Page 175 - 86 human physiology part-2

Chapter 19

Digestive System

The changes assocated with aging of the digestive system include loss of strength and tone of the
muscular tissue and it's supporting muscular tissue, decreased secretory mechanims, decreased motility
of the digestive organ's, along with changes in neorosensory feedback regarding enzyme and hormone
release, and diminished response to internal sensations and pain. In the upper GI tract common changes
include periodontal disease, diffuclty in swallowing, reduced sensitivity to mouth irritations and sores,
loss of taste, gastritis, and peptic ulcer disease. Changes that may appear in the small intestine include,
appendicites, duodenal ulcers, malabsoration, and maldigestion. Other pathologe's that increase in
occurance with age are, acute pancreatitits, jaundace, and gallbladder problems. Large intestinal
changes such as hemmorrhouds, and constipation may also occor. Cancer of the rectum are quite
common.

Urinary System

As we get older kidney function diminishes,by age 70 the filtering mechanism is only about half as
effective as it was at age 40. Because water balance is altered and the sensation of thirst diminishes
with age, older pepole are more suseptible to dehydration. This causes more urinary tract infections in
the elderly. other problems may include nocturia ( excessive urination at night ), incresed frequency of
urination, polyuria ( excessive urine production ), dysuria ( painful urination ), incontience, and
hematuria (blood in the urine). Somekidney diseases that are common as we age include, acute and
chronic kidney inflamation's, and renal calculi (kidney stone's). The prostate gland is often implicated
in various disorders of the urinary tract. Prostate cancer is the most common cancer in elderly males.
Because the prostate gland encircles part of the urethea, an enlarged prostate gland may cause difficulty
in urination

Respiratory Systems

With the advancing of age, the airways and tissue of the respiratory tract become less elastic and
more ridgid. The walls of the alveoli break down, so there is less total respiratory surface available for
gas exchange. This decreases the lung capicaty by as much as 30% by the age of 70. Therefore, elderly
pepole are more suscepticale to pneumonia, bronchitis, emphysema, and other pulmanary disorders.
For a more complete discussion of the respiratory system please visit the Respiratory System chapter

Lung cancer

Lung cancer is a cancer of the lungs characterized by the presence of malignant tumours. Most
commonly it is bronchogenic carcinoma (about 90%). Lung cancer is one of the most lethal forms of
cancer worldwide, causing up to 3 million deaths annually. Only one in ten patients diagnosed with this
disease will survive the next five years. Although lung cancer was previously an illness that affected
predominately men, the lung cancer rate for women has been increasing in the last few decades, which
has been attributed to the rising ratio of female to male smokers. More women die of lung cancer than
any other cancer, including breast cancer, ovarian cancer and uterine cancers combined. Current
research indicates that the factor with the greatest impact on risk of lung cancer is long-term exposure
to inhaled carcinogens. The most common means of such exposure is tobacco smoke.

390 | Human Physiology