medsci reproductive Flashcards
hypothalamus main functions
homeostatic regulator for reproduction, stress, body temp, hunger, thirst and sleep.
why is the hypothalamus a neuroendocrine organ
because it processes both neural and hormone information
pituitary main function definition
hormones are released from the posterior pituitary, neurosecretory cells possess long axon tracts that pass into the posterior pituitary. The neurosecretory peptide hormones are synthesised in the hypothalmus.
what are the two neurosecretory peptide hormones
oxytocin and antidiuretic hormone (ADH/vasopressin).
gonadotrophs
specalised secretory cells that stimulate release of LH and FSH (luteinising and follicle stimulating hormone).
Anterior pituitary role in neurosecretory systems.
neurosecretory neurones synthesise releasing and inhibiting hormones in their cell body into vesicles. VIA HYPOPHYSEAL portal vessels.
where is oxytocin and antidiuretic hormone synthesised in
the hypothalamus and transported to the posterior pituitary where they are stored and released.
oxytocin
Used to induce labour. Has major effects on smooth muscle contraction, causing milk ejection and contraction of the uterus during childbirth. Secretion is stimulated in response to nipples or uterine distension.
Gonadotrophs in the hypothalamus
produce gonadotrophins: follicle stimulating hormone (FSH) and luteinising hormone (LH)
Where are neurosecretory peptide hormones secreted into?
the hypophyseal portal vessels between hypothalamus and anterior pituitary.
Water soluble peptides and proteins
gonadotrophin releasing hormone from the hypothalamus, follicle stimulating hormone (AP), luteinising hormone (AP), oxytocin (PP).
Lipid soluble steroid hormones
androgens (testes), oestrogens (ovary) and progestagens (ovary).
What hormones are associated with the ovaries?
progestagens and oestrogen
is gonadotrophin releasing hormone (GnRH) water or lipid soluble
water soluble
what hormones associated with the testes?
androgens
is oxytocin water or lipid soluble
water
is luteinising hormone water or lipid soluble
water
is follicle stimulating hormone water or lipid soluble
water
are angrogens, oestrogens and and progesterones lipid or water soluble
lipid
adrenal glands in homeostasis and reproduction produce
estrogens and androgens
regulation of gonadotrophin secretion process
hypothalamus release only positive releasing gonadotrophin release hormone GnRH -> anterior pituitary gonadotrophs secreted -> release FSH and LH to gonads.
the regulatory process of pituitary secretory cells
The hypothalamus produce either releasing or release-inhibiting hormones to reach the anterior pituitary. Anterior pituitary secretory cells produce pituitary hormones which act on target tissues.
how does the regulatory process of pituitary secretory cells and regulation of gonadotrophin secretion in the reproductive system maintain homeostasis
This is a positive/neg feed back loop back on the on pituitary and hypothalamus to ensure homeostasis.
Negative regulation of gonadotrophin secretion
when the gonads produce androgens, oestrogens and progestagens the negative feedback respondds to these sex hormones and inhibit the release of hormones from hypothalamus and anterior pituitary.
androgens
produced from the adrenal cortex via adipose tissue which deal with heart growth, libido, bone health and muscle mass. Key properties include male sex development, spermatogenesis, sexual behaviour.
oestrogens
oestradiol, oestrone, oestriol and for purberty (layer- implantation of an embryo and growth of endmetrium). Regulations of menstrual cycle and bone growth.
two types of androgens
testosterone and 5a Dihydrotestosterone
5a dihydrotestosterone (DHT)
more active form of androgen involved in specific events, present during puberty and maintains male structures throughout lifetime, more potent than test. Important in early male development, spermatogenesis
androgens in females and males
mainly for men, females also have but 10-20x less than the average male.
testosterone
main secreting product of testes for development and maintenance of a male. More systemic and regulatory roles.
oestrogen’s in male vs female
females use estrogen more but males also use estrogen for bone growth, spermatogenesis and libido, however 20-10x less than females.
SRY gene
sex determining region on Y chromosome
progestagens
The major steroidal hormone of the corpus luteum of the placenta. Exclusive to female sex. Associated with preprations of pregnancy and maintenance. Only produced after ovulation and there for limited time.
how many chromosomes and how many pairs are sex chromosomes?
46 chromosones, 22 autosomes and 1 pair of sex chromosomes.
Sex determination and differentiation
Commitment of the bipotential gonad to the testis or an ovary, SRY gene (sex determining region on the Y chromosome provide pathway for testes to develop. Absence of Y = feminine trend.
phenotypic development of genital structures due to the action of hormones produced following gonadal development
This process is crucial for the differentiation and maturation of male and female genitalia. SRY, FSH and LH. Androgens and oestrogens.
Bipotential gonad
gonad with two potential outcomes of either female or male as it has both sex organs
Y chromosome present in sex determination
gonads develop into testes as testicular hormones are produced -> male sex
Female duct
mullerian duct
y chromosome absent
female gonads develop into female phenotype. (XX)
Male duct
wolffian duct
what produces a bipotential gonad
the mesoderm
bipotential gonad to male genitalia process
SRY gene on Y chromosome form testis via sertoli cells and leydig cells. Seritoli -> anti-mullerian hormone -> regression of mullerian duct.
Leydig -> test -> wolffian development -> BALLS.
bipotential gonad to female ovary process
without presence of Y chromosome, the ovary forms and produces oestrogens and progestagens which progress mullerian duct development and regress wolffian duct then produce femal internal genitals.
anti-mullerian hormone (AMH)
controls the mullerian duct regression in male differentiation.
bipotental gonad to male or female sex - which one is a faster process?
male genitalia progression as two hormones drive this process, the female estrogen and progestagens dont drive the development of mullerian duct. The progression naturally occurs.
when do the wolffian ducts regress in female differentiation
10 weeks
what do the wolffian ducts develop into
the seminal vesicles, epididymis and vas deferens.
what do the mullerian ducts progress into
the ovaries, fallopian tubes, uterus, cervix and upper vagina.
when does the testis descend from its internal position in male differentiation
~7th month the testis descend from its internal position in the scrotum.
what causes the mullerian duct to regress in male differentiation
AMH ANTIMULLERIAN HORMONE
External genitalia progression -
the male and female external genitalia develop from a single bipotential precursor.
how is the glans penis formed
the genital tubercule expands forming the glans penis
external genitalia male differentiation
fusion of urthral folds enclosing utrethral tube to form the shaft of the penis. Labioscrotal swellings fuse in the midline forming the scrotum. The genital tubercle (glans area) explans to form the glans penis
external genitalia female differentiation
urethral folds and labioscrotal swellings remain seperate forming the labia minora, the glans area (genital tubercle) forms the clitoris
difference between male and female external genitalia formation
the male urethral folds and labioscrotal swellings fuse whereas the urethral folds of the female remain seperate
what causes androgen insensitivity syndrome
mutation in androgen receptor gene which prevents androgen function. As there is no androgen function the exterior genitalia will appear female.
what forms the labia minora
urethral folds and the labioscrotum swelling that remains seperate
androgen insensitivity syndrome
person is XY, has testes but the genital ducts or external genitals are female. This is the result of a mutation in the androgen receptor gene which prevents androgen function. In the absence of androgen action the external genitalia will appear female.
glans area, genital tubercle differences in male and female sex differentiation
in the female it becomes the clitoris, in males it expands to form the glans penis
When is menarche (first menstrual period)
around 12-13 years and ovulation doesnt take place until 6-9 months after as positive feedback mechanisms of oestrogens are not fully developed yet. Therefore regular cycles persist after 1-2 years (menarche.)
Puberty
the gradual physical, emotional and sexual transition from childhood to adulthood. Considered the reawakening of the reproductive endocrine systems, which leads to full secondary sexual maturation with capacity for reproduction.
plasma levels of gonadotrophins in childhood
are very low until the initiation events leading to puberty
how is the onset of puberty recognised
by the production of the luteinising hormone, an increase in plasma LH is the first endocrine sign of puberty therefore the result of an increase in GnRH release. Gonadotrophin secretion (LH and FSH) occurs in early puberty at night during sleep, in late puberty daytime LH also increase.
sex steroids in response to the increase in plasma LH
increase in sex steroids
growth spirt stimulated by
steroid hormones (oestrogen and androgens with epiphyseal closure) by oestrogen. Growth spirt for females: around 11-12, males from 13-15 (greater height gain).
Secondary sexual characteristics
develop at different chronological ages in different individual, tanner stages allows abnormalities to be detected as there is a pattern.
staging criteria (tanner stage)
allows abnormalities to be detected and comparisons to be made between individuals
Female tanner stages
1) breasts development, oestrogen secretion appearance of breast bud and formation of breast mount.
2) pubic hair overlaps with breast development
3) height spurt
4) menarche
male tanner stages
1) testes enlargemetn (Leydig cells enlarge secrete test)
2) pubic hair
3) penis elongation
4) height spurt (spermatogenesis begins and apex strength spurt)
the timing of puberty
a critical weight must be attained before the activation of hypothalamus pituitary adrenal axis can occur. Rough mean weight of females at start of menarche is ~47kg
precocious puberty
appearance of physical and hormonal signs of puberty before 7 years in female and 9 years in males. Usually a gnRH (gonadotrophin releasing hormone) dependent problem, extreme cases are due to hypothalamic tumor which is recognised by tanner stages.
Fetal follicle amount in females
~7 million
delayed purberty
lack of physical and hormonal signs of puberty ~13 F and ~14 Male maximum. Occurs when gonadotrophin signals from pituitary are inadequate for sex steroid hormone secretion. Associated with syndromes like Kallmann, Klinefields and turner.
menopause
consequence of ovaries running out of follicles (50-52y) Lat episode of natural menstrual bleeding = end of reproductive life. (<1000 follicles, menopause where no follicles left or none respond).
Postmenopausal oestrogen production
by around one year after menopause the ovary has essentially ceased producing hormones (ovarian senescence). Oestrogen production reduces to less than 1/10 of previous.
weak oestrogen
oestrone
peri-menopause
symptoms of menopause , onset of irregular cycles around ~46-~50 years
ovarian senescence
ovary has ceased producing hormones
pre-menopause
before menopause, normal menstrual sped around 40 years
menopausal transition
is the phase leading up to menopause, marked by significant hormonal changes and a gradual decline in ovarian function. This transition can vary greatly in duration and experience from one individual to another.
symptoms of menopause
varies greatly due to oestrogen deprivation during the perimenopause. Consisting of vasomotor, genitourinary symptoms, bone metabolism, behavioural and psychological changes.
ovarian senescences
by ~1 yr after menopause, ovaries ceased producing hormones. Oestrogen production lowers to less than 1/10 of previous. Oestrogen (oesterone) arises mainly from production to the stomal cells of adipose tissue.
physiological and behavioural symptoms of menopause
depression, tension, anxiety, mental confusion and loss of libido.
vasomotor symptoms of menopause
changes in vascular structures such as instability of blood vessels, hot flushes and night sweats
bone metabolism symptoms of menopause
osteoporosis
menopause symptoms can be managed by
can be prevented or arrested by oestrogen treatment known as menopausal hormone therapy (inc oestrogen as these are caused by lack of oestrogen).
genitourinary symptoms of menopause
atrophic changes and vaginal dryness
unlike male testicles and sperm the ovarian function differs with cyclical activity from puberty to menopause
few oocytes are released in the process of ovulation = ~400, a mature oocyte is released every ~28 days (regular cycle).
female reproductive organs
vagina, uterus, ovaries, and uterine/ fallopian tubes - cervix
how is the uterus connected to ovaries?
uterine tube/ oviduct
what is the usual orientation of the ovary/uterus to vagina
anteflexed uterus, 90 degree orientation of the ovary/uterus in contrast to the vagina pointing anteriorly
retroflexed uterus
affects 20-30% women where it faces 90 degrees posteriorly. This could make it painful during intercourse or menstruation
Ampulla of uterine tube
optimum site for fertilisation
Endometrium
The endometrium is the inner lining of the uterus and plays a crucial role in the reproductive cycle and pregnancy, fertilised embryo goes down uterus and implant on endometrium. Innermost lining.
anteflexed uterus
normal uterus orientation
where does the fertilised embryo implant on in the uterus
endometrium.
The vagina
is an elastic muscular 7.5-9.0 cm tube extending from the cervix to the exterior of the body with three main functions.
what is the three functions of the vagina
passageway for elimination of menstrual fluid, it recieves the penis in sex and holds spermetozoa before it passes to the uterus and forms the lower portion of the birth canal through which the fetus passes during delivery.