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phys > Week 13 - The reproductive system > Flashcards

Week 13 - The reproductive system Flashcards

1
Q

Primary sex organs - Gonads

A

Testes and ovaries

  • gonads produce reproductive cells (gametes) → sperm and ova
  • gonads secrete steroid sex hormones → androgens (male) & oestrogens, progesterone (fem
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2
Q

Sex hormones role

A
  • development and function of the reproductive organs
  • sexual behaviour and drive
  • growth and development of many other organs and tissues sych as muscle
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3
Q

accessory reproductive organs - male

A
  • ducts
  • glands
  • external genitalia
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4
Q

regulation of reproductive system

A
  • reproductive system relies on the hypothalamic-pituitary gonadal axis (HPG)
  • the HPG axis is the communication between the hypotalamus, pituitary gland & gonads
  1. hypothalamus releases GONADOTROPIN RELEASES HORMONE (GnRH)
  2. pituitar gland releases FOLLICLE STIMULATING HORMONE (FSH) and LUTEINIZING HORMONE (LH)
  3. stimulate the ovaries and testes to produce their hormones including TESTOSTERONE (males) and ESTROGEN & PROGESTERONE (females) which communicate w/ the hypothalamus and pituitary gland
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5
Q

Testes

A

(male gonads)

  • located in scrotum
  • produce male gametes (sperm)
  • secrete TESTOSTERONE
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6
Q

Accessory organs

A
  • epididynis
  • vas (ductus) deferens
  • seminal , prostate and bulbourethral glands
  • urethra
  • penis
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7
Q

scrotum and temp regulation of testes

A

Sperm is not able to be produced at core body temp; cooler temp maintained via 3 mechanisms

  1. CREMASTER MUSCLE
    - in cold temperature or during sexual arousal will contract and pulls testes closer to body
  2. DARTOS MUSCLE (smooth muscle)
    - in cold temp will wrinkle skin, reduces surface area of scrotum (reduce heat loss)
  3. VENOUS PLEXUS (veins ascending near testicular artery)
    - countercurrent heat exchanger cools arterial blood entering testis
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8
Q

spermatogenesis

A
  • process in which male gametes, or sperm cells, develop
  • regulated by hormones from hypothalamus and anterior pituitary glans (HPG axis)
  • begins at puberty and continues for duration of lifespan
  • occurs in SEMINIFEROUS TUBULES of testes
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9
Q

Sperm cell

A
  • acrosomal cap: contains enzymes essential for fertilisation
  • head: contains nucleus and densely packed chromosomes
  • neck: chenrioles and microtubules
  • middle piece: contains mitochondria arranged around microtubules, provide ATP for movement
  • tail: is the only flagellum in human body, moves sperm
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10
Q

Seminal vesicle/ glands

A
  • produces viscous alkaline seminal fluid (~60-70% vol of semen)
  • fructose, citric acid, coagulating enzyme (vesiculase), and prostaglandins
  • duct of seminal gland joins ductus deferens to form ejaculatory gland
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11
Q

Prostate gland

A
  • encircles urethra inferior to bladder; size of peach put; smooth muscle contracts during ejaculation
  • secretes milky, slightly acidic fluid (~1/3 semen vol)
  • citrate, enzymes, and prostate-specific antigen (PSA)
  • role in sperm activation
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12
Q

bulbourethral glands

A
  • pea-sized glands inferior to prostate
  • produce thick, clear mucus during sexual arousal
  • lubricate glans penis
  • neutralise traces of acidic urine in urethra
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13
Q

semen

A
  • 2-5ml semen ejaculated, contains 20-150mil sperm/mL
  • contains fructose for ATP production; protects and activates sperm; facilitates sperm movement
  • alkaline secretions neutralises acidity of male urethra and fem vag & help enhanced motility
  • prostaglandins decrease viscosity of mucus in cervix; stimulate reverse peristalsis in uterus
  • suppresses female immune response
  • antibacterial action
  • clotting factors coagulate semen initially to prevent draining out; then liquefied; allowing sperm to start moving through female reproductive tract
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14
Q

the duct system

A
  • sperm travels through a series of ducts bathed in semen secreted by accessory organs.
  • semen provides nourishment and support to sperm
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15
Q

Straight tubules and efferent ductules

A
  • ciliated ducts collect sperm the testes and transport it to epididymis
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16
Q

ductus epididymis

A
  • 6m long coiled duct at posterior of testis

- site of sperm maturation and storage (fertile 40-60 days)

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17
Q

ductus deferens ( peristalsis during orgasm)

A
  • muscular tube ~45cm long passing up from scrotum through spermatic cord and inguinal canal to posterior surface of bladder
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18
Q

ejaculatory duct

A
  • a 2 cm duct formed from ductus deferens and seminal vesicle and passing through prostate to empty into urethra
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19
Q

male sexual response - erection

A
  • during sexual arousal a PARASYMPATHETIC REFLEX triggers releases of nitric oxide (NO) from blood vessels endothelial cells; relaxes arteriole walls
    → allow for a large vol of blood to enter tissue
    → inc. blood flow and widening blood sinuses causing an erection
  • erection is partially sustained by compression of veins that drain penis
  • corpus spongiosum does not become as rigid as corpora cavernosa; allows sperm and semen to travel through urethra
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20
Q

Ejaculation

A

Process to expel semen from penis; under SYMPATHETIC NERVOUS SYSTEM control that occurs in two stages

  • Emission: movement of sperm, testicular fluid, and prostate and seminal vesicle secretion into urethra
  • Expulsion: occurs as semen, sperm, and fluids from other regions of reproductive system accumulate in urethra
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21
Q

Orgasm

A

time period during which feelings of pleasure are experienced and coincides w/ ejaculation

  • resolution: or relaxation, follows organism and ejaculation; blood vessels CONSTRICT, forcing blood out of penis
  • a refreactory period occurs after ejaculation that varies in duration, where a man cannot achieve another organism
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22
Q

Testosterone

A
  • maintain hormone involved in regulation of spermatogenesis and male reproductive physiology including development of male characteristics
23
Q

multi-tiered negative feedback loop:

A

Hypothalamic-pituitary-gonadal (HPG) axis: regulates hormones involved in testosterone production and testicular function:
- 1. GONADOTROPIN-RELEASING HORMONE (GnRH)
- 2. FOLLICLE-STIMULATION HORMONE (FSH) and LUTEINIZING HORMONE (LH)
- 3. LH stimulates interstitial cells to produce testosterone
→ FSH stimulates sustentacular cells to secrete ANDROGEN-BINDING PROTEIN (keeps testosterone in vicinity of spermatogenic cells) & INHIBIN hormone

24
Q

Ovaries

A

Female gonads

  • produce fem gametes
  • secrete fem sex hormones, oestrogens(estradiol, estrone, estriole) and progesterone
25
Q

Accessory organs - fem

A
  • uterine (fallopian)tubes
  • uterus
  • vagina
  • greater vestibular glands
  • mammary glands
26
Q

external genitalia (vulva)

A
  • monis pubis: fatty area overlying pubic symphysis
  • labia majora: hair-covered, fatty skin folds
  • labia minora: skin fold rich sebaceous glands (produce an oily lubricant called sebum) lying within labia majora
  • clitoris: organ containing erectile tissue and contains many pressure, temo and tactile sensors
  • perineumL diamond shape region between pubic arch and coccyx
27
Q

vag - functions

A
  • discharge of menstral fluid
  • organ of copulation
  • birth canal of baby
28
Q

uterus walls

A
  • endometrium: shed during menstruation, layer varies in thickness depending on hormonal influences
  • myometrium: the muscular layer important for uterine contractions during menses and childbirth
  • perimetrium: outer serosa layer of uterus
29
Q

fallopian tubes

A
  • narrow ISTHMUS near uterus
  • AMPULLA: expansion at distal end that connects tube to INFUNDIBULUM
  • INFUNDIBULUM: funnel-shaped opening at distal end of uterine tube
  • FIMBRIAE: finger-like ciliated projections that extend from edges of infundibulum
30
Q

mammary glands

A
  • modified sweat glands → primary biological role is to produce MILK for newborn infant
  • during lactation, milk passes from alveoli into a series of MAMMARY DUCTS, which flow into LACTIFEROUS DUCTS that open into nipple
31
Q

Oogenesis

A
  • process in which femalte gametes, or ova, are produced
  • produces gametes via meiosis, cyclic event produces onle 1 egg each month
  • differs from spermatogenesis
    →begins before female infant is born, then suspended until puberty
    → once reactivated it continues until MENOPAUSE
    → occurs about once per month as a part of OVARIAN CYCLE
32
Q

oogenesis: birth- childhood

A

Before birth: female stem cells called OOGONIA complete their mitotic division

  • oogonia begin meiosis I between third and seventh month of fetal development; called PRIMARY OOCYTES
  • process to prophase I before their development is arrested

childhopd: primary oocytes remain in prophase I and don’t develop any further until puberty

33
Q

oogenesis: puberty - menopause

A

20-30 primary oocytes are stimulated to continue development

  • one or more primary oocytes complete first meiotic division to produce two haploid cells that differ in size
  • smaller cell contains DNA but little cytoplasm; called first POLAR BODY; usually degenerates
  • larger cell, SECONDARY OOCYTE, contains DNA & most of cytoplasm
  • secondary oocyte proceeds to metaphase II and its development is again arested
34
Q

Ovarian cycle

A
  • monthly series of events associated w/ maturation of an oocyte and its follicle in an ovary
  • avg 28 days
  • Hormone cycle : HPG axis. HYPOTHALAMUS→ PITUITARY → OVARIES→ UTERUS
  • estrogens and progesterone are involved in a multi’tiered regulation including positive & negative FB loops
  • Ovarian cycle: FOLLICAULAR PHASE, OVULATION, LEUTEAL PHASE
35
Q

Menstrual cycle (uterine cycle) - menstrual phase

A

uterus sheds endo metrial lining, resulting in menstruation

36
Q

Menstrual cycle(uterine cycle) - proliferative

A
  • a new lining is generated; begins to thicken (proliferate). ovulation takes place right at the end of the proliferative phase
37
Q

Menstrual cycle (uterine cycle) - secretory phase

A
  • endometrial glands secrete UTERINE MILK into uterine cavity to sustain embryo
38
Q

fertilisation

A
  • after ovulation, the oocyte is viable for 12-24 hours
  • after ejaculation, sperm is viable 24-72 hrs
  • for fertilisation to occur, intercourse must occur no more than 3 days before ovulation, 24 hours after ovulation

→ when a sperm fuses with an egg to form a zygote

39
Q

Sperm migration & capacitation

A

Sperm reach the uterine tubes in 10min (fertile up to 72 hours) but majority dont make egg

  • destroyed by vaginal acid
  • fail to penetrate the cervical canal mucus plug
  • go up wrong uterine tube
  • 2000-3000 ( out of 200M) spermatozoa reach vicinity of egg

to fertiise, egg must undergo CAPACITATION (thinning of acrosomal membrane)

  • takes up to 10 hrs
  • female fluids wash away inhibitory factors
  • sperm membrane becomes fragie and permeable to Ca2+
40
Q

fertilisation - steps

A
  • binding of sperm to egg causes changes to surface of ova
  • swillen sperm and egg nuclei called PRONUCLEI
  • chromosomes of 2 gametes mix
  • fertilized egg now called ZYGOTE
41
Q

blocks to polyspermy

A
  • only one sperm allowed to penetrate oocyte
  • two mechanisms ensure monospermy
    1. Fast block to polyspermy: membrane depolarisation prevents other sperm from fusing w/ the oocute membrane
    2. slow block to polyspermy: zonal inhibiting proteins (ZIPs)
  • destroy spem receptors
  • cause sperm already bound to receptors to detach
42
Q

implantation

A
  • fertilisation takes place in the fallopian tube. the zygote continues to divide in the days following fertilisation and travels to the uterus
  • implantation begins six to seven days after fertilisation when the trophoblast adheres to a properly prepared andometrium
  • implanted blastocyst is covered over by endometrial cells
  • implantation is completed by the fouteenth day after ovulation
43
Q

placenta

A

the placenta is a new, temporary organ which is generated after implantation
- placenta is the site of oxygen, nutrient & waste exchange
- formation of the placenta (placentation) from:
→ embryonic trophoblastic tissues
→ maternal endometrial tissues

44
Q

pregnancy

A
  • gestation (pregnancy)
    → lasts an avg of 266 (38wks) from conception to childbirth
    → gestational calendar measured from first day of the womans last menstrual period
  • birth predicted 280 days (40wks) from last menstrual period
    →3 three month intervals called TRIMESTERS
45
Q

hormonal changes during pregnancy

A
  • viability of the corpus luteum (in ovary) is maintained by HUMAN CHOROINIC GONADOTROPIN (hCG) secreted by the trophoblasts
  • hCG prompts the corpus luteum to continue to secrete PROGESTERONE & ESTROGEN
  • Between the second and third month, the placenta:
    →assumes the role of progesterone and estrogen production
    → is providing nutrients and removing wastes
46
Q

childbirth

A
  • PROGESTERONE inhibits contractions early in pregnancy
  • ESTROGEN stimulates contractions
  • Near full term → posterior pituitary releases more OXYTOCIN
    → directly stimulates myometrial contractions
    → stimulates fetal membranes to produce prostaglandins - synergists of oxytocin
  • stretching
    → increases contractility of smooth muscle
    →role in initiating labour
47
Q

childbirth - labour

A
  • labour contraction are self-amplifying cycle of stretch and contraction
  • Positive FB cycles inc. contraction
    Cervical stretching → oxytocin secretion →uterine contraction → repeat
    reflex arc from uterus → spinal cord →abdominal skeletal muscles
  • stretching of cervix, vagina and perineum → large fetal head in a narrow pelvic outlet
48
Q

Milk synthesis

A

Colostrum forms in late pregnancy

  • similar to breast milk; contains 1/3 less fat, thinner
  • first 1 to 3 days after birth
  • contains IgA protection

Synthesis is promoted by PROLACTIN (from pituitary)

  • begins 5 wks into pregnancy, by full term its 20x normal level
  • teroid hormones from placenta
49
Q

milk ejection

A
  • controlled by a NEUROENDOCRINE REFLEC
  • the production of milk by the mammary glands is a pos. FB system
  • hypothalamus to release PROLACTIN-RELEASING HORMONE (prh) and OXYTOCIN
  • the anterior pituitary responds by releases prolactin
  • OXYTOCIN (hypothalmus) helps release the milk from mammary glands
  • PROLACTIN (anterior pituitary) stimulates milk production
50
Q

Birth control: behavioural methods

A
  • abstinence
  • rhythm method
  • withdrawal (coitus interruptus)
51
Q

Birth control: Barrier methods

A

Prevent sperm from moving beyond vagina

  • inc. condoms, diaphragms, cervical caps, & sponges
  • many barrier methods particularly diaphram, cervical cap and sponge made more effective using chemical SPERMICIDE
52
Q

Birth control: Hormonal methods

A
  • oral contraceptives contain synthetic estrogens and progesterone which provide a negative FB for the release of FSH & LH.
  • depending on the contraceptive, it can work by preventing follicle maturation, ovulation or interfere w/ build of endometrium required for implantation
53
Q

Birth control: permanent methods

A

sterilisation methods:

  • vasectomy
  • hysterectomy
  • tubal ligation

phys (14 decks)

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