Reproductive system Flashcards
Where are gametes produced?
Gonads
- Male = testes
- Female = ovaries
Pelvis location & structure
- Where is the pelvis located?
- What makes up the pelvis?
- What are the bones of the pelvis?
- What are the joints of the pelvis?
- Bony basin b/w lower limb & the trunk
- Hip bones + sacrum + coccyx
- ilium
- ischium
- sacrum
- coccyx
- pubis
- Sacroiliac joint
- Pubic symphysis (can widen)
Pelvic Inlet & outlet (holes)
- Which is open and which is closed by muscles?
- Which is bigger?
- Inlet is open, outlet is closed by muscles
- Inlet always bigger than outlet
What are the pelvic subdivisions?
- False/greater pelvis
- True/lesser pelvis
Features of the pelvic subdivisions
- Which is superior region?
- Which is inferior region
- Where is the false/greater pelvis located?
- Where is the true/lesser pelvis located?
- Which contains the GI tract?
- Which contains the reproductive organs?
True/lesser
- inferior region
- b/w inlet & outlet
- contains reproductive organs
False/greater
- superior region
- situated above pelvic inlet
- contains GI tract
Female vs Male pelvis
- Subpubic angle?
- Inlet shape?
- Coccyx shape?
Female
- Broader subpubic angle
- Oval inlet
- Straighter coccyx
Male
- Narrower subpubic angle
- Heart-shaped inlet
- Curved coccyx
- What closes over the pelvic outlet?
- What are the muscles involved?
- What are the openings in the pelvic floor?
- Pelvic floor
- Levator ani & cocygeus
- Urethra
- Anal canal
- Vagina (females)
Perineum
- What does it contain?
- What are the two triangle divisions?
- External genitalia & anus
- Anterior: urogenital triangle
- Posterior: anal canal & fat
Male reproductive tract
- What path is it?
- What does it include?
- Path that sperm travel along
- Testes
- Epididymis
- Ductus (vas) deferens
- Ejaculatory duct
- Urethra
What is makes up the scrotum?
- 2 testes
- 2 spermatic cord
Testes
- What do the produce?
- What are they surrounded by?
- Sperm
- Testosterone
- Inhibin
- Dense fibrous capsule - tunica albginea
Seminiferous tubules
- Where are they found?
- What do they join to form?
- Contained in the lobules of the testes
- Join to form rete testes; which
- Join to form ductules leading to epididymis
What are the cells of the seminiferous tubules?
- Leydig cells: testosterone
- Sertoli cells: inhibin
- Spermatogenic cells: spermatozoa
Epididymis
- What is it made up of?
- Whare does the sperm enter & leave?
- Head, body & tail
- Enters from seminiferous tubules
- Exits via ductus deferens
Ductus Deferens (‘vas deferens’)
- What is it in?
- What is covered by?
- What does run behind?
- What does it dilate to form?
- In spermatic cord
- Covered by smooth muscle
- Runs behind bladder
- Dilates to form the ampulla
The spermatic cord
- How many?
- Where does it run?
- What does it contain?
- One on each side
- Runs b/w abdomen & testes
Contains
- Ductus deferens
- Blood vessels (testicular arteries & veins)
- Nerves
- Lymphatics
Ejaculatory ducts
- What are they formed by?
- Where does i t open?
- Formed by the union of the duct from the seminal vesicle & the ampulla
- Opens in the prostatic urethra
Urinary/ urethral sphincters
- External
- Internal
External
- Skeletal muscle, voluntary control of urination
Internal
- Detrusor muscle - closes bladder thus ensures sperm ejaculated through the urethra; retrograde ejaculation - sphincter doesn’t close, therefore ends up in bladder
What is the path of sperm?
Testes (manufactured) → epididymis → ductus deferens → ejaculatory duct → urethra
The Penis
- What is the Dual function?
- What makes up the cylindrical organ?
- What are the 3 cylindrical erectile tissues?
- What are their features?
- Urination
- Copulation
- Root (bulb)
- Body
- Glans, covered by prepuce/foreskin
→ 2 corpora cavernosa - main erectile tissue - dorsal aspect → 1 corpus spongiosum - contains urethra - forms bulb & glans - ventral aspect
The scrotum
- Where does it house the testes? And why?
- Which muscle is it lined by?
- Which muscle contracts? And why?
- Houses testes away from the body to maintain temp @ ~34 °C
- Lined by dartos muscle
- Cremator muscle - contracts for heat conservation (thermoregulation)
Accessory glands
- What do they produce?
- What are the 3 glands associated w/ male RS
- Produce most seminal fluid (composition, volume)
- Seminal vesicles
- Prostate gland
- Bulbourethral glands
Seminal vesicles
- How many?
- Location?
- What does it merge with and become?
- What does it produce?
- What does it contain?
- What does alkaline pH protect?
- 2
- Posterior to bladder, lateral to ampulla of ductus deferens
- Merges w/ ampulla to form ejaculatory duct
→ Produce viscous secretion
- 60% of semen
- Contain fructose & other nutrients to nourish sperm
- Alkaline pH protects sperm against acidic environment in urethra & vagina
Prostate gland
- Location?
- What does it produce?
- pH? Why?
- What does it contain
- What is contribute to?
- Inferior to bladder, wraps around prostatic urethra
→ Produces secretion
- 30% of semen
- Slightly acidic, milky fluid containing enzymes & PSA (prostate specific antigen)
- Contains citrate to nourish sperm
- Contributes to sperm activation, viability & motility
Bulbourethral glands
- How many?
- Location?
- What does it open into?
- How much does it contribute to semen vol.
- What do the secretions do?
- 2 glands
- Located in the urogenital diaphragm
- Open into spongy/penile urethra
- Contributes to 5% of semen vol.
- Secretions lubricate & neutralise acidity in urethra prior to ejaculation
Vasectomy
- What is it?
- Contraception; cut/tie ductus deferens
- Doesnt change seminal fluid vol.; bc accessory glands still functioning
- What is Gametogenesis?
- Males?
- Females?
- What type of control is it?
- How does it occur?
- Formation of the sex cells
- Males: spermatogenesis
- Females: oogenesis
- Under hormonal control
- Occurs via meiosis
- What is spermatogenesis?
- What type of cell division occurs?
- What are the 3 main stages of this cell division?
- Cell type
- Number of chromosomes
- Spermatogonia → mature spermatozoa (sperm)
- Occurs via meiosis
- Process:
1. Primary spermatocyte (diploid: 2n = 46)
Meiosis I
2. Secondary spermatocyte (n = 23)
Meiosis II
3. Spermatid/spermatozoa (haploid: n = 23)
Spermatogenesis during development
Spermatogonia migrate from yolk sac to testes & remain dormant until puberty
Spermatogenesis during puberty
- What does spermatogonia divide by?
- What does type B spermatogonia differentiate into?
What does it undergo to do this? - What is formed after this step?
- What do these undergo next?
- What do spermatids differentiate into?
- Where are spermatozoa released?
- How many spermatozoa are formed from 1 type B spermatogium?
- Spermatogonia divide by mitosis into type A&B spermatogonia (diploid - 46 chrom.)
- Type B spermatogonia differentiate into 1* sex cell/ 1* spermatocyte (diploid) which undergoes meiosis I
- Forms 2* spermatocytes (haploid)
- These undergo meiosis II to form spermatids (haploid)
- Spermatids differentiate into spermatozoa w/ a head, body & tail via spermiogenesis
- Spermatozoa released into lumen
- 1 type B spermatogium forms 4 spermatozoa
- How often does spermatogenesis take place?
- Where does sperm develop mobility?
- Where does sperm mature?
- Spermatogenesis takes place continuously daily after puberty
- Sperm develop mobility in epididymis
- Sperm mature in the epididymis
What is spermiogenesis?
Spermatid → Spermatozoon (change shape)
What is the spermiogenesis process?
1) Appearance of acromosomal vesicle & flagellum in spermatid
2) Growth of acrosome & flagellum
3) Shedding of excess cytoplasm (more streamline)
4) Mature sperm
- What hormone acts on the gonads?
- What is GnRH & where is it released from?
- What is LH & where is it released from?
- What is FSH & where is it released from?
- gonadotropin
- GnRH - gonadotropin releasing hormone
- released from hypothalamus (released in pulsatile fashion)
- LH - Luteinising hormone (a gonadotropin)
- from anterior pituitary
- FSH - Follicle stimulating hormone (a gonadotropin)
- from anterior pituitary
What are the reproductive hormones?
1) GnRH - gonadotropin releasing hormone
2) LH - Luteinising hormone (a gonadotropin)
3) FSH - Follicle stimulating hormone (a gonadotropin)
- What are the hormones in males?
- Where are they from?
Inhibin
- from sertoli cells
Testosterone
- from leydig cells
- Androgen
What is androgen?
- Hormones which develop male characteristics (eg gonads → testes; spermatogenesis, aggression & libido)
- Synthetic androgens (steroids) - therapeutic purposes
Endocrine controls of the testes
- What does LH stimulate the production of?
- What controls spermatogenesis?
- What does inhibin inhibit?
- What does the negative feedback of testosterine suppress?
- LH stimulates the production of testosterone
- FSH & testosterone control spermatogenesis
- Inhibin inhibits FSH
- Negative feedback of testosterone suppresses LH & GnRH
Oogenesis
- What is it the formation of?
- What does it require?
- When is it initiated? and when does it continue?
- Where do oocytes develop?
- Formation & development of the oocyte from oogonia
- Requires mitosis & meiosis
- Initiated before birth, continues b/w puberty & menopause
- Oocytes develop w/in ovarian follicles (one per follicle)
Generating the ovum - before birth
1) Oogonium (diploid) migrate to developing gonad
2) Population of oogonia ↑ by mitosis
3) Oogonia differentiate to form 1* oocytes (diploid)
- Encased in primordial follicle
- Many 1* oocytes undergo cell death (atresia)
4) 1* oocytes start meiosis
- Halts at prophase 1 until puberty begins
Generating the ovum - from menarche till menopause
1) Under GnRH influence, small number of follicles recruited each ovarian/mestrual cycle
2) Only one oocyte will complete development & ovulate
3) 1* oocyte completes meiosis I
- forms a 2* oocyte & first polar body (both haploid)
4) 2* oocyte starts meiosis II
- Halts at metaphase II until fertilisation
5) Meiosis II resumes when the sperm penetrates plasma membrane of the ovum at fertilisation
- If not fertilised, will die (atresia)
Oogenesis w/in developing follicle
- What develops in the developing follicle?
- Are follicles multilayered?
- What are the cells of the developing follicle?
- During ovulation what is released into the peritoneal cavity?
- Oocyte develops w/in developing follicle
- Follicles are multilayered
- Granulosa cells - produce estradiol
- Theca cells
- Ovulation: oocyte & corona radiata released into peritoneal cavity
Hypothalamus Hormones
- What is found and released in the hypothalamus?
- What does this stimulate?
- GnRH (gonadotropin releasing hormone)
- Release of FSH & LH
What are the Anterior Pituitary Hormones?
- FSH (follicle stimulating hormone)
- LH (luteinising hormone)
- Prolactin
FSH (follicle stimulating hormone)
- What does it signal
- What does it stimulate? And initiate?
- Signals to ovary
- Stimulates the growth of ovarian follicles & initiates estradiol production
LH (luteinising hormone)
- What 2 things does it stimulate?
- What does it cause?
- Stimulates completion of follicle & oocyte growth → estrogen secretion by follicle
- Stimulates ovulation (by causing ovum expulsion from follicle)
- Causes formation of corpus luteum from ruptured follicle → progesterone & estrogen secretion by corpus luteum
Prolactin
- What does prolactin stimulate?
- Stimulates production of milk in the mammary glands
What are the hormones produced in the Ovary (follicles)?
- Estradiol (developing follicles)
- Inhibin (granulosa cells)
- Progesterone (corpus leum
Estradiol (developing follicles)
- What does it assist with?
- What type of characteristics?
- What feedback?
- Assist follicle growth (w/ FSH), bone & muscle growth, endometrial growth
- Secondary sex characteristics
- Feedback to anterior pituitary (to alter circulating levels of FSH/LH)
Inhibin (granulso cells)
- What type of feedback?
- -ve feedback to anterior pituitary to suppress FSH
Progesterone (corpus luteum)
- What type of feedback?
- How does it maintain pregnant state?
- -ve feedback to supress GnRG (thus LH & FSH)
- Endometrial maturation, maintains pregnant state
Ovarian cycle
Follicular (preovulatory) phase
- day 1-14 (av. 14 days)
- ↓ FSH from the anterior pituitary
- Stimulates follicular growth growth
- Growing follicles secrete estradid & inhibin
- ↓ FSH from anterior pit. (-ve feedback)
- Growing follicles undergo astresia (except dominant one)
- Dominant follicle secretes large amounts of estradiol
- High estradiol stimulates surge of LH (+ve feedback)
- Follicle ruptures & ovulation occurs
- Oocyte enters peritoneal space & collected by uterine tube
Ovarian cycle
Lucteal (post-ovulatory) phase
- day 15-28 (av. 14 days)
- Ovulated follicle collapses & forms corpus luteum
- secretes progesterone, estradiole @ inhibin
- These ↓ FSH & LH secretion
- -ve feedback on hypothalamus
- Progesterone stimulates maturation of the endometrium
- glands become secretory
- If pregnancy doesn’t occur, the corpus luteum involutes (luteolysis)
- ↓ in progesterone & estradiol
- Endometrium breaks down & bleeds (menstruation)
- Removes -ve feedback on FSH & LH; cycle starts again
Menstrual/Endometrial cycle
Proliferative (& menstrual) phase
- Day 1-14
- Estradiol stimulates endometrial growth from ~ days 6-14
- Rapid tissue growth, incl. growth of glands & vasculature
Menstrual/Endometrial cycle
Secretory (& pre-menstrual) phase
- Day 15-28
- After ovulation (day14) - corpus luteum secretes progesterone
- Progesterone promotes endometrial maturation
- Glands become secretory
- Spiral arterioles grow & coil
- If pregnancy doesnt occur
- Corpus luteum atrophies (degenerates)
- Progesterone levels ↓
- Spiral arteries contract
- Endometrial tissue breaks down & bleeding occurs
- Shed tissue & blood removed via cervix & vagina (menstruation)
Interlinking of cycles
- Ovarian cycle: produces ovum each month to regulate the menstrual cycle
- Menstrual/endometrial cycle: ensures lining of uterus suitable for implantation
Breast (Mammary glands)
- Function?
- Location?
- What stimulates development of breast tissues?
- Structure?
- Function: nourish infants
- Lie on pectoralis major muscles
- Estradiol & progesterone stimulate development of breast tissue
- Lobes → lobules → alveoli → lactiferous ducts → lactiferous sinuses
Breast feeding Milk production (lactation)
- Rapid ↓ in circulating estradiol & progesterone after birth allows breast to respond to prolactin
- Prolactin stimulates milk prodution/secretion/synthesis
- Suckling stimulates continued production of prolactin
- Amount of prolactin determined by strength/duration of nipple stimulation during suckling
Breast feeding
Milk let-down/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
Posterior pituitary
- What is released?
- What does it act on?
- Oxytocin
- Acts on breast to cause milk let-down
Female perineum
- How many divisions?
- What is the Anterior division?
- What is the posterior division?
- 2 triangular division
- Anterior: urogenital triangle
- Urethral & vaginal opening: external genitalia (vulva)
- Poster: anal canal
- Anal canal & fat
External genitalia (vulva)
- Where is the Mons pubis?
- What is the labia structures?
- What is the space b/w labia?
- Vestibular gland location? Function?
- What does the clitoris consist of?
- In front of the pubic symphysis
- Major (labia majora) - larger & more lateral
- Minor (labia minora) - smaller & more medial; spreads around the urethral opening
- Space b/w = vestibule
- Deep to the labia
- Lubricate the vaginal orifice
Consist of: glans (singular), body, crura (x2), bulbs (x2)
Reproductive tract
- What does it allow
- What does it provide?
- What is it delivery of?
- What are the structures w/in?
- Allows transport of sperm & ova to the site of fertilization
- Provides a site for the developing embryo & fetus to grow - protection & nourishment
- Delivery of fetus
- Ovary
- Uterine tubes
- Uterus
- Cervix
- Vagina
egg → Ovary → uterine tube → uterus → cervix → vagina
Uterine tube (3 parts)
- What part is the most lateral portion?
- What is it shaped like?
- What does the fimbriae help with?
- What is the mid-portion part?
- What area?
- What occurs here?
- What part is the most medial portion?
1) Infundibulum (most lateral portion)
- Funnel shaped
- Fibriae (finger-like projections)
- Fimbriae hover over the ovary to help collect/guide the ovulated ovum to the opening in the infudundibulum
2) Ampulla (mid-portion)
- Dilated area
- Fertilisation normally occurs here
3) Isthmus (most medial portion)
- means “narrow passage”
Uterus
- Function?
- 3 major components
- Wall: 3 layers
- Position?
- Movement of sperm
- Implantation of blastocyst
- Retain & nourish embryo & fetus through pregnancy
- Allow parturition (childbirth)
- Fundus
- Body
- Cervix
1) Perimetrium - outer layer; connective tissue
2) Myometrium - middle layer; smooth muscle
3) Endometrium - inner layer; columnar epithelium (uterine glands & arteries)
- Position: anterior inclination (anteverted)
Cervix
- 3 sections?
- External os
- Cervical canal
- Internal os
Vagina
-Fibromuscular, distensible copulatory organ
Uterus
- Function?
- 3 major components
- Wall: 3 layers
- Position?
- Movement of sperm
- Implantation of blastocyst
- Retain & nourish embryo & fetus through pregnancy
- Allow parturition (childbirth)
- Fundus
- Body
- Cervix
1) Perimetrium - outer layer; connective tissue
2) Myometrium - middle layer; smooth muscle
3) Endometrium - inner layer; columnar epithelium (uterine glands & arteries)
- Position: anterior inclination (anteverted)
Cervix
- 3 sections?
- External os
- Cervical canal
- Internal os
Vagina
- Fibromuscular, distensible copulatory organ
- Also functions as part of the birth canal
- Lies b/w the bladder & rectum
- Extends from the perineum to the cervix
Blood supply
- Branches off?
- Uterus
- Vagina
- Ovary
- Branches off abdominal aorta & internal iliac arteries
- uterus: from uterine artery, which branches off internal iliac arter
- Vagina: From vaginal artery, branches off internal iliac
- Ovary: Ovarian arteries, which branches off abdominal aorta
Blood supply in myometrium & endometrium
Where?
- Where are spiral arteries?
- Uterine artery → arcuate arteries → radial arteries → spiral & straight arteries
- Spiral arteries move deeper into endometrium (closer to lumen): join venous supply
Ovaries
- Bilateral structures: lateral & posterior side of the uterus in the lateral portion of the true pelvic cavity
Consist of:
- Outer cortex (follicles)
- Inner medulla (connective tissue, blood vessel, nerves & lymphatics)
- Site of oogenesis & hormone production
Ligaments
What are the ligaments?
- Folds & presses over structures to create other ligaments
1) Broad ligament
- Mesometrium (“of the wobm”)
- Mesosalpinx (“of the tube”)
- Mesovarium (“of the ovary”)
2) Ovarian ligament
3) Suspensory ligament
4) round ligament
Pouches
- What do they allow?
1) Vesicouterine pouch: location
2) Rectouterin pouch: location
- Allow uterus to expand/enlarge during pregnancy
- Vesicouterine pouch: continuous fold of broad ligament anteriorly located over bladder
- Rectouterin pouch: continuous fold of broad ligament posteriorly located over rectum
What are the functions of ligaments & peritoneal sheaths?
- Anchor & support
- Have vasculature & nerves running thr’ them
- From important anatomical boundaries (i.e pouches)
What are the 3 cylindrical erectile tissues?
- 2 Corpora cavernosa
- 1 corpus spongiosum
Facia
- What are the different types of fascia surrounding the erectile tissues?
- Tunica albuginea - innermost
- Deep (Bucks) fascia - Middle
- Superficial fascia - outer
What is erectile tissue made up of?
- Trabeculae = smooth muscle fibres
- Lacunae = cavernous space
Vascular & nerve supply - penis
- What is the path of blood supply
- What does the internal pudendal artery supply?
- What are the arteries that branch to the penis?
→ Abdominal aorta → common iliac artery → internal iliac artery → internal pudendal artery
Pudendal artery supplies perineum & external genitalia
- Artery to the bulb
- Urethral artery
- Dorsal artery
- Deep (cavernosal) artery
Blood supply to penis ↑ during erections
- What swells? Why?
- What is compressed?
- Cavernous spaces swell due to blood
- Veins compressed as lacunae fill
Nerve supply to the penis
- What is the penis innervated by?
- What does this include?
- What does the pudendal nerve supply?
- Where does the pudendal nerve supply?
- Where is the autonomic innervation to the penis derived from?
- What does parasympathetic nerves stimulate?
- What do the deep arteries do?
- What does the sympathetic nerves stimulate?
- What does it include?
- What does the somatic motor stimulate
- Penis richly innervated by sensory & motor nerves
- Includes sensory fibres responsive to touch, pressure & temperature
- Pudendal nerve supplies sensory & somatic motor innervation to perineum & external genitalia
- Dorsal nerve of penis
- Autonomic innervation to penis derived from pelvic plexus - (parasympathetic & sympathetic)
- Parasympathetic (erection)- Stimulates production of NO (vasodilator) by deep arteries of penis
- Deep arteries dilate & fill lacunae in corpora cavernosum
- Sympathetic (ejaculation)- Stimulates contraction of smooth muscle (moves sperm - peristaltic contractions)
- Reproductive ducts
- Accessory glands
- Somatic motor (ejaculation) - Stimulates contraction of skeletal muscles around bulb of penis
Erection: Parasympathetic response to stimuli
- Afferent
- Where?
- What stimulations from the brain?
- Efferent
- What signals does it cause to the penis & bulbourethral gland?
- Afferent to spine
1) Visual, mental & other stimuli (from brain)
2) Stimulation of genital region, particularly glans (from pudendal nerve) - Efferent
1) Penis: deep artery dilation, erectile tissues fill w/ blood, penis becomes erect
2) Bulbourethral gland: secretes bulbourethral fluid
Emission: Sympathetic response
- Efferent signals to?
1) Ductus deferens (peristalsis, sperm → ampulla, ampulla contracts, sperm → urethra)
2) Seminal vesicles (Secretes components of seminal fluid)
3) Prostate gland (Secretes components of seminal fluid)
Expulsion: somatic & sympathetic reflexes
- Afferent signals to?
- Efferent?
- Accessory glands
- Additional secretions from?
- Contraction of what?
- What type of signals?
- What muscle contracts?
- What does it do to the penis?
- Afferent signals to spinal cord from semen in urethra
- Efferent sympathetic signals
- Additional secretions from prostate gland & seminal vesicles; contraction of internal urethral sphincter (urine stays in bladder)
- Efferent somatic signals
- Bulbocavemous muscle: contracts & rhythmically compresses bulb/root of penis, which compresses urethra; semen is expelled
Resolution: sympathetic reflex
- What happens to the penis?
- What type of signals?
- What constricts, ↓ blood flow to penis?
- What muscle contracts & what does it do to the blood?
- What does the penis become?
- Blood flow to penis ↓, becomes flaccid
- Efferent sympathetic signals
1 - Internal pudenal artery: constricts, ↓ blood flow to penis
2 - Trabecular muscle: contract, squeeze blood from erectile tissues
3 - penis becomes flaccid
Female sexual response
- What is it a similar sequence of compared to the men?
- Engorgement of what? in response to autonomic stimulation
- What is secreted?
- What happens to the vagina in response to tactile stimulation?
- What is there rhythmic contraction of in response to pudenal nerve?
- Similar sequence of reflex responses as in the male
- Engorgement of corpora of clitoris, bulbs of vestibule, labia & vagina in response to autonomic stimulation
- Lubricating fluid secreted through vaginal wall; secretion of mucus in vestibule (greater vestibular glands)
- ↑ width & length of vagina in response to tactile stimulation, uterus elevates upwards
- Rhythmic contraction of vaginal, uterine & perineal (pelvic floor) muscles in response to stimuli from pudenal nerve
Contraception - Natural methods
- What do they rely on?
- High or low failure rate?
What type of methods are there
- Rely on timing of coitus (1,3) or behaviour during coitus (2)
- High failure rate
1) Rhythm method (periodic abstinence)
2) Withdrawal method (coitus interruptus)
3) Lactational infertility
artificial Mechanical/physical barriers
1) Caps, diaphragms
- Used in what & with what?
- How long doe sit have to remain in for after intercourse?
- Why is it rarely used nowadays?
2) Condoms
- Price
- Availability?
- Difficulty to use?
- ↓ chances of what?
1) Caps, diaphragms
- Imperfect barrier; used in conjunction w/ spermicidal creams, sponges, etc
- Needs to remain > 6 hours after intercourse
- Rarely used nowadays; replaced by safer, more convenient methods
2) Condoms
- Cheap
- Readily available
- Easy to use
- ↓ risk of STIs & STDs
- Steroidal contraceptives
Combined oral contraceptives (‘the pill’)
- What does it contain
- What does it suppress?
- What does it affect
- Contain oestrogen AND progestin
- Suppress ovulation (affect feedback loops to the hypothalamus & pituitary)
- Affects mucus produced by cervix (prevents sperm penetration)
Steroidal contraceptives
Progestin-only pill -
1) Progesterone-only pill
- Low doses of what?
- Effects what?
2) Subdermal implant/injectable progestins
- Long or short acting?
- What doe sit act on?
Intrauterine device (IUD)
3a) Copper IUD
- Causes low what?
- ↓ what?
- toxic to?
- Impairs what?
3b) Hormonal IUD (eg mirena)
- What does it contain?
- What does it affect?
- What type of effects are there?
- What does it prevent?
1) - Low doses of progestin
- Effects on cervical mucus
2) - Long acting (over years)
- Act primarily by disrupting follicular growth & ovulation
3a) - Causes low grade inflammation
- ↓ sperm transport
- toxic to oocyte & zygote
- impais implantation
3b) - Contains progestins
- Affects cervical mucus, ↓ sperm transport
- Local effects on endometrium
- May prevent ovulation
Artificial - surgical contraception
- What are they?
- Tubal ligation
- Vasectomy
- Hysterectomy
Artificial - surgical contraception
- What do you cut in the tubal ligation?
- What do you cut in a vasectomy?
- What do you remove in a hysterectomy?
- What doesn’t this alter?
- What does it ensure?
- Tubal ligation - cut uterine tubes
- Vasectomy - Cut ductus (vas) deferens
- Hysterectomy - remove entire uterus
- Doesn’t alter sperm/oocyte production or ovulation
- Ensures sperm & egg cannot meet
Fertilisation
- How long does the ovum survive for?
- Where is the oocyte swept into? Where is it fertilised?
- What is fertilisation?
- Ovum survives ~24h
- Oocyte & surrounding cells swept into uterine tube; fertilised in the ampulla
- Fertilisation; when a male & female gamete fuse to form a diploid cell
Fertilisation process
1 - Capacitation
- Where does the sperm undergo changes?
- What happens to the sperm?
- How long does capacitation take?
2 - Fertilisation (3 Phases)
- Penetration of?
- Penetration of?
- Penetration of?
3 - Oocyte changes (after)
- What happens to the zona pellucida
- What is completed?
- What forms?
- What moves closer to the female pronucleus?
- What degeneragtes
4 - Pronuclei fuse
- What forms?
- What occurs?
- What is there initiation of?
- Sperm undergoes changes in female tract:
- ↑ motility & acrosome membrane becomes fragile
- 6-8h
- Penetration of corona radiata
- penetration of Zona pellucida
- Penetration of the oocyte cell membrane
- Zona pellucida becomes immpenetrable (blocks polyspermy)
- Meiosis II completes → ovum produced
- Female pronucleus forms
- Spermatozoon nucleus moves close to female pronucleus
- Spermatozoon tail degenerates
- Forms a single nucleus (n=46)
- Sex determination occurs
- Initiation of cleavage
Cleavage
- For 2 cells?
- For 4 cells?
- For 16 cells (morula)
- 2 cells ~ 30h
- 4 cells ~40h
- 16 cells (morula) ~3 days
Cleavage process
1) - What happens to the fertilised cell?
2) - What is formed & what are they called?
3) What happens by day 16?
4) What happens to the cell?
5) What happens in days 4-5?
1) Mitotic cell division of fertilised cell
2) 2 daughter cells each called a blastomere
3) By day 3; 16 cell morula
4) cells of morula rearrange:
- Inner mass = epiblast
- Outer mass = trophoblast
5) Days 4-5; fluid filled blastocyst
The blastocyst
- What are the 2 layers?
- What is the blastocyst inside of? & for how long?
1) - Inner cell mass = embryo/amnion
2) - trophoblast = embryonic placenta
- Blastocyst is inside zona pellucida until plantation
Implantation
1) - What does the blastocyst break out of?
2) - What happens in days 6-7?
3) - What happens on day 10?
4) - What 2 layers does the trophoblast form?
5) What invades the endometrium?
6) What does the trophoblast secrete?
7) What does this maintain?
1) blastocyst breaks out of zona pellucida
2) Days 6-7: moves to endometrium, implantation begins
3) Day 10: blastocyst completely implanted
4) Trophoblast forms 2 layers
- Inner - cytotrophoblast
- Outer - synctiotrophoblast
5) Outer cells invade endometrium; which envelops blastocyst
6) trophoblast secretes human chorionic gonadotropin (hCG)
7) Maintains the corpus luteum (ie corpus luteum doesnt die down into corpus albicans)
Ectopic pregnancy
- Where is the implantation?
- What is the visibility?
- Internal?
- Implantation outside of uterine cavity
- Rarely visible
- Internal haemorrhage
development week 2
- What are the 2 layers of embryoblast or inner cell mass?
- What are the 2 cavities that are formed?
- What is their function?
2 layers of embryoblast or inner cell mass
- Epiblast
- Hypoblast
2 cavities form
- Amniotic cavity: surrounds & protects developing cavity
- Yolk sac: primordial germ cells arise near here; first site of blood cell formation: used for early nutrition transfer
Placenta
- What does it allow & by what week does it allow this?
- Where does the embryo grow?
- What is the embryo connected to? What does this contain?
- What is the placenta made up of?
- Where does the exchange occur?
- What bathes in maternal blood?
- Allows diffusion of maternal fetal blood by week 4
- Embryo grows out from uterus wall
- Embryo connected to placenta via umbilical cord (contains fetal blood vessels - carry oxygenated to & deoxygenated away)
- Made up of both maternal tissue AND fetal (chirion = trophoblast) components
- Exchange (gas, nutrients, waste) occurs across chorionic villi (which contain blood vessels carrying fetal blood)
- Chorionic villi bathe in maternal blood → exchange
Parturition
- What happens to the cervix?
- What happens to the fetal membrane?
- What causes the birth of a baby?
- What happens to the placenta?
- What do contractions close?
1) Cervix dilates to allow fetal head through; Contractions; rupture of the fetal membranes
2) contractions (short); birth of baby
3) Placenta detaches; contractions close the maternal arteries that supplied the placenta
Development potency
- What are cells initially?
- What can they develop in to?
- What happens 5 days after fertilisation?
- What do these cells form?
- Initially; cells (morula) are totipotent; can develop into any cell in the body or placenta
- By 5 days after fertilisation blastocyst has 2 types of cells: trophoblast cells (will form placenta) & inner cell mass cells (form embryo)
- Cells are pluripotent: can form almost any cell type (not placenta cells)
- What is gastrulation?
- What forms in the epiblast during the 3rd week of gastrulation? What does this form? How?
- Formation of 3 germ cell layers from the 2-layered bilaminar disc
- Primitive streak forms; cells of the epiblast move into the primitive streak and form 2 new layers: the mesoderm and endoderm
What are the germ cell layer & what do they form?
Ectoderm (outer layer of skin)
- Brain & spinal cord
- Nerve cells
Mesoderm
- Muscle
- Connective tissue
- Kidneys
- Gonads
Endoderm
- Lining of the GI tract
- Respiratory system - lining of lungs & bronchi
- What is neurulation?
- Process?
- Process of forming a tube from a piece of ectoderm (neural tube)
1) Rises up at the edges to form the neural folds
2) Neural folds converge together
3) Neural folds fuse to form the neural tube
- What does intermediate mesoderm form?
- What does the paraxial mesoderm form?
- What does the lateral mesoderm form?
- Kidney/gonads
- Bone
- Skeletal muscle
- Endothelial cells
- Dermis
- Tendons
- Circulatory system
- Body Wall
What happens if the process of gastrulation goes wrong?
- To the fetal?
- What causes it?
- Fetal abnormalities & usually death
- Gene mutations or environmental effects (smoking, alcohol, etc)
Sensitivity to environmental chemicals
1) - 0-2 weeks (fertilised egg → embryonic disc)
2) - Embryo (3-8 weeks)
3) Fetus (9-38 weeks)
1) - Not sensitive
- High rate of lethality may occur
2) - Period of greatest sensitivity
- Development of organ systems
3) - ↓ sensitivity
- Period of functional maturation
