Assignment: Principles of the Endocrine System Study Guides

Assignment: Principles of the Endocrine System Study Guides

The word hormone is derived from the Greek hormao meaning ‘I excite or arouse’. Hormones communicate this effect by their unique chemical structures recognized by specific receptors on their target cells, by their patterns of secretion and their concentrations in the general or localized circulation. The major hormones discussed in this book are listed in Box 1.1.

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Box 1.1
Classification by structure of the major human hormones*.

Their functions can be broadly grouped into several categories: reproduction and sexual differentiation; development and growth; maintenance of the internal environment; and regulation of metabolism and nutrient supply. A single hormone may affect more than one of these functions and each function may be controlled by several hormones. For example, thyroid hormone is essential in development as well as many aspects of homeostasis and metabolism, whilst glucocorticoids, such as cortisol, are important both in growth and nutrient supply and are also modulators of immune function. The roles several hormones play in one function is exemplified by the control of blood glucose which involves the pancreatic peptide insulin and its counter regulatory hormone, glucagon, as well as cortisol, growth hormone and epinephrine. Hormones act in concert and thus, an abnormality in a controlled variable, such as blood glucose concentration may result from defects in the control of any one of several hormones.

The secretion of hormones is subject to negative feedback control, and there are several ways by which this is achieved (Box 1.2). Feedback loops may involve the hypothalamo-pituitary axis that detects changes in the concentration of hormones secreted by peripheral endocrine glands or a single gland may both sense and respond to changes in a controlled variable. The integration of feedback loops involving several hormones may be complex. Disturbances in feedback loops are clinically important and their significance in diagnosis is pivotal.

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Box 1.2
Principles of feedback control in the endocrine system. The activity of the thyroid gland, adrenal cortex and gonads is controlled by the feedback effects of their circulating hormones on the hypothalamic-pituitary axis. The secretory activity of glands (more…)

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Chemical signalling – endocrine, paracrine, autocrine and intracrine mechanisms
A chemical released by a specialized group of cells into the circulation and acting on a distant target tissue defines the ‘classical’ endocrine and neuroendocrine signalling mechanism. A paracrine mechanism is defined as chemical communication between neighboring cells within a tissue or organ (Box 1.3). Autocrine signals are those in which a chemical acts on the same cell whilst an intracrine signal is generated by a chemical acting within the same cell.

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Chemical classification of hormones and their synthesis
Hormones are derived from amino acids, from cholesterol (Box 1.4) or from phospholipids (Box 8.8). By far the most numerous are the protein or peptide hormones, ranging in size from just three to over 200 amino acids. Some hormones, such as insulin, are made up of two sub-units joined by disulfide bonds between two cysteine molecules whilst the glycoprotein hormones of the anterior pituitary gland are not only made up of two protein sub-units but also have complex sugar moieties attached.

Chemical structures of the three major classes of human hormones. Other hormones include those derived from tryptophan (serotonin and melatonin, Boxes 7.33 and 8.12) and those derived from fatty acids (eicosanoids, Box 8.8).

The steroid hormones, which include vitamin D and those secreted by the adrenal cortex and gonads, are derived from cholesterol. All adrenal and gonadal steroids have the same basic ring structure (Box 1.4) and despite superficial 2D structural similarity, the side chains and spatial orientation generate specificity.

The third group of hormones are those derived either from tyrosine or from tryptophan. A single tyrosine molecule yields the catecholamines, epinephrine and norepinephrine, the latter being both a neurotransmitter and a hormone. In the endo-crine system, these hormones are secreted by the adrenal medulla and are rapidly broken down once released into the circulation. The thyroid hormones are formed by the conjugation of two tyrosine molecules and resemble steroid hormones in binding to serum proteins and in the mechanism of action. Tryptophan is the precursor of serotonin (5-hydroxytryptamine) and melatonin synthesis. Finally, hormones derived from lipids and phospholipids include the major classes of eicosanoids including prostaglandins, prostacyclins, thromboxanes and leukotrienes

Important information for writing discussion questions and participation

Welcome to class

Hello class and welcome to the class and I will be your instructor for this course. This is a -week course and requires a lot of time commitment, organization, and a high level of dedication. Please use the class syllabus to guide you through all the assignments required for the course. I have also attached the classroom policies to this announcement to know your expectations for this course. Please review this document carefully and ask me any questions if you do. You could email me at any time or send me a message via the “message” icon in halo if you need to contact me. I check my email regularly, so you should get a response within 24 hours. If you have not heard from me within 24 hours and need to contact me urgently, please send a follow up text to

I strongly encourage that you do not wait until the very last minute to complete your assignments. Your assignments in weeks 4 and 5 require early planning as you would need to present a teaching plan and interview a community health provider. I advise you look at the requirements for these assignments at the beginning of the course and plan accordingly. I have posted the YouTube link that explains all the class assignments in detail. It is required that you watch this 32-minute video as the assignments from week 3 through 5 require that you follow the instructions to the letter to succeed. Failure to complete these assignments according to instructions might lead to a zero. After watching the video, please schedule a one-on-one with me to discuss your topic for your project by the second week of class. Use this link to schedule a 15-minute session. Please, call me at the time of your appointment on my number. Please note that I will NOT call you.

Please, be advised I do NOT accept any assignments by email. If you are having technical issues with uploading an assignment, contact the technical department and inform me of the issue. If you have any issues that would prevent you from getting your assignments to me by the deadline, please inform me to request a possible extension. Note that working fulltime or overtime is no excuse for late assignments. There is a 5%-point deduction for every day your assignment is late. This only applies to approved extensions. Late assignments will not be accepted.

If you think you would be needing accommodations due to any reasons, please contact the appropriate department to request accommodations.

Plagiarism is highly prohibited. Please ensure you are citing your sources correctly using APA 7th edition. All assignments including discussion posts should be formatted in APA with the appropriate spacing, font, margin, and indents. Any papers not well formatted would be returned back to you, hence, I advise you review APA formatting style. I have attached a sample paper in APA format and will also post sample discussion responses in subsequent announcements.

Your initial discussion post should be a minimum of 200 words and response posts should be a minimum of 150 words. Be advised that I grade based on quality and not necessarily the number of words you post. A minimum of TWO references should be used for your initial post. For your response post, you do not need references as personal experiences would count as response posts. If you however cite anything from the literature for your response post, it is required that you cite your reference. You should include a minimum of THREE references for papers in this course. Please note that references should be no more than 5 years old except recommended as a resource for the class. Furthermore, for each discussion board question, you need ONE initial substantive response and TWO substantive responses to either your classmates or your instructor for a total of THREE responses. There are TWO discussion questions each week, hence, you need a total minimum of SIX discussion posts for each week. I usually post a discussion question each week. You could also respond to these as it would count towards your required SIX discussion posts for the week.

I understand this is a lot of information to cover in 5 weeks, however, the Bible says in Philippians 4:13 that we can do all things through Christ that strengthens us. Even in times like this, we are encouraged by God’s word that we have that ability in us to succeed with His strength. I pray that each and every one of you receives strength for this course and life generally as we navigate through this pandemic that is shaking our world today. Relax and enjoy the course!

Hi Class,

Please read through the following information on writing a Discussion question response and participation posts.

Contact me if you have any questions.

Important information on Writing a Discussion Question

• Your response needs to be a minimum of 150 words (not including your list of references)
• There needs to be at least TWO references with ONE being a peer reviewed professional journal article.
• Include in-text citations in your response
• Do not include quotes—instead summarize and paraphrase the information
• Follow APA-7th edition
• Points will be deducted if the above is not followed

Participation –replies to your classmates or instructor

• A minimum of 6 responses per week, on at least 3 days of the week.
• Each response needs at least ONE reference with citations—best if it is a peer reviewed journal article
• Each response needs to be at least 75 words in length (does not include your list of references)
• Responses need to be substantive by bringing information to the discussion or further enhance the discussion. Responses of “I agree” or “great post” does not count for the word count.
• Follow APA 7th edition
• Points will be deducted if the above is not followed

• Remember to use and follow APA-7th edition for all weekly assignments, discussion questions, and participation points.
• Here are some helpful links
• The is a great resource