The Classic Comprehensive Handbook of Cat Care
NERVOUS AND ENDOCRINE SYSTEMS
Integrating the functions of the various parts of the body is the main function of the nervous system and of the endocrine system. You cannot normally see or feel any of the components of these systems when you examine your cat. Nonetheless, if one system or the other is functioning abnormally it is usually not long before some striking change will occur in your animal. In general, the nervous system (brain, spinal cord, and peripheral nerves) is responsible for rapid body adjustments to environmental and internal stimuli. The endocrine system, for the most part, is responsible for more gradual responses that are mediated by chemical substances secreted by endocrine glands into the bloodstream (hormones). Complete neurological and endocrine examinations are not a routine part of your or your veterinarian’s physical exams. For your information a brief outline of the functions of the various endocrine glands is listed. Look at the drawings of the internal anatomy to see where these various glands are located.
| ENDOCRINE GLAND | FUNCTION |
|---|---|
| Adrenal glands | Cortex: influences fat, carbohydrate, protein, and electrolyte metabolism. Affects water excretion and blood pressure; stimulates stomach acid secretion; inhibits inflammation and the immune system. Medulla: secretes adrenaline and noradrenaline, which raise blood sugar and help adaptation to stress. |
| Enteroendocrine cells of digestive tract | Secrete various hormones that regulate digestive tract motility and secretion of digestive enzymes. Some control over insulin secretion and the regulation of satiety. |
| Heart | Atrial natriuretic peptide: affects sodium and water balance. |
| Islet of cells of the pancreas | Secrete insulin, amylin, and glucagon, which affect blood sugar level and fat and protein metabolism. Insulin also stimulates the appetite at the brain hypothalamus level. |
| Kidney | Renin: Affects blood pressure and sodium balance. Erythropoietin: Enhances red cell production. |
| Ovaries | Influence development of feminine characteristics; influence sexual behavior, estrus, and pregnancy. |
| Parathyroid glands | Influence calcium and phosphorus metabolism. |
| Pineal body | Affects sexual development and sexual cycles by sensing photoperiods. |
| Pituitary- hypothalamus | Regulates the activity of the ovaries, testes, thyroid, and adrenal cortex. Secretes growth hormone, which stimulates growth of body tissues. Controls milk secretion and milk letdown. Affects body water balance and thermoregulation. May modulate both short- and long-term memory |
| Testes | Influence development of masculine characteristics; influence sex drive. |
| Thyroid | Controls metabolic rate and affects calcium and phosphorus metabolism. |
Don’t be surprised if your first examination of your cat takes an hour or two. If you have a kitten or an adult cat who has not been handled frequently before, it may take a full day to complete the exam because you may have to divide it into several parts separated by rest periods to compensate for your cat’s reluctance to hold still for examination. Repeat your physical examination at least once a week while you are learning what is normal for your cat. By doing this you will train your cat to cooperate, and you will soon find that you no longer need to refer to this book so often. The time it takes for you to perform the examination will shorten considerably as you practice. You should eventually be able to finish it in about fifteen minutes.
Most veterinarians become so skilled at physical examination that, until you become aware of what they are doing, you may not even realize that a physical examination is being performed. Your veterinarian may easily perform a routine physical in five or ten minutes. Special examinations, of course, take much longer.
Once you are familiar with your cat’s anatomy, how frequently you repeat certain parts of a physical examination varies. You can get a good idea of your cat’s general health by just being aware of his or her appetite and activity level. Be sure to examine the ears, eyes, teeth, and skin at least every two weeks. And examine the mammary glands of females, in particular, monthly. If your cat spends a considerable portion of time outside, you will probably have to make more of a conscious effort to do the examinations. Be sure to set aside several times a week to study your cat’s condition; most illnesses are best treated if discovered early.