Chapter 47 - Chapter 47 Chemical Signals in Animals Key...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 47: Chemical Signals in Animals Key Concepts Animals use at least six major types of chemical signals. Hormones are those chemical signals that are present in tiny concentrations and travel throughout the body to affect target cells. The information in hormonal signals helps animals respond to environmental change, develop as embryos, undergo sexual maturation, and achieve homeostasis. The production of a hormone is tightly regulated—usually by input from the nervous system. Some hormones bind to receptors inside target cells and change gene expression. Other hormones bind to receptors at the cell surface and lead to changes in protein activation. Section 47.1 Outline: Cell-to-Cell Signaling: An Overview Hormone Signaling Pathways What Are the Components of the Endocrine? Chemical Characteristics of Hormones How Do Researchers Identify a Hormone? o There are six major categories of chemical signals in animals (Figure 47.1): 1. Autocrine signals act on the same cell that secretes them. An example is cytokines ; most cytokines amplify the response of a cell to a stimulus. 2. Paracrine signals diffuse locally and act on neighboring cells. When the pancreatic hormones insulin , glucagon , and somatostatin act on nearby pancreatic cells, they ensure a smooth, steady response to changing blood glucose levels. 3. Endocrine signals are hormones produced by cells that may be organized into discrete organs called glands or that may be interspersed among the cells of other organs. 4. Neural signals are the chemical messengers called neurotransmitters . 5. Neuroendocrine signals are released from neurons but act on distant cells instead of acting at the adjacent synapse. 6. Pheromones are released into the environment and act on other individuals. Pheromones help coordinate reproduction in males and females or function in attracting mates.
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
These six chemical messenger classes do not coincide with six structurally distinct classes of molecules. A particular family of molecules may function as endocrine, autocrine, and paracrine signals in the same individual. Hormone Signaling Pathways o Hormones act via three pathways (Figure 47.2): – The endocrine pathway can send hormones directly from endocrine cells to effector cells. – The neuroendocrine pathway can release neuroendocrine signals that act on effector cells directly. – In the neuroendocrine–to–endocrine pathway, neuroendocrine signals stimulate cells in the endocrine system, which then respond by producing an endocrine signal that acts on effector cells to trigger a response. o All three pathways are regulated by negative feedback , or feedback inhibition , in which the product of a process inhibits its production. o In the case of the endocrine pathway, the response by the effector cells feeds back on endocrine cells to lower production of the hormone and down–regulate the response.
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern