IC3 Flashcards
How is testes descended?
Testosterone produced by fetal tests + shortening of gubernaculum stimulates the descent of testes from rear of abdominal cavity to 2 sides of scrotum; usually completed by 7th month of gestation
Term for undescended testes into adulthood
Cryptorchidism
Temperature of scrotum vs body temp
Scrotum: 35 degree Celsius vs Body: 37 degree Celsius
Which cell produces testosterone?
Leydig cells
Role of sertoli cells
Provide support for spermatogenesis
Where does spermatogenesis take place?
Seminiferous tubule
How long is spermatogenesis? Does it occur synchronously throughout the seminiferous tubule?
Around 64 days; No, different tubules are in different stages of spermatogenesis
What happens during male puberty?
- Onset of spermatogenesis
- Enlargement of testes and development of secondary characteristics
- Hormonal development ‘raging hormones’ -> Hypothalamus secretes GnRH every 1-3 hours -> stimulate release of FSH & LH from anterior pituitary
Predominant negative feedback of testosterone
Decrease GnRH release by acting on the hypothalamus, thus indirectly decreasing BOTH LH and FSH release by anterior pituitary.
Which hormone (other than testosterone) selectively inhibits FSH secretion?
Inhibin (produced by sertoli cells)
Effect of anabolic androgenic steroids on testes and testosterone
Anabolic androgenic steroids inhibits secretion of GnRH from hypothalamus -> decrease in LH and FSH release from gonadotrope -> Testosterone secretion & sperm production decrease & testes shrink
How is testosterone converted to dihydrotestosterone (DHT) & estradiol respectively?
By 5 alpha-reductase & aromatase
Which hormone contributes to hair loss in men,andhow?
DHT; shortens the growing phase of hair follicles, causing them to shrink until there are fewer visible hairs left on the scalp
What are androgens?
Any steroid hormone that promotes male secondary sex characteristics
What is an oocyte?
An immature ovum; found in ovary
Similarity btw ovary & testes
They are both gonads, produce sex hormones & are endocrine glands.
What is a primary follicle made up of?
Primary oocytes + surrounding granulosa cells
Follicular vs Luteal phase
Follicular: dominated by maturing follicles
Luteal: characterised by presence of corpus luteum
3 main types of estrogen made the body
- Estradiol (commonly found in women of childbearing age)
- Estriol (main estrogen during pregnancy)
- Estrone (only estrogen found in postmenopausal women)
What is the estrogen storage site?
Antrum
Role of FSH and LH in female repro system
- FSH: Maturation of follicle cells and induces antrum formation
- LH: Differentiation of follicle cells into luteal cells and ovulation (release of mature eggs)
What is corpus luteum?
Remnanat of egg release
Role of corpus luteum
Produces estrogen & progesterone:
1. High levels of progesterone cause inhibition both LH & FSH secretion
2. High levels of estrogen selective stimulates LH secretion
2 main functions of ovaries
- produce ova (oogenesis)
- Secrete sex hormones (estrogen and progesterone) which act together to promote fertilization of the ovum and to prepare the female reproductive tract for pregnancy.
Action of rising, moderate levels of estrogen
1) Hypothalamus - to inhibit GnRH secretion (decrease FSH, LH).
2) Pituitary - to inhibit FSH secretion.
*Follicular cells secrete inhibin (which then acts to inhibit FSH secretion).
-> LH secretion continues to rise slowly during the follicular phase .
Action of rising high levels of estrogen
As the follicle matures:
* Rising HIGH levels of estrogen act on the hypothalamus and pituitary to increase GnRH and selectively stimulate LH secretion -> POSITIVE-feedback
* Follicular cells secrete inhibin (which selectively inhibits FSH secretion). -> resultant SURGE in LH secretion
Massive increase in LH secretion brings about:
1) Differentiation of follicular cells into luteal cells
2) Ovulation (release of mature egg)
Luteal phase: Under influence of LH
- Under the influence of LH, the Corpus luteum (CL) secretes both estrogen (E) and progesterone (P) with P being its most abundant hormonal product to support ovum should fertilization occur
- P acts to inhibit both LH and FSH secretion.
- E Selectively stimulates LH secretion
-> without FSH and LH, new follicular maturation and ovulation is prevented
Luteal phase: No fertilisation
If no fertilization -> CL degenerates, no E or P is produced -> negative feedback inhibited -> New follicular phase begins
Signs of puberty (in succession)infemale
– Thelarche (earliest) – development of breasts
– Pubarche – growth of pubic and axillary hair
– Menarche – the first menstrual period
at what ages does menopause occur?
between the ages of 45 and 55
Signs of menopause
Cessation of menstrual cycles (12mths after last menstrual period)
Gradual atrophy genital organs
Vasomotor changes (regulation of blood vessel dilation & constriction -> hot flushes)
Skin changes
Psychological, emotional
Increased cholesterol level – risk of cardiovascular disease
Increased risk of osteoporosis (decreased bone mass due to less E)
