The body changes in every phase of life. It reacts to activity, nutrition, environment, emotions, and so many more actions. The body is an effective action/reaction mechanism, it is a fast response unit capable of adjusting too nearly every situation. The human mind is made for adaption on the highest possible level.
But there is partly lose control by most individuals after 50. The body of the city-dweller increases in fat% even with a proper lifestyle. Nutrition and environment are important and intrusive factors. Here is an oversight of the different organs and glands with their change during an increase of age.
|Organ or System||Physiologic Change|
|Body composition||↓ Lean body mass ↓ Muscle mass ↓ Creatinine production ↓ Skeletal mass ↓ Total body liquid|
|General cells||↑ DNA damage and ↓DNA repair capacity ↓ Oxidative capacity Accelerated cell senescence ↑ Fibrosis Lipofuscin accumulation|
|Central Nervous System||↓ Number of dopamine receptors ↑ Alpha-adrenergic responses ↑ Muscarinic parasympathetic responses|
|Ears||Loss of high-frequency hearing ↑Hair growth|
|Endocrine system||↑ Insulin resistance and glucose intolerance|
|Menopause, ↓ estrogen, and progesterone secretion ↓ Testosterone secretion ↓ Growth hormone secretion ↑ Bone mineral loss ↑ Secretion of ADH (arginine vasopressin/antidiuretic hormone) in response to osmolar stimuli|
|Eyes||↓ Lens flexibility ↑ Time for pupillary reflexes (constriction, dilation) ↑ Incidence of cataracts|
|Digestive tract||↓ Splanchnic blood flow ↑ Transit time|
|Heart||↓ Intrinsic heart rate and maximal heart rate Blunted baroreflex (less increase in heart rate in response to a decrease in BP) ↓ Diastolic relaxation ↑ Atrioventricular conduction time ↑ Atrial and ventricular ectopy|
|Immune system||↓ T-cell function ↓ B-cell function|
|Joints||Degeneration of cartilaginous tissues Fibrosis ↑ Glycosylation and cross-linking of collagen Loss of tissue elasticity|
|Kidneys||↓ Renal blood flow ↓ Renal mass ↓ Glomerular filtration ↓ Renal tubular secretion and reabsorption ↓ Ability to excrete a free-water load|
|Liver||↓ Hepatic mass ↓ Hepatic blood flow ↓ Activity of CYP 450 enzyme system|
|Nose||↓ Smell ↑Hair growth ↑Saliva increase|
|Peripheral nervous system||↓ Baroreflex responses ↓Beta-adrenergic responsiveness and number of receptors ↓ Signal transduction ↓ Muscarinic parasympathetic responses Preserved alpha-adrenergic responses|
|Pulmonary system / Respiratory system||↓ Vital capacity ↓ Lung elasticity (compliance) ↑ Residual volume ↓FEV1 ↑ V/Q mismatch|
|Vasculature||↓ Endothelin-dependent vasodilation ↑ Peripheral resistance|
|↓=decreased; ↑= increased;|
Adapted from the Institute of Medicine: Pharmacokinetics and Drug Interactions in the Elderly Workshop. Washington DC, National Academy Press, 1997, pp. 8–9.