E3. The male reproductive system Flashcards
what are the sex chromosomes
-female sex chromosomes: XX
-male sex chromosomes: XY
Y chromosome directs the development of a male
what is the primary male organ?
testis
what are the secondary male organs?
-Penis
-Scrotum
-Epididymis
-Vas Deferens
-Seminal vesicles
-Prostate gland
ONE NOTE
what are the main two functions of the testis?
1) Spermatogenesis: production of male gametes from primordial germ cell involving Seminiferous tubules, sertoli cells and sperm
2) Production of Testosterone involving leydig cells (interstitial)
ONE NOTE
Describe testes
-male gonades
- 250-300 compartments
- seminiferous tubules
- sperm production
- development of sperm
- spermatogenesis
- delivery of sperm to female
ONE NOTE
Describe cells of testis
-Leydig cells (interstitial cells) secrete testosterone
-Sertoli cells (epithelial cells) support sperm development
-smooth muscle: peristalsis which propel sperm
-Blood-testis barrier: tight junctions, luminal compartment, basal compartment
functions of sertoli cells?
-Support sperm development
-Secrete luminal fluid in which sperm develop
-Secrete androgen-binding protein: Androgen buffer, helps maintain steady androgens in lumen
-Target cells for testosterone and FSH: secrete chemicals that stimulate spermatogenesis
-secrete inhibin, hormone for negative feedback loop for FSH
Describe spermatogenisis: conversion of spermatid to sperm
ONE NOTE
function of sertoli cells 2
-secrete fluid into lumen of seminiferous tubules to support sperm development and transport
-provide nutrients for developing sperm
-secrete paracrines that stimulate spermatogenesis
-secrete inhibin
secrete mullerian inhibiting substance (MIS) in fetal life
-form blood-testis barrier
-secrete androgen-binding protein into lumen of semiferous tubules
what includes external genitalia?
penis and scrotum
Describe penis
-male copulatory organ: penetrates vagina and deposits sperm
-at rest, penis flaccid
-during sexual arousal, penis undergoes erection: blood flow to penis increases, engorges erectile tissue, penis swells and elongates
-ejaculation: sperm ejects through urethra
Describe scrotum
-suspended beneath penis
-houses testes
-sperm cannot develop at body temperature
-thin walled sac- 2 to 3 degrees cooler
-dartos and cremaster muscles contract to regulate temperature in cold
Describe the structure of the scrotum
-sperm doesn’t mature at ambient body temps
scrotal sac:
-Lack of fat
-Excess of sweat glands
-Wrinkled to increase surface area
-Convoluted network of arteries and veins
ONE NOTE
Describe accessory glands
-seminal vesicles: secrete alkaline fluid with fructose, enzymes, and prostaglandins
-prostate gland: secrete citrate and enzymes
-bulbourethral glands: secrete viscous fluid with mucus
ONE NOTE
Describe the reproductive tract
-seminiferous tubules-> rete testis -> efferent ductules -> epididymus (exit testis) -> vas deferens
-Vas deferens -> ejaculatory duct (from seminal vesicles) -> urethra (through prostate gland) ->
ONE NOTE
Describe semen
1) sperm from testis
2) stored in epididymis
3) transported through vas deferens
4) seminal vesicle adds: fructose, prostaglandins, seminogelin
5)prostate adds: basic solution for correct pH, prostate specific antigen (PSA)
ONE NOTE
what hormones control male reproduction
-steroid hormones: androgens, testosterone
-peptide hormones: Follicle stimulating hormone (FSH), Luteinising hormone (LH), gonadotrophin releasing hormone (GnRH)
What are gonadotrophins?
Gonadotropins are hormones that regulate the function of the gonads (testes and ovaries), stimulating the production of sex hormones and gametes such as follicle stimulating hormone (FSH) and luteinising hormone (LH)
what happens during male puberty?
-Hypothlamus produces GnRH
-Ant. Pituitary produces LH and FSH
-LH - Leydig cells - produce Testosterone
-FSH - Sertoli cells - initiate Spermatogenesis
-Secondary male sex characteristics produced by 5a Dihydrotestosterone
effects of testosterone before birth
-Masculinizes reproductive tract and external genitalia
-Promotes descent of testes into scrotum
Effects of testosterone on sex-specific tissues after birth
-Promotes growth and maturation of the reproductive system at puberty
-Is essential for spermatogenesis
-Maintains the reproductive tract throughout adulthood
other reproduction-related effects of testosterone?- sex and gonadotrophin
-Develops the sex drive at puberty
-Controls gonadotropin hormone secretion
effects of testosterone on secondary sexual characteristics?
-Induces male pattern of hair growth (e.g. beard)
-Causes the voice to deepen because of thickening of the vocal folds
-Promotes muscle growth responsible for the male body configuration
non-reproductive actions from testosterone?
-Exerts a protein anabolic effect
-Promotes bone growth at puberty
-Closes the epiphyseal plates after being converted to estrogen by aromatase
-May induce aggressive behaviour
