- Introduction
There is a lot more involved in aging than just grey hair, wrinkles or becoming a little shorter! Aging, like death, is an unfortunate certainty. However, individuals age at different rates, mostly due to physiological differences. Gerontologists (scientists who study aging) are of the opinion that aging results from the interaction of many lifelong influences, such as heredity factors, the environment, culture, diet, exercise, leisure, past illnesses, and many more.
Changes due to aging take place in all of the body’s cells, tissues and organs. These changes affect the functioning of all body systems. The human body is made up of trillions of different types of cells, all with the same basic structure. Tissues are layers of similar cells that perform a specific function. Different types of tissue group together to form organs. A system is an organization of organs that are arranged in such a way that together they perform complex functions. Systems are the most complex units of the human body.
Physiologically speaking the human body is at its peak at the age of 25. All organ systems in the human body undergo complex physiological changes with ageing, but the rate of change varies between various systems within an individual, as well as between individuals. As a result, there is no way to predict exactly how an individual will age.
- Cardiovascular system
Aging can be characterized by an increase in blood pressure, a slightly slower heart rate, a decrease in the amount of blood the heart can take, abnormal rhythms, and “heart murmur” sounds caused by stiffening and hardening of heart valves.
Cardiovascular aging results in changes such as arterial wall thickening and blood vessels “stiffening” (becoming less elastic), resulting in increases in systolic (contraction) arterial pressures, vascular resistance (to the flow of blood), and cardiac afterload (the pressure that the chambers of the heart must generate in order to eject blood out of the heart). Structural changes include a gradual loss of muscle fibers. The amount of blood that the heart pumps reduces by about 50% between the ages of 20 years and 90 years.
- Respiratory system
Aging affects the respiratory system through changes to the muscles (weakening of the diaphragm and other respiratory muscles); the bones of the ribcage (becoming thinner and changing shape); lung tissue (inability to keep the airways completely open and air sacs losing their shape); the nervous system (some loss in brain function that controls breathing may make breathing more difficult and less effective); and the immune system (it gets weaker and less effective in fighting lung infections). This results in greater risk for lung infections, shortness of breath, reduced oxygen levels and abnormal breathing patterns.
- Nervous system
The slowing of thought, memory and thinking processes are normally associated with aging, but the various components of the nervous system in effect undergo many changes with aging.
The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal. Its efficiency declines in old age, affecting, for example, the regulation of cardiovascular and urinary function.
The central nervous system gets affected by a decrease in neural density. By the age of 80 an estimated 30% loss of brain mass has already occurred, mostly grey matter. Aging also reduces the production of central neurotransmitters, for example serotonin, which effects mood, memory and motor function. Aging is also characterized by a reduction in the speed of processing and memory in the brain.
In the peripheral nervous system, aging results in some loss of motor, sensory and autonomic fibers, with an increasing decline in the signal transduction rate within the spinal cord and brain-stem.
- Kidneys
With aging the amount of kidney tissue and the number of filtering units (nephrons) decrease, with a resulting loss in surface area for filtration, while blood vessels harden, all resulting in blood being filtered more slowly.
The kidneys loses mass after the age of 40, from weighing about 400 g to around 300 g at age 90. The decline in renal blood flow starts from age 30 onwards, at the rate of about 10% per decade.
However, kidney function remains normal in a healthy aging person, but can be affected by factors such as health conditions or certain medicines.
- Gastrointestinal system
Aging increase the likelihood of esophageal and gastrointestinal disorders, due to physiological changes in the swallowing and peristalsis movements in the gastrointestinal tract. In addition there is a decline in the secretion of hydrochloric acid and pepsin, as well as an age-related decline in the absorption of some substances.
- Immune system
The immune system assist in protecting the body from foreign or harmful substances, such as bacteria, viruses, toxins and cancer cells, by making cells and antibodies that can destroy these harmful substances. Aging slows down the immune system’s responses and there are fewer immune cells in the body to assist with healing. A decline in the ability to detect and correct cell defects can lead to an increased risk of cancer.
It is also vital to remember that 80% of the body’s immune surveillance lies in the gastro-intestinal (gut) wall, where the microbiome (2 kg of beneficial bacteria) forms an integral part of this protection. With aging, as with chronic stress, the binding of these beneficial bacteria to the mucosal receptors in the gut wall becomes weaker. This also has an effect on digestion, absorption and bowel movement in the elderly.
For all these reasons it is essential to look after and maintain healthy gut function and immune surveillance as we grow older. This can be achieved by daily replenishment with a probiotic of human origin, plus Omega 3 and Vitamin D supplementation if necessary.
- Skin
With aging the epidermis (outer layer of skin) becomes thinner. Pigment containing cells decrease in number, resulting in a clear and pale look to the skin. Pigmented spots (age spots, liver spots), growth spots (skin tags, warts), and other blemishes appear on the skin. Age related changes in the connective tissue reduce the strength and elasticity of the skin. The blood vessels in the skin becomes more fragile and leads to easier bruising and bleeding under the skin. The subcutaneous layer of fat becomes thinner, leading to less natural insulation against cold weather. Sweat glands start to produce less sweat, with an adverse effect on cooling of the body.
Aging causes several structural changes in the skin, such as impairment of barrier function, reduced epidermal cell turnover, and a reduction in the number of keratinocytes and fibroblasts. Keratinocytes are the predominant cell type in the epidermis, the outermost layer of the skin, and their primary function is the formation of a barrier against environmental damage. Fibroblasts are the most common cells of connective tissue and plays a critical role in wound healing.
- Musculoskeletal system
Aging causes a loss of bone mineral density, more so in the case of women who lose bone at a rate of 2 – 3% per year after menopause, while men lose bone at a rate of about 1% per year after the age of 50. The loss of bone density increase the risk of fractures, osteopenia, and osteoporosis.
Aging also causes a decline in muscle mass (about 30% from the thirties to the eighties), as well as a loss of muscle strength.
- Endocrine system
The endocrine system consists of a complex network of tiny mini-factories that produce chemicals (called hormones) that influence and regulate the functioning of many other chemical processes in either neighboring or distant target cells in other organs and systems in the body. The endocrine network is closely integrated with the central and peripheral nervous systems, as well as the immune system. These tiny chemical factories either release their chemicals into the bloodstream, or into neighbouring cells, or even within cells themselves.
The endocrine system has key functions in the body, such as regulating the balance of sodium, water, calcium, and phosphate; controlling blood volume and pressure; regulating energy balance; coordination of the response to stress; and regulating reproduction, development, growth and senescence (biological aging).
As in any factory, these tiny mini-factories are also prone to wear and tear over time. Aging causes a decrease in the ability of cells and organs to respond to hormones, and the concentrations of many hormones decrease with age. An example in this regard is the reduced secretion of the male hormone testosterone in older men.
- Guidelines to healthy aging
Your health will show the effects of aging much sooner if you do not look after your precious body. A healthy lifestyle will surely slow down the aging process, and Harvard Medical School provides a number of guidelines for healthy aging:
- Regular exercise – about 30 minutes of moderate-intensity aerobic exercise and strength training per day – can help to prevent many diseases, such as type 2 diabetes, obesity, certain cancers, osteoporosis, osteoarthritis, and cardiovascular disease.
- A healthy diet with lots of colored vegetables and plant material can help to reduce the risk of many chronic diseases such as cardiovascular disease and certain kinds of cancer.
- By not smoking you also reduce the risk of cardiovascular disease and certain kinds of cancer.
- By avoiding the excessive use of alcohol, you reduce the risks of dependency, organ damage and even accidents.
- By keeping mentally and socially engaged, you reduce the risk of depression, stress and cognitive decline, while promoting wellbeing.
- Regular medical checkups assist with disease prevention and management.
- By introducing safety habits around the home, for example using handrails and assistive equipment, you can prevent falls and fractures.
Do remember, sleep is a wonderful restorative tonic at any age.
Sources:
Individual behaviors to encourage healthy aging for those 65 years or older. Harvard Health and Places Initiative, 2014. (www.research.gsd.harvard.edu)
Effect of aging of the body systems. Published online 25 October 2017. Encyclopedia Britannica Online. (www.britannica.com)
The physiology of aging. Published 3 October 2011. Medicine Journal (UK) (www.medicinejournal.co.uk)
Age-related physiological changes and their clinical significance. Published in The Western Journal of Medicine, December 1981. By Gerry R Boss, MD, and J Edwin Seegmiller, MD.
Aging changes in organs, tissues and cells. Review date 15 April 2017. MedlinePlus, website of the National Institutes of Health, USA. (www.medlineplus.gov)
Medical Physiology. A systems approach. Physiology handbook by Hershel Raff and Michael Levitzky. Published by McGraw Hill, 2011.
