1 / 46

ENDOCRINE SYSTEM

ENDOCRINE SYSTEM. General Overview. Major Control System Ductless Glands; Produce Hormones Diffuse into Blood Slow Initial Effects, but Effects Persist much longer Hormones act on specific Targets Regulated by Negative Feedback. Classification of Glands.

saxton
Download Presentation

ENDOCRINE SYSTEM

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ENDOCRINE SYSTEM

  2. General Overview • Major Control System • Ductless Glands; Produce Hormones • Diffuse into Blood • Slow Initial Effects, but Effects Persist much longer • Hormones act on specific Targets • Regulated by Negative Feedback

  3. Classification of Glands • Endocrine – ductless glands that secrete hormones into the blood stream • Exocrine – ducted glands that secrete their products onto a surface

  4. Hormones - General Function • Modify activity of target cells • Targets have specific receptors for the particular hormone • Distributed by blood

  5. Location of Receptors • Cell Surface • cell membrane • Intracellular • Cytoplasm • Nucleus

  6. There are Two Types of Hormones • Steroid Hormones • Attach to intracelluar receptor • Directly activate genes • Non-steroid Hormones • Attach to receptor on plasma membrane • A second messenger formsinside the cell to change cell’s activity

  7. Mechanisms of Hormone Action • Steroids (Synthesized from Cholesterol) • Hormone enters cell • Hormone forms complex with receptor • Complex binds to DNA in nucleus • Transcription of mRNA • New protein is synthesized in cytoplasm (Translation) • E.g. Testosterone

  8. Mechanisms of Hormone Action continued • Non-Steroids (Proteins/Peptides/Amine) • Hormone does not enter cell & acts as 1st messenger • Hormone binds to receptor on cell membrane • Enzyme is activated • 2nd messenger is produced • 2nd messenger affects cell function • E.g. Pituitary hormones

  9. How do Cells Respond to Hormones? • Precise response depends on target cell type •  or  rates of normal cellular processes: • Activates/deactivates enzymes • Stimulates protein synthesis • Opens/closes ion channels • Stimulates mitosis

  10. What Stimulates Endocrine Glands? • Hormonal - • Tropic hormones alter activity of other endocrine glands • Most common • Humoral • Changing levels of ions or nutrients trigger release of hormones • Neural • Nerve Impulses stimulate hormone release

  11. What if Hormone Levels are too High or too Low? • Cells can change the number of receptors they have: • Up Regulation • Low hormone levels • Number of receptors increases • Target’s responsiveness increases • Down Regulation • Excess hormone levels • Number of receptors decreases • Target’s responsiveness decreases

  12. Hypothalamus Pituitary Anterior Posterior Thyroid Gland Parathyroid Glands Adrenal Glands Cortex Medulla Pancreas Pineal Gland Thymus Gonads Endocrine Organs

  13. Hypothalamus • Integrates Nervous & Endocrine systems • Releasing Factors (hormones) stimulate secretion by Anterior Pituitary • Inhibiting Factors (hormones) are antagonistic to Releasing • Portal Circulation carries hormones to Anterior Pituitary • Nervous tissue carries hormones to Posterior Pituitary

  14. Pituitary Gland • Attached to Hypothalamus via infundibulum • Protected by sella turcica of sphenoid • Divided into 2 lobes: • Anterior (glandular) • Posterior (neural)

  15. Anterior Pituitary • “Master Gland” (makes & secretes various tropic hormones) • Tropic Hormones • Act on other Endocrine Glands • Serve as Hormonal Stimuli • Stimulate release of another hormone

  16. Anterior Pituitary continued • Human Growth Hormone (GH): • Target: All/Most Body Cells (esp. Bone & Muscle) • Action: Promotes Growth & Repair • Prolactin (PRL): • Target: Mammary Tissue • Action: Promotes milk production

  17. Anterior Pituitary continued • Thyroid Stimulating Hormone (TSH) • Target: Thyroid Gland • Action: Stimulates production of Thyroid Hormone

  18. Anterior Pituitary continued • Adrenocorticotropic Hormone (ACTH) • Target: Adrenal Cortex • Action: Controls production/secretion adrenal cortex hormones • Gonadotropic Hormones • Follicle Stimulating Hormone (FSH) • Target: Gonads (Ovaries/Testes) • Action: Production of gametes & sex hormones

  19. Anterior Pituitary continued • Luteinizing Hormone (LH/ICSH) • Target: Gonads • Functions: • Production of sex hormones • Prepare uterus for implantation • Develop corpus luteum in ovary

  20. Posterior Pituitary • Does NOT synthesize Hormones • Neural rather than glandular • Stores & Releases two hormones produced by hypothalamus • Oxytocin • Target: Uterus & Mammary Glands • Action: Stimulates Contractions to eject fetus & milk

  21. Posterior Pituitary continued • Antidiuretic Hormone (ADH) also called vasopressin • Target: Kidneys • Action: • Conserve Water (decrease urine volume) • Increase BP

  22. Thyroid Gland • Thyroid Hormone • T3 (Triiodothyronine), T4 (Thyroxine) • Target: All body cells • Action: Increase metabolic rate, regulate body temperature • Calcitonin • Target: Bone/Inhibits Osteoclasts • Action: Decrease blood Ca2+ (Hypocalcemia if excessive)

  23. Parathyroid Glands • Parathyroid Hormone • Target: Bone/Stimulates Osteoclasts • Action: Increase blood Ca2+ (Hypercalcemia if excessive)

  24. Adrenal Glands • Adrenal Cortex (outer/glandular) • Cortisol • Target: Many tissues • Action: make glucose, decrease inflammation • Aldosterone • Target: Kidneys • Action: Maintain Na+/K+ blood levels

  25. Adrenal Glands continued • Adrenal Medulla (inner/nervous) • Epinephrine/Adrenalin (Fear/Flight) • Norepinephrine/Noradrenalin (Anger/Fight) • Targets:Heart, Liver, Muscles, Blood Vessels, etc. • Functions: Prepare for sudden threat

  26. Pancreas • Endocrine (Islets of Langerhans) & Exocrine • Glucagon • Target: Liver • Action: Raises blood glucose • Insulin • Target: Most/All Cells • Action: Promotes glucose transport into cells (decreases blood glucose)

  27. Pineal & Thymus Glands • Pineal Gland (Endocrine & CNS) • Melatonin • Target: Hypothalamus • Action: Sets biological rhythms & promotes sleep • Thymus (atrophies at puberty) • Thymosins • Target: T cells of immune system • Action: T cell maturation (immunocompetence)

  28. Gonads • Ovaries • Estrogen • Target: Uterus, Ovaries, other • Action: prepare for fetus, secondary sexual characteristics • Progesterone • Target: Uterus • Action: maintains pregnancy, prevents uterine contractions

  29. Gonads continued • Testes • Testosterone • Target: Various body parts • Action: Secondary sexual characteristics

More Related