Digestive System Effects
Intestinal muscle tone decreases, causing a decline in peristaltic contractions causing constipation.
Straining to eliminate can stress the walls of blood vessels, causing hemorrhoids. The walls of the colon
lose firmness and can produce symptoms of painful and dangerous diverticulitis. Sphincters muscles can
reduce functionality leading to esophageal reflux and heartburn. The mucosal lining of the small intestine
becomes thinner thereby decreasing the efficiency of nutrient absorption. Digestive enzymes decrease
affecting impairing the absorption of vitamins and minerals in particularly B12, iron and calcium. Olfactory
senses (smell) are diminished and along with tooth loss gastric sensitivity can lead to dietary changes that
affect the entire body.
Nutritional requirements do not necessarily change, caloric requirements do. During each decade after 50,
caloric requirements are reduced by ten percent due to changes in metabolic rates, body mass, activity,
and exercise. There is still much study going on with regard to elderly nutritional requirements. However,
the elderly require Vitamin D supplementation if they are to absorb calcium efficiently. This is due to
changes in the skin, which leads to a decreased tolerance to heat and may cause the elderly avoid the
sun. Reduced sun exposure can result in a decrease in the absorption of Vitamin D. Vitamin D is normally
converted to the hormone calcitriol, which stimulates calcium absorption in the small intestine. Since the
synthesis of proteins and digestive enzymes decreases with age, the elderly should eat more easy-to-
digest proteins, i.e., more vegetable proteins and less animal proteins.
Endocrine System Effects
Metabolism is a function of the Endocrine system. The body's metabolic rate (how quickly the body
converts food into energy) slows. This can lead to obesity and an increase in LDL "bad" cholesterol levels.
Due to aging, changes in the endocrine system result in reduced levels of hormones, which do not
normally lead to hormonal deficiencies.
A decrease in thyroxine secretion by the thyroid gland results in a decrease in the metabolic rate, which is
one of the reasons the elderly are intolerant to cold.
Decreased function of the anterior pituitary produces less of the growth hormone resulting in a decrease in
protein synthesis used for developing muscle mass. In addition, growth hormone reductions are
responsible for an increase of fat storage and the reduced ability to utilize fat for energy.
Decreases in the levels of adrenal cortical hormones reduce inflammatory responses, protein synthesis
and salt balance. However, the levels are usually sufficient to maintain homeostasis (balance) of water,
electrolytes, and nutrients. The adrenal glands (atop the kidneys) produce less cortisol, which regulates
blood pressure, cardiovascular function and the body's use of proteins, carbohydrates, and fats. The
reduction of cortisol affects the body's ability to convert glucose to glycogen by the liver. Norepinephrine is
also secreted by the adrenal glands is used for the reverse conversion of glycogen to back to glucose and
fats to fatty acids for energy. Both Norepinephrine and Epinephrine (adrenaline) are secreted by the
adrenal glands as part of the "fight or flight" response, thereby raising heart rate and blood pressure.
The pancreas produces digestive enzymes and insulin. Insulin production diminishes with age, which
limits conversion of glucose to glycogen in liver and muscles for later energy use. In general, insulin acts
to reduce levels of glucose. In muscle, insulin assists in protein synthesis, as well as, the cellular uptake of
glucose and facilitates its conversion to glycogen used for muscular energy. In adipose (fat) tissue, insulin
assists in the cellular uptake of glucose and its conversion to fatty acids as triacylglycerols for storage. In
the liver, insulin facilitates glucose conversion to glycogen for energy. Reduction in insulin production can
reduce the level of cellular energy since the cells cannot access the calories contained in the glucose.
In general, unless there are pathological conditions, the endocrine system functions near normal levels
into aging.