Quiz 10: The Endocrine System

Biology

The nervous and endocrine systems share four primary similarities with each other. These two systems allow every cell in the body to communicate with each other. This is accomplished through the release of chemicals, either neurotransmitters or hormones that bind specific receptors on target cells. In many cases, the nervous and endocrine systems share the same chemical messengers. Norepinephrine and epinephrine are two examples. They are released as hormones by the endocrine system and neurotransmitters by the nervous system. Negative feedback is the primary control mechanism for the endocrine and nervous systems. Negative feedback is a type of control mechanism in which the release of chemical messengers is controlled by the chemical messengers themselves. In other words, when a specific chemical messenger is no longer needed, signals inhibit further release of the chemical messenger. Lastly, both systems maintain homeostasis. They accomplish this by coordinating and regulating the activities of other cells, tissues, organs, and systems of the body.

1)The thyroid gland is a bi-lobed endocrine gland located in the neck. It releases the hormone calcitonin produced by C cells located throughout the gland. Calcitonin regulates calcium ion concentrations in the body. It is released in response to elevated calcium ion concentrations and functions to decrease blood calcium levels. It targets the bones and kidneys. Thus, the key for term 1) is h. calcitonin. 2)The pineal gland synthesizes melatonin. The rate of melatonin production varies in day and night, lowest in the daily hours, and highest during the night hours. This hormone has antioxidant activity that protects central nervous system from oxidants such as nitric oxide and hydrogen peroxide. Besides, it helps in establishment of circadian rhythms. The daily physiological processes follow a regular day-night pattern, which is a consequence of melatonin functions. Thus, the key for term 2) is e. melatonin. 3)Polyuria is a condition, which is characterized abnormal discharge of urine. The reason may be abnormalities in the hormone, aldosterone, diabetes mellitus, nephrogenic diabetes insipidus, or may be as simple as intake of excessive fluids. Thus, the key for term 3) is g. excessive urine production. 4)Parathyroid gland is secreted in response to low calcium levels in the blood. The chief cells of parathyroid gland secrete parathormone (PTH). They stimulate osteoclasts, inhibit the bone-building functions of osteoblasts, and reduce excretion of calcium ions in urine. Thus, the key for term 4) is l. stimulated by low calcium levels. 5)The thymus gland is located in the mediastinum. It is relatively enormous in size ranging from neck to heart in the new born. After puberty the size of the gland diminishes, by the age of 50, the gland may weigh less than 12g. Thus, the key for term 5) is b. atrophies in adults. 6)Adrenal cortex secretes steroid hormones. It has three distinct zones, the outer zone produces mineralocorticoids, the middle zone produces glucocorticoids, and the inner zone produces androgens. Thus, the key for term 6) is k. androgens, glucocorticoids, and mineralocorticoids. 7)The heart contains endocrine cells situated in the right atrium. In response to changes in the blood volume, these endocrine cells synthesize and release a peptide hormone, atrial natriuretic peptide. The activity of this peptide hormone is to promote the loss of sodium ions and water by kidneys, inhibits the release of renin, and inhibits the secretion of antidiuretic hormone. Thus, the key for term 7) is c. atrial natriuretic peptide. 8)Pancreas lies between the stomach and proximal part of the small intestine. It contains both exocrine and endocrine cells. Cells of the endocrine pancreas form clusters known as pancreatic islets or the islets of Langerhans. They are scattered among the exocrine cells. They two distinct types of cells in the islets of Langerhans secrete insulin and glucagon. Thus, the key for term 8) is a. islets of Langerhans. 9)Follicle stimulating hormone (FSH) and Luteinizing hormone (LH) are collectively called gonadotropins as they are primarily involved in development of reproductive organs and secondary sexual characters. The FSH and LH are secreted by anterior lobe of the pituitary gland, acts on the gonads. Thus, the key for term 9) is j. FSH and LH. 10)The hypothalamus is a neural region that provides highest endocrinal control. It is a link between nervous and endocrine systems. The coordinating systems of the hypothalamus regulate the activity of the nervous and endocrine systems by secreting releasing hormone and inhibitory hormones that act on pituitary gland. Thus, the key for term 10) is i. secretes regulatory hormones. 11)Pituitary gland is otherwise called as hypophysis that secretes different hormones. It is a small oval shaped gland located in the sella turcica. It hangs beneath the hypothalamus and responds according to the secretions of the hypothalamus. Thus, the key for term 11) is f. hypophysis. 12)The growth hormone (GH) is particularly active in children and adolescents. The effects of which, includes protein synthesis and cellular growth. It supports the muscular and skeletal development. Thus, the key for term 12) is d. stimulates cell growth and protein synthesis.

A hormone is a chemical messenger released by the endocrine system. They are released into the blood by a variety of endocrine organs and glands. They are released from one tissue and act on other tissues in the body. They bind target receptors all throughout the body and have long-lasting effects. Hormones are classified based on their chemical structure, such as peptide hormones or steroid hormones.