Reproductive Flashcards
1
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Functions - Male reproductive
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1) Synthesis of male hormones (androgens)
2) Production of gametes (spermatogenesis)
3) Deliver sperm
2
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Testosterone
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- Aid in gametes production
* Regulate sexual maturation and development of secondary sex
3
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Production of gametes (spermatogenesis)
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- Begin during puberty
* Generated by meiosis
4
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Travel path of sperm
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Sperm travels from the testes, epididymis, vas deferens, ejaculatory duct and urethra before being expelled out of the penis during ejaculation
5
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Scrotum
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Sac of skin, keeps temperature 3 degrees below internal temperature
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Testes (Gonads)
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Produce sperm in lobules through seminiferous tubules, then the spermatozoa are moved into epididymis for maturation
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Germ cells
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Spermatogenic cells
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Myoid cells
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Help squeeze sperms out of the seminiferous tubules
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Leydig cells (interstitial endocrine cells) in between tubules
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Testosterone synthesising
10
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Sertoli cells (sustentocytes)
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Provide nutrients and essential signals to the dividing cells
11
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Penis
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Contains erectile tissue covered by fibrous connective tissue with vascular spaces to enable erection
12
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Duct system
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- Epididymis
- Ductus (vas) deferens:
- Ejaculatory duct,
- Urethra
13
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Organs
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- Scrotum
- Testes (Gonads)
- Penis
14
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Accessory glands
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- Seminal vesicles
- Prostate gland
- Bulbourethral gland
15
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Epididymis
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Sperm maturation (non-motile become motile) able to swim, travel 20 days through the epididymis, move into vas deferens during ejaculation
16
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Ductus (vas) deferens
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Sperm storage and transport organ which propels sperm to the urethra by peristalsis during ejaculation
17
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Ejaculatory duct
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Passes sperm into the prostate gland where it empties into the urethra
18
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Urethra
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Carries both urine and semen, and secretes lubricating mucous into lumen before ejaculation
19
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Seminal vesicles
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• 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
20
Q
Prostate gland
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Secretes 1/3 of semen volume which is milk acidic fluid
Adds prostate specific antigen (PSA) and citrate
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Bulbourethral gland
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Produce thick clear mucous that neutralises acidic urine before ejaculation
22
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Sperm consist of
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- Head
- Mid-piece
- Acrosome
- Nucleus
- Mitochondria
- Tail
23
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Head
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Nucleus for genetic material and acrosome to enter egg
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Mid-piece
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Has mitochondria
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Tail
Propels cell forward
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Spermatogenesis and testosterone production begins when
Hypothalamus release GnRH signals the pituitary to release gonadotropin hormones
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Follicle stimulating hormone (FSH)
Stimulates spermatogenic cells to produce sperm
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Luteinizing hormone (LH
Stimulates the interstitial cells to release testosterone
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Functions - Female reproductive
* Produce female gametes-ova/eggs – gametogenesis)
* Produce the female sex hormones (oestrogen & progesterone)
* Provide an environment for the developing embryo/foetus
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Ovaries
Produce oocytes in outer cortex (at ovulation, one egg is released) and produce sex hormones
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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.
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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
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Layers of uterus
* Perimetrium
* Myometrium
* Endometrium
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Perimetrium
The outermost layer of uterus
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Myometrium
Middle smooth muscle layer, contracts during birth and menstruation
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Endometrium
The inner most layer
| Fertilized egg resides there during development
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Vagina
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Thin muscular tube
Three functions:
• Acts as birth canal
• Transports menstrual flow from body
• Receives penis and semen during sexual intercourse
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Mammary glands
Produces milk under hormonal & nervous influence
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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
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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)
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Maturation of ovarian follicles occurs due to
FSH
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Maturation of ovarian follicles stages
1) Primordial Follicle
2) Primary Follicle
3) Secondary Follicle
4) Vesicular (Graafian) Follicle
5) Ovulation
6) Corpus luteum
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Primordial Follicle
Most immature, surrounded by a single layer of flat follicle cells
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Primary Follicle
Singe layer becomes two layers of cuboidal granulosa cells; oocyte enlarges
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Secondary Follicle
Granulosa cells secrete fluid containing large amounts of oestrogen into a cavity within the follicle called the antrum
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Vesicular (Graafian) Follicle
Follicle continues to enlarge as more fluid is secreted, forms a bulge on the surface of the ovary
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Ovulation
Each month one Graafian follicle ruptures releasing the egg
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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
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Ovarian cycle phases
Phase 1: Follicular phase
| Phase 2: Luteal phase
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Uterine cycle phases
Menstrual phase
Proliferative phase
Secretory phase
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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
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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
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Uterine cycle
Describes the changes that occur in the endometrium during the menstrual cycle
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Menstrual phase
* Lasts from days 1 to 5
* Functional part of the endometrium breaks down
* Passes out of the body through cervix & vagina
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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
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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
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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
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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
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Fertilisation
The joining or fusion of sperm and ova
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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
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Zygote to blastocyst Implantation
1) Zygote
2) Morula
3) Blastocyst
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Implantation
* Occurs between 6-12 days after ovulation
* Inner cell mass will become the foetus
* Trophoblast cells secrete human chorionic gonadotropin hormone (hCG)
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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
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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
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Placenta roles
* Nutritional role
* Excretory roles
* Respiratory roles
* Endocrine roles
* Immune roles
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Gastrulation
Later embryonic development
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Ectoderm
Development of nervous system & skin epidermis
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Endoderm
Development of epithelial linings of the digestive, respiratory & urogenital systems and associated glands
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Mesoderm
Development of everything else
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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
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Reproductive hormones
* hCG (human chorionic gonadotrophin)
* Progesterone
* Oestrogen
* hPL (human placental lactogen)
* Relaxin
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Stages of labour
1) Dilation
2) Expulsion stage
3) Placental stage
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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
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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
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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
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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
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hPL (human placental lactogen) - Fertilisation
Peptide hormone secreted by placenta, action similar to Growth Hormone and Prolactin, regulates nutrient levels and metabolism
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Relaxin - Fertilisation
* Peptide hormone secreted by placenta late in pregnancy
| * Allows uterus to enlarge and pelvis to stretch during birth
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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
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Expulsion stage
* Vaginal stretch stimulates contraction of abdominal walls
* Periodic contractions increase in frequency (1 every 1-3 min)
* Fetus expelled
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Placental stage
* Expulsion of placenta
* Myometrial contraction limits bleeding
* All placenta fragments must be removed to prevent postpartum bleeding
