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Chapter 47 Endocrine Regulation.

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Presentation on theme: "Chapter 47 Endocrine Regulation."— Presentation transcript:

1 Chapter 47 Endocrine Regulation

2 The endocrine system Endocrine glands, cells, and tissues that secrete hormones Hormones are an important type of chemical signal by which cells communicate Secreted into the interstitial fluid and typically transported by the blood Bind with receptors or in specific target cells

3 Some types of endocrine signaling

4 Four main chemical groups
Fatty acid derivatives Prostaglandins and the juvenile hormone of insects Steroids Secreted by the adrenal cortex, ovary, and testis, as well as the molting hormone of insects

5 Four main chemical groups, cont.
Amino acid derivatives Thyroid hormones and epinephrine Peptides or proteins ADH and glucagon are peptide hormones Insulin is a small protein

6 Major chemical groups of hormones

7 Hormone secretion Typically regulated by negative feedback mechanisms
Hormone is released in response to some change in a steady state Triggers a response that counteracts the changed condition This process restores homeostasis

8 Regulation by negative feedback

9 Steroid and thyroid hormones
Hydrophic molecules Pass through the plasma membrane Combine with receptors within the target cell The hormone-receptor complex may activate or repress transcription of messenger RNA coding for specific proteins

10 Mechanism of action of steroid hormones

11 Peptide hormones are hydrophillic and do not enter target cells
Combine with receptors on the plasma membrane of target cells Many hormones bind to G protein-linked receptors Act via signal transduction

12 Overview of peptide hormone action

13 Mechanism of action of hormones that use G protein-linked receptors and second messengers

14 Most peptide hormones are first messengers
Carry out their actions by way of second messengers Cyclic AMP (cAMP) Calcium ions

15 Phospholipid products as second messengers

16 Inositol trisphosphat (IP3) and diacylglycerol (DAG)
Second messengers that Increase calcium concentration Activate enzymes

17 Receptor tyrosine kinases
Enzyme-lined receptors Bind growth factors, including insulin and nerve growth factors

18 Signal amplification Occurs as each hormone-receptor complex stimulates the production of second messenger molecules Second messengers activate protein kinase molecules that activate protein molecules

19 Four functions of hormones in invertebrates
Neurohormones secreted by neurons rather than endocrine glands

20 Four functions of hormones in invertebrates, cont.
Help regulate Metabolism Growth and development Regeneration Molting Metamorphosis Reproduction and behavior

21 Regulation of growth and molting in insects

22 Human endocrine glands

23 Some endocrine glands and their hormones

24 Consequences of endocrine malfunction

25 Nervous and endocrine regulation
Integrated in the hypothalamus, which regulates the pituitary gland

26 Oxytocin and ADH Produced by the hypothalamus
Released by the posterior lobe of the pituitary

27 Hypothalamus Secretes
Releasing hormones Inhibiting hormones These regulate the hormone output of the anterior lobe of the pituitary

28 Anterior lobe of the pituitary
Secretes the growth hormone, prolactin Several tropic hormones that stimulate other endocrine glands

29 The hypothalamus regulates the anterior lobe of the pituitary gland

30 Growth hormone (GH) Anabolic hormone that stimulates body growth
Stimulates the liver to produce insulin-like growth factors (IGFs), which promote skeletal and tissue growth

31 Thyroid gland Secretes Stimulate the rate of metabolism Thyroxine
Triiodothyronine Stimulate the rate of metabolism

32 Regulation of thyroid secretion
Depends mainly on a negative feedback system Anterior pituitary gland Thyroid gland

33 Thyroid hyposecretion
Childhood cretinism Adult myxedema Thyroid hypersecretion Most common cause is Grave’s disease Goiter associated with both hyposecretion and hypersecretion

34 Regulation of thyroid secretion by negative feedback

35 Calcitonin, secreted by the thyroid, acts antagonistically to PTH
Parathyroid glands Secrete PTH Regulates calcium level in the blood Stimulates calcium release from bones Calcitonin, secreted by the thyroid, acts antagonistically to PTH

36 Regulation of calcium homeostasis by PTH and calcitonin

37 Islets of Langerhans Secrete insulin Secrete glucagon
Stimulates cells to take up glucose and so lowers blood glucose Secrete glucagon Raises blood glucose concentration Diabetes mellitus Results in decreased use of glucose

38 Islets of Langerhans

39 Adrenal glands Secrete hormones that help the body cope with stress
Adrenal medulla secretes Epinephrine Norepinephrine Adrenal cortex secretes Sex hormones

40 Adrenal gland

41 Response to stress

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