Hormones and Regulation

Question 1

Puberty

Answer 1

Developmental changes a child undergoes to become sexually mature and physiologically ready for reproduction

Females:8-14
Males: 10-16

Question 2

Control of puberty and reproductive system

Answer 2

Hormones of Hypothalamic-Pituitary-Gonodal Axis

Hypothalamus releases GnRH in pulsatile manner.
stimulates release of FSH and LH from anterior pituitary gland

Question 3

Role of FSH and LH

Answer 3

Act on gonads to stimulate synthesis and release of sex steroid hormones nd support gametogenesis

Question 4

Rise in FSH

Answer 4

Increase in oestrogen synthesis and oogenesis in females and onset of sperm production in males

Question 5

Rise in LH

Answer 5

Stimulates an increase in production of progesterone in females and an increase in testosterone production in males

Question 6

Physical Changes during puberty - Females

Answer 6

Thelarche
- Breast development

Pubarche

• Growth of hir in pubic area
• mediated by testosterone

Menarche

• First menstrual period
• Arises due to increase in FSH and LH

Question 7

Physical Changes during puberty- males

Answer 7

Genital Changes

• Increase in testicular size
• Growth of scrotal skin
• Growth of panic

Pubarche

Question 8

Growth spurt

Answer 8

Product of complex interaction between gonadal sex steroids (estradiol/ testosterone), GH and insulin-like growth factor (IGF-1)

GH levels rise in puberty due to increase in sex steroids and their positive effect on pulsatile release of GH from anterior pituitary gland
RIse in GH causes a rise an anabolic hormone IGF-1, csauses somatic growth via its metabolic actions

Question 9

Precocious puberty

Answer 9

appearance of secondary sexual characteristics before

Question 10

Causes/ types of precocious puberty

Answer 10

Iatrogenic
- result of exposure to exogenous oestrogen

True/ complete
- early maturation of HPG axis resulting in high level of GnRH, FSH and LH. My be due to CNS lesions near or in posterior hypothalamus, CNS neoplasms, harmatomas, primary hypothyroidism

Incomplete
- increased level of oestrogen in girls and androgens in boy that are independent of GnRH

Question 11

Delayed/ absent puberty

Answer 11

Absence of secondary sexual characteristics by age of 13 in girls or 16 in boys

Question 12

Causes of delayed/absent puberty

Answer 12

Hypogonadotrophic hypogonadism

Hypergonaadotropic hypogonadism

Question 13

Conditions associated with delayed/ absent puberty

Answer 13

Turner’s Syndrome (45 XO)
Klinefelter’s Syndrome (47 XXY)
Androgen Insensitivity syndrome
Kallmann Syndrome

Question 14

Normal duration of menstrual cycle

Answer 14

21-35 days

Question 15

regulation of menstrual cycle

Answer 15

Hypothalamus, anterior pituitary and ovaries

GnRH from hypothalamus stimulates LH and FSH release from anterior pituitary gland.

Question 16

Role of LH and FSH in menstrual cycle

Answer 16

Gonadotrophins that act primarily on the ovaries.

FSH: binds to granuloma cells to stimulate follicle growth, permit conversion of androgens (from theca cells) to oestrogen and stimulate inhibit secretion

LH: acts on theca cells to stimulate production and secretion of androgens.

Question 17

Feedback systems controlling menstrual cycler

Answer 17

Moderate oestrogen levels exert negative feedback on HPG axis.

High oestrogen levels (in absence of progesterone) positively feedback on HPG axis.

Oestrogen in presence of oestrogen exerts negative feedback on HPG axis.

Inhibin selectively inhibits FSH at anterior pituitary.

Question 18

Ovarian cycle

Answer 18

Follicular Phase
Ovulation
Luteal Phase

Question 19

Follicular Phase

Answer 19

Beginning of new cycle.
Follicles begin to develop independently of Gonadotropins.
Increase in FSH and LH
Stimulate follicle growth and oestrogen production

Rise of oestrogen- negative feedback reduces FSH levels.
Only one follicle can survive

Follicular oestrogen becomes high enough to potentiate +ve feedback at HPG- increasing GnRH and Gonadotropins

LH levels increase.

Granulosa cells luteinised and become receptors for LH

Question 20

What do non-dominant follicles form

Answer 20

Polar bodies

Question 21

Ovulation

Answer 21

In response to LH surge, follicle ruptures and mature oocyte is assisted to Fallopian tube by fimbria.
Remains viable for fertilisation for ~24 hours.
Following ovulation, follicle remains luteinised, secreting oestrogen and progesterone,
Reverts to -ve feedback on HPG axis.
Negative feedback + Inhibin ->stalls cycle in anticipation of fertilisation

Question 22

what tissue forms in ovary at site of rupture follicle following ovulation
+ what is its role

Answer 22

corpus luteeum,

Produces oestrgoens, progesterone and Inhibin to maintain conditions for fertilisation and implantation

Question 23

Luteal phase

Answer 23

Formation of corpus lute. At end of cycle in absence of fertilisation, corpus luteum spontaneously regresses after 14 days.
Significant fall in hormones, relieving negative feedbackl, resetting HPG axis

Question 24

Fertilisation

Answer 24

If fertilisation occurs, syncytiotrophoblast of embryo produces HcG exerting luteinising effect -> maintaining corpus luteum.
Supported by placental HcG and produces hormones to support pregnancy.

Question 25

Uterine cycle phases

Answer 25

proliferative secretory menses

Question 26

Proliferative phase

Answer 26

Runs alongside follicular phase. Prepares reproductive tract for fertilisation and implantation. Oestrogen inhibits fallopian tube formation, thickening of endometrium, increased growth and motility of myometrium and production of thick alkaline cervical mucous.

Question 27

Secretory phase

Answer 27

Runs alongside luteal phase Progesterone stimulates - further thickening of endometrium into glandular secretory form. - thickening of myometrium -reduction of motility of myometrium - thick acidic cervical mucus production - changes in mammary tissue - other metabolic changes

Question 28

Menses

Answer 28

Marks beginning of new menstrual cycle. Occurs in absence of fertilisation once corpus luteum has broken down and internal lining of uterus is shed menstrual bleeding usually lasts 2-7 days with 10-80ml blood loss

Question 29

Dysmenorrhoea

Answer 29

Painful periods

Question 30

Endometriosis

Answer 30

Growth of endometrial tissue outside of the uterus

Question 31

menopause

Answer 31

end of female reproductive life. physiological process which begins as perimenopause at ~45 and progresses until final menopause's and end of fertility Menopause is defined when a women has had amenorrhoea for 12 months.

Question 32

early menopause

Answer 32

before 45 years

Question 33

perimenopausal

Answer 33

women progressing towards menopause

Question 34

hormone changes during menopause

Answer 34

reduction of circulating oestrogen - reduced sensitivity of ovary to circulating gondaotropins Increase in anovulatory cycles Significant increase in FSH and lH - low levels of circulating oestrogen - decrease in developing follicle reduces amount of Inhibin release

Question 35

vasomotor changes during menopause

Answer 35

hot flushes associated with peripheral vasodilation and transient rise in body temperature. Pulsatile LH relese influences central temperature control

Question 36

urogenital changes during menopause

Answer 36

decrease in oestrogen - marled atrophy of vagina and thinning of myometrium. can result in dyspareunia Bladder and urethra can also atrophy. Lead to symptoms of urinary incontinence and increase in UTIs

Question 37

bone density in menopause

Answer 37

oestrogen protects bone mass and density through reducing activity of osteoclasts. Drop in oestrogen causes increase in bone resorption. results in acceleration of age-related loss of bone density and increased frequency in fractures.

Question 38

ischaemic heart disease and menopause

Answer 38

oestrogen offers protective effect against her disease. | Oestrogen reduces levels of LDL cholesterol whilst raising HDL cholesterol.