Physiology Magdy Sabry Endocrine glands and reproduction

162 Pages·2000·20.354 MB·English

by  Dr.Magdy Sabry

HUMAN
PHYSIOLOGY
FOR MEDICAL STUDENTS
I I
ENDOCRINE GLANDS & REPRODUCTION
MAGDI SABRY, MD
professor of physiology
Faculty of Medicine
AI-Azhar University
CAIRO
All rights reserved, no part oft his book may be reproduced in any
manner without ~t•ritten permission from the author or publisher.
For information, please call Tel. [phone].
DEDICATED TO
MY TEACHERS THROUGHOUT MY LIFE, particu/ur(r the
.fir.\1 2 teuc:hers. my late pc11·ent.\·.
MY FAITHFUL LATE WIFE, the light that disappeared
fhnn l~fe hut i ... ,. el•erla.'iling inside me.
MY SONS, SHERIF, AMR AND ESSAM, AND THEIR WIVES,
file
thl'ir lol'e gil•c•s me.: !tope am/ inleresl in am/ malw.\· their
lwppiue. ., . .. ,. my chic~{gottl.
MY GRANDCHILDREN, AHMED, NOURHAN AND SAMA
SHERIF, YASMIN AND MOHAMMED AMR, AND A YA ESSAM.
tlu• beautiful yomtg angel.-; that ftm•t• added a new kind of
lwppine.'is to my life.
PREFAC
With recent adwmces in the field of human physiology, it has
become urgent to prm•ide till up to date re1•iew 011 the subject.
T/li' book is prrJI'ided to help medical .\tudent' in uml£'n tanding
modem human physiology./t presents the 11'/tolt .\f(bjecf in a
brief, comprehensive, and up to date form.
Great effort was done to perfect such a vast subject in a11 easily
understandable expressio11 and in a suc:lt reasomtiJ/e bulk. It includes
as muc:lt simplified am/ clear illustrations a.\ possiiJ/e.a11d to maintai11
simplicio•. they have been presented 111 a diagrrt111111atic form,
photographs 11•ere greatly excluded.
Tlte major part of my gratitude should be gh•e11 to all 11•110 taught
me, am/ to my late '"~fe and so11s 11'/to, patient~)'. supported me duri11g
prepamtio11 t~f litis book
A11y suggestions, remarks or criticism will be great~)' welcomed,
ltearfiZI' appreciated and l'f!I:J' much considered.
I !tope this book will be a reallte/p to umlergraduate medical student'
as well a.\ to postgraduates and candidates of ltigltt•r degrees, ill the
field ofllllmtm physiology.
:vlAGDI SABRY 1989
Second edition 1994
Third edition 2000
I 'd un· 111 lhl· fmulh ~cliliun
Hli\ IIL'II' etfition i\ oriJ,:illa/ hmh ill \/lllpi! llll(/ COIIIt'l/(\. fl/ tfwptc•r.. hlll'l.'
ht'l'll t''J;It mil·cly re,•i,rtl uml tlfltltllt•d. Hort' ./h:ttre:o. ami illmtrllliom art'
illlrmlttl't'tl, ant! rcn'llf dam urc• m!t/C'tl i!f,cwllt'N' v~t•dal(r llhoutthr mt• ·lumi"'"
of action of llonnont'\, ant! a/mf/\1 all \llhjcct' l1111't' ht t'll t'OIIIflll'lt'(l' rcll'rilft'll.
I CONTENTS I
SECTION I : THE ENDOCRINE GLANDS page
Chapter 1 : The hor1nones ................................................................... !
Chapter 2: The pituitary gland (the hypophysis) .......................... lO
Chapter 3 : The thyroid gland.......................................... 33
Chapter 4 : The adrenal (suprarenal) cortex................................ 49
Chapter 5 : The adrenal (suprarenal) medulla............................ 66
Chapter 6: The parathyroid glands & calcium metabolism 72
Chapter 7: Endocrine fi.mctions oft he pancreas....................... 84
Chapter 8 : The pineal gland (the epiphysis) ............................... 96
SECTION II : REPRODUCTION
Chapter 1: Sexual deve/poment and puberty ..................... 97
Chapter 2: The male reproductive system.................................. I 03
Chapter 3: The female reproductive system............................. 116
SECTION I
ENDOCRINE GLANDS

CHAPTER 1
LTr·- · 1
'ORMCNF<='
In the human body, there arc 2 systems that regulate the functions of other
systems. These arc the nervous and the endocrine systems. The endo
crine glands are ductless glands that secrete lwrmones directly into the
bloodstream through which they reach other sit~:s ( target organs) wh~:rc
they exert their action;;. They include the folio'' ing gland (figure I).
PI N.EAL
4 PAQAT~YROIOS
----------- - THYMUS
'
-- --
2 SUPRAQENALS
.,
.... CORr~XIl
MEDUI.I.A
--PANCQEAS
(lskcs o/
Lam_;frrhans)
2 TESTES in Male
/ ( 2 OVARIES in Fcemalcz.
' fplvs p/oca.·'l!o in
,/ \ ,crq9n oncyj)
I
,I
w
I '
Figure I :The human endocrine glands.
Section 1- Chapter 1 Properties o(hormnnes
(I) Pituitary gland (the hypophysis).
(2) Thyroid gland.
(3) Parathyroid glands (usually 4 glands).
(4) Adrenal (or suprarenal) glands (2 glands, each contains conex & ncdulla)
(5) Sex glands or gonads (2 testes in males unci 2 ovaries in females).
(6) Islets of Langcrhans (in the pancreas).
(7) Pineal gland (the epiphysis).
(8) Thymus gland (refer to blood).
:::_ All glands arc important for normal body function, but the anterior
pituitaty, adrenal cortex and parathyroid glands are essential to life.
I I
OTHER ENDOCRINE ORGANS
In addition to the endocrine glands mentioned above, the following
organs also exert endocrine functions besides their original functions :
1. The kidneys : These secrete (a) Renin (b) E'J'fllropoietin
(c) 1,25 -dihydro.\)•c/wlecalciferol (the actil·e metoho!ite of vitamin DJ).
2. The heart : The atria secrete ANP (Atrial Natriuretic Peptide)
which causes natriuretic and hypotensive effects (refer to kidney).
3. The hypothalamus : This secretes (a) The hypophysiotropic
hormones, which r!flect the activity <~!'the anterior pituitaJ:v gland (b)
Antidiuretic hormone (or vasopressin) ami oxytocin, which are stored in
then releosed.fi'om the posterior pituitarv gland (rclcr to the pituitary gland).
4. The placenta (page 139).
5. The lungs (rdcr to rcspimtion).
6. The liver (refer to digestion).
Apart from these "general hormones" secreted by the
endocrine glands and rhe other endocrine organs, there are also "local
hormones" that act at (or near) the sites of their secretion. These include
(a) The gastrointestinal hormones (e.g. gastrin, secretin, CCK, etc.) (b)
The 11arious chemicaltransmillers released by nerve endings.
I I
PROPERTIES OF HORMONES
1. They cxcr1 no tljfa'ti on the glands t!tat secrete them.
2. Some hormones affect cell activity allover the body (e.g. the growth
hormone) while others act only on specific lfll~~et cells (e.g. sex hormones)
3. In the target cells. they trigger (initiate) certain biochemical reac
tions which often continue for sometime after disappearance of the hor
mones from the bloodstream.