Week 2- physiology of the reproductive system Flashcards
what are the two stages of sperm production?
spermatocytogenesis- diploid spermatogonia undergo meiosi forming 4 haploid spermatids
spermiogenesis- each haploid spermatid undergoes differentiation to become spermatozoa
what are the functions of Sertoli cells?
- guide sperm towards lumen
- form a blood testes barrier by forming tight junctions- immunologically safe
- secretes fluid to move immobile sperm
- aids in transfer of nutrients
- phagocytosis of any dead cells
- prodcues androgen binding protein to maintain a high concentration of testosterone
- produces hormones and responds to FSH
what are the steps of spermiogenesis?
- Golgi apparatus pieces assemble together to form the acrosome
- mitochondria arrange themselves in a parallel position next to where the tail starts to form
- the centriole lines up between the nucleus and tail
- mitochondria line up in the first part of the tail and excess cytoplasm is removed by sertoli cells
what happens to the sperm in the epididymis?
binding sites on head of sperm are closed to stabilise the cell membrane until capacitation occurs. sperm become motile
what is the function of the components of the seminal fluid?
alkaline- protects sperm from acidic environment
fructose- energy
coagulation factors- sperm coagulates into ball of fluid for delivery into vagina
prostaglandins- decrease female immune response to semen
what is the composition and function of the prostatic fluid in semen?
thin milky fluid with citrate and zinc
prostate specific antigen- liquifies coagulated ejaculate15 minutes after ejaculation so sperm can be motile.
what is the function of the bulbourethral glands?
secrete mucus to help the transport of sperm
what are the characteristics assessed on a sperm count?
quantity- volume, sperm concentration, total sperm count
morphology
motility
vitality- how many live
what hormone do Leydig cells respond to
LH
how is dihydrotestosterone formed?
testosterone is converted to DHT by 5-alpha reductase
which enzyme converts testosterone to oestrogen?
aromatase
how is testosterone produced in leydig cells?
cholesterol is converted to pregenolone which is either converted to DHEA then to androstenediol which is converted to testosterone by 3-beta-HSD or progesterone is converted to progesterone by 3-beta-HSD which is then converted to androstenedione which is converted to testosterone by 17beta3-HSD.
at any stage 3-beta-HSD can first pathway to change to the second pathways
what are the function of androgens?
- differentiation of male genitals
- sperm and semen production
- secondary sexual characteristics- puberty
what is the function of inhibin and where is it produced?
inhibits FSH production
produced by Sertoli cells
what causes respiratory distress syndrome in preterm newborns?
surfactant deficiency