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This unit on “The Affects Of Hormones On Human Development” will deal with the anterior lobe of the pituitary gland, the adrenal glands (the adrenal medulla and the adrenal cortex), placenta, islets of Langerhans, the thyroid gland and the ovaries and testis.
Basic information is presented about hormones, and general information is given on hormones and the specific influence they exert on the activity of the target gland.
The unit can be taught to students in grades five through eight.
The science and health teachers are encouraged to use a team teaching approach. Other features included in the unit are content, lesson plans, resources, and a bibliography.
Often children will ask questions repeatedly until they have the chance to assimilate the new facts they are learning. This unit can help students by letting them know that we are receptive to their questions and ready to provide answers, either on a one-to-one basis or to the class as a whole.
As a classroom teacher, you may want to take an active part in reinforcing or extending the basic learning your students will be gaining from this unit.
I encourage you to work closely with other educators in the school. You may be interested in reviewing the materials that are written by the other six teachers in “The Hormones and Reproduction Program”.
The endocrines are the great chemical regulators of bodily function. The substances which are secreted by the endocrines, and which serve as chemical messengers are called hormones, from the Greek hormon meaning arouse to activity. Another version of the word means vital principle which, the Greek believed, was contained in certain body secretions and generally enlivened the body.
Along with the nervous system, the endocrine system serves as the major means of controlling the body’s activities. The nervous system is built for speed; it enables the body to adjust its internal processes rapidly, as changes take place in the environment. The endocrine, on the other hand, regulate continuing process of longer duration including the body’s growth, sexual maturation and ability to reproduce. The pituitary at the base of the brain; the thyroid gland in the neck, the adrenals, a perched atop the kidney like miniature peaked caps; the insulin-making islets of Langerhans in the pancreas; the ovaries in the abdomen of the female; the testicles in the scrotum of the male. The placenta, which feeds the unborn child, also behaves like an endocrine, manufacturing special chemicals essentials to successful pregnancy.
Endocrines are bits of tissue tucked away in obscure corners of the body. But in the widespread control they exercise over the body, they are little giants.
All hormones regulate one or more chemical reactions in the body, but they seem to work in many different ways. Hormonal activity must remain in delicate balance or the entire body will be thrown out of balance.
Endocrinology is the study of endocrine systems. The primary function of endocrine system is to regulate physiological processes by means of groups of chemical messengers called hormones. These substances are released by an endocrine organ into the blood in which it travels to another site in the body where it exerts its effect.
Physiological organization is brought about by higher centers of the brain, the hypothalamus, of the nervous system and by chemical substances in the circulatory fluids which are carried everywhere in the body, bringing about local changes, inequilibruim of physical and chemical conditions and affecting correlations of these changes in a bodywide way.
The functions of the body are regulated by the nervous system and by hormones. In general, the nervous system regulates the rapidly changing activities such as skeletal movements, smooth muscle contraction, and many glandular secretions. The hormonal system regulates the many metabolic functions of the body and the varying rates of chemical reactions. Hormones influence transport of substances through cell membranes and various aspects of cell metabolism and tissue growth. In some instances there are specific interrelationship between nervous stimuli and hormonal secretion. There are also many interactions between hormones, so that a disturbance in one endocrine gland can interfere with activities of other hormones. Hormones are specific in action and for specific cells respond.
In general, hormones are secreted into extracellular fluids and have effect on distant organs. In local hormones some physiologically active substances are released from specific sites in tissue.
The anterior pituitary controls the overall growth of the body. The anterior lobe originates embryonically from the epithelial lining of the pharynx. The anterior portion has many functions and several of its hormones have been isolated.
In the average person the anterior pituitary hormones are of great concern because it regulates other endocrines.
The gonadotropic or follicle-stimulating, FSH and luteinizing hormones, LH, are intimately connected with ovarian function and menstruation. In the male, the follicle-stimulating hormone induces the development of spermatozoa in the testicle while the luteinizing hormone stimulates the production of the male sex hormone, testosterone.
The lactogenic hormone prolactin is necessary for the initiation of the flow of milk and normal laction following pregnancy.
The adrenocorticotropic hormone, ACTH, promotes hydrocortisone production in the presence of stress. (i.e. Punch on the nose or fever or worry) Hydrocortisone raises blood sugar (for healing process) and acts as an anti-inflammatory.
The thyrotropic or TSH, signals the thyroid to manufacture thyroxine when the level gets too low. Without thyrotropic hormone, thyroid gland undergoes atrophy; in the presence of excess, the thyroid increases in glandular tissue and function.
Endocrine control works both ways. Just as a thermostat, which fires a furnace into activity when the room temperature drops, is itself turned off when the temperature rises high enough, the production of each of the stimulating hormones in the pituitary is suppressed by the presence in the blood of the hormone which it stimulated. Thus, as the level of thyroxine drops, TSH is poured out to goad the thyroid cells into activity; but as soon as production has been speeded up, the very presence of thyroid hormone in quantity in the bloodstream blocks the pituitary’s release of more TSH until thyroid activity slows down again. The result of this cycle is the maintenance of a remarkably steady balance of thyroid hormone in the bloodstream at all times. Such a feedback system serves to regulate the levels of adrenal hormones and sex hormones in much the same way.
Adrenaline is the trade name for epinephrine. On the other hand norepinephrine serves as an effective aide to epinephrine, causing an increase in the rate of heartbeat and constricting the skin capillaries so that blood is forced out of them and shunted, by the action of the epinephrine to the body’s major organs.
A number of hormones which may be divided into four groups: Mineralocorticoids or Aldosterone which promotes retention of sodium and water in the body effecting blood pressure, glucocorticoids hydrocortisone which acts to raise blood glucose levels and as an anti-inflammatory agent, steroids, related to sex hormones. See diagram.
In Addison’s disease, progressive destruction of the cortex of the adrenal, usually as the result of tuberculosis gives rise to symptoms resulting from deficiencies of the hormones listed above. In the Waterhouse-Friderichsen syndrome, destruction of part or the whole of one or both glands by hemorrhage occurring in the course of meningitis due to meningococci leads to sudden collapse and death unless very prompt treatment by replacement of the absent hormones is available. The most common cause of Addison’s disease is pituitary tumor.
a cyst causing enlargement only, or malignant (solis tumor).
The function of the thyroid is to serve as a storehouse for iodine and to secrete into the blood stream thyroid hormone, which has a stimulating effect on growth and metabolism. The thyroid affects other ductless glands and the sympathetic nervous system. In a reverse manner, other endocrine glands in turn influence the thyroid; this is particularly true of the pituitary gland, which has a multiplicity of influences on the endocrine system.
Diseases of the thyroid may be classified as hypofunction, hyperfunction, tumors, goiter, cancer or inflammatory disease.
The hormone produced by the thyroid is now called thyroxine which exercises control over the rate at which food is converted into heat and energy in all the body’s cells. See figure below. Without sufficient thyroxine the individual feels constantly cold, drowsy, unable to do anything without considerable exertion. Respirations are slow, heart rate sluggish, appetite and sex functioning both below pars. Sometimes there is a weight gain despite a distinctly meager diet. The opposite of hypothyroidism is hyperthyroidism. An individual with this condition is likely to be nervous, jittery and overactive, with a pounding heart and labored respirations, able to gorge yet lose weight, as though all the body fires were burning out of control.
Two secretions are formed in the pancreas, The pancreatic fluid is an external secretion and is poured into the duodenum during intestinal digestion and the secretion formed by the islets of Langerhans are the internal secretions of insulin and glucagon, which are absorbed by the blood, carried to the tissues, and aid in regulating glucose metabolism.
Several types of cells are in t¥e islet group. The beta cells secrete insulin, and the alpha cells secrete glucagon. Insulin increases cell permeability to glucose. See figure below.
Insulin promotes the utilization of glucose in tissue cells and thereby decreases blood glucose concentration.
Insulin is essential for the maintenance of normal levels of blood glucose. Hypoglycemia can result from increased insulin secretion or from the injection of too much insulin. Hyperglycemia and glycosuria, a condition which the urine contains glucose, may result from insufficient secretion of insulin. Marked increased levels of blood sugar, if untreated, lead to coma and death. This condition is known as diabetes mellitus.
The function of the ovaries is the production of ova, and the sex hormones, progesterone and estrogens. The ovaries are glands of internal secretion, or endocrine glands. Two types of hormones are produced, the estrogenic group of which estradiol is the most important, and corpus luteum hormone or progesterone. These substances are concerned with the changes characteristic of menstruation, those following impregnation which are necessary for the development of the fertilizated ovum, and the changes in the ma??mary glands occurring during pregnancy. The ovary produces hormones that cause development of the female genital organs and secondary sex characteristics. The ovary is directly stimulated or inhibited by hormones from other endocrine glands, notably the pituitary.
In early fetal life both the ovaries and the testicles lie in front of and below the kidneys. During fetal growth they descend. The ovaries finally lodge on the side wall of the pelvic cavity. The testicles normally continue downward and descend through and out of the abdomen in the region of the groin to the scrotum. This descent may be arrested along any portion of this pathway, and one or both testicles may remain in the abdominal cavity, in its wall or groin. The condition is known as cryptorchidism. Men with undescended testicles because sperm gets too warm, are sterile but are sexually normal otherwise. The situation is corrected by an operation in which the undescended testicles is brought down to its normal scrotal position. This operation is best done at or shortly after puberty.
In some cases glandular injections will cause the testicle to descend without operative interference.
Diseases affecting the testicles are tumors, which are rare and infections.
The testes are controlled by hormones secreted from the anterior pituitary. Two pituitary hormones are involved in regulation of testicular function, one for the endocrine component and the other for the gametogenic component. Luteining hormone, LH acts on leydig cells to stimulate testosterone secretion and follicle-stimulating hormone or FSH acts on the seminiferous tubules to promote spermatogenesis. (See figures A,B, and C).
- 1. Hormone
- 2. Endocrine
- 3. Gland
- 4. Homeostasis
- 5. FSH
- 6. TSH
- 7. ACTH
- 8. STH
- 9. LH
- 10. Ovaries
- 11. Testis
Write at least one hormone associated with each gland.
- A. Pituitary Gland
- B. Adrenal lands
- C. Thyroid land
- D. Islets of Langerhans
- E. Ovaries
- F. Testis
- G. Placenta
What could happen if homeostasis does not occur? Will the body continue to operate the same?
WHAT HAPPENS IN ENDOCRINE GLANDS
Structurally, all established hormones are peptides or proteins, steroids, or amino acid derivatives.
- A. Hormone is made, and stored. At appropriate response stored hormone is released.
- Examples: The protein hormones....Insulin
- Thyroid Stimulating Hormone
- Follicle Stimulating Hormone
- Luteinizing Hormone
- B. The enzymes involved in the synthesis of the hormone are stimulated following an appropriate response.
- Examples: The steroid hormones....Estradiol
- The amino acid derivatives....Thyroxine
Name three hormones that are protein, steroid and amino acid. Also name their target glands.
Lesson Plan IV
APPLY WHAT YOU KNOW
Today is not a happy day for you. You came to school late and you are tired. You are angry with your boyfriend and can’t function in school.
Do The Following:
- 1. Explain briefly the physiological response to stress.
- 2. Differentiate between the actions of epinephrine and morepinephine.
- 1. Controls the rate at which the body oxidizes food ___
- 2. Helps the body prepare for greater activity ___
- 3. Master gland, which regulates growth ___
- 4. Helps to lubricate food and break down starches before they reach the stomach ___
- 5. Lubricates the skin and the hair ___
- 6. Produces milk ___
- 7. Secretes insulin, which helps the body use carbohydrates ___
- 8. Gland in the skin which helps to maintain normal body temperature ___
- 9. Lubricates the eyes ___
- 10. Man’s largest gland, which secretes bile, converts sugar into glycogen and stores it ___
Fallopian tubes ___
Prostate gland ___
___Seminal vesicles ___
Vas deferens ___
- 1. Name the hormones of the anterior pituitary and explain the function of each.
- 2. Which of the adrenal hormones are essential for life? Explain.
- 3. What is the name of the scientist who studies the endocrine system’
- 4. What are proteins?
- 5. What are Amino Acids?
Kaplan, Sandra N., Change For Children: Ideas and Activities For Individualized Learning. Revised Santa Monica, Ca.: Goodyear Publishing Co., Inc., 1980.
Swanson, Call P., The Cell, Prentice Hall Inc., Englewood Cliff, New Jersey, 1964.
Kelly, Patricia, M. The Mighty Cell, Day, 1967.
Thompson , Stephanie, Know Your Body. Chicago, Ill., Rand McNally and Co., 977.
Hormones and Reproductive Behavior, Silver, Rae and Feder, Harvey H., W.H. Freeman and Company, 1983.
Protein Shape and Biological Control, “Scientific American”.
The Structure of Cell Membranes, Fox, Fred, “Scientific American”.
Ribosomes, Normura, Masayasu, “Scientific American”.
Gene Structure and Protein Structure, Yanofsky, “Scientific American”.
The Genetic Code, Crick, F.H.C., “Scientific American”.
The Structure of the Hereditary Material, Crick, F.H.C., “Scientific American”.
The Nucleotide Sequence of a Nucleic Acid, Holley, Robert W., Scientific American”.
Protein, Doty, Paul, “Scientific American”.
Nelso, Waldo A., Textbook of Pediatrics, Phila, W.B. Saunders Company, 1975.
Miller, Majorie A., Anatomy and Physiology, 16th edition, New York, The MacMillan Company, 1972.
Plant, T.M. “Gonadal Regulation of Hypothalamic CIonadotropin-Releasing Hormone Release in Primates”, Endocrine Rev. 7:75, 1986.
Watson, James D., The Double Helix: A Personal Account of the Discovery of the Structure of DNA, San Francisco: W.H. Freeman and Company, 1981.
Contents of 1988 Volume V | Directory of Volumes | Index | Yale-New Haven Teachers Institute