Classification of Hormones And their Mechanism Of Action Mode of action of Hormones Classification of Reproductive Hormone

2. Classification of Hormone
And their Mechanism Of Action
Dr. Muhammad Awais

3. Hormones
 Hormones are chemical messengers, directly secreted into the blood or
extracellular fluid, which bind specific receptors on target cells

4. Classification of Hormones
 The following Three categories of classification of hormones
1. According to Chemical Nature
2. According to Origin
3. According to Nature of Action

5. According to Chemical Nature
 Steroid Hormones
e.g. Testosterone, Estrogen, Progesterone
 Amine Hormones
e.g. T3, T4, epinephrine, norepinephrine.
 Peptide Hormones
e.g. Oxytocin and vasopressin
 Protein Hormones
e.g. Insulin and glucagon
 Glycoprotein Hormones
e.g. LH, FSH
 Eicosanoids Hormones
e.g. Prostaglandins.

6. On the Basis of Origin
 Reproductive hormones primarily derived from four major organ or
system
o Hypothalamus
o Anterior and posterior lobe of pituitary gland
o Gonads (testis and ovary including their interstitial tissues and corpus
luteum)
o Placenta and Uterus

7. 1-PIH (Prolactin inhibiting hormone)
 Source; Hypothalamus
 Function; inhibit prolactin release
2-PRH (Prolactin releasing hormone)
 Source; Hypothalamus
 Function; stimulate prolactin release
3-GnRH (Gonadotropin releasing hormone)
 Source; hypothalamus (synthesized and then stored in the medial basal
hypothalamus)
 Function;
 stimulate tonic release of FSH and LH.
 stimulate preovulatory surge of FSH and LH.

8. FSH(Follicle stimulating hormone)
Source; Gonadotropes in anterior lobe .
Function;
 stimulate follicular growth in female and
 Spermatogenesis in male
 Maturation of ovarian follicle or graffian follicle
LH(Lutenising hormone )
SOURCE;
 Gonadotropes in anterior lobe of pituitary.
Function;
 stimulate ovulation and lutinisation of ovarian follicle(corpus luteum) in
female
 Testosterone in male from interstitial cells (leyding cells)

9. Prolactin;
Source;
 Anterior lobe of pituitary .
 Function;
 initiate and maintains lactation .
 Promotes maternal behavior.
Oxytocin;
Source;
 supraoptic nucleus of hypothalamus and ovary ( corpus luteum)
Function;
 stimulate uterine contraction
 Milk letdown
 Ovarian oxytocin involved luteal function acts on endometrium to induce
PGF2alpha.

10. Melatonin;
Source;
 pineal gland.
Function ;
 induction of ovarian cycles in ewes
 inhibition of cyclicity in mare.
Estrogen(E2)
Source;
 theca interna of the ovarian follicle and
 Fetal placental unit
Function;
 to induce behavioral estrus in the female
 Physical development of female
 Secondary sexual characteristics in female
 Stimulate duct growth and cause the development of the mammary gland
 To increase body weight gain and growth

11. Progesterone;
Source;
 luteal cells of corpus luteum
 Placenta (fetoplacental unit) and
 Adrenal gland
Function;
 prepare the endometrium for implantation and maintenance of pregnancy.
 Acts synergistically with estrogen to induce behavioral estrus
 Develop the secretory tissue of the mammary glands
 Inhibit estrus and the ovulatory surge at high level

12. Testosterone;
Source;
 leyding ,s cells in the testis and
Limited amount by adrenal cortex
Function;
 develop and maintain accessory sex gland
 Stimulate secondary sexual characteristics in male
 Sexual behavior
 Spermatogenesis
Relaxin ;
Source;
 primarily by the corpus luteum during pregnancy.
 Some species placenta and uterus
Function;
 Dilation of cervix and vagina before parturition
 Inhibit uterine contraction

13. Inhibin ;
Source;
 sertoli cells in male
 Granulosa cells in female
Function;
 inhibit release of FSH to a level’
 Maintain number of ovulation.
Activin ;
Source;
 follicular fluid in female
 Rete testis fluid in male
Function;
 stimulates FSH secretion.

14. eCG (PMSG); (Equine chorionic gonadotropin)
Source;
 endometrial cups of fetal origin
Function;
 FSH like activity
 Stimulates formation of accessory corpora lutea in mare.
hCG ;(human chorionic gonadotropin)
source;
 syncytiotrophoblastic cells
function;
 LH like activity
 maintains corpus luteum of pregnancy in primates

15. Prostaglandins;
Source;
 almost all body tissue secrete them, endometrium of uterus
Function;
 regression of the corpus luteum
 Contraction of smooth muscles in reproductive and GIT, erection
,ejaculation, sperm transport, ovulation, formation of corpus luteum,
parturition, and milk ejection

16. Hypothalamus
Anterior pituitary
Posterior pituitary
Thyrotropin
ACTH
Somatotropin
LH
FSH
Prolactin
Vasopressin
Oxytocin
Thyroid
Adrenal
Cortex
Adrenal
MedullaPancreas Ovary Testis
Muscles
liver Tissues
Liver,
muscles
EstradiolTestosteroneInsulin,
glucagon,
somatostatin
T3 Cortisol
aldosterone
Mammary
glands
Reproductive
organs
Epinephrine
Releasing
hormones
Nervous

17. According to Nature of Action
 General Hormones: Growth hormone influence nearly all the body tissues,
similar is the case with Thyroid and Insulin hormones, hence they fall in
general category.
 Specific Hormones: these hormones affect functions of specific organs,
e.g. FSH and androgens.
 Local Hormones: Prostaglandins, Acetyl cholin, Histamine act locally to
their site of production.

18. Mechanism of Action
 The first step of a hormone’s action is to bind to specific receptors at
the target cell.
 Some receptors are located on cell membrane while some are located
in cytoplasm and nucleus.
 These receptors are protein in nature and usually 2000-100,000
receptors are present on each cell.
 Receptors are located on specific in/on target cells

19. Mode of Action of Lipophilic
Hormone
 Hormones like steroid bind with protein receptors present inside the cell.
These hormones are lipid soluble and hence can easily cross cell
membrane.
 The combined receptor protein–hormone then diffuses into or is
transported into the nucleus.
 The hormone receptor complex then binds with specific regulatory
sequence of the DNA called hormone response element → transcription of
specific genes → mRNA→ Protein synthesis.

21. Mode of Action of Hydrophilic
Hormone

22. References
 Pathway to Pregnancy and Parturition By P.L. Senger, Ph. D.
 Guyton Text Book of Medical Physiology
 http://www.biologydiscussion.com/hormones/classification-
hormones/classification-of-hormones-5-categories/18429
 https://www.boundless.com/physiology/textbooks/boundless-anatomy-and-
physiology-textbook/endocrine-system-16/hormones-150/mechanisms-of-
hormone-action-774-807/
 https://en.wikivet.net/Reproductive_Hormones_Overview_-
_Anatomy_%26_Physiology
 http://animal--husbandry.blogspot.com/2010/07/reproductive-hormones.html
 https://bhsagriculture.wikispaces.com/The+Role+of+Hormones+in+the+
Regulation+of+animal+reproduction+and+behaviour
 Pakdairyinfo.com