1. (20 points) The pituitary gland is often thought of as the “master” endocrine
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Question
1. (20 points) The pituitary gland is often thought of as the “master” endocrine gland because of its regulatory role over other endocrine glands. Make an argument in favor of designating the hypothalamus as the master endocrine gland instead of the pituitary gland. Use specific examples of endocrine pathways to show how the hypothalamus interacts with the anterior and posterior lobes of the pituitary gland in a regulatory manner. Also describe the physical structures through which the hypothalamus communicates with each lobe.
2. (20 points) A particular group of similar cells responds to 2 different hormones that are secreted when blood sugar falls. Hormone A is lipid-soluble and the Hormone B is water-soluble. Hormone A is released from its gland directly in response to a drop in blood sugar. Hormone B is released at the end of a pathway that involves the release of 2 other hormones prior to the release of hormone B. Without identifying specific hormones, contrast the homeostatic regulatory pathways that would involve the release of these 2 hormones and the restoration of normal blood sugar. Consider the water vs. lipid solubility and the different ways in which each hormone release is regulated in your answer.
3. (20 points) Perhaps the best way to appreciate the importance of hormones in the regulation of bodily functions is to observe what happens when they are not working properly. Select an endocrine disorder associated with hypersecretion or hyposecretion of either growth hormone, cortisol, or thyroid hormone. Describe the normal effectors and effector actions associated with that hormone. Explain why hyper or hyposecretion of that hormone produces the symptoms associated with the particular disorder you are describing.
4. (20 points) Describe how the reproductive cycles of the testes, ovaries, and uterus are regulated by hormones. Include specific hormones and their sources in your discussion. Using this information, explain how estrogen in females and testosterone in males, could be used as hormonal contraceptives.
Explanation / Answer
The endocrine system mainly consists of the ductless glands that include the hypothalamus,the pituitary gland ,the pineal gland a,thyroid gland. The nervous system and the endocrine system are complementary both in form and function.the nervous system is stimulated by the nerve impulses and the reaction is generated simultaneously which may last from few milliseconds to seconds and is short lived while the hormones secreted by the endocrine glands may take few minutes to few hours to few days to stimulate and their effect may be long lasting.
the endocrine glands are generally referred to as the ductless glands as there secretions are directly diffused into the surrounding cells from where they are picked up by the blood stream and circulated.the hormones secreted by these glands are regulated in a particular gland that detects the high or low level of that particular biochemical that either acts as a stimulator or the inhibitor or by a complex regulatory mechanism that involves the brain,hypothalamus and the pituitary gland.
The Pituitary gland was considered to be the master gland as it controls several other glands but now it is very well known that the action of pituitary gland is directed by the hypothalamus which acts as link between the brain and the endocrine system. The hypothalamus is highly involved in the function of the pituitary gland.
The hypothalamus is about the size of an almond and is located below the thalamus ,posterior to the optic chiasma and above the pituitary gland and is involved in the homeostasis of the body. when the hypothalamus receives the signal from the nervous system it secretes hormones what are known as the neuro hormone that either stimulate or inhibit the pituitary gland too secrete the hormones.Thus it can be seen that hypothalamus is the master of the master gland directing its secretions.
The hypothalamus and pituitary gland are thus connected by both chemical and nervous pathways.As noted earlier the hypothalamus is just the size of an almond and has several nuclei with a variety of functions .the posterior part of the hypothalamus is called as the the median eminence,and contains the nerve endings of many neurosecretory cells,which run down into the pituitary gland through the infundibular stalk. The maxillary bodies ,the third venrticle and the optic chiasma are the important structures that are associated with the median eminence adjacent to it.
The hypothalamus is connected to many regions of the brain that included the cerebral cortex thus allowing the intellectual and functional signal along with the external signals like physical and emotional stress to be channelized into the hypothalamus to the endocrine systems from where the signals exert their effects throughout the body.
the hypothalamus not only produces the neurotransmitters and neuropeptides but also produces several neurohormones that alter the anterior pituitary gland and the hormones oxytocin and vassopressin that act distantly.
The hormones that are secreted are incorporated into the secretory vesicles and are carried through the axons of the enrve cells to be stored in the nerve terminals located in the median eminence or the posterior pituitary gland , when the nerve is stimulated these contents are extruded into the capillary network .
In case of the hormones that have effect on the function of the pituitary the secretory granules carry their contents through the hypophyseal portal circulation and are delivered into the anterior pituitary gland.
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