can impact fluid and electrolyte balance
23
Q

How does the skin change with age?

A
  • thinning of the skin layers
  • changes in collagen structure: superficial laxity
  • irregular pigmentation
  • reduction in 7-dehydrocholesterol (precurson to vitamin D when exposed to sunlight)
24
Q

What is the precursor to vitamin D and what age groups may need a supplement?

A
  • infants need vitamin D supplement

- 50+

25
Q

What are some cognitive changes that occur with aging?

A
  • less receptors but increased sensitivity

- reduction in short term memory, encoding and retrieval, and executive function

26
Q

What are some immune system changes that occur with aging?

A
  • immune function capacity decreases with age
  • reduced bone marrow and blood cell production
  • lower resistanc to infectious disease
  • autoimmune phenomena increases with age
  • chronic mild inflammatory response
27
Q

What are some neuroendocrine changes that occur with aging?

A

hypothalamus-pituitary hormone system

  • is the regulator of development, growth, puberty: maintenance of homeostasis
  • is the pacemaker that signals the onset and termination of each life stage
  • estrogen and testosterone (HPG axis)
  • appetite and thirst (hypothalamus)
28
Q

What are the components of the hypothalamus-pituitary system?

A

The hypothalamus intergrates information

  • has sympathetic and parasympathetic function
  • regulates behaviors like fear, sexual, and eating
  • its endocrine function acts on the pituitary gland by secreting hormones

The pituitary gland releases hormones that have peripheral effects

  • GH, thyroid stimulating hormone, adrenocorticopic hormone, LH, FSH, prolactin, oxytocin, and antidiuretic hormone (ADH)
  • act on peripheral endocrine glands like the adrenal cortex, and thyroid glands
29
Q

What are the components of the HPA axis?

A

Hormones act on the adrenal gland

  • in the medulla, epineprine and norepinephrin act on the sympathetic neural system to change blood pressure and metabiolism
  • in the cortex, glucocorticoids mineralocorticoids and androgens effect them

There is a decrease in HPA function with age which results in a decline in hormones and feedback mechanisms

30
Q

How does neuroendocrine function effect appetite regulation with aging?

A
  • there is a decrease in ghrelin

- there is an increase in satiety hormones and neuropeptides like CCK, leptin, and amylin

31
Q

What is the anorexia of aging?

A
  • about 20% of older adults experience a reduction in appetite
  • there are higher rates in adults with chronic conditions

Energy expenditure is decreased

  • thermic effect of food is delayed and/or decreased
  • physical activity decreases
  • resting metabolic rate decreases
  • taste and smell of food decreases, more satiety hormones, decreased nitric oxide, lower parts of the stomach fill faster and leads to antral stretching causing early satiety
32
Q

What are some of the pathological mechanisms of the anorexia of aging?

A
  • poor oral health (dysphagia)
  • mental health and cognitive function
  • medications
  • diseases of the GIT
  • cachexia of disease
  • inflammation
33
Q

How do you treat anorexia of aging?

A
  • appetite stimulating medications but are mostly ineffective
  • address social factors related to obtaining and preparing food
  • nutritional support if undernourished and unable to meet nutritional needs through foods (oral nutrition, external nutrition, and parentaral nutrition)
34
Q

When is oral nutritional support recommended for older adults?

When is it not recommended?

A
  • when they are undernourished and require an increase in energy, protein and micronutrient intake)
  • prior to and after surgery (particularly hip)
  • help to treat stomach ulcers

Not recommended if they can consume foods. First increase energy and protein content of foods and introduce fortified foods and use sensory and texture modifications to increase intake.

Nutrition drink are expensive and high in sugar and they are unlikely to help with anorexia bc of early satiety

NUFS 356 (24 decks)

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