Getting Pregnant Flashcards
What is normal sperm count?
> 20 x10^6
What is the normal ejaculate volume?
2-6ml
What are the phases of the human sexual response?
Excitement phase
Plateau phase
Orgasm phase
Resolution phase
What happens in the excitement phase?
Arousal in response to psychogenic and/or somatogenic stimuli
What happens in the plateau phase?
Period of sexual excitement before orgasm
Increased sexual pleasure with increased stimulation
What happens in the orgasm phase?
Quick successions of muscular contractions with pleasure
Ejaculation in males
What happens in the resolution phase?
Return to haemodynamic norm
Followed by a refractory period in males
What is the first stage of the male sexual response?
Erection
How is an erection produced?
Stimulants
- psychogenic
- tactile
Spinal reflex to somatic/autonomic efferents
- pelvic nerve
- pudendal nerve
Haemodynamic changes
What autonomic system maintains the erection?
Parasympathetic
What is the parasympathetic innervation to the penis?
Pelvic nerve + pelvic plexus
Cavernous nerve to corpora + vasculature
What is the neurophysiology of an erection?
Inhibition of sympathetic arterial vasoconstrictor nerves
Activation of PNS
Activation of autonomic nerves = release nitric oxide
What is the role of nitric oxide in an erection?
Nitric oxide diffuses into vascular smoth muscles + causes vasodilation
What can cause erectile dysfunction?
Psychological
Tears in fibrous tissues of corpora cavernosa
Vascular
Drugs
What can be used to help erectile dysfunction?
Viagra
How does Viagra work?
Slows rate of cGMP degradation
What is the second stage of the male sexual response?
Emission + ejaculation
What autonomic system is involved in ejaculation?
Sympathetic
How does emission occur?
Movement of semen into prostatic urethra
Contraction of smooth muscle in prostate, vas deferens + seminal vesicles
What is ejaculation?
Expulsion of sperm
What happens during ejaculation?
Contraction of glands and ducts
Bladder internal sphincter contracts
Why does the bladder internal sphincter contract?
Prevent semen entering bladder
What is the effect of oestrogen on cervical mucus?
Thin, stretchy mucus - supports transport of male gamete
What is the effect of progesterone + oestrogen on cervical mucus?
Thick, sticky mucus - forms a plug
Where is the site of semen deposition?
External os of cervix
What happens to the sperm once in female reproductive tract?
Capacitation
- sperm cell membrane changes to allow fusion with oocyte
- tale movement changes to more whip like action
How long are sperm fertile for?
48-72 hr
How long are oocytes fertile for?
6-24 hr
What is the acrosome?
Head of sperm - containing enzymes
Derived from golgi region in spermatid
What happens in the acrosome reaction?
Sperm pushes through corona radiata
Binding of sperm to ZP3 glycoprotein of zona pellucida
Triggers acrosome reaction
Enzymes digest zona pellucida
How is polyspermy prevented?
Cortical reaction
- release of cortical granules
What happens when fertilisation occurs?
Calcium waves activated following fusion of oocyte + sperm membranes
Oocyte continues meiosis 2
Pronuclei move together
Mitotic spindle forms - cleavage of cells
Formation of morula
