Endocrine System & Environmental and Thermoregulatory Factors

2nd part of final 3

What major endocrine glands show age-related changes?

Pituitary, pancreas, adrenal, and thyroid glands.

What is the role of the anterior pituitary gland in aging?

It plays a major role in hormone production and is significantly involved in age-related endocrine changes.

How does aging affect thyroid hormones?

Reduced TSH from the anterior pituitary leads to lower T3 and T4, decreasing glucose metabolism and protein synthesis.

How does a decline in thyroid hormones affect Resting Metabolic Rate (RMR)?

It contributes to reduced RMR, along with increased fat mass, decreased lean mass, and reduced water content from cell loss.

What is andropause?

The gradual decline in testosterone levels in aging men.

What happens to DHEA levels with aging?

DHEA/DHEAS from the adrenal cortex decline progressively after age 30, reaching 20–30% of youthful levels by age 75.

What role does DHEA play in aging?

It's a biomarker of aging, affects anabolic hormone levels, and influences protein turnover.

How does IGF-1 change with age?

It decreases in parallel with declines in Growth Hormone (GH), reducing protein synthesis and tissue growth.

What lifestyle factors may slow endocrine-related aging?

Nutritional supplements, diet, and physical activity (though more research is needed on mechanisms).

How does aging affect heat dissipation?

Heat dissipation declines ~4% per decade, even in adults as young as 40 during exercise-heat stress.

Why do older adults produce more heat during exercise?

Due to higher metabolic cost at a given absolute workload, such as increased O2 use when walking at the same speed as younger adults.

What primarily determines heat loss mechanisms during exercise?

Relative exercise intensity (% VO2max), not age alone.

How does sweat rate change with age?

Sweat gland density remains the same, but gland output declines, reducing evaporative cooling.

What is sweat rate more closely related to—age or fitness?

Cardiorespiratory fitness (VO2max).

What causes impaired vasodilation in older adults?

Reduced skin blood flow due to aging and decreased cardiac output, impairing blood delivery to the skin.

How does Type 2 diabetes (T2DM) affect heat tolerance?

T2DM reduces microvascular response, sweating, and heat dissipation—even in well-controlled cases without neuropathy.

How does chronic disease impact thermoregulation during exercise?

Conditions like heart failure reduce skin blood flow and vasodilation, decreasing heat tolerance even with normal core temperature and sweating.

Can older adults improve thermoregulation?

Yes. Heat acclimatization and physical training improve vasodilation, sweat rate, and blood flow redistribution.

What is dementia?

A group of symptoms caused by brain changes, leading to confusion, memory loss, difficulty with familiar tasks, language issues, and mood/behavior changes.

Is dementia a normal part of aging?

No, although risk increases with age, dementia is not caused by brain tissue loss alone.

: What brain areas experience tissue loss with age?

Cerebral cortex, hippocampus, and cerebral white matter.

At what age can CNS tissue loss begin?

As early as the third decade of life (~30 years old).

How can fast motor units be preserved with aging?

By continuing to move quickly and lift heavy loads, preventing their degradation and conversion to slow fibers.

What happens when fast motor units degrade with age?

They may be reinnervated by slow motor units, preserving function but reducing speed.

How large is the total surface area of the body’s endothelium?

Comparable to about eight tennis courts.

What hormone released by the liver decreases with age alongside GH?

IGF-1 (Insulin-like Growth Factor 1)