Lecture 42 - Reproductive Physiology Flashcards
Posterior pituitary
Secretes hormones synthesized in the hypothalamus into circulation
Oxytocin
Anti-directed hormone (ADH) (aka vasopressin)
anterior pituitary
Hypophyseal portal system
Hormones synthesized in the hypothalamus control release of hormone release from the anterior pituitary
Hormones synthesized in anterior pituitary released into circulation to control hormone release from other glands
what are trophic hormones?
o Hormones secreted by the anterior pituitary that stimulate hormone secretion from other glands (aka stimulating hormones – SH)
what are _trophs?
o Cells that secrete trophic hormones (anterior pituitary)
what is _statin?
Inhibiting hormone
the role of positive feedback amplification
o The stimulus evokes a reflex which enhances the stimulus
o Increases the signal to drive the reflex, thus amplifying response
the role of negative feedback regulation
o Self-regulating
o The stimulus which switches on the reflex evokes a response that alleviates the stimulus
o Activating the reflex restores the system to balance
Explain the role of binding proteins in circulation as important mediators in hormone delivery
o Binding proteins regulate the availability of steroid hormones for receptor binding
o Binding proteins can also compartmentalize steroid hormones
Binding proteins found in blood
o Albumin
o Corticosteroid-binding globulin (CBG)
o Sex hormone-binding globulin (SHBG)
Chromosomes in somatic cells
o Diploid cells
o 23 pairs of chromosomes for a total of 46
o Each pair is homologous since contain similar genes in same order
o One member of each pair is from each parent
o 22 autosomal and 1 pair of sex chromosomes
chromosomes in gametes
o Haploid cells
o Single set of chromosomes for a total of 23
o Produced by special type of division – meiosis
mitosis
o Cell division
o After division have diploid cell (2n chromosomes)
o Somatic cell
meiosis
o Gamete formation
o After meiosis haploid cell (n chromosomes)
o Gamete cell (sperm or ovum)
meiosis - sperm
o Four daughter cells
meiosis - ovum
o Single ovum
o + 3 polar bodies (functionally redundant)
spermatogenesis
o Spermatogonia – diploid germ cell
o Undergoes mitosis to produce two daughter cells
Cell 1 (type A) remains a germ cell
Cell 2 (type B) undergoes spermatogenesis
on set of sperm production
puberty
oogenesis
o Begins during fetal development
o Fetal period = Oogonium
o Childhood (no development)
o Puberty to menopause each mouth
oogonium
o Mitotic division during fetal period
o 7 million daughter cells (decreases to 2 million – known as atresia)
o 12-25 weeks = meiosis begins (development of primary oocyte)
o 14-36 weeks = primary follicle forms, arrested meiosis (prophase 1, sister chromatids)
oogenesis - puberty
o FSG stimulates oogenesis to restart
o Primary oocyte develops to secondary oocyte (meiosis I completes, haploid cell)
o Ovulation
o Fertilization (meiosis II completed post fertilization)
describe the hormonal regulation of spermatogenesis
o Regulated by the interplay of GnRH, FSH, LH, testosterone, inhibin and other factors. This system ensures continuous production of sperm cells in the testes and maintenance of male reproductive function.
Gonadotrophin-releasing hormone (GnRH)
o Release of GnRH from hypothalamus begins the process of spermatogenesis
o Released every 60-90 mins
o Stimulates anterior pituitary to release two important hormones (FSH and LH)
Follicle-stimulating hormone (FSH)
o Released by anterior pituitary
o Stimulates Sertoli cells, which provide physical and nutritional support to developing sperm cells
Luteinizing hormone (LH)
o Released from anterior pituitary
o Acts of Leydig cells, which produce testosterone
