Reproductive system Flashcards
Which bones make up the pelvis?
Ilium Ischium Sacrum Coccyx Pubis
Which joints make up the pelvis?
Pubic symphysis
Sacroiliac joint
What does the false/greater pelvis contained?
Position?
GI tract
Superior region of pelvis
What does the true/lesser pelvis contain?
Position?
Reproductive organs
Inferior region of pelvis
Compare the female and male pelvis
- Subpubic angle
- Females broader, males narrower - Coccyx
- Females straighter, males curved - Inlet
- Females oval, males heart-shaped
What muscles make up the pelvic floor?
- Levator ani
2. Coccygeus
What does the pelvic floor close over?
The pelvic outlet
Openings in the pelvic floor
Urethra
Anal canal
Vagina
What does the scrotum contain?
2 testes + 2 spermatic cords
What do testes produce?
Sperm, testosterone + inhibin
What are the testes surrounded by? What is this?
Tunica albuginea, a dense fibrous capsule
Seminiferous tubules
- Located where?
- Lead to?
- Contains which cells?
- In the lobules of the testes
- Join to form rete testis
- Leydig cells, Sertoli cells, spermatogenic cells (spermatozoa)
What do Leydig cells produce?
testosterone
What do Sertoli cells produce?
Inhibin
Epididymis
- 3 sections?
- Sperm enter at and exit via?
- Site of what?
- Head, body, tail
- Enter from seminiferous tubules (via rete testis then tubules)
- Exit via ductus deferens
- Site of sperm maturation
What is the ductus deferens covered by?
Smooth muscle
What does the ductus deferens dilate to form?
The ampulla
What do the spermatic cords contain?
- Ductus deferens
- Venous plexus
- Testicular artery
- Nerves
- Lymphatics
- Cremastor muscle
What are the ejaculatory ducts formed by?
The duct from the seminal vesicle + the ampulla
Urinary sphincters in males
External: skeletal muscle; voluntary control of urination
Internal: detrusor muscle; closes bladder to ensure no sperm is ejaculated through urethra
What is retrograde ejaculation?
Sperm end up in bladder (bc internal sphincter didn’t close)
Path of sperm
Testes –> seminiferous tubules –> rete testis –> efferent ductules –> epididymis –> ductus deferens –> ampulla –> ejaculatory duct –> prostatic urethra –> membranous urethra –> spongy/penile urethra
3 sections of the penis
root, body, glans
What are the 3 cylindrical erectile tissues in the penis? Which contains the urethra and what does it form?
- Corpora cavernosa (2); main
- Corpus spongiosum; contains urethra, forms bfulb + glans
Function of scrotum; lined by which muscle?
- Thermoregulation (maintain temp at ~34 degrees)
- Dartos muscle
Function of dartos muscle?
Contracts the skin covering the scrotum for heat conservation
What are the 3 male RS accessory glands?
- Function
- Seminal vesicles
- Prostate gland
- Bulbourethral glands
Seminal vesicles:
- Components of secretion?
- Function?
Viscous secretion:
- 60% of semen
- Fructose to nourish sperm
- Alkaline to protect sperm
Prostate gland
- Components of secretion?
- Function
Secretion: - 30% of semen - Acidic - Citrate to nourish sperm Contributes to sperm activation, viability and motility
Bulbourethral glands
- Opens into?
- Contributes how much to semen vol.?
- Function of secretions?
- Spongy urethra
- 5% of semen vol.
- lubrication
- Alkaline to neutralise acidity in urethra prior to ejaculation
What is a vasectomy?
Does it change seminal fluid vol.?
- Contraception; cut/tie ductus deferens
- No, bc doesn’t affect accessory glands
What is spermatogenesis?
The formation of mature spermatozoa from spermatogonia
What cell is formed at each stage of meiosis for spermatogenesis?
Diploid: primary spermatocyte - Meiosis I Haploid: secondary spermatocyte (2) - Meiosis II Haploid spermatid (4)
Spermatogonia:
- Migrate from? To?
- Remain dormant until?
- Yolk sac to testes
- Puberty
What happens to spermatogonia at puberty?
- Divide by mitosis into type A and B spermatogonia
- Type B differentiate into primary spermatocyte (then continue meiosis)
What is spermiogenesis?
- Process?
- Differentiation of spermatids into spermatozoa
1. Appearance of acromosomal vesicle + flagellum in spermatid
2. Growth of acromosome + flagellum
3. Shedding of excess cytoplasm
4. Mature sperm
What is a gonadotropin?
Hormone that acts on the gonads
GnRH
What is it?
What is it released from?
Stimulates release od?
- Gonadotropin releasing hormone
- Released from hypothalamus
- FSH + LH
Males: LH: What is it? What is it released from? Stimulates?
- Luteinising hormone (a gonadotropin)
- Released from anterior pituitary
- Production of testosterone
Males: FSH: What is it? What is it released from? Function?
- Follicle releasing hormone (a gonadotropin)
- From anterior pituitary
- Stimulates spermatogenesis
What are androgens?
Hormones which develop male characteristics (e.g. gonads –> testes)
What does testosterone do?
- stimulates spermatogenesis
- Inhibits LH + GnRH (negative feedback)
Males:
What does inhibin do?
Inhibits FSH secretion, thus inhibiting spermatogenesis
What makes up the female perineum?
Urogenital triangle - urethral and vaginal opening - external genitalia (vulva) Anal triangle - anal canal and fat
Components of the female external genitalia
- Mons pubis
- Labia majora + minora (vestibule b/w)
- Vestibular glands (lubricate vaginal orifice)
- Clitoris (glans, body, crura (2), bulbs (2))
Structures of the female reproductive tract?
Ovary Uterine tubes Uterus Cervix Vagina
3 Parts of the uterine tube + characteristic of each
- Infundibulum (most lateral; fimbriae)
- Ampulla (site of fertilisation)
- Isthmus (most medial)
Functions of uterus
- Movement of sperm
- Implantation of blastocyst
- Retain and nourish embryo + fetus through pregnancy
- Allow parturition
3 layers of the uterus wall + composition
- Endometrium
- Columnar epithelium
- Uterine glands + arteries - Myometrium
- Smooth muscle - Perimetrium
- Connective tissue
Blood supply to uterus
Abdominal aorta –> common iliac artery –> internal iliac artery –> uterine artery –> uterus
Blood supply to vagina
Abdominal aorta –> common iliac artery –> internal iliac artery –> vaginal artery –> vagina
Blood supply to ovary
Abdominal aorta –> ovarian artery –> ovaries
Blood supply in myometrium and endometrium
Uterine artery –> arcuate arteries –> radial arteries (through myo) –> spiral and straight arteries
Regions of the ovaries + what they contain
- Outer cortex
- follicles - Inner medulla
- connective tissue, blood vessels, nerves, lymphatics
What occurs in the ovaries
Oogenesis + hormone production
Female ligaments
- Broad ligament
- Ovarian ligament
- Suspensory ligament
- Round ligament
Which ligaments does the broad ligament form?
- Mesometrium (uterus)
- Mesosalpinx (tube)
- Mesovarium (ovary)
Female pouches
- Vesicouterine pouch: fold of broad ligament over bladder (anterior)
- Rectouterine pouch: fold of broad ligament over rectum (posterior)
What is oogenesis?
development of the oocyte from oogonia w/in an ovarian follicle
Oogenesis: type of cell at each stage of meiosis
- incl. when they’re halted if relevant
- (Diploid) primary oocyte
- Meiosis I (halted at prophase I until puberty) - (Haploid) secondary oocyte + polar body
- Meiosis II (halted at metaphase II until fertilisation)
Haploid oocyte + 3 second polar bodies
How are polar bodies formed?
By the uneven distribution of the cytoplasm during meiosis
Layers of follicle inside ovary
Oocyte Zona pellucida corona radiata antrum Ganulosa cells (attach to corona radiate on one side of the oocyte) Basement membrane Theca folliculi
What is released from the ovary during ovulation
Oocyte + corona radiata
Females:
FSH
- released from?
- function?
- Anterior pituitary
- Signals to ovary to stimulate the growth of ovarian follicles and initiate estradiol production
Females:
LH
- Released from?
- Function?
- Anterior pituitary
- Stimulates completion of follicle and oocyte growth (estrogen secretion by follicle)
- Stimulates ovulation
- Causes formation of corpus luteum from ruptured follicle (progesterone and oestrogen secretion by corpus luteum)
Prolactin:
- Released from?
- Function?
- Anterior pituitary
- Stimulates milk production in mammary glands
Estradiol
- Released from?
- Function?
- developing follicles in ovary
- Assists in follicular, bone, muscle and endometrial growth
- feedback to anterior pituitary to alter circulating levels of FSH/LH
Inhibin
- Released from?
- Function?
- granulose cells in ovary
- negative feedback to anterior pituitary to suppress FSH
Progesterone
- Released from?
- Function?
- Corpus luteum in ovary
- Negative feedback to suppress GnRH (thus FSH/LH)
- Endometrial maturation, maintains pregnant state
Oxytocin
- Released from?
- Function?
- Posterior pituitary
- Acts on breasts to cause milk let-down (ejection)
What is menarche? What is it caused by?
- First menstrual period
- due to increased estrogen production
What is menopause? caused by?
- Cessation of menstruation
- Decreased estradiol and progesterone due to decreased responsiveness of follicles // FSH/LH high
Ovarian cycle:
2 phases + what happens
- Follicular phase: day 1-14
(i) increased FSH from AP
- Follicular growth
(ii) Growing follicles secrete of estradiol + inhibin
- decreased FSH
- Growing follicles atresia
(iii) Dominant follicule secretes large amount of estradiol
- Surge of LH
(iv) Follicle ruptures + ovulation occurs
- oocyte released into peritoneal space - Lucteal phase: day 15-28
(i) Ovulated follicle collapses and forms corpus luteum
- secretes progesterone, estradiol, inhibin
(ii) Decreased FSH + LH secretion
(iii) Progesterone stimulates maturation of endometrium
- Glands become secretory
(iv) If no pregnancy
- corpus luteum involutes
- menstruation
- removes negative feedback on FSH and LH
Menstrual cycle:
Phases + what happens
- Proliferative phase: Day 1-14
(i) Estradiol stimulates endometrial growth from days 6-14
- Rapid tissue growth (incl. glands + vasculature) - Secretory phase: day 15-28
(i) Corpus luteum secretes progesterone
(ii) Progesterone promotes endometrial maturation (prepare for a zygote)
- spiral arteries grow + coil
- glands become secretory - No pregnancy
- corpus luteum degenerates
- decreased progesterone levels
- spiral arteries contract,
- uendometrial tissues break down and bleeding occurs
- Menstruation
Breasts:
- Function?
- Position?
- What stimulates development of tissue?
- Nourish infants
- Lie on pectorals major muscles
- Estradiol and progesterone
Structure of breasts
lobes –> lobules –> alveoli –> lactiferous ducts –> lactiferous sinuses
Breast feeding stages
- Lactation (milk production)
- Rapid decrease in estradiol and progesterone after birth allows breasts to respond to prolactin
- Prolactin stimulates milk production
- Suckling stimulates continued production of prolactin (amount determined by strength/duration of nipple stimulation) - Milk ejection reflex
- Suckling also stimulates oxytocin secretion
- Oxytocin stimulates contraction of smooth muscle around alveoli
- Milk goes into lactiferous ducts, allowing infant to feed
What forms layers surrounding the erectile tissues in the penis?
What are these layers?
Fascia
- Tunica albuginea: innermost
- Deep (Buck’s) fascia (surrounds tunica albuginea)
- Superficial fascia: outermost, surrounds deep fascia
What 2 structures make up erectile tissue?
- Trabeculae: smooth muscle fibres
- Lacunae: Cavernous space
Blood supply to the penis (pathway)
Abdominal aorta –> common iliac artery –> internal iliac artery –> internal pudendal artery
Males:
What does the internal pudendal artery supply blood to?
Which arteries branch off to supply the penis?
- Perineum and external genitalia
- Branches:
Artery to bulb
Urethral artery
Dorsal artery
Deep (cavernosal) artery
Veins draining the penis?
- Subtunical veins (in corpora cavernosa)
- Deep dorsal vein
- Superficial dorsal vein
How does the blood supply to the penis change during erection?
Increased blood flow:
- Cavernous spaces swell
- Lacunae fill
What is the nerve supply to the penis?
- Pudendal nerve
- supplies sensory and somatic motor innervation to perineum (incl. penis) –> dorsal nerve of penis - Pelvic plexus
- supplies autonomic innervation
- Parasympathetic and sympathetic
What is the parasympathetic NS response in males?
Erection
- Stimulates production of NO (vasodilator) by deep arteries of penis
What is the sympathetic NS response in males?
Ejaculation
- Stimulates contraction of smooth muscle in reproductive ducts and accessory glands
What is the somatic motor NS response in males?
Ejaculation
- Stimulates contraction of skeletal muscles around bulb of penis
Neural control of the sexual act
- Erection
- Parasympathetic response to stimuli
- Afferent signals: from brain (E.g. visual, tactile) via somatic pudendal nerve (stimulation of genital region/glans)
- Efferent signals (psychological stimulation): to penis (deep artery dilation, erectile tissues fill w/ blood, erection) + bulbourethral gland (secretes bulbourethral fluid) - Ejaculation
(i) Emission (Sperm and seminal fluid –> urethra)
- Sympathetic response
- Efferent signals: to ductus deferens (peristalsis; ampulla contracts; sperm to urethra) + seminal vesicles (seminal fluid) + prostate gland (seminal fluid)
(ii) Expulsion (ejection of sperm)
- Somatic and sympathetic reflexes
- Afferent signals: to spinal cord (stimulated by semen in urethra)
- Efferent signals: to accessory glands (additional secretion + smooth muscle contraction of internal urethral sphincter) + bulbocavernosus muscle (contracts to compress bulb/root of penis + urethra) - Resolution
- Sympathetic reflex
- Efferent signals to: internal pudendal artery (constricts to reduce blood flow) + trabecular muscles (contract, squeeze blood from erectile tissues) + Penis (flaccid)
Female sexual response
- Autonomic stimulation: engorgement of corpora of clitoris, bulbs of vestibule, labia and vagina
- Lubricating fluid secreted through vagina wall + secretion of mucus in vestibule
- Increased length + width of vagina (tactile stimulation, uterus elevates up)
- Rhythmic contraction of vaginal, uterine + perineal muscles (in response to pudendal nerve)
Natural methods of contraception
+ how they work/characteristics
- Rhythm method (periodic abstinence)
- Relies on timing of coitus - Withdrawal method
- Relies on behaviour during coitus - Lactational infertility
- Relies on timing of coitus
Artificial methods of contraception: physical barriers
+ how they work/characteristics
- Caps
- Need spermicidal creams, etc.
- Must leave in for 6+ hours - Condoms
- Cheap
- Readily available
- Easy to use
- Reduce risk of STDs
Artificial methods of contraception: steroidal contraception - Combined oral contraceptives
- Contain estrogen + progestin
- Suppress ovulation + mucus production by cervix
Artificial methods of contraception: surgical contraception
+ how they work
- Tubal ligation
- Cut uterine tubes - Vasectomy
- Cut ductus deferens - Hysterectomy
- Removes entire uterus
How long does an ovum survive for?
Approx. 24 hours
Process of fertilisation:
- Capacitation
- Fertiisation
- Oocyte changes
- Pronuclei fusion
- Capacitation
- Sperm undergoes changes in female tract (increased motility + softens acrosome)
- 6-8 hours - Fertilisation
(i) Penetration of corona radiata
(ii) Penetration of zona pellucida
(iii) Penetration of the oocyte cell membrane - Oocyte changes
- Zona pellucida becomes impenetrable (blocks polyspermy)
- Meiosis II completes to form haploid ovum (+ polar body)
- Female pronucleus forms
- Spermatozoon tail degenerates - Pronuclei fuse
- Becomes zygote (46 chromosomes)
- Sex determination
- Initiation of cleavage
Stages of ovum cleavage (+ time length)
Blastomere: 2 cells approx. 30 hours
4 cells approx. 40 hours
Morula: 16 cells (morula) approx. 3 days
Process of ovum –> blastocyst
- Mitotic division of ovum to form blastomere (approx. 30h)
- Continued division to form 16 cell morula (approx. 3 days)
- Cells of morula rearrange to form an inner mass (epiblast) and an outer mass (trophoblast)
- Fluid-filled blastocyst formed (days 4-5)
What do the 2 layers of the blastocyst form?
- Inner cell mass (embryo blast) –> embryo
2. Outer cell mass (trophoblast) –> placenta
Process of implantation (incl. which day/s where relevant)
- Blastocyst breaks out of zona pellucida
- Days 6-7: blastocyst moves to endometrium, implantation begins
- Day 10: blastocyst completely implanted
- Trophoblast forms 2 layers
- inner: cytotrophoblast
- outer: synctiotrophoblast - Outer cells invade endometrium, which envelops blastocyst
- Trophoblast secretes hCG
- Corpus luteum maintained
What is an ectopic pregnancy
Implantation outside of uterine cavity
What is the development of the cell during week 2
- Bilaminar disc formation
- Cavity formation
- Bilaminar disc formed from embryblast/inner cell mass (layers: epiblast (ectoderm) + hypoblast)
- 2 cavities form: amniotic cavity (surrounds and protects developing embryo) + yolk sac (primordial germ cells arise near here; used for early nutrient transfer)
Placenta:
- Function?
- Occurs where?
- Composed of?
- Allows diffusion of maternal fetal blood by week 4; Exchange occurs across chorionic villi (chorion formed by trophoblast) which contain blood vessels carrying fetal blood, which bathe in maternal blood
- Anchors/protects fetus
- Allows gas and nutrient exchange
- Made up of maternal tissue AND fetal tissue
Process of parturition
- Dilation of cervix to allow fetal head through; contractions; rupture of the fetal membranes
- Short contractions; birth of baby
- Placenta detaches; contractions close the maternal arteries
Potency of morula cells
Totipotent
Potency of embryonic stem cells
Pluripotent (all but placenta cells)
What is gastrulation?
Formation of 3 germ cell layers from the bilaminar disc
Gastrulation: what happens at week 3?
- Primitive streak forms in the epiblast
- Cells of epiblast move towards primitive streak and migrate downwards, pushing the old hypoblast out + forming the mesoderm and endoderm
What does the ectoderm form?
- Epidermis
- Brain and spinal cord
- Nerve cells
What does the mesoderm form?
- Muscle
- Bone
- Kindey
- Gonads
- Connective tissue
What does the endoderm form?
- GI tract lining
- Respiratory system (lining of lungs and bronchi)
What is neurulation? Process?
- The formation of a neural tube from a piece of ectoderm
- Process:
1. Ectoderm rises up at the edges to form the neural folds
2. Neural folds converge together
3. Neural folds fuse to form the neural tube
Sensitivity to environmental chemicals:
- 0-2 weeks (fertilised egg –> embryonic disc)
- 3-8 weeks (embryo)
- 9-38 weeks (fetus)
- Usually not sensitive; high rate of lethality may occur
- greatest sensitivity; development of organ systems
- Decreasing sensitivity; period of functional maturation
Stages of reproductive tract development
- Gonad development
- Oocyte + sperm development from germ cells
- Development of the male + female ducts
- Development of structures to deliver sperm to oocyte
Which germ cell layer does the repro tract form from? Where do the cells migrate from?
- Mesoderm
- Yolk sac
What is SRY? What happens in its presence/absence?
- Sex determining region on the Y chromosome
- If present; gonads –> testis
- If absent; gonads –> ovary
What is the mesonephros?
Mesoderm tissue from which the gonads and kidneys are developed from
Duct development
Before + after differentiation
- Before differentiation, 2 tubes from mesoderm
- Mesonephric (Wolffian) duct; associated with gonads
- Paramesonephric (Müllerian) duct; separated from gonads - After differentiation
- The duct not associated with the person’s sex degenerates
- SRY gene = Androgens present = male duct kept
- No SRY gene = no androgens present = female duct kept
How is the uterus formed from the paramesonephric duct?
The lower parts of the paramesonephric ducts fuse
What is müllerian inhibiting substance (MIS) / anti-müllerian hormone (AMH)?
Produced in males
causes paramesonephric duct to degenerate
How do the testes pass through the abdominal wall to the scrotum?
Using the inguinal canal
Genitalia development
- Indifferent stage
2. Presence/absence of androgens; differentiation
How can abnormalities of external genitalia arise?
- Female fetus exposed to androgen
- Male fetus cannot respond to androgen (e.g. mutated receptor)
- XY females lack a functional SRY gene
Example of an androgen
Testosterone, DHT
Differentiation of genital ridge/gonads
Male: testis
Female: Ovary
Differentiation of germ cells
Male: spermatozoa
Female: oocyte
What genitalia does the Müllerian/paramesonephric duct differentiate into?
- Vagina
- Uterus
- Uterine tubes
What genitalia does the Wolffian/mesonephric duct differentiate into?
- Epididymis
- Ductus deferens
- Seminal vesicles
Differentiation of genital tubercle
Male: penis
Female: clitoris
Differentiation of genital folds
Male: spongy urethra
Female: labia minora
Differentiation of genital swellings
Male: Scrotum
Female: labia majora
What happens in the ovaries of females during childhood? (b/w birth and puberty)
Follicular cells develop around each primary oocyte, to form primary follicles
Development of the oocyte in the ovary incl. the follicle after ovulation.
- Primary oocyte
- Primary follicle
- secondary oocyte + secondary follicles
- Mature follicle
- Ovulation
- Corpus luteum
- Corpus albicans
What happens to the primary oocytes in the ovaries of females after puberty?
- Primary oocytes resume meiosis to form secondary oocytes
- Follicle cells develop to form secondary follicles
- Outer layer granulose cells differentiate to form theca cells
What is copulation?
The insertion of an erect penis into the vagina for the purpose of reproduction.
The process of sperm being deposited into the vagina?
Insemination
Artificial methods of contraception: steroidal (Progesterone-only) contraception
Progesterone-only pill
(i) Progesterone-only pill
- Low doses of progestin
- Effects on cervical mucus
Artificial methods of contraception: steroidal (Progesterone-only) contraception
Subdermal implant/injectables
- Long acting (years)
- Disrupt follicular growth + ovulation
Artificial methods of contraception: steroidal (Progesterone-only) contraception
Copper IUD
- Low grade inflammation
- toxic to oocyte + zygote
- Impairs implantation
Artificial methods of contraception: steroidal (Progesterone-only) contraception
Hormonal IUD (Mirena)
- Affects cervical mucus
- Thickens endometrium
- May affect ovulation
