محاضرة فسيولوجي.....Endocrine system

ENDOCRINE SYSTEM

*Definition:- -It is group of glands distributed all over body to secrete hormones to perform certain functions.

*Hormone:- - Are substances secreted by endocrinal gland…….

*concentration of hormones:

-It is very low in blood……

-It is estimated i nanograms/ or by micrograms / or milligrams…

*When secretion of hormones occur?

-According to body needs

-so for example Insulin is secreted to control glucose level in blood……….

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_There are some hormones which affect all body system as insulin…………..

_Other hormones act on target organ for example Estrogen the female hormone act only on genital system……………….

_AS a difference between endocrine system and nervous system that endocrine effect lasts for long time…while nervous is immediate as reflex action.

_Some hormones are antagonist(do functions opposite to each other)

for example : Insuline decrease blood glucose level.....while glucagons increase blood glucose level

_Hormones follow certain rhythm ….As they are not always secreted by the same amount..but some are 24 hour rhythm(change in all the 24 hours) ……..as cortisone…………while some increase at morning and decrease at night………..And some are month rhythm as progesterone and estrogen.

*General natures of hormones:-

_Hormones is of one of three origins only:

.protein and poly peptide

.steroid hormones

.simple amino acids

*Sites of endocrinal glands:-

A-In brain: a-Hypo thalamus b-Pitutary gland

B-In neck: a-Thyroid gland

b-para thyroid gland

C-In abdomen: a-pancreas

D-Above kidney: a-one supra renal gland on each kidney.

E-In pelvis: a-Female::two ovaries

b-Male:two testis

*To classify the nature of hormones of each gland:-

.Hypo thalamus—Pitutary—Parathyroid – Pancrease : Are of protein and poly peptide natures……….

.Supra renal cortex –ovaries and testis :steroid hormones which are mainly formed of cholesterol………..

.Supra renal medulla –Thyroid hormones: simple amino acids……….

_For each hormone there is mechanism of action according to its nature.

*1st mechanism of action:-

-Of the protein and poly peptide hormones.
_For hormone to affect an organ :::There are sensitive receptors for the hormone on the organ it should affect to pick up that hormone…so the hormone start its biochemical changes.

_So if hormone is of nature of protein and poly peptide so receptors of it are on the cell membrane…and it only cause the activation of the already present enzymes in cell..

_Hormone is called:Primary messenger.

_The biochemical reaction is called:secondry messenger.

Nooooooooote……:-

-Protein and poly peptides are found as:-

A-Secondry messenger with cyclic AMP (CAMP)

B-Primary messenger with calcium level.

C-Secondry messenger with cell membrane..and those are phospholipids where the hormones affect it are Inositol and Diacyl glycerol.

*Second mechanism of action:-

-Mechanism of steroid hormones of testis- ovary- and supra renal cortex.

-Steroid hormones receptors are in side the cell in cytoplasm.

-When the receptor pick up the hormone it forms (Hormone receptor complex)

-Then the complexbegin to form RNA in sequence of protein.

-The new protein formation is secondry.

-Steroids effect is slow.

*Third mechanism:-

-As in case of cortisone.

-Receptors are in nucleus.

Nooooooooooootes:-

_Hypo thalamus regulates pituitary gland so it secrets homone called Trophic hormone.

_While pituitary gland controlall glands below it.

ايه الحلاوه دى

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ِكرا يا اسماء ربنا يكرمك انا كان فايتنى اول جزء بس والحمد لله نقلته

انا هضيف اخر جزء فى المحاضرة

Regulation of hormones secretion

this process is important to

1 to keep the percentage of hormones in blood constant

2 to prevent over activity of gland

3to keep the level of hormones acoording to the body needs

mechanism of regulation

1regulation by release inhibitory factors from the hybothalamus to increase or decrease the secrtion of hormones

2 feed back:when thyroxen increas it inhibit the pitutary gland that inhibit the hybothalamus that inhibit the gland
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و انا كان فايتني آخر جزء

و لمروركم جميعا
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funny really is that a lecture may be but it is aconclusion not a
lecture

shokran geddan ya gama3a
جزاكم الله خيرا
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شكرا

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