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Endocrine system
Presentation · March 2020
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Wefak Jbori Albazi
University of Kerbala
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Endocrine system
Pro.dr.wefak albazi
Kerbala university 2020
Endocrinology
Endocrinology:- is the study of the
endocrine system in the body. This is a
system of glands which secrete
hormones. Hormones are chemicals
which affect the actions of different
organ systems in the body.
Hormones
*Hormones – organic biologically active compounds of
different chemical nature( small molecule , protein
,glycoprotein or lipid) that are produced by the
endocrine glands, enter directly into the blood or
lymph .
hormones are regulatory molecules secreted
directly to the blood stream and to the target tissue
where it produce its effects. which are bind to
specific receptors that encourages growth or
influences how the cells and tissues function.
Hormone chemical structure
1-Peptides (Insulin , GH,
calcitonin ,ADH ,Oxytocin ….)
2-steroids (estrogen,
aldosterone , testosterone ….)
Hormone effects
1-endocrine when a hormone is released into the
circulation and then travels in the blood to produce a
biologic effect on distant target cells.
The target organ contains cells that express
hormone-specific receptors and that show a biologic
response upon hormone binding.
Paracrine
2- Paracrine when a hormone released from one
cell produces a biologic effect on a neighboring
cell.
3-Autocrine
3-Autocrine :- when a hormone produces a
biologic effect on the same cell that
released it.
4-intracrine
4-intracrine hormone is synthesized
and acts intracellularly in the same
cell
Comparison between nervous and
endocrine system
Hormone action
Depend on the type of hormone
Peptide hormone (water soluble , large molecules , ve charge ) hormone action is the 2nd messenger
(Gs, Gq and Gi)
Steroid hormone (lipid soluble ) Steroid hormone
pathway directly inter to the cell
Hormone action 2nd messenger
processes
Hormone action 2nd messenger processes
Steroid hormone pathway directly
inter to the cell
Steroid hormone pathway directly inter
to the cell
Control of Hormone Release
1-hormonal control (feed back mechanism )
2- Neural control( adrenal medulla hormone epi and
nor epi …)
3-nutrient or ion regulation( glucose , Ca , K…)
4-genetic control (GH …)
half-life
the time that hormone required for half of
the hormone to be cleared from the blood.
GH( 6 to 20 minutes). Steroid and thyroid
hormones more than two hours.
Hormone transport
Hormone circulate in the
blood
1-freely hydrophilic H
(peptides)
2- bound to carrier
proteins( hydrophobic H
steroids )
*reservoir , prolong
hormones half life . eg.
albumin ,globulins,
synthesized by the liver )
Endocrine glands
1- Unicellular ( epithelial cell in the stomach)
2- Multicellular
A -Pure endocrine glands
Pituitary gland
Thyroid gland
Adrenal gland
B- mixed gland
Hypothalamus , Pancreases(exocrine secretion
(digestive enzymes and bicarbonate secretion )
Heart ( ANP), Kidney (Erythropoietin , Renin )
Reference
1- Anatomy & Physiology - The Unity of Form and Function
3rd Edition 16-9-Saladin.
2-Guyton Medical Physiology notes 13th ed (2)notes2
Essentials_of_Anatomy_and_Physiology_0803615469
thanks
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