Reproductive Flashcards
Functions - Male reproductive
1) Synthesis of male hormones (androgens)
2) Production of gametes (spermatogenesis)
3) Deliver sperm
Testosterone
- Aid in gametes production
* Regulate sexual maturation and development of secondary sex
Production of gametes (spermatogenesis)
- Begin during puberty
* Generated by meiosis
Travel path of sperm
Sperm travels from the testes, epididymis, vas deferens, ejaculatory duct and urethra before being expelled out of the penis during ejaculation
Scrotum
Sac of skin, keeps temperature 3 degrees below internal temperature
Testes (Gonads)
Produce sperm in lobules through seminiferous tubules, then the spermatozoa are moved into epididymis for maturation
Germ cells
Spermatogenic cells
Myoid cells
Help squeeze sperms out of the seminiferous tubules
Leydig cells (interstitial endocrine cells) in between tubules
Testosterone synthesising
Sertoli cells (sustentocytes)
Provide nutrients and essential signals to the dividing cells
Penis
Contains erectile tissue covered by fibrous connective tissue with vascular spaces to enable erection
Duct system
- Epididymis
- Ductus (vas) deferens:
- Ejaculatory duct,
- Urethra
Organs
- Scrotum
- Testes (Gonads)
- Penis
Accessory glands
- Seminal vesicles
- Prostate gland
- Bulbourethral gland
Epididymis
Sperm maturation (non-motile become motile) able to swim, travel 20 days through the epididymis, move into vas deferens during ejaculation
Ductus (vas) deferens
Sperm storage and transport organ which propels sperm to the urethra by peristalsis during ejaculation
Ejaculatory duct
Passes sperm into the prostate gland where it empties into the urethra
Urethra
Carries both urine and semen, and secretes lubricating mucous into lumen before ejaculation
Seminal vesicles
• Joining of both ducts form ejaculatory duct
• Secretes alkaline seminal fluid
• 70% of semen volume
Increase sperm motility or fertilising ability through
• Fructose
• Coagulation enzymes
Prostate gland
Secretes 1/3 of semen volume which is milk acidic fluid
Adds prostate specific antigen (PSA) and citrate
Bulbourethral gland
Produce thick clear mucous that neutralises acidic urine before ejaculation
Sperm consist of
- Head
- Mid-piece
- Acrosome
- Nucleus
- Mitochondria
- Tail
Head
Nucleus for genetic material and acrosome to enter egg
Mid-piece
Has mitochondria
Tail
Propels cell forward
Spermatogenesis and testosterone production begins when
Hypothalamus release GnRH signals the pituitary to release gonadotropin hormones
Follicle stimulating hormone (FSH)
Stimulates spermatogenic cells to produce sperm
Luteinizing hormone (LH
Stimulates the interstitial cells to release testosterone
Functions - Female reproductive
- Produce female gametes-ova/eggs – gametogenesis)
- Produce the female sex hormones (oestrogen & progesterone)
- Provide an environment for the developing embryo/foetus
Ovaries
Produce oocytes in outer cortex (at ovulation, one egg is released) and produce sex hormones
Uterine tubes
After ovulation, cilia on fimbriae and oviducts guide egg towards uterus which takes 5 days. Fertilisation will take place in ampulla if it occurs.
Uterus
- Hollow muscular organ
- Three regions called fundus, body, and cervix.
- Receives, retains & nourishes the fertilised ovum
- During birth the uterus contracts to expel the baby & placenta
Layers of uterus
- Perimetrium
- Myometrium
- Endometrium
Perimetrium
The outermost layer of uterus
Myometrium
Middle smooth muscle layer, contracts during birth and menstruation
Endometrium
The inner most layer
Fertilized egg resides there during development
Vagina
Thin muscular tube Three functions: • Acts as birth canal • Transports menstrual flow from body • Receives penis and semen during sexual intercourse
Mammary glands
Produces milk under hormonal & nervous influence
Hormone release
Hypothalamus ↑ release of GnRH which stimulates anterior pituitary to release FSH and LH which stimulates the development of follicles and production of oestrogen in the ovaries
Menstrual cycle
28 days, day one is first day of menstrual flow followed by ovarian cycle (maturation of follicles) and uterine cycle (changes in uterus)
Maturation of ovarian follicles occurs due to
FSH
Maturation of ovarian follicles stages
1) Primordial Follicle
2) Primary Follicle
3) Secondary Follicle
4) Vesicular (Graafian) Follicle
5) Ovulation
6) Corpus luteum
Primordial Follicle
Most immature, surrounded by a single layer of flat follicle cells
Primary Follicle
Singe layer becomes two layers of cuboidal granulosa cells; oocyte enlarges
Secondary Follicle
Granulosa cells secrete fluid containing large amounts of oestrogen into a cavity within the follicle called the antrum
Vesicular (Graafian) Follicle
Follicle continues to enlarge as more fluid is secreted, forms a bulge on the surface of the ovary
Ovulation
Each month one Graafian follicle ruptures releasing the egg
Corpus luteum
Ruptured follicle forms a new structure called the corpus luteum
Cells of the corpus luteum secrete large amounts of progesterone and small amount of oestrogen
Ovarian cycle phases
Phase 1: Follicular phase
Phase 2: Luteal phase
Uterine cycle phases
Menstrual phase
Proliferative phase
Secretory phase
Follicular phase
- Day 1 until ovulation
- Ovarian follicles develop from primordial cells to Graafian follicles due to influence of FSH
- Developing follicles cause increased amounts of oestrogen
- Causes sudden increase in LH (LH surge) which stimulates ovulation
Luteal phase
Day of ovulation until day before the menstrual flow begins
• LH surge causes development of the corpus luteum & its secretion of progesterone
• Corpus luteum will degenerate 10 days after ovulation if no pregnancy event and decrease in progesterone secretion
Uterine cycle
Describes the changes that occur in the endometrium during the menstrual cycle
Menstrual phase
- Lasts from days 1 to 5
- Functional part of the endometrium breaks down
- Passes out of the body through cervix & vagina
Proliferative phase
- Lasts from days 6 (menstrual flow stops) to 14
- Blood vessels & glands that form the endometrium regenerate (proliferate) due to increased oestrogen levels from developing follicles
Secretory phase
- Lasts from days 15 to 28
- Endometrial glands secretes glycogen, blood vessels continue to develop
- Changes are caused by increased progesterone levels (development of corpus luteum)
- As corpus luteum degenerates, decrease in progesterone levels
- Decrease in blood supply to endometrial cells, cells die, breakdown and menstrual flow starts again
Oestrogen - Female reproductive
Source - Ovaries: developing follicles and corpus luteum
Stimulates release of - FSH (and LH)
Effects -
• Stimulate growth and maturation of reproductive organs and breast at puberty and maintain their adult size and function.
• Promote proliferative phase of uterine cycle;
• Stimulate production of watery cervical mucus
• Promote oogenesis and ovulation
• During pregnancy stimulate growth of the uterus and mammary glands
Progesterone - Female reproductive
Source - Ovary: mainly the corpus luteum
Stimulates release of - LH
Effects -
• Coopreates with oestrogen in stimulating growth of breasts;
• Promotes the secretory phase of the uterine cycle
• Production of viscous cervical mucus
• Surge after ovulation to enhance fertilisation opportunity
• During pregnancy, quiets the myometrium and help achieve milk-production from breasts
Fertilisation
The joining or fusion of sperm and ova
Steps for fertilisation
- Sperm penetrate the corona radiata and the zona pellucida of the oocyte
- Takes many sperm to release enough enzyme from the acrosome to penetrate the egg
- Depolarisation of the cell membrane of the fertilised egg and release of calcium ions to prevent polyspermy (fertilisation by more than one sperm)
- Fertilisation of an egg by sperm forms a zygote, the genetic information of the sperm fuses with the egg nucleus to complete fertilization
Zygote to blastocyst Implantation
1) Zygote
2) Morula
3) Blastocyst
Implantation
- Occurs between 6-12 days after ovulation
- Inner cell mass will become the foetus
- Trophoblast cells secrete human chorionic gonadotropin hormone (hCG)
Human chorionic gonadotropin hormone (hCG) - Female reproductive
- To maintain the corpus luteum (secretion of progesterone and oestrogen) for 6 weeks to prevent menstruation
- Promote placental development
- Levels drop once ending month 2 pregnancy
- Maintain low levels for rest of pregnancy
Placentation
- Formation of temporary placenta from embryonic and maternal tissue
- Placenta is fully formed and functional by the end of the third month of pregnancy
- Maternal and embryonic blood supplies don’t intermix
Placenta roles
- Nutritional role
- Excretory roles
- Respiratory roles
- Endocrine roles
- Immune roles
Gastrulation
Later embryonic development
Ectoderm
Development of nervous system & skin epidermis
Endoderm
Development of epithelial linings of the digestive, respiratory & urogenital systems and associated glands
Mesoderm
Development of everything else
Maternal adaptions to pregnancy
- Anatomical – uterine enlargement, weight gain, relaxation and widening to pelvis
- Metabolic – rate increases,
- Cardiovascular – blood volume increases, cardiac output increases
- Gastrointestinal – morning sickness from hormones
- Urinary – increased glomerular filtration rate
- Respiratory
Reproductive hormones
- hCG (human chorionic gonadotrophin)
- Progesterone
- Oestrogen
- hPL (human placental lactogen)
- Relaxin
Stages of labour
1) Dilation
2) Expulsion stage
3) Placental stage
Lactation
- Suckling stimulates mechanoreceptors in nipple to trigger release of prolactin-releasing factors (PRF)
- Anterior pituitary then releases prolactin to stimulate milk production for next feedi
hCG (human chorionic gonadotrophin) - Fertilisation
- Similar structure and action to LH, levels fall after Corpus Luteum phase
- Regulate placental oestrogen secretion
- Stimulate testosterone secretion in male foetus
- Pregnancy test
Progesterone - Fertilisation
- Levels rise throughout pregnancy, first by Corpus Luteum then by placenta, most important hormone in maintaining pregnancy
- Maintenance and development endometrium
- Inhibition and relaxation of smooth muscle
- Metabolic changes, fat storage, physiological adaptation
Oestrogen - Fertilisation
- Levels rise throughout pregnancy, placenta lacks key enzymes for oestrogen synthesis- performed by foetal adrenal gland- foetus regulates placental oestrogen secretion
- Stimulate prolactin secretion, synthesis of oxytocin receptors •Inhibit LH and FSH,
- Stimulate breast and uterus growth
hPL (human placental lactogen) - Fertilisation
Peptide hormone secreted by placenta, action similar to Growth Hormone and Prolactin, regulates nutrient levels and metabolism
Relaxin - Fertilisation
- Peptide hormone secreted by placenta late in pregnancy
* Allows uterus to enlarge and pelvis to stretch during birth
Labour - Dilation
- Fall in progesterone concentration
- Prostaglandins - appear important in initiating contractions
- Reflex release of oxytocin from posterior pituitary stimulates myometrial smooth muscle - increasing contraction
Expulsion stage
- Vaginal stretch stimulates contraction of abdominal walls
- Periodic contractions increase in frequency (1 every 1-3 min)
- Fetus expelled
Placental stage
- Expulsion of placenta
- Myometrial contraction limits bleeding
- All placenta fragments must be removed to prevent postpartum bleeding
