Urogenital System Flashcards
what does the urinary system comprise of?
kidneys, ureter, bladder and urethra
what is the function of the urinary system?
to eliminate water from the body, regulate blood volume and pressure, control levels of electrolytes and metabolites and regulate blood pH
through what does the blood enter the kidneys?
renal arteries
though what does blood exit the kidneys?
renal veins
what filters blood in the kidneys?
nephrons
through what does urine enter the kidneys?
ureters
through what does urine exit the kidneys?
urethra
which germ layer forms the majority of the urinary system?
intermediate mesoderm
when are pronephric ducts formed?
4th week
where are pronephric ducts formed?
cervical region
what do pronephric ducts induce?
adjacent mesenchyme to condense into pronephroi
what do pronephroi form in fish and amphibians?
functional nephrons
in what direction does the ductal system extend?
caudal
what it the mesonephros?
the first functional kidney in the early embryo
when do the phenephric ducts begin to degenerate?
by the 25th day, but not until they extend caudally to form the mesonephric duct
what is the adult kidney called?
metanephric kidney
where are human kidneys found?
in the paravertabral gutter, on either side of the abdomen
which kidney is slightly lower than the other?
the right kidney is slightly lower than the left
what is located on top of each kidney?
adrenal gland
how many nephrons does the average kidney have?
1 million
what happens in the glomerulus and bowmans capsule?
blood pressure drives water and solutes out of the blood and into the bowmans capsule
which parts of the urinary system are formed of endoderm?
bladder and urethra
what does the intermediate mesoderm form during embryonic folding?
a longitudinal mass called the urogenital ridge
what does the urogenital ridge form?
the urinary and genital systems
what is the nephrogenic cord?
the part of the urogenital ridge that forms the urinary system
what is the gonadal ridge (or genital ridge)?
the part of the urogenital ridge that forms the genital system
what are the names of the three different kidneys that are formed during development?
pronephros, mesonephros and metanephros
what do the nephric ducts fuse with and when?
the clocea on day 26
what is the clocea?
an endodermal sac that links to both the digestive tract and the allantois
what are pronephroi?
rudimentary and non-functional nephrons
what induces adjacent mesenchyme to condense into mesonephroi?
the mesonephric duct
when does the metanephroi (permenant kidney) begin to form?
5th week
when do the mesonephroi become functional?
end of the 11th week
what happens to urine in the embryo?
it is secreted into the amniotic cavity where it contributes to amniotic fluid
what acts on the nephric duct to induce the formation of the ureteric bud?
the metenephric mesenchyme
what is another name for the nephric duct?
metanephric diverticulum
what is the main inductive signal involved in forming the metanephric kindey?
Glial-Cell-Derived Neurotrophic Factor (GDNF)
what signals does the mesenchyme release?
BMP4
what does BMP4 ensure?
that only a single ureteric bud is formed by each nephric duct
caudal mesonephric ducts sprout ureteric buds that grow into what?
a metanephric blastula
what happens to the ureteric ducts?
they bifurcate and induce cranial and caudal lobes in the metanephric blastula
the tip of each collecting duct induces the blastemal cap to form what?
a nephric vesicle
what will the nephric vesicle form?
bowmans capsule, proximal and distal convoluted tubules and the loop of henle
what are the testes?
paired organs that lie outside of the pelvis in scrotal sacs
what to testes produce?
sperm and male hormones
what is the epididymus?
tightly coiled tubes adjacent to the testes
what does the epididymus do?
acts as a maturation and storage vesicle for sperm
what is the vas deferens?
a long, thin tube that carries sperm from the epidiymus to the penis
where is the seminal vesicle?
it is attached to the vas deferens along the side of the bladder
what does the seminal vesicle do?
it produces seminal fluid which nourishes the spermatozoa
what is the prostate?
it surrounds the ejacultory ducts at the base of the urethra below the bladder. it produces seminal fluid which nourishes the spermatozoa
what are the ovaries?
small paired organs located near the lateral walls of the pelvic cavity
what do the ovaries produce?
ovum and female hormones
what are the fallopian tubes?
paired oviducts that lead from the ovaries to the uterus
where does fertilisation occur?
in the fallopian tubes
what is the uterus?
a pear shaped muscular organism that provides nutritional support and mechanical protection for the implanted embryo. contractions of the uterus are important for pushing the fetus out during birth
what does PGC stand for?
primordial germ cells
when are the PGCs formed and where?
during gastrulation in week 2 in the caudal epiblast layer
where do the PGCs migrate to?
the gonadal ridge via the umbilical cord, gut and dorsal mesentery
where is the gonadal ridge?
in the intermediate mesoderm between the forelimb and hindlimb
what are gonads?
testes in males and ovaries in females
what do PCGs promote the development of?
gonads
what does the gonadal ridge form?
the somatic cells of the gonad
what do the gonads proliferate to form?
primitive sex cords
what happens to males sex cords?
they grow into the gonadal ridge to form the testis cords
what do the testis cords form?
seminiferous tubules composed of sertoli cells
what does the mesenchyme form (males)?
leydig cells
what are leydig cells responsible for?
testosterone production
what does the anti-mullerine hormone do?
cause degeneration of the mullerian duct
what is turners syndrome?
a sterile female - XO
what is klinefelters syndrome?
sterile male - XXY
how many base pairs does the Y chromosome have?
59million
how many protein coding genes does the Y chromosome have?
45-53
which arm of the Y chromosome contains the SRY gene?
the short arm
what does the SRY gene specify?
testes development and therefore the male sex
what regions contain genes that are shared with the X chromosome?
the pseudoautosomnal region
what is SRY?
a DNA binding protein/transcription factor
what proteins does SRY encode?
proteins belonging to the SOX family
what do mutations in SRY cause?
swyer syndrome
what is swyer syndrome?
female anatomy but cannot produce female hormones, therefore no secondary sexual characteristics
in the genital ridge, what does SRY activate the transcription of?
SOX9
what is SOX9?
a closely related transcription factor that drives testes development
in the absence of SRY, what happens?
WNT4 is transcribed in the genital ridge and ovarian development takes place
what is physical appearance determined by?
hormones secreted by the gonads
what drives the development of male characteristics?
testosterone from testes
what does AMH induce?
the degeneration of mullerian ducts and the absence of the female reproductive tract
in the absence of testosterone and AMH, what happens?
mesonephric ducts degenerate and mullerian ducts differentiate into female reproductive tract
what does the development of female characteristics require?
the absence of testosterone and the production of oestrogen
what is congenital adrenal hyperplasia?
XX individuals have more masculine genitals than normal
what causes congenital adrenal hyperplasia?
an autosomal recessive mutation in genes that encode enzymes responsible for the synthesis of adrenal hormones (cortisol and aldosterone). leads to increase in level of testosterone.
what do female sex cords do?
they remain in the cortex of the gonodal ridge and form ovarian cords
what do ovarian cords form?
granulosa (follicle) cells that surround the developing ova
what does mesenchyme form (female)?
Thecal cells
what are thecal cells responsible for?
oestrogen production
what does the mullerian duct form in females?
the caudal ends of the mullerian ducts fuse to form oviducts, uterus and the upper third of the vagina
what makes up the lower two thirds of the vagina?
endoderm
how many females have a uterine defect?
1%
what is the most common uterine defect?
a seperated uterus
how does the male genitalia form?
urogenital folds fuse and genital tubercle elongates to form the penis. invagination of the ectoderm covering the glans forms distal urethra. labioscrotal folds form the scrotum.
how does the female genitalia form?
genital tubercle bends inferiourly to form the clitoris. urogenital folds remain separated to form labia minora. labiosacral folds form the labia majora.
when is primary sex determined?
sex chromosome carried by sperm
which sex forms in the absence of SRY?
female
what is 5-a-reductase deficiency?
when a genetically male (XY) infant is born with indifferent genitalia
what causes 5-a-reductase deficiency?
autosomal recessive mutations in the gene encoding isofrom 2 of 5-a-reductase
what is androgen insensitivity syndrome?
genetically male (XY) infant with prenatal feminisation, ranging from ambiguous genitalia to full female appreance
what is androgen insensitivity syndrome caused by?
a recessive mutation in androgen receptor gene
