Reproductive and Urinary Systems Flashcards
What does sexually dimorphic mean?
Being physically distinct e.g. males and females are physically distinct.
Sexual development is programmed in…
The genome
XY / XX
What does gonads mean?
The reproductive organs
E.g. males - testes contain sperm
E.g. females - ovaries contain eggs
Testosterone is…
A potent androgen
Where is testosterone synthesised?
Males - leydig cells of the testes
Females and males - adrenal cortex
What other androgens are synthesised within the adrenal cortex? (Both sexes)
DHEA (dehydroepiandrosterone)
Androstenedione (weak androgens)
Development of pubic / body hair is due to…
DHEA
What does testosterone metabolise into in males?
Dihydrotestosterone (active metabolite)
Regulated by enzyme 5a - reductase
Another product of metabolism of testosterone that affects women:
Estradiol
Regulated by Aromatase
Is the process of synthesis of steroid hormones the same in both men and women?
Yes but there are different factors that stimulate the processes.
Role of testosterone in males: (4)
- increased growth of body hair
- thickening of skin
- muscle growth, widening of shoulders
- thickening of the vocal cords
Where does DHT (activated) bind to?
Where do they go after?
Cytoplasmic androgen receptors - promoting release of heat shock protein.
Then migrated to nucleus and binds to specific regions of DNA that contain androgen response elements (ARE) .
What happens to testosterone levels through life?
Hormone levels unchanged until puberty
Then maintained through adult life and declined in old age
Hormonal control of male reproduction are secreted by: (3)
Hypothalamus
Testes
Anterior pituitary gland
Which organ is responsible for regulating hormone production in both males and females?
Hypothalamus
What happens when there is an internal / environmental stimuli to the hypothalamus?
It will trigger GhRH to be released activated anterior pituitary leading to LH and FSH being released, which leads to gamete production.
Ovary produces..
female sex hormones and female germ cells.
Females are born with a fixed number of..
follicles in the ovaries
How long is the ovarian cycle in women?
28 days
What 2 phases make up the ovarian cycle?
Follicular phase
Luteal phase
What hormone regulates the Follicular phase?
FSH
Explain the Follicular phase (3)
FSH stimulates follicles in ovaries to mature.
oestrogen released which stimulates pituitary gland to release LH.
Increase in LH causes ovulation.
What happens to the remaining cells of graafian follicle in ovaries?
What about if no fertilisation?
Will turn into corpus luteum which releases oestrogen but mainly progesterone which a signal to pituitary gland to not be active.
Level of progesterone decreases which stimulates process to happen again - stimulates pituitary gland to produce FSH.
What is menses?
shredding of the uterus lining.
Progesterone helps build up…
uterus lining once again.
What is the theca?
Located below the surface epithelium and is under the influence of LH to synthesise androgens.
What is the Granulosa cells?
Under the influence of FSH, releases AMH hormone.
Main steroid hormones in women..
Estrogens C18 (Granulosa cells)
What other steroid hormones may be present and when?
Estrone E1 - post menopause
Estirol E3 - in pregnancy
Name 2 other types of steroid hormones:
Where are they produced?
Progestagens C21 (Corpus luteum) e.g. progesterone
Androgens C19 (Theca) e.g. testosterone.
The actions of estrogen are mediated by…
The estrogen receptor (ER) which binds to DNA and controls gene expression.
What does the estrogen:ER complex do?
Binds to specific DNA sequences called a hormone response element to activate the transcription of target genes.
Why are estrogens important? (4)
- for maturation of germ cells
- development and regulation of female reproductive system
- maintaining pregnancy
- anabolic effects on bone and cartilage.
What age does menopause occur?
45-55 years
Why does menopause happen?
Ovaries fail to respond to FSH, number of remaining follicles decrease.
What increases during menopause?
LH and FSH - to try to compensate low estrogen level; hot flushes.
What does progestin do in the presence of oral contraceptives? (2)
Causes thinning of the endometrium which prevents implantation of a fertilised egg.
Thickens the mucus in the cervix, preventing sperm from reaching eggs.
What do Estrogen and progestin do in the presence of oral contraceptives?
Prevent eggs from being released from the ovaries.
