1. Chapter 45 Notes Chemical Signals in Animals

2. Introduction to Regulatory Systems An animal hormone is a chemical signal that is secreted into body fluids and communicates messages within the body - broadcasted through the body Target cells: cells that are equipped to respond to hormones

3. Introduction to Regulatory Systems Endocrine glands: hormone-secreting organs that secrete chemical messengers directly into body fluids Endocrine system - helps control chemical composition and volume - ensures successful growth and development

4. Introduction to Regulatory Systems - gamete production, fertilization, embryo development and nourishment, and delivery - regulates metabolism - regulates response to environmental changes (starvation, dehydration, temperature)

5. Introduction to Regulatory Systems

6. Vertebrate Endocrine System The hypothalamus and pituitary integrate many functions of the vertebrate endocrine system Hypothalamus: - receives information from the internal and external environment

7. Introduction to Regulatory Systems - when it detects a change, it releases hormones that stimulate or inhibit specific cells in the pituitary gland (linking the nervous and endocrine systems) - produces oxytocin and ADH which are stored in the posterior pituitary

8. Introduction to Regulatory Systems

9. Pituitary gland: - connected to the hypothalamus by neurosecretory cells - stores ADH and oxytocin - produces and releases several hormones that influence the other glands of the body

10. Introduction to Regulatory Systems - growth hormone (GH) is released from the anterior lobe; it stimulates the uptake of amino acids by cells throughout the body and promotes protein synthesis

11. Introduction to Regulatory Systems

12. Effects of hormones Synergistic effects: the effects of two or more hormones complement each other; response is “summation” of individual effects - ex. the production and secretion of milk requires estrogen, progesterone, prolactin, and oxytocin

13. Introduction to Regulatory Systems Antagonistic effects: the effect of one hormone opposes the other - ex. insulin lowers blood sugar while glucagon raises it

14. Introduction to Regulatory Systems