intrinsic aging

Examples of intrinsic aging in the following topics:

• Effects of Aging on the Integumentary System

  • The integumentary system undergoes intrinsic and extrinsic cutaneous aging, primarily involving the dermis.
  • Intrinsic and extrinsic aging are terms used to describe cutaneous aging of the skin and other parts of the integumentary system.
  • The effects of intrinsic aging are caused solely by internal factors.
  • Sometimes called chronological aging, intrinsic aging is an inherent degenerative process due to declining physiologic functions and capacities.
  • Wrinkles form due to intrinsic (loss of collagen) and extrinsic (photodamage) aging.

• Aging and the Immune System

  • As aging occurs, the immune system begins to lose its ability to ward off pathogens.
  • Immunosenescence refers to the gradual deterioration of the immune system brought on by natural age advancement.
  • This age-associated immune deficiency is found in both long- and short-living species as a function of age relative to life expectancy.
  • There is a notable decline in the total number of phagocytes in older adults, coupled with an intrinsic reduction of their bactericidal activity.
  • The functional capacity of T-cells is most influenced by the effects of aging.

• Capacity of Different Tissues for Repair

  • The peripheral nervous system (PNS) has an intrinsic ability for repair and regeneration.
  • The axons themselves also lose the potential for growth with age.
  • The remodeling phase takes three to five years depending on factors such as age or general condition.

• Asthma

  • Asthma may also be classified as atopic (extrinsic) or non-atopic (intrinsic).
  • Strict reduction of dust mite allergens, for example, reduces the risk of allergic sensitization to dust mites, and modestly reduces the risk of developing asthma up until the age of 8 years old.

• Regeneration of Nerve Fibers

  • While the PNS has an intrinsic ability for repair and regeneration, the CNS is for the most part incapable of self-repair and regeneration.
  • The axons themselves also lose the potential for growth with age.

• Aging and the Urinary System

  • As with other organs, kidney function may be slightly reduced with aging.
  • As the kidneys age, a number of events occur.
  • The bladder wall changes with age.
  • Under usual conditions, kidney function remains normal in an aging person, although sometimes kidneys in an aging person may function more slowly than those of a younger person.
  • Summarize the changes that may occur in the urinary system with aging

• Aging and the Heart

  • As a person ages, the walls of the heart thicken, the heart becomes heavier, valves stiffen and leak, and the aorta becomes larger.
  • After age 30, changes in the blood vessels that serve the brain tissue that reduce nourishment to the brain, resulting in the malfunction and death of brain cells.
  • By age 80, cerebral blood flow is 20% less and renal blood flow 50% less than at age 30.
  • The health of the myocardium depends on its blood supply, and with age there is greater likelihood that arthrosclerosis will narrow the coronary arteries.
  • Arrhythmias are also more common with age, as the cells of the conduction pathway become less efficient.

• Tissues and Aging

  • All body systems and their composite tissues are affected by aging.
  • In the skeletal system, aging is accompanied by the loss of bone tissue.
  • Muscle bulk and strength declines especially after the age of 70, and as much as 30% of skeletal muscles are lost by age 80.
  • Sensitivity to odors and taste decline with age.
  • By the age of 70, the filtering mechanism is only about half as effective as it was at age 40.

• Muscles that Cause Movement at the Foot

  • Although many extrinsic muscles attach within the dorsal compartment, there are only three intrinsic muscles which act on the foot and two extrinsic muscles which act on the foot rather than the ankle.
  • Extensor Digitorum Brevis - The extensor digitorum brevis muscle is a deep-lying intrinsic muscle lying beneath the tendon of the extensor digitorum longus.
  • Extensor Hallucis Brevis - The extensor hallucis brevis muscle is an intrinsic muscle of the foot lying between the extensor digitorum longus and lateral to extensor hallucis longus.

• Coagulation

  • The coagulation cascade is classically divided into three pathways: the contact (also known as the intrinsic) pathway, the tissue factor (also known as the extrinsic pathway), and the common pathway.
  • The intrinsic pathway (contact activation pathway) occurs during exposure to negatively charged molecules, such as molecules on bacteria and various types of lipids.
  • When factor X is activated by either the intrinsic or extrinsic pathways, it activates prothrombin (also called factor II) and converts it into thrombin using factor V.