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Endocrine System

Endocrine System. Homeostasis. Maintaining internal balance in the body Organisms must keep internal conditions stable even if environment changes Regulation Nervous system Nerve signals control body functions Endocrine system Hormones Chemical signals control body functions.

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Endocrine System

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  1. Endocrine System

  2. Homeostasis • Maintaining internal balance in the body • Organisms must keep internal conditions stable even if environment changes • Regulation • Nervous system • Nerve signals control body functions • Endocrine system • Hormones • Chemical signals control body functions

  3. Endocrine System • includes the organs of the body that secrete hormones directly into body fluids such as blood • Regulates chemical reaction in cells and therefore control functions of the organs, tissues, and other cells

  4. Hormones • Endocrine glands • Ductless • Release hormones • Into bloodstream to be carried to target tissues • Hormones • Chemicals secreted by a cell that affect the functions of other cells • Growth hormones • Sex hormones • Response hormones • Metabolism hormones • And more…

  5. Negative & Positive Feedback Loops • Control Hormone Levels • Negative feedback loop • Hormone release stops in response to decrease in stimulus • Stimulus (eating) raises blood glucose levels • Pancreas releases insulin in response to elevated blood glucose • Blood glucose decreases as it is used by the body or stored in the liver • Insulin release stops as blood glucose levels normalize

  6. Negative & Positive Feedback Loops • Positive Feedback Loop • As long as stimulus is present, action of hormone continues • Infant nursing at mother’s breast stimulates hypothalamus stimulates posterior pituitary • Oxytocin released stimulates milk production & ejection from mammary glands • Milk release continues as long as infant continues to nurse

  7. Endocrine Glands • Pineal gland & thymus gland are ductless but little is know about their endocrine function • Pineal gland • Secretes melatonin • Supports body’s biological clock • Thought to induce sleep • Thymus gland • Produces thymosin • Important in the development of immune responses in newborns

  8. Endocrine Glands • Thyroid Gland • Composed of right & left lobe on either side of trachea • Major hormones • Thyroid hormone • Stimulates protein synthesis & increase metabolism • Calcitonin • Lowers blood calcium levels

  9. Endocrine Glands • Parathyroid Glands • Four small oval bodes located on the dorsal aspect of the thyroid gland • Major hormone • Parathyroid hormone (PTH) • Agonist to calcitonin by raising blood calcium levels

  10. Endocrine Glands • Adrenal Glands • Glands on top of kidneys • Adrenal Cortex (outer) • Increases blood glucose • Increases salt reabsorption • Sexual characteristics • Adrenal medulla (inner) • Epinephrine (adrenaline) & Norepinephrine (noradrenaline) • Sympathomimetic • Mimic the actions of the sympathetic nervous system

  11. Endocrine Glands • Pancreas • Located near & partly behind the stomach • islets of Langerhans • Hormone-producing cells • Produce insulin • Lowers blood sugar • Produce glucagon • Raises blood sugar

  12. Endocrine Glands • Pituitary Gland • (hypophysis) “Master Gland”- controls several other endocrine glands • Pea-sized gland located at the base of the brain • Consists of an anterior lobe (adenohypophysis) & posterior lobe (neurohypophysis)

  13. Endocrine Glands • Ovaries • Produce the ovum & hormones responsible for female sex characteristic & regulation of the menstrual cycle • Estrogen • Female sex characteristics • Progesterone • Maintains pregnancy • Testes • Produce the spermatozoa & testosterone • Testosterone is an androgen • Stimulates secondary sex characteristics

  14. Common Diseases and Disorders

  15. Acromegaly • Cushing’s disease

  16. Common Diseases and Disorders (cont.)

  17. Common Diseases and Disorders (cont.)

  18. Gigantism Goiter

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