Module 6 - Topic 1-2: Sexual Reproduction and the Male Reproductive System Flashcards
Meiosis
reshuffling of chromosomes during gamete production
increases genetic diversity
enables adaption
Fertilization
fusion of gametes to form complete organism
Chromosomes
2 sister chromatids that are joined by a centromere
Karotype
total 23 pairs
autosomes
22 homologous pairs of body chromosomes
sex chromosomes
1 pair
xx
female
xy
male
Genetic crossover
occurs in meiosis 1 in prophase 1
pairing up and close alignment of homologous chromosomes allows this to occur
Disjunction
when each gamete receives an x chromosome
Mitosis divisions
1
crossover of homologous pairs - mitosis
doesnt occur
daughter cell number and genetic composition - mitosis
two
each is identical to mother cell
roles in body - mitosis
produces cells for growth and tissue repair
meiosis divisions
2
crossover - meiosis
occurs in prophase 1
daughter cell number and genetic composition
4
each hapliod has half as many chromosomes as mother cell and is genetically different
roles in body - meiosis
produces reproductive cells
Non disjunction
chromosomes do not separate during meiosis
aneuploidy
incorrect diploid number of chromosomes
Non disjunction of chromosomes
often lethal
trisomy 21
downs syndrome
3 21 chromosomes
Non disjunction of sex chromosomes
one daughter cell gets both x chromosomes and one gets none
triplo X
no exhibitable features
turners syndrome
XO
ova has no x chromosome
sterile
webbed neck with no secondary sexual features
Klinefelters syndrome
XXY
in men only
Congenital Anomalies
infectious diseases
teratogens
congenital disorders
Function of male reproductive system
deliver sperm to female
production of male gametes
production of male sex hormones
Parts of the male reproductive system
tunica vaginalis spermatic cord epididymis testes penis urethra scrotum dartos muscle
tunica vaginalis
pouch of serous membrane that covers testes
derived from the vaginal process of peritoneum
spermatic cord
fibrous connective tissue sheath
contains vans deferens, blood and lympathic vessels and nerve fibres
sperm development
in seminiferous tubules and epididymis
vas deferens
directs and propels sperm into urethra, after sperm has passed through epididymis
transports sperm from epididymis to ejaculatory ducts for production of ejaculation
spermatogenesis
involves meiosis
requires hormonal stimulation
lasts entire life
Seminiferous tubules
sperm factories
divided into lobules
connected to epididymis via rete testis
outer layer of seminiferous tubules
stem cells from which sperm arises
located near basement membrane of tubules
spermatogonia
sperm stem cells
inner core of seminiferous tubules
mature spermatozoa developing
located in tubule lumen
Supporting cells of seminiferous tubules
sertoli cells
leydig cells
sertoli cells
sustentocytes located in walls of tubules supply nutrients to sperm form blood testicular barrier secrete hormones that moderate sperm production
leydig cells
interstitial cells
located inbetween tubules
secrete testosterone
promote sperm maturation
spermatozoa head
nuclear material
acrosome
acrosome
releases enzyme hyaluronidase and proteinases to facilitate ovum penetration
spermatozoa midpiece
contains many mitochondria to provide energy
spermatozoa tail
flagellum that propels sperm
contains microtubules
perfect sperm shape
oval head and long tail
testes
contain 1-4 seminiferous lobules surrounded by 5 layers of smooth muscle like myoid cells
scrotum
supporting muscles help regulate temperature
dartos and cremaster
dartos muscle
skinned
smooth
cremaster muscle
suspender
skeletal
Epididymis
sperm storage until ejaculation
highly coiled
site of maturation and learning to swim
surface area of epididymis
allows absorption of testicular fluid to feed sperm
inguinal hernia
more common in males
due to width of inguinal canal to allow spermatic cord
urethra
terminal portion of the male duct system
transports both urine and semen
ABP
prompts spermatogenic cells to bind to testosterone which triggers spermatogenesis
seminal glands
joins with vas deferens
secretes alkaline fluid, fructose fluid and hormones to increase sperm motility
prostate gland
doughnut shaped
encircles urethra
prostate fluid
activates sperm
milky
slightly acidic
contains prostate specific antigen
bulbo urethral gland
pea sized
produced thick clear mucus for lubrication of urethra and glans penis
neutralisation of acidic urine left in urethra
semen
milky white sticky mixture
contains sperm, testicular fluid and accessory gland secretions
neutralises acid environment
penis
copulatory organ of male
delivers sperm to female reproductive tract
excitation leads to erection or ejaculation
erection
leads to parasympathetic relex releasing local nitric oxide
relaxes smooth muscle and dilates arterioles of penis
leads to engorgement
opens urethra ready for ejaculation
ejaculation
propulsion of semen from male duct system
under sympathetic control
triggered by critical levels of erection provocation
bladder sphincter constricts
primary spermatocyte
daugther cell becomes physically separated from spermatogonia and bloodstream and enters meiosis
blood testis barrier
barrier between spermatogonia and developing sperm cells
prevents immunological responses to genetically foreign cells
secondary spermatocytes
product of first meiotic division
spermatids
product of secondary meiotic division
small round haploid cells without sperm characteristics
spermatozoa
developing spermatids leaving the epithelium of seminiferous tubules
hormonal regulation
hypothalamus releases GnRh which acts of anterior pituitary
anterior pituitary releases LH and FSH
seminiferous tubules produce inhibin
inhibin and testosterone inhibit production of gnRH, LH and FSH via negative feedback
LH
controls production of testosterone by leydig cells
FSH
controls spermatogenesis in seminiferous tubules
stimulates release of ABP
ABP
prompts spermatogenic cells to bind to testosterone
