SKELETAL MUSCLE MUSCLE AGING

SKELETAL MUSCLE MUSCLE AGING

1. From the age of 40 there is an progressive lose of bone mass, that increase in women during the years after the cessation of the ovarian activity

   • The woman lose +40% of the bone mass in the column and almost 60% of the hip
   • DETERMINING FACTORS OF THE MODIFICATIONS IN THE REMODELING
     • NUTRICIONAL FACTORS
       • Deficit
         • calcium
           • The calcium estimulate the secretion of parathormone
             • This hormone increase the bone reabsorcion of calcium and the production of calcitriol
           • In the old man the intake of calcium is under the normal suggest of intake
           • 1.500 mg/d is the normal consume
         • Vit D
           • Acelerate the bone replacement
           • mineralization inhibition
           • treatment with vitamin D supplements may reduce the rate of osteoporotic fractures in the elderly
     • HORMONAL FACTORS
       • Sexual hormone and growth hormone have an anabolic effect on bone
       • In males, testosterone is the main androgen and is 95% responsible for testicular synthesis
         • With age, a progressive decrease in androgen activity is observed, which depends on a certain decrease in testicular synthesis and, above all, on an increase in the levels of transporter protein (SHBG), which reduces the fraction of free testosterone
       • In premenopausal women, more than 95% of estradiol is synthesized in the ovaries.
         • After the cessation of ovarian activity, the small concentrations of estradiol that are detected in the blood of postmenopausal women result from transformation in the liver and other tissues, such as adipose
           • Endogenous estrogens may also influence bone loss experienced by elderly postmenopausal women
     • PARACRINE FACTORS
       • serum osteoprotegerin (OPG) concentration progressively increases with age
         • probably to counteract the increase in resort activity in elderly people
     • MECHANICAL FACTORS
       • Long bones and vertebral bodies require small but frequent loads to maintain bone mass.
       • the mass and strength of the skeleton are determined by the need to resist the loads and deformities imposed by the extreme activities of daily life
     • GENETIC FACTOR
       • Maternal history of fracture is associated with an increased risk of fracture in daughters
       • In people, the multiplicity of environmental factors makes it difficult to know the heritability of fractures
       • osteoporosis is considered a complex genetic trait.
   • MUSCLE AGING
     • Lean body mass decreases between the ages of 35 and 70, mainly due to the loss of skeletal muscle mass and the progressive decrease in the number and size of muscle fibers
     • the peak of muscle mass is reached in youth, around the age of 25, and remains relatively stable until the age of 50
     • The loss of muscle is mainly due to the decrease in the number of muscle fibers, especially type II or fast-twitch fibers and, to a lesser extent, to their atrophy
   • MUSCLE DENERVATION
     • Muscle denervation causes a loss of motor units and therefore muscle fibers in the elderly.
     • Up to the age of 60, the number of motor units is maintained acceptably, but from this age on, a progressive decrease is seen in the number of motor neurons in the anterior horn of the spinal cord and in the number of neuromuscular junctions in the peripheral nerves.
   • PROTEIN METABOLISM
     • The alteration in protein metabolism could explain the slight muscle loss that appears before the age of 60
     • Unlike what happens with muscle denervation processes, protein synthesis begins to decline from the age of 50 and continues to do so until later in life.

2. UNIVERSIDAD DE COLIMA

3. FACULTAD DE MEDICINA

4. 4TO SEMESTRE

5. INGLES

6. PETER DESIRE LIPPEVELD

7. Miguel Angel Montero Arreola

8. PMC. (2017, 14 junio). Exercise Promotes Healthy Aging of Skeletal Muscle. NCBI. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5045036/