W6b: the reproductive system Flashcards
male and female reproductive system
gonads: M= testes; testosterone and sperm
F= ovaries; oestrogen, progesterone, ova (eggs)
reproductive tract: M= epididymis, ductus deferens, ejaculatory duct
F= fallopian tubes, uterus, cervix
accessory sex glands: M= prostate + bulbourethral gland, seminal vesicles. F= mammary glands in breasts, bartholin’s glands
external genitalia: M= penis. F= vagina
the testes
testes is contained within scrotum which is divided into 2 by the dartos muscle which contracts or relaxes in response to temp change to maintain optimal temp for spermatogenesis
seminiferous tubules: site of testosterone and sperm production
- 80% of testicular mass is composed of highly coiled ST
- consist of SERTOLI and GERM CELLS: S= support spermatogenesis. G= undergo spermatogenesis
- interstitial tissue contain LEYDIG CELLS= secrete testosterone
epididymis: site of maturation of sperm
ductus deferens: transport pathway for sperm
control of testicular function
GnRH released
stimulates LH AND FSH in APG and is secreted
stimulates SERTOLI AND LEYDIG CELLS to secrete testosterone and support spermatogenesis
when TESTOSTERONE TOO HIGH, it inhibits hypothalamus to stop secreting GnRH
funcitons of test
before birth: masculinises reproductive tract n external genitalia, descent of testes in scrotum
after birth: promote growth n maturation of reproductive tract during puberty and maintains it after
secondary sexual characteristics: hair growth, dep voice, muscle growth n sex drive
non-rep actions: bone growth, induce aggressive behaviour
spermatogenesis
- production of sperm
- spermatogonia is the germ cells that undergo mitosis to start spermatogenesis
- primary spermatocytes formed
- first meiotic division: each 1 forms 2 2nd spermatocytes
- second meiotic division: 4 spermaids formed from original germ cell
- spermatids mature into spermatozoa (plural for spermatozoon)
process takes 64-74 DAYS
anatomy of spermatozoon
- about 60 micrometers long
- nucleus contains chromosomes
- acrosome helps penetrate oocyte
- middle piece contain mitochondria
epididymis
- could tube that connects each testis to ductus deference aiding transport of sperm
- tortuous canal, 5.5 cm long
- head, body and tail
- maturation of sperm in body of epididymis
ductus deferens
45cm long
transports sperm thru contractions of smooth muscle walls
cans tore sperm for several months
- connects epididymis to the ejaculatory ducts
- begins at tail of epididymis and extends upwards thru the spermatic cord into pelvic cavity
- loops over ureter and down the posterior side of the bladder
- joins the seminal vesicle duct to form the ejaculatory ducts
ejaculatory ducts
small paired tubes- one on either side of body
1-2 cm long
- formed by unions of ductus deferens and seminal gland duct
- forms just superior to the base of prostate and pas inferiority and - - anteriorly thru the prostate
- terminate in prostatic urethra
what are the accessory male sex glands
seminal glands
prostate gland
bulbourethral gland
seminal glands
- provides 60% of semen volume, contain fructose, prostagladins
- empties seminal fluid into last ration of ductus deferens where it forms ejaculatory duct
- pair of sac-like structures, 5cm long
- lie on posterior aspect of base of bladder
- outer areolar coat, middle smooth muscle layer, inner mucus layer, lined with columnar epithelium
prostate gland and bulbourethral gland
P: large, single gland that surrounds ejaculatory ducts and urethra
- outer fibrous coat, middle smooth muscle, inner layer of columnar epithelium
- provides 25-30% volume of semen, contains alkaline fluid to protect sperm from acicids environment of female reproductive tract
B: pea shaped gland situated blow prostate on either side of urethra
- secrete mucus for lubrication of urethra
- alkaline fluid that neutralises the acidity in urethra
- 5% of semen volume
spermatic cord
suspends the testes in the scrotum
contains the testicular artery/ veins, lymphatic vessels, vas deferens and testicular nerves
the cord ‘outlines’ the vas deferens
male urethra
- shared terminal duct of the genital and urinary system
- serves as passageway for both semen and urine
- 20cm long
- passes thru prostate, muscle of perineum and penis
- divided into, prostatic urethra, membranous urethra and spongy urethra
female reproductive system
ovaries (female gonads)
fallopian tubes
uterus
cervix
vagina
the ovaries
- produce ova and female sex hormones
- paired, oval shaped organs on either side of uterus, connected medially by ovarian ligament to the uterus
- located in ovarian fossa
- connected laterally to pelvic wall by suspensory ligament
what does each ovary have
- outer cortex that contains ovarian follicles at various stages of development
- inner medulla for blood and lymph vessels and nerves
- protective outer layer: tunica albuginea
- surface epithelium
function is to produce ova thru oogenesis and produce hormones
fallopian tubes
pair of tubes protruding out of superior portico of uterine cavity and aid in transport of ova to uterus
10cmx1cm
isthmus, ampulla and infundibulum are three parts (medial to lateral)
infundibulum has fimbriae (finger like projections) to catch the egg from the ovary
uterus
thick muscular organ between bladder and rectum
has 3 parts: fundus (top), body (sire of implantation) and cervix (connects uterus to vagina)
has 3 layers: perimetrium (outer layer), myometrium (muscle layer), endometrium (mucous layer)
cervix
- lower part of uterus
- 2 regions: ectocervix, endocervical canal
- ectocervix projects into vagina, its opening is the external os
- endocervical canal ends at the uterus in the internal os
ligaments of the uterus
Round Ligament
- Helps keep the uterus tilted forward (anteverted position).
- Extends from the uterus, passes through the inguinal canal, and attaches to the labia majora.
Broad Ligament
- A large, sheet-like ligament that supports the uterus, fallopian tubes, and ovaries.
- Extends from the sides of the uterus to the pelvic walls.
Cardinal Ligament (Transverse Cervical Ligament)
- Provides strong support to the cervix and upper vagina, preventing uterine prolapse.
- Runs from the cervix and upper vagina to the lateral pelvic walls.
Uterosacral Ligament
- Supports the uterus by anchoring it to the sacrum (back of the pelvis).
- Runs from the cervix and upper vagina to the sacrum.
the vagina
fibromuscular organ, approx 9cm long
exit to uterus
it is made up of 4 layers: (sup to deep)
- adventitia= fibrous layer
- fibromuscular= inner circular and outer longitudinal muscle layer
- elastic lamina propria= dense connective tissue layer
- stratified squamous epithelium= provides protection
oogenesis and menstrual cycle
oogenesis occurs thru cyclic changes to the female reproductive system
- changes brought by oestrogen and progesterone
- during each cycle, uterus is prepped for implantation and nurturing the embryo
- if no fertilisation, the uterus sheds its lining as menstrual flow and repeats every month
- if yes then uterus is prepped for pregnancy
describe the first step of oogenesis (process of egg formation in ovaries)
pre-birth:
- primordial germ cells in foetal ovaries undergo mitosis to produce many oogonia
- some develop into primary oocytes (immature egg cells) which start to undergo meiosis (I)
- meiosis (I) is arrested until puberty (temp stopped)
- each primary oocyte becomes surrounded by a layer of granulosa cells forming a primordial follicle
by birth a female has approx 1-2 million primary oocytes
what’s the second step of oogenesis
puberty to menopause:
- hormonal changes activate periods and oogenesis resumes
- here, 4000 primary oocytes are present and around 400 will mature and ovulate in reproductive lifetime
- each month FSH and LH secreted by APG stimulates primordial ovarian follicles and a few become primary ovarian follicles
- each of these contain primary oocyte surrounded by granulosa cells
primary ovarian follicles matures into secondary ovarian follicle and then tertiary ovarian follicle
one primary oocyte completes meiosis (I) and a secondary oocyte is formed with a first polar body
part 2 of second step of oogenesis
- Meiosis II starts
- Tertiary follicle ruptures and releases it’s secondary oocyte – this is ovulation
- remnants of the tertiary follicle is the corpus luteum
- Secondary oocyte is expelled into the pelvic cavity and is swept - into the fallopian tubes helped by the fimbriae
- If fertilisation does not occur the cells degenerate
- If sperm are present and penetrate the secondary oocyte then meiosis II resumes
- Secondary oocyte splits into 2 haploid cells: OVUM and second polar body
- Nuclei of the sperm and ovum unite forming a diploid zygote
So one primary oocyte gives rise to a single ovum, in contrast to males in which one spermatocyte produces four sperm
control of ovarian function
regulation of hormone secretion by ovaries involves with negative and positive control:
N= Estrogen and progesterone levels, once high, inhibit the release of FSH and LH to regulate the ovarian cycle and prevent overstimulation.
P= A surge in estrogen before ovulation causes the brain to release a large amount of LH, triggering ovulation.
what changes in the uterus
oestrogen preps the way:
- promotes growth of endometrium
- protons formation of progesterone receptors
progesterone acts on the oestrogen primed endometrium:
- loosens and softens CT, makes implantation easier
- promotes secretion of glycogen
- quietens uterine activity
what is teh breast composed of
glandular tissue
fibrous tissue
fatty tissue
the female breast
- composed of 15-20 lobes
- each lobe subdivided into lobules which constrain milk producing sac called glandular alveoli
- milk passed from alveoli into secondary tubules and then to the mammary ducts
- smaller ducts merge into large lactiferous ducts and converge towards nipple
- lactiferous sinuses are expansions of the duct near nipple where milk is temp stored
lactation
functions of mammary glands are synthesis, secretion and ejection of milk
production is stimulated primarily by prolactin
ejection is stimulated primarily by oxytocin
