Reproductive system Flashcards
1
Q
Functions of the reproductive system
A
- Not essential to the life of the individual – ensures species survival
- Produces haploid gametes (gametogenesis)
- Store, nourish and transport haploid gametes for fertilisation (internal or external: oviparous, ovoviviparous, viviparous)
2
Q
What are the sex chromosomes that determine the gonadal sex in mammals and birds
A
XY/ZZ for testes and XX/ZW for ovaries
3
Q
What does androgen release in utero do
A
causes masculinization of genitalia in mammals
4
Q
What does oestrogen release in ovo cause
A
feminization of genitalia in birds
5
Q
What covers the female reproductive organs
A
the peritoneum
6
Q
Where is the internal female reproductive organs located
A
shares the pelvic cavity with the bladder and rectum
7
Q
Which hormones are produced in the ovaries
A
oestrogen and progesterone
8
Q
Eggs in the ovaries
A
there is a total number in birth (arrested in meiotic phase) which decreases during life. Eggs mature within the ovaries
9
Q
Follicle development - stage 1
A
Primordial follicles
Primary oocyte, enclosed by single layer flattened follicular/granulosa cells and basal lamina
At puberty primordial follicles are stimulated -> primary follicles
10
Q
Follicle development - stage 2
A
Primary follicle (uni-layered). Oocyte enlarges and follicular/granulosa cells increase in size = cuboidal. Oocyte produces zona pellucida: glycoproteins, important in binding of spermatozoa. Primary follicle (multi-layered). Follicular/granulosa cells increase in number; increase in thickness – stratified. Zona pellucida assembled
11
Q
Follicle development - stage 3
A
Secondary follicle. Spaces develop containing follicular fluid = coalesce to form a cavity. Production of estrogen by granulosa cells
12
Q
Follicle development - stage 4
A
Graafian (tertiary) follicle. Antrum. Large fluid filled cavity. Surrounded by corona radiata = ‘glowing crown’ nutrition
13
Q
Ovulation
A
Proteolytic activity stimulated by gonadotropin (LH). Oocyte expelled into entrance of the uterine tube
14
Q
What is the corpus luteum
A
the empty follicles that is left once the egg has been released
15
Q
Corpus luteum function
A
Follicular cells release. Produces progesterone and estrogen
16
Q
What does corpus luteum mean
A
yellow body
17
Q
what does corpus albicans mean
A
white body
18
Q
What is a corpus albicans
A
cells replaced by collagen ‘scar’
19
Q
What are the 2 types of cells that form the epithelium of the uterine tubes
A
- Secretory (peg) - watery secretion for gamete nourishment
- Ciliated – cilia beat rate increases in response to estrogen
20
Q
Name the structures that form the uterine tubes
A
Intramural, isthmus, ampulla and infundibulum
21
Q
Name the structures that form the uterus
A
- fundus - top
- body - middle
- Bottom - cervix
22
Q
What is the endometrium
A
the epithelial layer. Menstrual cycle; zygote embeds itself
23
Q
What is the myometrium
A
interwoven smooth muscle/CT - hormonal response = hypertrophy/hyperplasia
24
Q
What is the prevalence of uterine fybroids (leiomyoma)
A
prevalence 75% of people > 30 years
25
Parts of the female external reproductive organs
glans and crus clitoris, vestibule, mons pubis, labia majora, labia minora, vaginal opening, urethral opening, corpus cavernosum
26
What does the anterior pituitary gland secrete for the female reproductive system
LH and FSH
27
What forms of estrogen are there
estradiol, estrone, estriol
28
What is oogenesis
production or development of an ovum
29
Estrogen functions
1. Essential for ova maturation and release
2. Establishment of female secondary sexual characteristics
3. Essential for transport of sperm from vagina to fertilisation site
4. Continue to breast development in anticipation of lactation
30
Progesterone functions
1. Regulates the development of the endometrium
2. Important in preparing suitable environment for nourishing a developing embryo/fetus
3. Contributes to breasts’ ability to produce milk
31
What does a follicle need to grow through ovulation
LH and FSH
32
How many follicles grow during each cycle
Each cycle 15-20 follicles develop but only one continues to ovulation – the rest die
33
At birth how many primordial follicles are present in ovary
1-2 million
34
What starts just prior to puberty
GnRH pulse generations begin
35
What do developing follicles release
oestrogens
36
What does the estrogen that the follicle release trigger
Development of female secondary characteristics (eg fat deposition, growth of reproductive tract)
37
What does a rise in adrenal androgens cause
Growth of auxillary hair, libido and pubertal growth spurt
38
When does a females first period occur
When sufficient GnRH, LH and FSH are present
39
What terminates the menstrual cycle
menopause
40
What are the 2 phases of the menstrual cycle
follicular phase and luteal phase
41
Follicular phase
First half of the 28-day cycle. Dominated by presence of maturing follicles. Follicle produces oestrogens
42
Luteal phase
Second half of the 28-day cycle. Characterised by presence of corpus luteum. Corpus luteum produces progesterone (& oestrogen)
43
What does the hypothalamus to secrete in order to stimulate LH and FSH secretion
gonadotropin-releasing hormone (GnRH)
44
FSH and LH levels at the beginning of the cycle
rise due to GnRH release
45
What does the rising FSH and LH stimulate
oestrogen release from the developing follicle
46
What does rising oestrogen levels inhibit
FSH but not LH
47
What can also inhibit FSH
inhibin
48
oestrogen showing positive feedback
stimulates positive feedback on the follicle causing further oestrogen release; oestrogen levels significantly rise (autocrine signalling)
49
What happens on day 14
LH surge : High oestrogen levels stimulate the anterior pituitary to produce large amounts of LH. Positive feedback. Ovulation occurs due to LH surge
50
What is ovulation
when a released oocyte enters oviduct where it may or may not be fertilized
51
What is the luteal phase
when the corpus luteum produces progesterone
52
What does progesterone inhibit
LH and FSH release from the anterior pituitary
53
When does the corpus luteum degenerate
after 10 days
54
Which hormones drop after the corpus luteum degenerates
progesterone and oestrogen levels significantly drop causeing FSH and LH levels to rise and a new cycle to begin
55
Corpus luteum function
1. Oestrogens responsible for endometrium thickening
2. Progesterone responsible for endometrium development and maintenance
3. Progesterone inhibits LH and FSH secretion
56
endometrium development - menstrual phase (day 1-4)
Endometrium lining of the uterus is disintegrating
Bleeding occurs from ruptured blood vessels in endometrium
Blood and disintegrating outer layers of endometrium expelled as menstrual fluid
57
Endometrium development - proliferative phase (6-14)
Oestrogen secreted by developing follicle leads to growth and thickening of the endometrium
Uterine glands develop in endometrium but do not produce anything yet
58
Endometrium development - secretory phase (day 16-28)
Corpus luteum formed (from day 14) secretes progesterone and oestradiol
Progesterone stimulates the uterine glands to secrete “uterine milk”, which is high in protein and glycogen
Provides correct environment should ovum fertilisation occur
59
Endometrium development - new phase
If fertilisation does not occur, CL regresses and progesterone and oestrogen not produced
Endometrium cannot be maintained and necrosis occurs
Expelled with blood as menstrual fluid
Menstruation usually lasts 3-5 days (20-200ml blood lost)
60
Fertilization
Sperm deposited in vagina travel through cervical canal, uterus and up to the upper third of the oviduct.
61
where is the site of fertilizsation
the oviduct (upper third)
62
when must fertilization occur
within 24-36 hours of ovulation
63
how long can sperm survive in a female reproductive tract
2-7 days
64
When does the fertilized ovun reach the uterus
3-4 days
65
Why does it take this long for the fertilised egg to reach the ovum
Gives time for the endometrium to develop into a suitable state for implantation of developing blastocyst
66
What is produced at day 9 of implantation
By day 9, the blastocyst/developing placenta produces human chorionic gonadotrophin (hCG) at high levels for 8 weeks, before decreasing from regressing hCG prevents corpus luteum
67
What happens when the egg is not fertilized
the corpus luteum stops secreting progesterone and decays. Degenerates into a corpus albicans. Uterine lining sloughs off without progesterone and is expelled
68
What happens when the egg is fertilized
the corpus luteum stops secreting progesterone and decays. Degenerates into a corpus albicans. Uterine lining sloughs off without progesterone and is expelled
69
What does HCG prevent
the corpus luteum from degenerating into a corpus albicans
70
How are high risk pregnancies monitored
Beta-hCG levels monitored. Titers of hCG that do not rise rapidly in early pregnancy may signal lack of growth or possible miscarriage.
71
Why are pregnancy tests after 16 weeks negative
HCG levels are low
72
What contracts during childbirth
the myometrium - strong contraction
73
Estrogen : progesterone ratio stimulating contractions
High oestrogen:progesterone ratio that occurs towards the end of pregnancy upregulates oxytocin receptors in myometrium so circulating oxytocin can bind
74
Oxytocin stimulating contractions during childbirth
Pressure of foetus against the cervix stimulates oxytocin secretion and causes contractions. Contractions leads to more oxytocin production. Positive-feedback cycle progressively increases until cervical dilation and delivery are complete
75
Lactation - during gestation
Elevated placental oestrogen and progesterone promote development of ducts and alveoli in mammary glands
76
Lactation - prolactin
Stimulates synthesis of enzymes essential for milk production by alveolar epithelial cells. Withdrawal of placental steroids at birth initiates lactation
77
Lactation - sustained by suckling
Triggers release of oxytocin and prolactin. Oxytocin causes milk ejection. Prolactin stimulates synthesis of more milk to replace milk ejected
78
Oxytocin function
exual activity, penile erection, ejaculation, pregnancy, uterine contraction, milk ejection, maternal behavior, social bonding, stress
79
What do testes produce
sperm and male hormones (androgens, e.g., testosterone)
80
Location of testes in utero
descend from the abdominal cavity via the inguinal canal and enter the scrotum.
81
What is the capsule that surrounds the testis
tunica vaginalis
82
What is the tunica vaginalis split into
parietal layer and visceral layer
83
Location of the tunica albuginea and what does it form
encapsulates the testes and forms projections that project into the testes (septa)
84
What is the space in-between the septa called
lobules
85
Where are the seminiferous tubules
a coiled tubular structure within each lobule
86
Location of the straight tubule
at the end of the seminiferous tubules
87
What forms the rete testis
when the straight tubules join together at the end
88
Location of the efferent ductules
come off the rete testis and connect to epididymis
89
What happens to sperm cells once they have been secreted
secereted from lining of the seminiferous tubules, travel via duct system and then stored in epididymis
90
Structure of epididymis
has a head, body and tail
91
Vas (ductus) deferens location
connects t6o the end of the epididymis. Is carried through the spermatic cord which travels in the inguinal canal. It comes up and over the bladder, then passes posteriorly and medially behind it
92
Vas deferens function
carries sperm from the epididymis to the ejaculatory ducts
93
Seminal vesicle location
lie either side of the ductus deferens and terminates at prostate gland
94
seminal vesicles function
produces seminal fluid (proteins, amino acids etc)
95
How is the prostate felt
through anterior wall of rectum
96
Glands present in male reproductive system
2 seminal vesicle glands, prostate glands and 2 bulbourethral glands
97
4 parts of the urethra
preprostatic prostate (above the prostate), prostatic urethra, membranous and spongy
98
Function of internal urethra sphincter
prevents back flow of semen into bladder
99
What is the urethral crest
a fold of mucosa in the prostatic urethra which forms a crest
100
Urethral sinus location
either side of the urethral crest
101
urethral sinus function
where prostatic ducts drain into
102
What does the urethral crest form
a circular enlargement which is called the seminal colliculus
103
Names of the openings in the seminal colliculus
3 openings: Middle opening is called prostatic utricle, either side is for the opening of the ejaculatory duct
104
What do the blood vessels from the anterior pituitary conncet
the hypothalamus, anterior pituitary and the rest if the body
105
What does the hypothalamus secrete for the male reproductive system
gonadotropin releasing hormone (GnRH)
106
Where does GnRH travel to and activate
the anterior pituitary (via portal blood) to release LH and FSH which travels to the male testes
107
What surround the seminiferous tubules
interstitial space (capillaries/blood vessels found)
108
Where does LH and FSH enter the male reproductive system
interstitial space
109
What cells are found in the interstitial space
Leydig cells (interstitial cells)
110
What cells are found in the seminiferous tubules
sertoli cells and spermatogonia ((male germ cell – becomes sperm)
111
What does LH target in the male reproductive system
targets leydig cells to secrete tesosterone
112
What cells does testosterone target and what are its effects
nurse cells and has peripheral effects (e.g., maintain labido, stimulates bone/muscle growth, maintenance of secondary characteristics, maintenance of accessory glands and organs of the male reproductive system.
113
What happens when testosterone levels are too high
negative feedback - anterior pituitary inhibits LH release
114
FSH target and function in male reproductive system
targets the sertoli cells, stimulating ABP (androgen binding protein) release
115
What does ABP release require
FSH and testosterone
116
What does ABP stimulate
the synthesis of sperm (spermatogenesis/ spermiogenesis) which ends up in the lumen of the seminiferous tubule. ABP binds to testosterone within the seminiferous tubule, which in turn stimulates sperm production
117
What else do sertoli cells secrete
inhibin - negative feedback as it decreases pituitary production of FSH, in order to regulate sperm production.
