Human Reproductive System Flashcards
What are the important endocrine glands in the human reproductive system?
- Hypothalamus
- Pituitary (Anterior and posterior)
- Gonads
What is the function of the gonads in the reproductive system?
Produce gametes and reproductive hormones
What are the water soluble hormones important in the reproductive system?
Peptides and proteins, including:
- GnRH
- FSH
- LH
- Oxytocin
Where is GnRH produced?
Hypothalamus
Where does GnRH act?
The anterior pituitary and the gonads
Where are FSH and LH produced, and what releases them?
The anterior pituitary, where they are released by GnRH
Where is oxytocin produced?
The posterior Pituitary
What are the lipid soluble hormones involved in the reproductive system?
Androgens
Oestrogens
Progestagens
Where are androgens produced?
Testes
Where are oestrogens and progestagens produced?
The ovary
What are the principal androgens, and how do they differ?
Testosterone
5- alpha dihydrotestosterone
Both are made from cholesterols, although they have different side-groups
5 alpha is much stronger than regular testosterone
What are the principal oestrogens and what are they for?
Oestradiol- main oestrogen
Oestrone- weaker, more important for menopause
Oestriol- softens the cervix for childbirth
What hormones released from the hypothalamus are responsible for reproduction, and how are they regulated?
There is only one hormone- GnRH. There is no equivalent inhibiting hormone.
It relies on negative feedback for regulation (apart from ovulation, which uses positive feedback).
How are reproductive hormones released from the hypothalamus?
They are pulsatile- a burst is released every 1-2 hours.
Why is it beneficial that GnRH travels from the hypothalamus to the ant. pituitary via a specific portal system?
It means that the hormones are not lost in general blood circulation.
Why is it important to have a hypothalamus- ant. pituitary - gonadal axis?
It allows the signals to be amplified.
What are the 5 different classes of hormone produced by the hypothalamus?
Somatotrophs Thyrotrophs Lactotrophs Corticotrophs Gonadotrophs
How does the posterior pituitary function, what hormones is it responsible for and what are their functions?
Secretory hormones are synthesized in the hypothalamus, travelling bound to carrier proteins down the axon and into the posterior pituitary, to terminals where they are stored in secretory vesicles.
When an AP arrives, they are released into the bloodstream.
Hormones are oxytocin and ADH.
ADH retains water, while oxytocin affects smooth muscle contraction, causing milk ejection and uterine contractions. It also has a role in pair bonding.
How does the anterior pituitary function, and what does it release?
The hypothalamus produces inhibiting and releasing hormones, and nerve impulses causes their release into the primary plexus and down to the anterior pituitary. These act on specific secretory cels, which secrete their products into the efferent veins.
What is the hypophyseal portal system?
A vascular arrangement in which blood flows from one capillary bed to another without going through the heart. It prevents signal dilution.
What is pulsatile release?
Secretions are released in discrete bursts, and separated by periods of little or no secretion
Why is pulsatile release important?
It prevents desensitization and down-regulation of receptors.
What are the hormones regulating gonadal activity?
FSH and LH
What do FSH and LH do in the female?
FSH: Promotes growth/development of ovarian follicles
LH: Secretion of female sex hormones and the trigger for ovulation