Reproduction Key Concepts Flashcards
What are the male gonads?
testes = sperm
What are the female gonads?
ovaries = egg
What is meiosis the production of?
haploid (sex) cells
How many chromosomes do haploid cells have?
23 chromosomes
How many chromosomes are there when fertilisation occurs? (sperm and egg joining)
46
what do the testes produce?
spermatozoa (sperm)
what are the testes made of?
lobules (coiled seminiferous tubules) that produce sperm
Where does the mediastinum of the testes empty into?
epididymus
What do the interstitial cells (leydig) produce?
hormones
Epididymus
spermatozoa maturation
ductus deferens
spermatozoa storage
urethra (male)
ejection of sperm/ semen
glands (seminal, prostate, bulbourethral)
semen production
external genitalia (male)
scrotum (temperature control for sperm production) and penis
lobules
- seminiferous tubules (tightly coiled)
- sperm production takes place here
empty into mediastinum
- interconnected passageways called rete testis
- empty into the efferent ductules that connect to the epididymus
interstitial cells (leydig)
- present in space around seminiferous tubules
- produce male sex hormones (androgens)
Where does spermatogenesis occur?
in the seminiferous tubules with support from the nurse cells
Sermatogenesis
sperm production and maturation
What begins in the outer most layer of seminiferous tubules and each step moves towards the lumen?
spermatogenesis
mitosis of spermatogenesis
of the stem cell (spermatogonium)
meiosis of spermatogenesis
creation of spermatids (haploid cells)
spermiogenesis
maturation from spermatid to sperm (with acrosome and flagella)
movement of sperm
seminiferous tubule > epididymus > ductus deferens > ejaculatory duct > urethra > external body
semen production
seminal, prostate and bulbourethral glands form semen with sperm from ejaculatory duct
What type of stimulation do nurse cells support the production of sperm under?
FSH stimulation
What does LH stimulate? (male reproductive system)
stimulates androgens (testosterone) production from the interstitial cells of leydig
What is important for male sex characteristic’s, male sex organ development and sperm maturation?
Testosterone
What ultimately controls the production and maturation of sperm?
GnRH, LH, FSH, Inhibin and Testosterone
key female reproductive organs
ovaries, fallopian tubes, uterus, vagina, external genitalia and mammary glands
ovaries
produce the haploid gametes via meiosis = oocyte and hormones
fallopian tubes
- deliver oocyte to uterus
- usually the site of fertilisation
uterus
protection, development of embryo/ foetus/ menstruation
vaginal canal/ vagina
sexual intercourse/ removal of menstrual fluids/ birth canal
external genitalia (female)
openings, lubrication, sexual arousal
mammary glands
milk production
ovary histology
the ovaries are where oogenesis occurs to produce an oocyte ready for fertilisation
uterus histology
muscular organ that will house the fertilised oocyte, protect the developing embryo and help it grow
3 layers that make up the uterus
perimetrium, myometrium + endometrium
perimetrium
outer serosal wall of the uterus
myometrium
muscular layer of the uterus
endometrium
inner most epithelial layer that grows and provides the attachment location for the oocyte
What is the ovarian cycle?
is the cycle of formation of the oocyte and hormone production associated with this process
How many steps are there in the ovarian cycle?
7
Step 1 of the ovarian cycle
during foetal development
Step 2-4 of the ovarian cycle
(days 1-13) - follicular phase of each cycle ovarian cycle
Step 5 of the ovarian cycle
(day 14) ovulation, marks change to next phase of ovarian cycle
Step 6+7 of the ovarian cycle
(days 15-28) luteal phase of each ovarian cycle
When does meiosis I occur?
from 3-7 months of foetal development
When does meiosis I halt?
in prophase until puberty
What in puberty stimulates some primary oocytes each month to finalise meiosis I and form a secondary oocyte?
Hormones
Meiosis II
the secondary oocyte halts in metaphase until oocyte released and fertilisation with a spermatozoa occurs, and it becomes a mature ovum
What is the menstrual cycle?
is the process of readying the uterus for receiving the fertilised oocyte (ovum)
proliferative phase of the menstrual cycle (days)
day 8-14 replacement of the functional zone
ovulation at day 14
marks change to new phase of the menstrual cycle
secretory phase of menstrual cycle (days)
day 15-28 - secretion/ thickening of functional zone
menses of menstrual cycle (days)
day 0-7 - will take place if there is no fertilisation of the oocyte with a spermatozoa
Key hormones in female reproduction
GnRH, LH, FSH, Estrogen, Progesterone + Inhibin
GnRH in female reproduction
triggers release of LH and FSH
LH + FSH in female reproduction
trigger production of estrogen, progesterone and androgens. also control aspects of ovarian cycle
estrogen and progesterone in female reproduction
sex hormones (many effects), roles in ovulation and the menstrual (uterine) cycle to prepare uterus for ovulation/ implantation
Inhibin in female reproduction
decreases the release of Lh and FSH (negative feedback) and therefore the main sex hormones
ovarian cycle step 1
GnRH stimulates FSH and LH secretion
ovarian cycle step 2
FSH and Lh stimulate follicles to grow, mature and secrete sex hormones
Ovarian cycle step 3
negative feedback inhibits gonadotropin release (inhibin + estrogen levels)
ovarian cycle step 4
sudden rise of estrogen results in short positive feedback to stimulate surge of LH and FSH and trigger ovulation
ovarian cycle step 5
progesterone levels will rise and take over from estrogen and corpus luteum is maintained
ovarian cycle step 6
if no pregnancy occurs then corpus luteum degrades, all hormone levels drop and process starts again
Three phases of the menstrual cycle
menses, proliferative and secretory
menses phase of the menstrual cycle
uterus shed all but the deepest part of the endometrium (hormones are low at this stage)
proliferative phase of the menstrual cycle
functional layer of the endometrium is rebuilt under influence of estrogens. ovulation occurs at the end of this phase
secretory phase of the menstrual cycle
14 day phase where the endometrium prepares for an embryo to implant under rising levels of progesterone from the corpus luteum. if fertilisation does not occur then corpus luteum degenerates and hormone levels drop which deprives the endometrium of hormonal support, oxygen and nutrients and the functional endometrial layer will start to slough off (menses)
pregnancy
- Events that occur from fertilization until the infant is born.
conceptus
- The developing offspring.
Gestation period
- Period from the last menstrual period until birth
pre-embryo
- Conceptus from fertilization until it is two weeks old.
embryo
- Conceptus during the third through the eighth week
foetus
- Conceptus from the ninth week through birth.
How many trimesters is pregnancy divided into?
3 trimesters of approximately 12-14 weeks each
sperm penetration
1 sperm normally enters and binds to zona pellucida and then fuses with the oocyte, and this process prevention of others from binding and entering
what joins with a spermatozoa to form a zygote?
oocyte
What happens when a zygote is formed initially?
it becomes a diploid cell and begins to divide
what activates the formation of the blastomere?
fertilisation
What day approx. is the blastocyst formed?
day 5-6 and consists of ~100 cells
Where does the blastocyst implant into and continue to develop?
the uterine wall
What happens during gastrulation?
- forms 3 germ layers (ectoderm, endoderm and mesoderm)
- these create the organs (organogenesis) and the extraembryonic membranes including yolk sac, amnion and chorion
What happens during placentation?
- formation of the placenta from trophoblasts, mesoderm and maternal tissues
- develops whilst embryo is developing
- placenta will allow for communication and nutrient/ oxygen movement from mother to baby
what forms the 3 embryonic layers that give rise to the embryo/ organ system?
gastrulation
embryogenesis and organogenesis
- formation of head and tail from 4 weeks
- organogenesis form different layers (ectoderm, endoderm and mesoderm)
- formation of organ systems
- established in the 1st trimester, then continue to develop and grow in the 2nd and 3rd trimesters until foetus is ready for delivery
hCG in pregnancy
maintains endometrium
Oestrogens and progesterones in pregnancy
produced bybthe corpus luteum and then the placenta. maintain pregnancy and endometrium. stimulate labour and delivery
hPL and Placental Prolactin in pregnancy
preparation of mammary glands
Relaxin in pregnancy
increases pelvic flexibility (while baby grows) and cervical dilation (delays oxytocin until uterine contractions should begin)
metabolic changes due to pregnancy
- glucose sparing effect from hormones
- 10-30% increase in nutritional requirements
cardiovascular changes due to pregnancy
increased blood volume, increased cardiac output and decreased blood pressure
renal changes due to pregnancy
- dilation/ enlargement of the kidneys/ ureters
- increased urine production
respiratory changes due to pregnancy
increased ventilation, increased oxygen and decreased carbon dioxide
gastrointestinal changes due to pregnancy
- morning sickness from increased hormones
- decreased motility and gastric emptying –> relaxin
mammary gland changes due to pregnancy
growth and development of lactation
uterine changes due to pregnancy
increased size to accommodate growing foetus
contractions of the uterus and dilation of the cervix in response to:
- estrogen increases triggering oxytocin release and prostaglandin production stimulates the myometrium to contract
- relaxin dilates the cervix
What are labour’s 3 stages?
dilation, expulsion and placental
dilation phase of labour
onset of labour, cervix dilates and water breaks
expulsion stage of labour
foetus pushed through fully dilated cervix (10cm) out through vaginal canal
placental stage of labour
tearing of the placenta from the endometrium and ejection out of the uterus
lactation
breast milk for new born nourishment / protection
what hormone controls milk production?
prolactin
changes after birth
- 3 vascular shunts shut off after lungs inflate and pattern of blood flow and pressure is changed suddenly
- creates the normal circulatory system of the human body
