Chemical Control in Animals: The Endocrine System

1. Chapter 32 Chemical Control in Animals:TheEndocrine System

2. Chapter 32 Definition of hormone Hormone: Chemical substance produced in one part of the body and transported usually by the blood stream to specific sites (target tissue) where it regulates an appropriate response.

3. Chapter 32 Animal Hormones • Classes of animal hormones • Peptide hormones • Amino acid derivatives • Steroid hormones • Prostaglandins • Functions of animal hormones • Binding to surface receptors • Binding to intracellular receptors • Negative feedback for hormone synthesis and release

4. Chapter 32 Mode of Action 1. Affect membrane to alter transport of substances 2. Affect activity of the gene (transcription) 3. Affect protein synthesis (translation) 4. Change the amount of availability of a cofactor

5. Chapter 32 Mode of Action cont’d 5. Act as a coenzyme itself 6. Stimulate or inhibit the formation of cyclic AMP (2nd messenger) 7. Play a role in maintenance of specific receptor molecules

6. Chapter 32 The MajorEndocrine Glands of Humans • Click boxes to go to expanded views

7. Chapter 32 Endocrine Glands,Hormones, and Target Cells Hormone distributed throughout body Hormone entersbloodstream Endocrine cellsrelease hormone Receptor ontarget cell Capillary Nerves w/o right receptors:no binding occurs;no hormonal effects Hormone-receptorComplex Muscle w/right receptors:binding occurs;hormonal effects appear

8. Chapter 32 Peptide and Amino-Acid Hormones

9. Chapter 32 Lipid-Soluble Steroid Hormones

10. Chapter 32 Steroid and lipid hormones HormoneTargetMajor response Glucocorticoids Liver, gluconeogenesis, lymphatic anti-inflammatory tissue, catabolic muscle Mineralo- kidney Na+ absorption corticoids Progesterone Uterus decrease mobility, preparation for implantation

11. Chapter 32 Steroids cont’d HormoneTargetMajor response Androgens Accessory differentiation sex organs, 2° sex char., muscle anabolic Estrogen Accessory uterotrophic sex organs transport, secondary sex char. Prostaglandins Accessory inhibit or sex organs stimulate uterine contractility

12. Chapter 32 The Hypothalamus Controls the Pituitary Pituitary Hypothalamus NeurosecretoryCells ReleasingHormone AnteriorLobe PosteriorLobe

13. Chapter 32 Hormones &Breastfeeding (2) Secretesoxytocin (3) Causes musclesto contract (1) Sucking stimulatesnerve endingsthat stimulatehypothalamus (4) Delivers milk

14. Chapter 32 The Thyroid and Parathyroid Glands Dietary iodineinsufficiencycan lead to goiter

15. Chapter 32 Negative Feedback inThyroid Gland Function 1. Cold stimulates hypothalamus to secrete releasing hormone 6 1 2. Triggers release of thyroid stimulating hormone (TSH) AnteriorPituitary 3. Stimulates thyroid to release thyroxine 2 Thyroid 4. Increases metabolic rate, generating heat 5 5. Thyroxine inhibits productionof TSH 6. Higher temperature inhibits hypothalamus 3 4

16. Chapter 32 The Pancreas ControlsBlood Glucose Levels eating hunger insulin-producingcells high bloodglucose low bloodglucose pancreas glucagon-producingcells in pancreas glucagon insulin body cells body cells cells burnfat cells burnglucose liver Convertsglucoseto glycogen Causes liverto convertglycogen to glucose Lowersbloodglucose raises bloodglucose

17. Chapter 32 Determining endocrine function Step 1 Removal of gland suspectedof endocrine function Step 2 Make extract of tissue and administer it to animals with hormone deficiency

18. Chapter 32 Function example F. G. Banting and C. H. Best (1922) 1. Pancreas removed from dog effects: • a) glucose content of blood rises rapidly • b) urine gives positive glucose test • c) nitrogen excretion elevated • d) death within 2 or 3 weeks 2. Extract made of pancreas. 3. Extract injected into diabetic dog, abnormalities reversed.

19. Chapter 32 The Adrenal Glands Adrenal Cortex Adrenal Medulla • Produces: • glucocorticoids, • testosterone, • aldosterone. • Produces: • epinephrine, • norepinephrine. (kidney)

20. Chapter 32 The End