1. Endocrine System
By: Destiny, Lexie, and Tiffany

2. Endocrine Glands Are ductless & secrete hormones into bloodstream
Hormones go to target cells that contain receptor proteins for it
Neurohormones are secreted into blood by specialized neurons
Hormones affect metabolism of targets

3. Common Aspects of Neural & Endocrine Regulation
Both NS & endocrine system use chemicals to communicate
Difference between NTs & hormones is transport in blood & more diversity of effects in hormone targets
Some chemicals are used as hormones & NTs
Targets for both NTs & hormones must have specific receptor proteins
Must be way to rapidly inactivate both

4. Mechanisms of Hormone Action

5. Mechanisms of Hormone Action
Target cell receptors show specificity, high affinity, & low capacity for a hormone
Lipid hormones have receptors in target's cytoplasm &/or nucleus because can diffuse thru plasma membrane
Receptors for water-solubles are on surface of target cell

6. Mechanism of Thyroid Hormone Action continued
T3 & receptor bind to 1 half-site
Other half-site binds retinoic acid
Two partners form heterodimer that activates HRE
Stimulates transcription of target gene

7. Pituitary Gland

8. Pituitary Gland
Pituitary gland is located beneath hypothalamus at base of forebrain

9. Pituitary Gland continued
Is structurally & functionally divided into anterior & posterior lobes
Hangs below hypothalamus by infundibulum
Anterior produces own hormones
Controlled by hypothalamus
Posterior stores & releases hormones made in hypothalamus

10. Anterior Pituitary continued
Growth hormone (GH) promotes growth, protein synthesis, & movement of amino acids into cells
Thyroid stimulating hormone (TSH) stimulates thyroid to produce & secrete T4 & T3
Adrenocorticotrophic hormone (ACTH) stimulates adrenal cortex to secrete cortisol, aldosterone
Follicle stimulating hormone (FSH) stimulates growth of ovarian follicles & sperm production
Luteinizing hormone (LH) causes ovulation & secretion of testosterone in testes
Prolactin (PRL) stimulates milk production by mammary glands

11. Anterior Pituitary continued
Releasing & inhibiting hormones from hypothalamus are released from axon endings into capillary bed in median eminence
Carried by hypothalamo-hypophyseal portal system directly to another capillary bed in A. Pit.
Diffuse into A. Pit. & regulate secretion of its hormones

12. Hypothalamic Control of Posterior Pituitary
Supraoptic nuclei of hypothalamus produce ADH
Paraventricular nuclei produce oxytocin
Both transported along hypothalamo-hypophyseal tract to posterior pituitary
Release controlled in hypothalamus by neuroendocrine reflexes

13. Thyroid Gland

14. Thyroid Gland Is located just below the larynx
Secretes T4 & T3 which set BMR & are needed for growth, development

15. Thyroid Gland Consists of microscopic thyroid follicles
Outer layer is follicle cells that synthesize T4
Interior filled with colloid, a protein-rich fluid

16. Production of Thyroid Hormones
Iodide (I-) in blood is actively transported into follicles & secreted into colloid
Where it is oxidized to iodine (I2) & attached to tyrosines of thyroglobulin
A large storage molecule for T4 & T3
TSH stimulates hydrolysis of T4 & T3s from thyroglobulin & then secretion

17. Diseases of the Thyroid - Hypothyroidism
People with inadequate T4 & T3 levels are hypothyroid
Have low BMR, weight gain, lethargy, cold intolerance
& myxedema = puffy face, hands, feet
During fetal development hypothyroidism can cause cretenism (severe mental retardation)

18. Parathyroid Glands
Are 4 glands embedded in lateral lobes of thyroid gland
Secrete Parathyroid hormone (PTH)
Most important hormone for control of blood Ca2+ levels

19. Effects of Parathyroid Hormone

21. Adrenal Gland

22. Adrenal Glands Sit on top of kidneys
Each consists of outer cortex & inner medulla
2 arise differently during development

23. Adrenal Glands Medulla synthesizes & secretes 80% Epi & 20% NE
Controlled by sympathetic
Cortex is controlled by ACTH & secretes:
Cortisol which inhibits glucose utilization & stimulates gluconeogenesis
Aldosterone which stimulate kidneys to reabsorb Na+ and secrete K+
& some supplementary sex steroids

24. Effects of Epinephrine Secretion from
Adrenal Medulla

25. Metabolic Effects of Epi & Norepi
Are similar to glucagon, stimulating glycogenolysis & lipolysis

26. Pancreas Located along small intestine and stomach; retroperitoneal
Exocrine gland
Produces pancreatic digestive juices
Endocrine gland
Consists of pancreatic islets
Composed of
Alpha cells; secrete glucagon
Beta cells; secrete insulin
Delta cells; secrete somatostatin

27. Miscellaneous Glands & Hormones

28. Pineal Gland Is located in basal forebrain near thalamus
Secretes melatonin in response to activity of suprachiasmatic nucleus (SCN) of hypothalamus

29. Pineal Gland continued
SCN is primary timing center for circadian rhythms
Reset by daily light/dark changes
Melatonin is involved in aligning physiology with sleep/wake cycle & seasons
Secreted at night & is inhibited by light
Inhibits GnRH (antigonadotropic) in many animals

30. Thymus Is located around trachea below thyroid
Produces T cells of immune system & hormones that stimulate them

31. Sex & Reproductive Hormones
Gonads (testes & ovaries) secrete steroid hormones testosterone, estrogen, & progesterone
Placenta secretes estrogen, progesterone, hCG, and somatomammotropin

32. Estrogen
Causes epiphyseal discs (cartilaginous growth plates) to seal (ossify) which stops growth
Is necessary for proper bone mineralization & prevention of osteoporosis
Stimulates osteoblast activity & suppresses formation of osteoclasts