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CHAPTER 45 CHEMICAL SIGNALS IN ANIMALS. Egg. Larva. Pupa. Adult. Introduction. Endocrine system الجهاز الهرموني is one of the main internal communication وسائل الاتصال الداخلي systems. The animal hormone-secreting cells الخلايا المفرزة للهرمونات constitute the endocrine system.

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  2. Introduction • Endocrine system الجهاز الهرمونيis one of the main internal communication وسائل الاتصال الداخلي systems. • The animal hormone-secreting cells الخلايا المفرزة للهرمونات constitute the endocrine system. • Hormone secreting organs are called Endocrine Glands (ductless glandsالغدد الصماء). • Hormone is a chemical signal اشارة كيميائية secreted into blood stream يتم افرازها الى تيار الدم and regulates communicating messages تنظم وسائل الاتصالwithin the body. • Target cell الخلية المستهدفة is the site of action of the hormone موقع العمل • Types of hormones are • Polypeptide Hormones • Amino acid derivatives Hormones • Steroid Hormones Tropic hormones:الهرمونات المحفزة (المنبهة) target other endocrine glands

  3. Most chemical signals bind to plasma-membrane proteins, initiating signal-transduction pathways. Mechanism of chemical signaling: The chemical signals secreted by a cell either: I): Protein hormones: Bind to a receptor protein بروتين مستقبل on the surface of the target cell. Fig. 45.3a, Page 959

  4. II) Steroid hormones: Penetrate تخترق the cell and bind to a receptor protein inside the targetcell • Estrogen, progesterone, vitamin D. Fig. 45.3b, Page 959

  5. الصنوبرية النخامية الدرقية الكظرية The Vertebrate Endocrine System • Tropic hormones (الهرمون المنبه للغدد) • Target other endocrineglands. • Human has 9 endocrine glands. Fig. 45.5, Page 960

  6. The hypothalamus and pituitary integrate many functions of the vertebrate endocrine system • The hypothalamus integrates endocrine and nervous function. • Neurosecretory cells of the hypothalamus produce hormones. • Releasing hormones stimulate the anterior pituitary to secrete hormones. • Inhibiting hormones prevent the anterior pituitary from secreting hormones. 1)- Pituitary gland:secrets 9 hormones( 7 hormones by the anterior part and 2 hormones by the posterior part).

  7. A)- Anterior pituitary hormones. • Growth hormone (GH): a protein. • Stimulates growth and metabolism. • Gigantism:العملقةexcessive GH during development. • Acromegaly تضخم الاطراف: excessive GH production during adulthood. • dwarfism القزمية: childhood GH deficiency. • Prolactin (PRL): a protein. • Stimulates milk production انتاج اللبنand secretion from mammary glandالغدد اللبنية. • Gonadotropins (Gonotropicمحفز للمناسل): glyocoproteins. • Follicle-stimulating hormone (FSH). • Stimulates production of sperms and ova. • Luteinizing hormone (LH) المُحفز لتكوين الجسم الأصفر. • Stimulates ovaries and testes.

  8. Thyroid-stimulating hormone (TSH): a glycoprotein. • Stimulates thyroid gland. • Adrenocorticotropic hormone (ACTH): a peptide • Stimulates adrenal cortex secretion of glucocorticoids • Melanocyte-stimulating hormone (MSH): a peptide. • May play a role in fat metabolism. • Endorphins: peptides. • Inhibit pain perception. • Effects mimicked by heroin and other opiate drugs.

  9. Melanocyte-stimulating H. Adrenocorticotropic Also called gonadotropine hormones هرمونات المناسل The anterior pituitary gland hormones Fig. 45.6b, Page 963

  10. B)- Posterior pituitary hormones. • Oxytocin: a peptide. • Stimulates contraction of the uterus and mammary glands. • Secretion regulated by the nervous system. • Antidiuretic hormone (ADH):مُضاد لإدرار البول a peptide. • Promotes retention of water by the kidneys (in Kidney tubules). • High level decreases urination and viceversa. • Secretion regulated by water/salt balance. • 2- Pineal gland:الغدة الصنوبرية is a small mass of tissue near the center of the mammalian brain and involved in biorhythms. • The pineal gland secretes the hormone, melatonin, an amine. • Involved in biological rhythms associated with reproduction. • Secretion regulated by light/dark cycles.

  11. Antidiuretic H • Posterior pituitary(neurohypophysis)stores and secretes hormones produced by the hypothalamus. Fig. 45.6a, Page 963

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