Sex hormones

Question 1

Sex hormones

Answer 1

Androgens(testosterone - testes) , oestrogens and progestins (ovaries).
Produced by the sex organs, which also produce inhibin.
Small amount of androgens produced by adrenal cortex
During pregnancy the placenta also secretes progesterone and oestriol (a weak oestrogen, large quantities)

Question 2

Androgens

Answer 2

For example testosterone
Synthesised and secreted from leydig cells, under the influence of LH
Carried around the body bound to Sex Hormone Binding Globulin (SHBG) and have a short half-life (few mins)
Metabolised by the livet
Act via binding to androgen receptors inside calls

Question 3

Androgen physiological actions

Answer 3

Development and maintenance of male secondary sexual characteristics (deep voice, hair growth), increased secretions from sebaceous glands, adolescent growth spurt (epiphysis closing), anabolic actions, agression and libido
In fetus - male sexual development

Question 4

Progesterone

Answer 4

Produced primarily by the placenta and corpus luteum of the ovary.
Responsible for maintenance of pregnancy
Relaxes smooth muscle in uterus
Responsible for mammary gland development and endometrial development

Question 5

Oestrogens

Answer 5

Primarily produces in ovaries (placenta during pregnancy)
Maintain secondary sexual characteristics in female -
Uterine,vaginal and breast development
Altered distribution of body fat
Decreased reabsorption of bone

Question 6

Estrous cycle

Answer 6

Oestrogens and progestins cooperate to maintain female mdnstrual cycle. This includes - development and release of ovum and maintenance of hormone secretion. This is an unstable pattern and relies on homeostasis.
Has a proliferative phase, luteal phase and secretory phase.

Question 7

Proliferative phase

Answer 7

Graafian follicle, vontaining ovum, develops under the influence of FSH and low oestradiol. Rising oestrodiol stimulates LH secretion hy positive feedback, LH and FSH peak during ovulation and formation of corpus luteum.

Question 8

Luteal phase

Answer 8

Corpus luteum secretes progesterone, this has a lobg negative feedback effdct to inhibit LH/FSH secretion.

Question 9

Secretory phase

Answer 9

Uterus lining (endometrium) changes, if no egg implants cycle restarts and endometrium is sloughed off. If fertilisation takes place then the corpus luteum is maintained tor abour 3 months by hCG then the placenta takes over production of progesterone and oestrodiol

Question 10

Menopause

Answer 10

Menstrual cycle halts at About 50yrs of age
Oestrogen and progestin levels fall
Treatment with HRT used to be common but less so now
Can also use oestrogens and progestins as contraceptives