Endocrine system, its classification, chemical signals, receptors, hormones, Pituitary gland..pptx

Endocrine system, its classification, chemical signals, receptors, hormones, Pituitary gland.

1. The Endocrine System

2. Functions of Endocrine System

3. Chemical signals Chemical signals or Ligands Molecules released from one location that move to another location to produce a response. Intracellular response – produces from one part of a cell and travel to another part of the SAME cell 1- Autocrine 2- Paracrine 3- Neuromodulators 4- Pheromones

4. Receptors Chemical signals bind to proteins and glycoproteins (RECEPTORS) Specificity – Tendency for each receptor site to bind to a specific chemical signal and not the others.

5. Membrane-bound receptors Extend across the cell membrane, with their receptor sites outside the surface of the cell membrane Responds to chemical signals that are large, and water-soluble Intracellular receptors Chemical signals DIFFUSES and bind to the intracellular receptor located at the cytoplasm or nucleus

6. Hormones are distributed in the blood to all parts of the body, but only its corresponding target tissue responds to each type of hormone Influences target cells by chemically binding to their receptors. 2,000-100,000 receptors for a particular hormone Hormones that pass in the blood and act on distant cells are called Circulating hormones or ENDOCRINE PARACRINE - Hormones that act on neighboring cells AUTOCRINE – Acts on the same cell Local hormones usually are inactivated quickly Hormones

7. Pituitary and Hypothalamus Pituitary gland / Hypophysis – Small gland about the size of pea Rest in the depression of sphenoid bone inferior to the hypothalamus of the brain. Infundibulum – Stalk connecting the pituitary gland to the hypothalamus Once known as “Master Gland”

8. Pituitary and Hypothalamus

9. Growth hormone Thyroid-Stimulating Hormone (TSH) Adrenocorticotropic Hormone (ACTH) Gonadotropins Leutinizing hormone (LH) Interstitial Cell-stimulating hormone (ISCH) Prolactin Melanocyte-Stimulating Hormone Hormones of the Anterior Pituitary

10. A- Dwarfism B- Gigantism

11. In gigantism - ACROMEGALY - facial features and hands become abnormally large Somatomedins – Protein chemical signal which together with Growth hormone to bind to the receptors of bone and cartilage tissues to stimulate growth 2. Thyroid-Stimulating Hormone (TSH) Binds on Membrane-bound receptors of the thyroid gland , causes to secrete thyroid hormones. ↑ TSH- Thyroid gland enlarges

12. 3. Adrenocorticotropic Hormone (ACTH)

13. 4. Gonadotropins Binds on Membrane-bound receptors of the gonads. Regulates growth, development, and of functions of gonads

14. 5. Prolactin Binds on Membrane-bound receptors in the cells of the Breast , during pregnancy and stimulates the production of milk. 6. Melanocyte-Stimulating Hormone Binds on Membrane-bound receptors on melanocytes and causes them to synthesize melanin. ↑ ACTH - Darkening of the skin

15. 1. Antidiuretic hormone (ADH) Binds to Membrane-bound receptors and increases water reabsorption by kidney tubules. Resulting to less water lost in urine. Can cause blood vessels to constrict (vasopressin) Hormones of the Posterior Pituitary 2. Oxytoxin Binds on Membrane-bound receptors and causes Uterine contraction and milk ejection (milk let-down)

16. Thyroid Gland

17. Thyroid Hormones Binds to intracellular receptors in cells and regulate the rate of metabolism in the body. Participates in normal rate of growth and development. Hypothyroidism Infants – Cretinism - Mentally retarded and short in stature, with abnormally formed skeletal structures. Adults – reduced rate of metabolism, sluggishness, reduced ability to perform routine task.

18. Hyperthyroidism Elevated rate of metabolism, extreme nervousness, and chronic fatigue. Grave’s disease – bulging of the eyes ( exopthalmia ). Thyroid gland requires iodine to synthesize thyroid hormone. Iodine is taken up by thyroid follicles, hormone synthesis Thyroxine / tetraiodothyronine (T4) Triiodothyronine (T3) Lack of iodine results in reduced T3 and T4 synthesis

19. Grave's disease Cretinism

20. Para-thyroid Gland

21. Adrenal Glands Adrenal Medulla – Inner part (narrow or middle) Secretes Epinephrine (adrenaline) and small amounts of Norephinephrine Released in response to stimulation of Sympathetic nervous system Fight or Flight hormones

22. Pancreas, Insulin, Diabetes

23. Diabetes Mellitus

24. Testosterone – Main sex hormone in male Responsible for the growth and development of male reproductive structures, muscle enlargement, growth of body hair, voice changes, and male sexual drives. Testes and Ovaries

25. Estrogen & Progesterone

26. Thymus Gland

27. Pineal Body

28. Reference: Essentials of Anatomy & Physiology Fifth edition Seeley • Stephens • Tate

29. Thank You…