Human reproduction Flashcards
Function of the scrotum
it provides an optimum temperature for sperm production
testes function
produces the male gametes(spermatozoa)
urethra
a tube that connects the the bladder to the outside, passes through the penis and transfers urine and semen to the outside
penis
organ that is used to pass semen into the reproductive system
vas deferens function
a tube that takes the sperm from the testis to the urethra during ejaculation
epididymis function
it is where sperms collect and mature
prostate glands functions
produces an alkaline secretion that neutralises any urine left in the urethra
it also aids sperm mobility
seminal vesicle
gland that produces nutrient secretions that help sperm mobility
describe the process of spermatogenesis
spermatogonia undergoes mitosis to form a germinal epithelium on the outer layer of the seminiferous tubule
the spermatogonia grow into primary spermatocytes, which are diploid
the diploid primary spermatocytes undergo meiosis 1 to produce secondary spermatocytes
secondary spermatocytes undergo meiosis 2 to form spermatids, which are haploid
the haploid spermatids differentiate into spermatozoa. the spermatozoa grows
site of spermatogenesis
seminiferous tubules
function of the sertoli cells
they nourish the spermatozoa once they are formed
throughout spermatogenesis, which cells provide nutrients for the different stages of the process
sertoli cells
functions of the ovaries
they produce the female gametes
they secrete the hormones oestrogen and progesterone
function of the fallopian tube (uterine tube)
it is the site of fertilisation
it connects to ovaries to the uterus
myometrium
a muscular layer of the uterus
endometrium
it is where the blastocyst gets implanted if fertilisation occurs
cervix
a muscular ring that closes the entrance to the uterus. it dilates during birth
vagina
muscular tube that leads to the outside of ther body
vagina
muscular tube that leads to the outside of the body
urethra function
it connects to the bladder, allowing the passage of urine
bladder
it stores urine
describe the process of oogenesis
oogonia formed before birth undergoes mitosis to form primary oocytes
primary oocytes start to divide by meiosis but stop at prophase 1
the primary oocytes are surrounded by follicle cells forming the primary follicles
At puberty, FSH from the pituitary glands stimulate some of the primary follicles to develop into secondary follicles
the primary oocyte completes the first meiotic division to form a haploid secondary and a small polar body
the secondary oocyte is now in the graafian follicle. it starts meiosis 2 but stops at metaphase 2
it migrates to the surface of the ovary where it bursts, projecting the secondary oocyte into the fallopian tube. This is ovulation.
Meiosis 2 is only completed if fertilisation occurs.
An ovum is formed during fertilisation
fertilization can only take place after
capacitation
what happens during capacitation
*removal of glycoprotein from the outer layer of the sperm and plasma proteins from the seminal fluid
*removal of cholesterol (this weakens the cell membrane)
the effect of capacitation
it causes a change in the membrane covering the acrosome, thereby increasing the chance of binding the sperm to the secondary oocyte
during capacitation, …………………. in the uterus causes the ………………. of the sperm to become more permeable to ……………….. …………. which increases the ………….. ………………. and starts ………………….. reaction
enzymes
membrane
calcium ions
tail activity
acrosome
describe the journey of the sperm to meet with the secondary oocyte
the sperm are released from the epididymis and travel along the vas deferens out of the penis through the urethra
spermatozoa are deposited at the top of the vagina
they swim through the cervix along the lining of the uterus into the oviduct where they meet the secondary oocyte
describe the acrosome reaction
contact with the outer jelly coat results in the acrosome membrane rupturing and the release of the hydrolytic protease enzymes
these enzymes digest the corona radiata and the zona pellucida
entry of the head of the sperm into the secondary oocyte stimulates the completion of meiosis 2. this produces the ovum and the second polar body
corona radiata and zona pellucida
glycoprotein layers around the secondary oocyte
Spermatozoa are produced in the ?
Seminiferous tubules
cortical reaction
process that produces a fertilization membrane and prevents polyspermy
describe what happens in cortical reaction
entry of a single sperm causes calcium ions to be released from the SER
this causes cortical granules in the ovum to release enzymes that change the structure of the zona pellucida to produce a fertilization membrane, which prevents the entry of any further sperm
the nucleus of the ovum fuses with the nucleus of the sperm to form a diploid zygote
blastocysts
a hollow ball of undifferentiated cells
the cleavage
this is the first division in a series of mitotic divisions that result to the formation of the blastocyst
implantation
this is when the blastocyst reaches the uterus and is embedded into the endometrium
following fertilisation the ovum is known as the ……………..
why is this
zygote
because the nucleus of the spermatozoa and the ovum fuse immediately after fertilisation
the zygote divides by……………. to form the blastocyst
mitosis
outer layer of the blastocyst
trophoblast
the trophoblast later develops into the?
chorion
chorion
the fetal part of the placenta
function of the trophoblast
produces HCG which maintains the corpus luteum for the first 16 weeks of pregnancy
what is the significance of the trophoblastic villi penetrating the endometrium
it increases the surface area for the absorption of nutrients
what happens when cells of the chorion move into the chorionic villi
they form the chorionic villi, which are larger than the trophoblastic villi
the placenta connects the …………… to the ………………….. wall
embryo/ foetus
uterus
blood from the embryo travels to the placenta through arteries of the ……………….. and returns via the ………………….
umbilical cord
umbilical vein
the 5 major roles of the placenta
it takes over the corpus luteum to secrete the hormone progesterone and oestrogen
for gas exchange with the mother’s circulation
allows the mother’s antibodies to protect the foetus by passive immunity
it protects the foetus from the mother’s immune system
it serves as a barrier to high blood pressure and toxins in the mother’s blood
how does the placenta protect the foetus from the mother’s immune system
by preventing white blood cells from the mother passing into the foetal blood circulation
amnion
a membrane derived from the inner cell mass of the blastocyst
what happens when amniotic fluid starts to accumulate
the amnion membrane is eventually pushed outwards
during development, the amniotic protects the foetus by?
maintaining the optimum temperature for the development of the foetus
providing lubrication
contributing to lung development
acting as a shock absorber
function of progesterone and oestrogen
they inhibit the secretion of FSH and LH, thereby preventing more follicles from forming, so ovulation will not occur
progesterone also suppresses the uterine wall’s ability to?
contract
function of oestrogen
inhibits the secretion of LH
it also stimulates the growth of the uterus to accommodate the foetus and growth and development of mammary glands
the decrease in progesterone levels allows the secretion of?
oxytocin and prolactin
function of oxytocin
causes the contraction of the myometrium
when oxytocin is released, positive feedback leads to …………….. and ……………………..
a further increase in oxytocin levels and stronger contractions
oxytocin is secreted by the
posterior pituitary gland
prolactin is released by
the anterior pituitary gland
function of prolactin
it stimulates the mammary glands to synthesise milk
one of the major causes of female infertility
blocked uterine tubes
effect of blocked uterine tubes
prevents fertilisation taking place
it also prevents zygote from moving down the uterine tube
causes of blocked fallopian tubes
endometriosis
chlamydia
treatment for female infertility
IVF treatment
what is IVF treatment
this is when fertilisation takes place outside of the body and the zygote is implanted into the endometrium afterwards
describe the processes that occur in IVF treatment
ovulation is stimulated using hormones at a specific dose to induce several follicles to develop at the same time
the oocytes are collected using a tube inserted through the vagina
about a 100000 sperm are placed on a petri dish per oocyte
three days later, any fertilised oocytes can be re-introduced into the uterus
