Chapter 5: Sex Hormones Flashcards
What are the three classes of sex hormones and examples of each?
1. Progestins L> progesterone 2. Estrogens L> estradiol 3. Androgens L> testosterone L> 5 alpha-dihydrotestosterone
What is a catalyzing enzyme?
- enzymes that do not have a direct influence on the body but trigger things
What are two examples of catalyzing enzymes?(their function as well)
- Aromatase
L> converts testosterone to estradiol - 5-alpha-reductase
L> converts testosterone to the more potent 5alpha-dihydrotestosterone (DHT)
Testosterone levels vary _______.
- cyclically
What are the two different testosterone cycles in men?
- shorter cycle: 2-4 hours, 3 to 4 fold variability
2. longer cycle: 24 hours- higher midnight to noon than noon to midnight.
Explain testosterone levels in women?
- variability
- peak concentration
- 2-fold variability over the course of the menstrual cycle
- peak concentrations around the time of ovulation
(more likely to get prego)
Testosterone has a short/long half life?
short
What is the half life of testosterone?
function?
- 45 mins
L> this allows blood levels to change fairly quickly and impact on target tissues occurs in less than an hour.
Estradiol is synthesized from what and in which sexes?
- testosterone
- both
Where does the conversion of estradiol occur?
- testis
- ovary
- brain (see fig 5.3)
What role does the conversion of estradiol to testosterone play in?
- prenatal sexual differentiation
Progesterone is a male or female sex hormone?
L>but??
- female
L>BUT it occurs in small amounts in males but role in sexual behaviour is unknown
Sex steroids act by activating specific what?
L> function?
- receptor molecules
- L>steroid receptors control gene expression and affect the cells structure, function or growth.
Proteins and peptide hormones are products of what?
- genes
Give four examples of proteins and peptide hormones.
- Oxytocin
- Gonadotrophin-releasing hormone
- Prolactin
- Growth Hormone
Oxytocin
- synthesized where?/stored?
- reaches high levels when?
- thought to enhance what?
- synthesized n the hypothalamus and stored in the pituitary before release (fig 5.4)
- reaches high levels during breast feeding, childbirth and orgasm
L> thought to enhance orgasm and to facilitate interpersonal bonding and trust
Gonadotrophin-releasing hormone
- synthesized where?
- function?
- synthesized in the hypothalamus and transported to the pituitary
- stimulates the release of follicle stimulating hormone (FSH) and luteinizing hormone (LH)
Prolactin
- function?
- prepares the breast for lactation
- may promote parental behaviour…not 100% sure though
Growth hormone
- function
- stimulates growth throughout the body and plays an important role at puberty.
Testosterone has one effect? many effects? in men
many
Testosterone in men:
1.Testosterone facilitates _____ and regulates ___ secretion.
- spermatogenesis
- LH
Testosterone in men:
2. Testosterone influences _____ via the central nervous system, especially the ______?
- sexual behaviour
- medial preoptic area of the hypothalamus