1 / 24

Endocrine System

The endocrine system consists of various glands that secrete hormones directly into the bloodstream, acting as chemical messengers. Key glands include the hypothalamus, pituitary, thyroid, parathyroid, adrenal glands, and gonads (ovaries and testes). Hormonal control is largely managed through feedback mechanisms, primarily negative feedback, while some hormones are released in response to nervous control. Each gland has specific roles, such as metabolism regulation by the thyroid or stress response coordination via adrenal hormones.

nenet
Télécharger la présentation

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. ENDOCRINE GLANDS • • Secrete hormones directly into bloodstream • • Ductless • EXOCRINE GLANDS • secrete substances through a duct (sweat, salivary, lacrimal and pancreas)

  3. Function of the Endocrine System • – to secrete hormones – chemical messengers that coordinate and direct target cells and organs.

  4. Hormonal Control • NEGATIVE FEEDBACK • • Drop in hormone level triggers a chain • reaction to increase secretion, for example • 1. Blood level of hormone falls • 2. Brain gets message and sends out • hormone to stimulate gland • 3. Gland stimulates more hormone • 4. When blood levels of hormone increase, • the brain hormones stop

  5. Nervous Control – in some cases, sympathetic • nervous system causes direct release of hormone • from gland (for example, when stress causes the • adrenal medulla to secrete adrenalin)

  6. Hormone Transport in Blood • Water-soluble hormones are transported dissolved in blood plasma. • Others circulate in blood, bound to plasma proteins. • The free hormone diffuses across capillary walls to encounter its target cells.

  7. The Endocrine System • Consists of several glands located in various parts of the body • Specific Glands • Hypothalamus • Pituitary • Thyroid • Parathyroid • Adrenal • Kidneys • Pancreatic Islets • Ovaries • Testes

  8. Hypothalamus • Produces several releasing and inhibiting factors that stimulate or inhibit anterior pituitary’s secretion of hormones. • Produces hormones that are stored in and released from posterior pituitary.

  9. Hypothalamus • Also responsible for: • Regulation of water balance • Esophageal swallowing • Body temperature regulation (shivering) • Food/water intake (appetite) • Sleep-wake cycle • Autonomic functions

  10. PITUITARY GLAND • • Tiny structure the size of a grape • • Located at the base of the brain • • Connected to the hypothalamus • • Divided into anterior and posterior lobes • • The “Master Gland”

  11. Pituitary Gland • Two areas • Anterior Pituitary • Posterior Pituitary • Structurally, functionally different

  12. Anterior Pituitary Lobe • • GROWTH HORMONE –GH(SOMATOTROPIN) - responsible for growth and development • • PROLACTIN – develops breast tissue, • stimulates production of milk after childbirth • • THYROID-STIMULATING HORMONE – TSH - • stimulates thyroxine • • ADRENOCORTICOTROPIC HORMONE (ACTH) – stimulates adrenal cortex

  13. Anterior Pituitary Lobe (cont) • • FOLLICLE-STIMULATING HORMONE (FSH) - • stimulates growth of graafian follicle andproduction of estrogen in females, sperm in males • • LUTEINIZING HORMONE – LH – stimulates • ovulation and formation of corpus luteum, which produces progesterone in females

  14. Posterior Pituitary Lobe • • VASOPRESSIN – converts to ADH • (antidiuretic hormone) in the bloodstream, acts on kidney to concentrate urine and preserve H2O in the body • • OXYTOCIN – released during childbirth • causing contractions of the uterus

  15. THYROID GLAND • • Butterfly-shaped mass of tissue • • On either side of larynx, over trachea • • H-shaped

  16. Thyroid Hormones • • Main hormone – THYROXINE – is controlled • by the secretion of TSH • • Thyroxine controls the rate of metabolism • • CALCITONIN – controls calcium ion concentration in the body, prevents hypercalcemia

  17. PARATHYROID GLANDS • • Four glands, each the size of a grain of rice • • Attached to posterior thyroid • • Produce PARATHORMONE which helps • control blood calcium level, prevents • hypocalcemia

  18. THYMUS • • Endocrine gland and lymphatic organ • • Located behind the sternum, above and in • front of the heart • • Begins to disappear at puberty

  19. ADRENAL GLANDS • • Located on top of each kidney • • Adrenal cortex secretes hormones known at • corticoids – they are anti-inflammatory • • They are: mineralcorticoids, glucocorticoids, • and sex hormones

  20. Adrenal Hormones • • ANDROGENS are male sex hormones • • Adrenal medulla secretes epinephrine • (adrenalin) and norepinephrine • • ADRENALIN is a powerful cardiac stimulent – “fight or flight” hormones that prepare the body for an emergency situation

  21. GONADS • • Ovary in female • • Testes in male • • Estrogen – development of female reproductive organs, secondary sex characteristics • • Progesterone – plays a part in the menstrual • cycle • • Testosterone – male reproductive organs and • secondary sex characteristics

  22. PANCREAS • • Located behind the stomach • • Endocrine and exocrine functions • • Involved in production of INSULIN by ISLETS • OF LANGERHANS • • Insulin – promotes utilization of glucose by the • cells, fatty acid and amino acid transport, and • facilitates protein synthesis

  23. Other Hormones • PROSTAGLANDINS – tissue hormones, can • cause constriction of blood vessels, muscle • contractions. Can be used to induce labor.

More Related