13.10: Physiological Roles of Steroid Hormones

Sierra Barnhart AndChelsalyn Corcoran

13.10: Physiological Roles of Steroid HormonesSynthesis of Steroid HormonesCholesterol is starting material for synthesis of Steroid Hormones.Aliphatic side chain on the D ring is shortened.Six Carbon unit is removed.Secondary alcohol group on 3rd carbon is oxidized to a ketone.Progesterone is produced.Progesterone- starting compound for the sex hormones and adrenocorticoid hormones.

Adrenocorticoid HormonesProducts of the adrenal glands.Classified in groups by function:Mineralocorticoids-regulate concentration of ions.Glucocorticoids- Control carbohydrate metabolism.Corticoid- means site of secretion is the outer part of the gland.Aldosterone- one of most important mineralocorticoids. Increased secretion enhances the re-absorption of Na+ and Cl- ions in kidney tubules. Increase the loss of K+

Continued.Na+ concentration controls water retention in tissues. Controls tissue swelling.Cortisol- major glucocorticoid. Increase glucose and glycogen concentration. Fatty acids from body proteins are transported to liver, cortisol manufactures glucose and glycogen. Ketone derivative. Anti-inflammatory. Synthetic derivatives used for inflammatory diseases of organs:Bronchial asthma, rheumatoid arthritis

Sex HormonesTestosterone- most important male sex hormonePromotes normal growth of genital organsDuring puberty: testosterone production is increased Causes deep voice, facial and body hairMost important female sex hormone- estradiolSynthesized from testosterone by aromatization of A ring.

ContinuedEstradiol and progesterone regulate menstrual cycle.Beginning of cycle: estradiol rises causing the uterus lining to thicken. The luteinizing hormone triggers ovulation.If ovum is fertilized, progesterone will inhibit ovulation. Estradiol and progesterone prepare the uterine lining to receive the fertilized ovum.

ContinuedIf no fertilization: progesterone stops and estradiol decreases.Causes the uterine lining to thin down, and menstrual bleeding occursBlocking progesterone terminates a pregnancyProgesterone interacts with a receptor in the nucleus of cells.Receptor then changes its shape.MifepristoneMifepristone also called RU486 acts as a competitor to progesterone.Blocks the action of progesterone by binding to the same receptor cites.Progesterone molecule cant reach the receptor molecule so uterus isnt prepared for implantation and ovum is aborted.After pregnancy is established, RU486 will be taken up through 49 days of gestation.

ContinuedSupplement to surgical abortion.Binds to the receptors of glucocorticoid hormones tooUsed as an antiglucocorticoid. Also recommended to alleviate Cushing syndrome (overproduction of cortisone)Morning after pill is different:Can be taken up to 72 hours after unprotected intercourseActs before the pregnancy takes place

2 kinds on the market as prescription drugs:Levonogestrel- progesterone- like compoundPreven- combination of levonogestrel and ethynil estradiolEstradiol and progesterone regulate secondary female sex characteristics.RU486 used as an antiprogesterone can prevent certain types of breast cancer.

Male and Female Sex HormonesTestosterone and estradiol are not exclusive to males or females.A small amount of estradiol is produced in malesSmall amount of testosterone in femalesOnly when hormonal balance becomes upset, can one have symptoms of abnormal sexual differentiation.

13.11 What Are Bile Salts?Oxidation products of cholesterol Cholesterol is oxidized to the trihydroxy derivativeThe end of the aliphatic chain is oxidized to the carboxylic acid. The latter forms an amide bond with an amino acid.

Bile salts are powerful detergentsOne end of the molecule is hydrophilic, due to its negative charge, and the rest is hydrophobicCan spread dietary lipids in the small intestine into emulsions, facilitating digestion.Similar to soap on dirt

Eliminated in fecesRemove extra cholesterolEliminated through bile saltsSolubilize deposited cholesterol in the form of cholesterol particles

13.12 What are Prostaglandins, Thromboxanes, and Leukotrienes?Prostaglandins 1930s Kurzrok andLeibDemonstrated semi fluid causes a hysterectomized uterus to contractUlf von Euler isolated the compounds from semenThought they came from prostate glad, thus prostaglandin

Seminal gland secretes 0.1 mg/ day in matured menSmall amounts present in both male and femaleSynthesized from arachidonic acid by ring closure at carbons 8 and 12Cyclooxygenase (COX) catalyzes reactionProduct is PGG Persecutor of PGE PGF

E group has carbonyl group on carbon number 9Subscript represents number of double ponds in the hydrocarbon chainF group two hydroxyl groups on ring at 9 and 11

CyclooxygenaseTwo forms:COX-1: catalyzes physiological production of prostaglandins (always present add more)COX-2: responsible for prostaglandins in inflammationThromboxanesClass of arachidonic acid derivatives is thromboxanesRing closureDeived from PGHRing is cyclic acetalInduces platelet aggregation

LeukotrienesAct to meditate hormonal responsesDerived from arachidonic acidNo ring closure

Occur mostly in white blood cellsFound in body tissueCreate long-lasting muscle contractions Stronger than histamines

Cause fever and inflammationInhibiting uptake by leukotriene receptors stops effectsZafirlukast helps to control chronic asthma