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Reproductive system > Lecture 11– Getting pregnant: sex and fertilisation > Flashcards

Lecture 11– Getting pregnant: sex and fertilisation Flashcards

1
Q

Maturation of sperm in the epididymis – the sperms journey (continues!)

  • *
A
  • On entry, spermatozoa not capable of movement
  • Once at the tail of the epididymis they are capable of movement and have the potential to fertilise
  • Addition of secretory products to surface of sperm
  • Maturation
    • Dependent on support of the epididymis by androgens
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2
Q

constituents of semen

A
  • Spermatozoa
  • Seminal plasma
  • Seminal plasma derived from accessory glands of the male reproductive tract
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3
Q

function of semen

A
  • Transport medium
  • Nutrition
  • Buffering capacity
  • Role for prostaglandins in stimulating muscular activity in the female tract
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4
Q

seminal palsma contirbutions from

A
  • seminal vesicles
  • prostate gland
  • bulbourethral glands (Cowpers glands)
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5
Q
  • Seminal vesicles
    *
A
  • 60% of volume
  • Alkaline fluid (neutralises the acid: male urethra and female repro tract)
  • Fructose, prostaglandins, clotting factors (semenogelin)
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6
Q
  • Prostate gland
A
  • 25% volume
  • Milky, slightly acidic fluid
  • Proteolytic enzymes (breakdown clotting proteins, re-liquefying semen in 10-20 minutes)
  • Citric acid, acid phosphatase
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7
Q
  • Bulbourethral glands (COwpers glands)
A
  • Very small volume
  • Alkaline fluid
  • A mucous that lubricates the end of the penis and urethral lining
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8
Q

normal values of semen

A
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9
Q

next step after sperm and egg mature

A

Next step….

  • Male and female gametes need to meet in the female reproductive tract
  • Male gamete needs to travel 100,000 times its own length
  • Fertilisation site is normally ampulla of uterine tube
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10
Q

Fertilisation site is normally

A

ampulla of uterine tube

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11
Q

The human sexual response….

*

A
  • Excitement phase
    • Psychogenic and/ or somatogenic stimuli
  • Plateau phase
  • Orgasm phase
  • Resolution phases
  • Return to haemodynamic normal followed by a refractory period in males
    • Before the male is ready to initiate excitement phase
    • In the female no refractory phase
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12
Q

male sexual stimulations

A
  • psychogenic
  • tactile (sensory afferents of penis and perineum)
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13
Q

male sexual response after stimulation

A

spinal reflex

somatic and autonomic efferents

  • pelvic nerve (PNS)
  • pudendal nerve (somatic)

cause haemodynamic changes- namely vasodilayion

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14
Q

tunica albiginea qualities

A

verg rigid - not much venous return

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15
Q
  • Erection requires
A
  • Sinusoidal relaxation
  • Arterial dilation- blood rushes into corpus cavernosum and spongiosum= erection
  • Venous compression
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16
Q

summarise erection

A
  • Sympathetic- inhibition (reduction of tone at arterioles)
  • Parasympathetic- activates
17
Q

which fibres are involved with parasympathetic innervation

A
  • Lumbar and sacral spinal levels
  • Pelvic nerve and pelvic plexus
  • Cavernous nerve to corpora and vasculature
18
Q

Neurophysiology of erection

A
  • Inhibition of sympathetic arterial vasoconstrictor nerves
  • Activated PNS- vasodilation
  • Activation of non-adrenergic, non-cholinergic, autonomic nerves to arteries, releasing Nitric oxide (NO)
19
Q

role of NO in erection

A
  • Post-ganglionic fibres release ACh
  • Ach binds to M3 receptor on endothelial cells
  • A rise in [Ca2+]i , activation of NOS and formation of NO
  • NO diffuses into vascular smooth muscle and causes relaxation (vasodilation)
  • NO also released directly from nerves
20
Q

Erectile dysfunction causes

A
  • Psychological (descending inhibition of spinal reflexes)
  • Tears in fibrous tissue of corpora cavernosa
  • Vascular (arterial and venous)
  • Drugs
21
Q

emission is the

A
  • Movement of semen into prostatic urethra
  • Caused by contraction of SM in prostate, vas deferens and seminal vesicles
22
Q

ejaculation

A

expulsion of semen- sympathetic response

23
Q

outline ejaculation

A
  • Contract of the glands and ducts (smooth muscle)
  • Bladder internal sphincter contracts
    • Preventing retrograde ejaculation
  • Rhythmic striatal muscle contraction (pelvic floor, and perineal muscles ischiocavernosus, bulbospongiosus)
24
Q

Menstrual cycle changes in female tract

*

A
  • The character of cervical mucus changes over the course of the menstrual cycle
  • Oestrogen
    • Thin, stretchy
  • Oestrogen and progesterone
    • Thick, sticky; forms a plug
25
Q

ways to test fertility

A

fern test

spinnbarkeit mucus

26
Q

sperm deposition

A
27
Q

capacitation

A
  • Further maturation of sperm in female reproductive tract (6-8h)
  • Sperm cell membrane changes to allow fusion with oocyte cell surface
  • Tail movement changes from beat to whip=like action (b)
  • Now capable of undergoing the acrosome reaction (C)
28
Q

uterus anteversiona dn anteflexion changes during the sexual response

A
29
Q

Fertile window- window of opportunity for fertility

A

Spermatozoa will survive for 3 days in the vagina

  • Spermatozoa 48 -72hr
  • Oocytes 6 –24 hr (max)
  • Fertile period: sperm deposition up to 3 days prior to ovulation or day of ovulation
  • Gamete transport
    • Oocyte: beating cilia & peristalsis of uterine tube
    • Sperm: own propulsion
30
Q

Overview of events in fertilisation

A
  • Occurs normally in the ampulla of the uterine tubes
  • Requires loss of sperm outer shell (acrosome)
  • Penetration of ovum membrane, fusion of ova and sperm membrane
  • Eventual formation and fusion of pronuclei
31
Q

the acrosome is derived from the

A
  • golgi region of developing spermatids
  • contains enzyme necessary for fertilisation
32
Q

Acrosome reaction- allows the sperm to

A
  • Sperm pushes through corona radiate
  • Binding of sperm surface receptor ZP3 glycoprotein of zona pellucida
  • Triggers acrosome reaction  digestion of zona pellucida
33
Q

Fertilisation

*

A
  • One sperm penetrates leading to fusion of plasma membranes
  • Cortical reaction
    • Blocks polyspermy
34
Q

completion of meiosis II

A
  • series of calcium waves are activated following fusion of oocyte and sperm membrane
  • resumption of meiosis II occurs
  • pronuclei move together
  • mitotic spidlle froms leading to cleavage
35
Q

assisted reproductive technology

A
  • oocytes fertilised in vitro and allowd to divide to the 4 or 8 cell stage
  • morula transferred into the uterus
  • pre-implanation genetic diagnosis (PGD)
    • a cell can be safely removed from the morula and tested for serious heritable conditions priot to transfer of the embyro into the mother
36
Q

the blastocyst and hatching

A
  • first differnetiation
    • inner and outer cell masses
  • formation of the balstocyst
  • blastocyst hatches from zona pellucida
  • it is no longer constrained - free to enlarge
  • can now interact with uterine surface to implant
37
Q

implantation

A
  • outer cell mass (trophoblast) interacts sigh endometrium
  • endometrium controls degree of invasion
  • ectopic implantation
    • at sites other than endometrium lined uterine cavity
    • invasion not controlled
  • implantation in lower uterine segment can cause placenta praevia

Reproductive system (28 decks)

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