REPRODUCTIVE HORMONES (STEROIDS: Derived from cholesterol (Estrogens…
STEROIDS: Derived from cholesterol
Uses: Development of Secondary female characteristics, regulation of menstrual cycle,
Testosterone 50%, 2-3dihydrotestosterone (DHT) 100%, DHEA 4%, Androstenodione 8%,
Uses: development of male secondary sex characteristics, genitalia growth, larynx growth, pubic and axillary hair, increased sexual acts and thoughts, increased labido,
Progesterone 100%, 17a hydroxyprogesterone, 40-70%, 20a hydroxyprogesterone 5%
Uses: gestation, supports endometrium, evolves mamillary glands
Steroids must takes a metabolic pathway when synthesising from cholesterol into other hormones with the use of enzymes
Lipophillic: diffuse through the phospholipid bilayer and binds to intranucleur receptors
PROTEINS AND PEPTIDES: Chains of 3-200+ amino acids
LH: from AP. acts of testis (leydig cells) and ovary (thecal, luteal and granulosa cells). Made up of Achain of 92aa and 2 carbohydrate chains + Bchain of 121 aa and 2 carbohydrate chains
FSH: From AP. Acts on sertoli cells and granulosa cells. Made up of Achain of 92aa and 2 carbohydrate chains + Bchain of 111 aa and 2 carbohydrate chains
Human chorionic gonadotrophin (hCG) from syncytiotrophoblasts. Acts on luteal cells in the ovary and leydig cells in the fetak testis. Made up of Achain of 92aa and 2 carbohydrate chains + Bchain of 145 aa and 2 carbohydrate chains
Polypeptides with one or two chains, grouped into families on basis of molecular structure
Inhibin: effects granulosa cells and sertoli cells: intraovarian and intertesticular activity, gonad-pituitary interactions
Anti Mullarian hormone: causes the regression of the mullarian ductS = responsible for the development of male genitalia, descent of the testis, inhibits growth of early follicles
Relaxin: corpus luteum, partuation(ripening of the cervix), separation of pubic symphysis for assistance in child birth
Small peptides (oligopeptides) 3-10aa
Synthesised in form of larger polypeptide precurser
Active cleaved prior to secretion
Gonadotrophin releasing hormone: neurosecretory cells of hypothalamus, controls the release of gonadotrophins
Oxytocin: from hypothalamus stored in posterior pituitary gland. Is involved in parturition, milk led down and bonding.
Kisspeptin: neuropeptide from hypothalamus, controls GnRh and fertility
Are responsible for tissue growth and function
Large single peptide chains (191-199aa)
Prloactin: acts on mammary glands (lactation) and hyperprolactinemia supresses fertility
Human chorionic somatommotrophin (hCS): made from syncytiotrophoblasts, mobilizes fatty acids during pregnancy
Growth hormone: from AP is responsible for puberty and growth
Hydrophillic: Bind to receptors on the membranes surface which causes a secondary messenger to diffuse into the cell and influence/have the desired effect
Determinants of Hormone Action (4)
2. Blood concentration: Production rate/ clearance rate
The presence of binding sites also determines hormone levels in the blood. Hormones may also be metabolized in their target tissues = enzymatic conversion of circulating hormone by target cell into a more usable form eg, testosterone to 5a-dihydrotestosterone
are hydrophillic, they bind the receptors on the cell membrane and cause a secondary response to diffuse into the cell and carry out the response.
: are hydrophobic, they enter the target cell via the membrane and bind to intranucleur receptors.
being bound or unbound determines its effects (hormone can only have an effect if not already bound to another receptor; as they aren't "biologically active".)
4. Receptor expression
: high receptor density (strong response) = reduced receptor density ( decrease sensitivity) = diminished response
low receptor density (weak response) = increased receptor density (increased sensitivity) = stronger response. Closely related molecules can bind to the same receptor, these can be antagonists (decrease response) or agonists (increase response)
3. Secretion Patterns:
Different secretion patterns alter the actions of a hormone.
: secreted in bursts.
: secreted ones daily.
: less than once daily.
: once yearly.
: once hourly.
: more than once daily.
EICOSANOIDS: Derived from arachidonic acid
Postaglandins is the main reproductive group
Aspirin blocks synthesis of PG (good for cramps)
synthesised by seminal vesicle, myometrium, cervix (important for parturition)
Hormones: chemical messengers.
: into blood stream.
into a duct or tube.
adjacent/local cells, eg. leydig cells.
: affects the tissue which releases it eg. granulosa cells.
Slow release, wide spread, long lasting effects
3 Types: Steroids, Protiens and eicosanoids