Sex And Fertilisation Flashcards
(27 cards)
What is the layer of cells surrounding the oocyte in the Graafian follicle called ? What is its origin ?
Cumulus oophorus (inner layer called corona radiata )
Originate from the granulosa cells
When does the spermatozoa become motile ?
When reaches epididymis
What is the normal site of fertilisation ?
Ampulla of Fallopian tube
What are the different phases of the human sexual response and what happens ?
Excitement phase (psychogenic and somatomedin stimuli )(erection in male )
Plateau phase
Orgasm phase
Resolution phase (return to normal haemodynamic norm and refractory period (only in male ))
What is the male response in excitement phase ? What are the stimuli ?
Erection
In response to Psychogenic and Somatogenic stimuli (Tactile ,sensory afferent often is and perineum )
Which nerves are involved in erection ?
Pelvic nerve and plexus (parasympathetic )
Cavernous nerve to corpora vasculature
Pudendal nerve (somatic)
What are the 3 neurophysiological mechanism involved in erection?
Inhibition of sympathetic tonic arterial vasoconstriction
Activation of parasympathetic input
Activation of autonomic nerves to arteries releasing Nitric oxide
Which vascular changes are required for erection?
Arterial dilation
Sinusoidal relaxation
Venous compression
What is the role of Nitric oxide in erection ?
Neurones release Ach
Binds to Muscarinic M3 on endothelial cells (GPQ)
Rise in calcium cause NOS to produce NO
Some NO also released directly from nerves
NO goes into smooth muscle cells
Activates Guanylate cyclise > cGMP >PKG > vasodilation
What can cause erectile dysfunction ?
- Psychological (descending inhibition of spinal reflex )
- Tears in fibrous tissue of corpora cavernosa
- Vascular damage
- Drugs (anti hypertensive , antidepressants )
What is the mechanism of action of sildenafil aka viagra ?
Inhibit PDE 5 (phosphodiesterase 5) which is responsible for degradation of cGMP
>so more cGMP
»more PKG
»>more vasodilation
What is emission in the male sexual response ?
Movement of seven into prostatic urethra
Contraction of smooth muscle in prostate ,vas and seminal Vesicle
Why can adiministration of sympathetic antagonist cause dry orgasm ?
Sympathetic nervous system controls the emission and ejaculation response > Blocking of SNS > no ejaculation
What 3 phenomenon happen at ejaculation ?
- Contraction of gland and ducts
- Bladder internal sphincter contracts (prevent retrograde ejaculation )
- Rhythmic striatal muscle contractions (pelvic floor , perineal muscles ) voluntary
What are the 2 main perineal muscles involved in ejaculation ?
Ischiocavernous
Bulbospongiosus
How does the cervical mucus change under influence of different hormones ? And which stage of menstrual cycle ?
Before ovulation ,oestrogen : thin and stretchy
After ovulation,progesterone+oestrogen : thick,sticky , forms plug
Which test is used to assess the cervical mucus ?
Fern test
What happens to semen at the site of deposition ?
Temporary coagulation to prevent it going out
After ejaculation Which further maturation of sperm happens and where ?
In female tract (6-8hrs)
Capacitation:
-membrane changes for fusion
-capable of undergoing acrosomal reaction
-Tail movement change from beat to whip-like action
Spermatozoa is fertile for …
Oocyte is fertile for …
?
Spermatozoa : 48-72hrs
Oocyte : 6-24 hrs
What is the origin of the acrosome and what does it contain> ?
From Golgi region Contains enzymes (Hyaluronidase )
Why is the acrosome leader reaction important and what triggers it ?
- triggered by binding of sperm surface receptor to ZP3 (glycoprotein of zone pellucida )
- Acrosomal reaction release enzymes which digest zone pellucida to penetrate oocyte
What are the consequences of membrane fusion ?
- induction of Cortical reaction (calcium dependant release of granules containing protease ) to prevent polyspermy
- induction of calcium waves to finish meiosis 2 and initiation of development
What is the particularity of cells of the morula ?
Totipotent : capacity to differentiate in any cell type
