Biology Homework Chapter 26: The Endocrine System

Homework

• Reading Preparation
• WebLecture
• Study Activity
• Preparation work for chat
• Online Quiz
• Lab Instructions

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Textbook assignment: Chapter 26: Chemical Regulation, all.

Study Notes

• 26.1 The endocrine system is an organization of glands that produce hormones (including that regulate metabolic functions, growth, and specialized development in other parts of the body (target cells). Local regulators that operate on cells near their point of origin include prostglandins. Pheromones can affect other individuals.

  Note that nerve cells can also secrete chemical signals called neurotransmitters, which in some cases are identical to hormones released by endocrine glands.

• 26.2 Signal transduction occures when hormones transported by the blood or lymph systems cause activity in their target cells.
  • Steroid hormones diffuse through the cell membrane and bind to receptors inside the cell; the resulting complex then enters the nucleus and binds to DNA, activating transcription of specific genes.
  • Amino-acid derived hormones bind to receptors on the cell membrane; the resulting complex releases relay proteins that may either act as enzymes on metabolic functions; or move into the nucleus to control gene expression.
• 26.3 Chemical controls called endocrine disruptors affect hormones in both target species to help control them, but also affect hormone behavior in many other species exposed to the chemicals.
• 26.4 The major glands of the human endocrine system are located in the head and torso. It is useful to map the gland to its location, type of hormone produced, and major effects on metabolic functions. (see charts in text!)
• 26.5 The hypothalamus is the "master" gland, controlling the development and activity of other endocrine glands such as the pituitary and thyroid. Both the hypothalamus and pituitary gland produce multiple hormones; these control pain and affect the rate of excretion, functions of other glands, growth, and differentiation of cells at different stages of maturity. Feedback from several hormones to the hypothalamaus triggers its regulation of the pituitary.
• 26.6 The thyroid produces two similar hormones, which control growth and metabolic rates. Negative feedback mechanisms control the amount of each in the blood stream.
  • Low thyroid activity can result in depression and inactivity; no thyroid activity leads to goiter.
  • High thyroid activity can result in weight loss (high metabolic rates).
  
  Thyroid and parathyroid gland excretions of the antagonistic parathyroid hormone (PTH) and calcitonin hormones control calcium (Ca+) levels in the blood. Calcitonin lowers Ca+ levels and PTH raises them. The Ca+ levels control muscle contractions. Low Ca+ levels can cause convulsions.
• 26.7 The gonad glands (ovaries and testes) secrete hormonas that control reproduction.
• 26.8 Pancreatic gland secretions control sugar levels. Rising blood glucose leves stimulates insulin production, which triggers absorbtion of glucose by blood and liver cells, reducing free glucose concentrations.
• 26.9 Diabetes is the result of failing to control sugar levels. The three kinds of diabetes are
  • Type I (insulin dependent), resuting from the destruction of pancreatic beta cells, so that the pancreas cannot produce sufficient insulin.
  • Type II (insulin independent), which occurs when beta cells fail to take up insulin.
  • Type III (pregnancy onset), which occurs in some pregnant women leading to large birth weight and increasing the danger for the mother.
• 26.10 Adrenal gland secretions control responses like the "fight or flight" response, which is a reaction to stress. Glutocorticoids in particular address pain, but they can cause other serious side effects.
• 26.11 There is no one-to-one correspondence between hormones and their effects for every hormone. Chemicals like prolactin can cause a diversity of effects in an individual, depending on current circumstances, similar to how "context sensitive" commands work on computers.
• 26.12 Hormons appear to affect the way we behave. The interesting question then becomes how much of our behavior is on compulsion by biological impulses, and how much of what we do arises from deliberate choice?

Web Lecture

Read the following weblecture before chat: The Endocrine System

Take notes on any questions you have, and be prepared to discuss the lecture in chat.

Study Activity

Perform the study activity below:

Chat Preparation Activities

• Essay question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
• Mastery Exercise: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.

Chapter Quiz

• Required: Complete the Mastery Exercise with a score of 85% or better.
• Optional: Test yourself with the textbook multiple choice questions and note any that you miss that still don't make sense. Bring questions to chat!
• Go to the Moodle and take the quiz for this chapter.

Lab Work

Read through the lab for this week; bring questions to chat on any aspect of the lab, whether you intend not perform it or not. If you decide to perform the lab, be sure to submit your report by the posted due date.

• Lab Instructions: If you have elected to do Scholars Online Biology Investigation #1, complete that lab at this time. Alternatively, you may do Field Lab #5

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