Human Reproduction Flashcards

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1
Q

Testes (Male)

A
  • Structure: Oval shaped structures located in the scrotum
  • Function to facilitate the production of male gametes (sperm)
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2
Q

Scrotum (Male)

A
  • Function: To support the testes. Allows the testes to be 3 degrees colder than normal body temperature
  • Structure: A skin-covered pouch externally located to the body
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3
Q

Lobule (Inside the Testes) (Male)

A
  • Structure: 300-400 per testis, contains the seminiferous tubules
  • Function: To house the seminiferous tubules
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4
Q

Seminiferous Tubule (Inside the Testes) (Male)

A
  • Function: To produce sperm cells through the process of spermatogenesis
  • Structure: Small convoluted tubules, located in the lobule lined with cells that will undergo spermatogenesis
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5
Q

Interstitial Cells (Inside the Testes) (Male)

A
  • Function: To secrete the male hormone testosterone
  • Structure: Clusters of cells located between the seminiferous tubules
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6
Q

Epididymis (Male)

A
  • Function: Facilitates the storage and maturation of sperm
  • Structure: Convoluted tube located on the rear surface of each testis. Approximately 5-6m long.
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7
Q

Vas Deferens (Male)

A
  • Function: To carry sperm from the epididymis to the urethra
  • Structure: The epididymis continues to form the vas deferens
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8
Q

Urethra (Male)

A
  • Function: Common duct for transporting both urine and semen
  • Structure: The tube that leads from the bladder to the external environment
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9
Q

Seminial Vesicle (Male)

A
  • Function: Secretes a thick fluid that is rich in sugar. Approx. 60% of the semen volume.
  • Structure: Gland located between the bladder and the prostate. Approximately 5cm long.
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10
Q

Prostate Gland

A
  • Function: Secretes an alkaline fluid that becomes part of the semen.
  • Structure: A gland located below the bladder.
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11
Q

Bulbourethral Gland (Male)

A
  • Function: Secretes a clear mucous that precedes seminal fluid to lubricate
  • Structure: Two glands located beneath the prostate about the size of a pea.
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12
Q

Penis (Male)

A
  • Function: Facilitates the transfer of sperm into the vagina
  • Structure: Projection external to the body
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13
Q

Erectile Tissue (Male)

A
  • Function: Facilitates the enlargement, and stiffening (erect) of the penis to allow successful introduction to the vagina
  • Structure: Three spongy vascular tissues that are filled with blood during sexual arousal
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14
Q

Pathway that sperm travels

A
  • TESTIS -> EPIDIDYMIS -> VAS DEFERENS -> 3 SEMEN PRODUCING GLANDS -> URETHRA
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15
Q

Ovaries (Female)

A
  • The primary sex organs of the female are the two OVARIES, which produce the ova (eggs).
  • Each ovary is almond shaped and about 3cm in length, and is supported inside the abdominal cavity by ligaments.
  • The ovaries are comprised of a mass of connective tissue called the STROMA, which is surrounded by a layer of cells containing GERM CELLS that will develop into the ova.
  • Each germ cell is enclosed in a FOLLICLE. As a follicle matures it moves to the surface of the ovary and ruptures.
  • Each germ cell is enclosed in a FOLLICLE. As a follicle matures it moves to the surface of the ovary and ruptures.
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16
Q

Uterine Tube

A
  • The egg inside is expelled into the funnel-like opening of the UTERINE TUBE (also called Fallopian tubes or Oviducts).
  • The uterine tube carries the egg from the ovary to the uterus.
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17
Q

Fimbrae

A
  • At the end of each uterine tube there are finger-like projections called FIMBRIAE which help guide the egg into the tubes.
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18
Q

Cilliated Epithelium

A
  • CILLIATED EPITHELIUM lines the tubes, and the beating cilia carry the egg towards the uterus.
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19
Q

Uterus

A
  • The UTERUS (or womb) is a single, hollow pear shaped organ situated behind the bladder and in front of the rectum.
  • The uterus protects and nourishes the developing foetus during pregnancy.
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20
Q

Endometrium

A
  • The wall of the uterus is made up of smooth muscle with a soft mucous membrane lining called the ENDOMETRIUM.
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21
Q

Cervix

A
  • At the lower end (or neck) of the uterus
  • The cervix protrudes into the VAGINA which is a muscular canal that leads to the outside of the body.
  • It is lined with mucous membranes and is about 10cm long.
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22
Q

Hymen

A
  • The fold of tissue partially covering the external opening of the vagina
  • This is stretched and torn when intercourse occurs for the first time or by other means.
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23
Q

Vulva and folds of skin

A
  • The vagina opens to the exterior in a region called the VULVA which is made up of the external genital organs of the female:
  • The LABIA MAJORA – which are two fleshy folds of skin made of fat and fibrous tissue. They contain many glands that produce an oily secretion. Their outer surfaces are covered with hair after puberty, which the inner surfaces are smooth and moist from the oily secretions.
  • The LABIA MINORA – which are two smaller folds of skin without fat and pubic hair that sit beneath and between the labia majora. They surround the space into which the urethra and vagina open.
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24
Q

Clitoris

A
  • Contains erectile tissue, blood vessels and nerves. It is found at the upper end of the labia minora and is very sensitive to touch and becomes engorged with blood when stimulated.
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25
Q

Pathway that Ovum travels

A
  • OVARY -> UTERINE TUBE -> UTERUS -> CERVIX -> VAGINA
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26
Q

Endocrine Gland

A
  • ENDOCRINE GLANDS secrete chemical messengers called HORMONES into the extracellular fluid that surrounds the gland. The secretion then enters the blood stream and is transported to a TARGET ORGAN on which it will have an effect.
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27
Q

Pituitary Gland

A
  • The Pituitary gland is found just below the brain and above the roof of the mouth.
  • The pituitary gland secretes two GONADOTROPINS which target both the gonads.
  • Follicle Stimulating Hormone (FSH)
  • Luteinising Hormone (LH)
28
Q

FSH (Female)

A
  • Target organ – follicles of ovaries
  • Stimulates the development and maturation of the ovarian follicle.
  • The ovarian follicle secretes its own hormone, Oestrogen.
  • Secretion of FSH is reduced as Oestrogen levels increase.
29
Q

LH (Female)

A
  • Target organ – cells of ovaries
  • Promotes final maturation of ovarian follicle, ovulation and formation of corpus luteum.
  • Maintains Corpus Luteum. Corpus luteum secretes its own hormones, progesterone and oestrogen.
  • Gradual reduction in LH secretion as Progesterone levels increase.
30
Q

Oestrogen (Female)

A
  • Target organ – various
  • Released by the ovarian follicle and corpus luteum.
  • Promotes the development and maintenance of female reproductive system and secondary sexual characteristics.
  • Prepares the follicle for release of the egg.
  • Controls the growth of endometrium after the degeneration and menstruation.
31
Q

Progesterone (Female)

A
  • Target organ – Uterus, Placenta and Breasts
  • Released by the corpus luteum and placenta (if pregnancy occurs).
  • Stimulates endometrial growth and maintains endometrium.
  • Development and maintenance of placenta.
  • Development of milk-secreting glands.
32
Q

HCG (Female)

A
  • Target organ – Corpus Luteum
  • Produced by the developing placenta.
  • Maintains the corpus luteum until the placenta itself can secrete oestrogen and progesterone.
  • Once this occurs the corpus luteum will degenerate.
33
Q

Lactogenic Hormone (Prolactin) (Female)

A
  • Target organ – Breasts
  • Secreted by the pituitary gland.
  • Important in the preparation and maintenance of milk production.
34
Q

Oxytocin (Female)

A
  • Target organ – Uterus or Breasts
  • Secreted from the Pituitary gland.
  • Stimulates contraction of smooth muscle of uterus during labour.
  • Promotes contraction of muscle cells surrounding breast lobules for milk letdown.
35
Q

FSH (Male)

A
  • Target organ – Seminiferous tubules
  • Stimulate spermatogenesis in seminiferous tubules
36
Q

LH (Male)

A
  • Target organ – Interstitial cells of testes
  • Stimulates production of male sex hormone (testosterone) in the interstitial cells of the testes
37
Q

Testosterone (Male)

A
  • Target organ – various
  • Produced by the interstitial cells of the testes
  • Development and maintenance of male reproductive system and secondary sexual characteristics
  • Stimulates spermatogenesis
38
Q

Secondary Sexual Characteristics

A
  • Both Oestrogen and Testosterone bring on the development of SECONDARY SEXUAL CHARACTERISTICS at the onset of puberty.
  • These are characteristics that are associated with a person’s sex but not directly involved in sexual reproduction.
  • In both sexes, pubic hair and armpit hair develops
  • In the female – enlarging of breasts, broadening of hips, growth of pelvic bones and deposition of fat around these areas.
  • In the male – facial hair, increase in size of larynx and lengthening of vocal cords which leads to a deeper voice.
39
Q

Ovarian Cycle

A
  • Females are born with approx. 400,000 immature eggs
  • However, these eggs are dormant until puberty
  • Around each immature egg is a structure called the primary follicle
  • Firstly, in response to follicle stimulating hormone (FSH) released from the anterior pituitary gland, the follicle layer may thicken, and fluid fills the space between the egg
  • It is now known as a secondary follicle
  • The secondary follicle secretes the hormone Oestrogen
  • As FSH continues: the secondary follicle continues to enlarge and drifts to the surface of the ovary
  • At this stage it is mature and is called a Graafian Follicle
  • Due to the increased presence of oestrogen (signalling the follicle is mature) the pituitary gland stops making FSH, and releases a hormone called Luteinising hormone (LH)
  • The LH surge causes the Graafian follicle to rupture, and the ovum is expelled into the fallopian tube
  • The expulsion of the ovum is called ovulation
  • The ovum is pushed along the fallopian tubes to the uterus in the hope of being fertilised by a sperm cell
  • Meanwhile, the Graafian follicle collapses to form a “yellowish” structure called the Corpus Luteum
  • The corpus luteum secretes oestrogen and progesterone, which causes the endometrium to thicken, in case of conception
  • Lastly, if fertilisation does not occur, the Corpus Luteum breaks down and becomes a structure called the Corpus Albicans
40
Q

Menstrual Cycle

A
  • The menstrual cycle is a series of changes that occurs to the lining of the uterus (called the Endometrium) in response to hormone changes in the ovarian cycle
  • The first stage in the menstrual cycle is swelling of the endometrium
  • It becomes thicken and softer and there is an increase in the number of blood vessels and mucus glands there
  • This occurs while the follicle is maturing, due to the increasing production of oestrogen
  • It continues to thicken after ovulation under the influence of progesterone
  • If the ovum is not fertilised, the Corpus Luteum degenerates, meaning the hormones Oestrogen and Progesterone are no-longer produced
  • The loss/reduction in these hormones results in the endometrium lining being shed and expelled through the vagina in a process called menstruation or “period”
  • However, if the ovum is fertilised, the Corpus Luteum continues to grow and secrete hormones that prevent the endometrium from shedding
  • It continues to function for about 3 months until it starts to degenerate
  • It is still present in the ovary at childbirth
41
Q

Menarche

A
  • The onset of menstruation in females
  • Marks the start of puberty and indicates that she is now fertile
  • Occurs regularly once a month unless interrupted by a pregnancy
42
Q

Menopause

A
  • The time when menstruation becomes irregular and eventually ends
  • The female loses her ability to ovulate and thus is no longer fertile
43
Q

Sexual Intercourse

A
  • For fertilisation to occur, the sperm need to be brought into contact with the ova
44
Q

Erection

A
  • Penis becomes enlarged and firm due to blood rushing into the spaces of the erectile tissue
45
Q

Ejaculation

A
  • When sexual stimulation of the penis becomes sufficiently intense, rhythmic contractions of the epididymis, vas deferens and the three glands occur.These contractions propel the contents of the ducts and glands into the urethra and out the body
  • The ejaculated material consists of semen which contains the sperm.
  • Each ejaculation expels about 3 mL of semen containing 200-300 million sperm.
46
Q

Orgasm (Male)

A
  • Accompanying the ejaculation is a rapid heart beat, increase in blood pressure and breathing rate, and pleasurable sensations
47
Q

Orgasm (Female)

A
  • When the female is sexually stimulated, erectile tissue of the vaginal opening fills with blood and secretions of mucous from the glands increase which lubricate the epithelial lining of the vagina.
  • When sexual arousal in the female reaches sufficient intensity an orgasm or CLIMAX occurs.
  • This is similar to the male, but no ejaculation occurs. There may be however an increase in secretion of cervical mucous.
  • A female does not need to reach climax for fertilisation to occur.
48
Q

Insemination

A
  • The process where the sperm are released into the vagina
  • Once within the vagina, the sperm travel through the cervix and uterus, into the uterine tubes.
  • This occurs very quickly, within minutes due to the swimming motion of the sperm.
  • Muscular contractions of the uterus and uterine tubes also help transport the sperm.
  • The SPERM MORTALITY RATE is very high, of the hundreds of millions that are deposited, only a few thousand reach the uterine tubes.
49
Q

Fertilisation

A
  • The fusion of a sperm and egg, and occurs in the uterine tubes when the egg is one third of the way down the tube.
50
Q

Process of Fertilisation

A
  • The mature egg is surrounded by a layer of follicle cells known as the Corona Radiata, held together by an acid
  • The tips of the sperm contain an enzyme that break down the acid holding the cells together
  • Thousands of sperm acting together will eventually loosen the cells allowing one sperm to fuse with the Ovum
  • The entrance of one sperm into the egg stimulates:
  • The formation of a Fertilisation membrane around the egg, to prevent any other sperm entering the ovum
  • The completion of the second mitotic division of the ovum (secondary oocyte)
  • Once the sperm enters the ovum, the tail is absorbed, and the head begins to move through the cytoplasm in the form of a Male Pronucleus
  • The nucleus of the ovum develops into a Female Pronucleus
  • This fuses with the male pronucleus to form a single nucleus (now diploid).
  • The fertilised ovum is called a zygote.
51
Q

Fertility Drugs (Infertility Treatments)

A
  • Ovulation induction – when a woman has ovulation problems a variety of ‘fertility drugs’ (these include natural hormones, such as LH and FSH) can be used to stimulate egg growth and ovulation. If ovulation can be successfully induced conception may occur naturally.
  • Fertility drugs are also used to produce multiple eggs for IVF procedures and to improve the condition of the endometrium.
52
Q

Artificial Insemination by Donor (Infertility Treatments)

A
  • Why?
  • Man is sterile, unable to produce sperm
  • How?
  • Semen is donated by a donor
  • Characteristics of males are matched
  • Around the time ovulation is expected the women visits her doctor and the donors sperm is injected into the upper vagina for 3 or 4 days
  • 70-80% of couples achieve success
53
Q

In Vitro Fertilisation (IVF) (Assisted Reproductive Technology) (Infertility Treatments)

A
  • Why?
  • Women is unable to produce viable egg or man has low sperm count. Combination of reasons
  • How?
  • Taking the ovum from the mother, fertilising it outside the body, then transplanting the embryo to the uterus
  • Success – Nationally 20%
54
Q

Gamete Intrafallopian Transfer (GIFT) (Assisted Reproductive Technology) (Infertility Treatments)

A
  • Why?
  • Combination of reasons
  • How?
  • Eggs and sperm are mixed together immediately after eggs have been collected. The mixture is then injected into the women’s fallopian tubes
  • This allows egg and sperms to mix naturally
  • Can only be used in women with undamaged fallopian tubes and males with normal sperm count
  • 20-30% success
55
Q

Zygote Intrafallopian Transfer (ZIFT) (Assisted Reproductive Technology) (Infertility Treatments)

A
  • Why?
  • Combination of reasons
  • How?
  • Collected eggs are fertilised in a dish in a lab and then transferred to the women’s fallopian tubes at the one-cell or zygote stage of development (the day after fertilisation)
  • Requires 2 operations 24hrs apart, one to collect eggs and one to place the zygote in the fallopian tube.
56
Q

Tubal Embryo Transfer (TET) (Assisted Reproductive Technology) (Infertility Treatments)

A
  • Why?
  • Combination of reasons
  • How?
  • Similar to ZIFT but allows fertilised eggs to divide
  • Transferred to the fallopian tube 2 days after fertilisation at 2-cell or 4-cell stage.
57
Q

Intracytoplasmic Sperm Injection (ICSI) (Assisted Reproductive Technology) (Infertility Treatments)

A
  • Why?
  • When sperm count is very low
  • How?
  • A single sperm is injected into a single egg and the resulting embryo transplanted into the women’s uterus
  • Sperm is injected through a micropipette into the region below the outer covering of the egg
  • Success: 29% < 35
58
Q

Donor Egg or Embryo (Assisted Reproductive Technology) (Infertility Treatments)

A
  • Why?
  • Unable to conceive using her own eggs
  • How?
  • An egg donated by another women is mixed with the sperm of her partner and the resulting embryo is implanted into her uterus.
59
Q

Preimplantation Genetic Diagnosis (PGD) (Assisted Reproductive Technology) (Infertility Treatments)

A
  • Why?
  • Couples that are likely to produce a child with a genetic defect
  • How?
  • Detects a range of genetic defects
  • Early in embryonic development, one or two cells are removed and tested
  • Only embryos that are found to be healthy are implanted in the uterus
  • Is it ethical to discard the embryos that are found to have a detect?
60
Q

Surrogacy (Assisted Reproductive Technology) (Infertility Treatments)

A
  • Why?
  • When a female is unable to become pregnant or carry the child to full term and treatments have failed
  • How?
  • Where a woman has agreed to bear a child for a couple
  • The man provides semen either naturally or through artificial insemination
  • In some cases, the surrogate mother, after giving birth will decide to keep the baby, which causes great emotional and legal problems for both parties.
61
Q

Ethical Issues (Infertility Treatments)

A
  • When does human life begin?
  • Churches views
  • Harvesting stem cells from embryos for research?
  • Disposal of surplus embryos?
62
Q

Sexually Transmitted Infections (STI’s)

A
  • STIs are infections that can be spread during sexual contact
  • They used to be called STDs or sexually transmitted diseases
  • Some infections like herpes and warts can be transmitted by skin-to-skin contact
  • STIs can be scary because most of them have no symptoms, so you don’t know you have them,
  • Young people are especially at risk of an STI called chlamydia, which is very common.
  • If chlamydia is left untreated, it could leave you infertile (which means you can’t have a baby)
  • Condoms are the only form of contraception that will protect you from both STIs and unplanned pregnancy.
63
Q

Preventing the production of ova or sperm (Contraception)

A
  • Contraceptive Pills
  • Theses contain varying proportions of oestrogen and progesterone
  • Estrogen-based (combined) pills:
  • Send false messages to the brain and prevent ovulation
  • Make mucus thick/sticky, making it difficult for sperm to swim through
  • Alters the endometrium lining so it is less receptive for implantation
  • Progesterone based-pills cause:
  • A thicker mucus to form in the cervix, thus preventing sperm entering the uterus
  • Be aware: Substances such as antibiotics and Vitamin C interfere with the function of these hormones, so can render the pill ineffective
64
Q

Preventing Fertilisation of the Ovum (Contraception)

A
  • Sterilisation – Vasectomy:
  • In males the vas deferens can be cut, thus preventing sperm leaving the testes
  • Sperm production continues but the sperm are broken down and are reabsorbed by the body
  • After a vasectomy men can still ejaculate (seminal fluid only) and continue to produce testosterone (it does not affect their sex drive)
  • In some cases a vasectomy can be reversed
  • Sterilisation – Tubal ligation:
  • In females the Fallopian tubes are cut or sealed thus preventing fertilisation
  • Ovulation and menstruation continue after the operation and sex drive is not affected
  • In some cases a tubal ligation is reversible
  • Natural Methods:
  • Coitus interruptus: The man withdraws before ejaculating
  • Douching: Washing out the vagina after intercourse
  • Ovulation or rhythm method: A woman calculates her ‘safe’ period based on her body temperature and appearance of vaginal secretions.
  • NB none of these methods should be regarded as reliable
  • Mechanical barrier methods:
  • These include: Male and female condom, Cervical Cap, Diaphragm, Vaginal Sponge
  • These devices are moderately effective, especially if used in combination with a chemical barrier, such as a spermicide
  • Only the male condom offers protection against the transmission of STIs
65
Q

Preventing Implantation (Contraception)

A
  • Intra-uterine device (IUD)
  • IUDs are small anchor/T-shaped plastic devices inserted into the uterus by a doctor
  • Modern IUDs contain either copper or hormones which prevents fertilisation
  • The IUD itself prevents implantation
  • Intra-uterine device (IUD)
  • IUDs can be left in place from 5 to 10 years
  • IUDs are an effective form of contraception
  • Post-Coital Contraception
  • The ‘morning after pill’ can be used in emergency situations up to 72 hours after intercourse If there is a risk of an unwanted pregnancy
  • These drugs contain high levels of oestrogen and/or progesterone which prevent implantation