10 - Sexual Function and Fertilisation Flashcards
What are the reactions that occur in the sperm just before/during fertilisation?
- Capacitation
- Acrosome reaction
Where does the sperm start to mature and how?
- In the epididymis not capable of movement but by the end near vas def it is
- Addition of secretory products to surface of sperm
- All this dependent on androgens
What is the function of semen?
Seminal plasma + Spermatozoa
- Transport medium
- Nutrition
- Buffering capacity against acidic vagina
What is seminal plasma made up of?
Semen clots due to clotting factors from the seminal vesicles but then prostate has enzymes that break the clotting factors down. Can cause issues with fertility
What are some parameters of the male you need to look at when they are having issues with fertility?
- Morphology
- Motility
- Coagulation
What are the phases of the human sexual response?
- Excitement: psychogenic and somatic stimuli
- Plateau: if stimuli maintained
- Orgasm: if stimuli maintained and threshold reached
- Resolution: return to haemodynamic norm
Same in males and females but males have refractory period after resolution phase
What is the neural response of the excitement phase in males to gain an erection?
- Parasympathetic efferents dominate the pelvic nerve and the sympathetics have to be inhibited
- Somatic efferents from pudendal nerve
What is the physiology of getting an erection?
- Sinusoid relaxtion in CC
- Arterial dilation
- Venous compression by tough tunica albugenia around CC
What parasympathetic nerve innervates the corpus cavernosum?
Cavernous nerve from the pelvic nerve (S2-S4) and pelvic plexus
What neurotransmitter is involved in getting an erection and how does it work on a cellular level?
- Sympathetics inhibited and NO released in response to rise in Ca
- NO causes smooth muscle relaxation
- cGMP is key regulator
What are some causes of erectile dysfunction?
- Psychological (poor spinal reflexes)
- Vascular disorders like diabetes
- Tear in fibrous tissue of corpus cavernosum
- Anti hypertensives and other drugs
- Neurological disorders
How can erectile dysfunction be managed?
- Increase amount of NO and cGMP with drugs
What is emission and how is it controlled?
- Semen is moved into prostatic urethra by smooth muscle contraction of the prostate, vas def and seminal vesicles
- Sympathetic innervation
What happens during ejaculation and what nervous control is it under?
- Sympathetic
- Expulsion of semen that requires contraction of IUS to prevent retrograde ejaculation and rhymic striated muscle contraction of pelvic floor
- Glands also contract but these are smooth muscle
How does cervical mucus change over the menstrual cycle?
- Oestrogen only: thin and stretchy to faciltate sperm entry
- Oestrogen and progesterone: thick and sticky to form a plug to prevent outside world getting in if fertilised and prevent further sperm entry
Where in the female reproductive tract does fertilisation occur?
Ampulla
What needs to happen in the female reproductive tract to the sperm to make it fully mature?
When is the fertile period in a woman?
What events happen during fertilisation?
- Enzymes in acrosome released to remove outer granulosa cells (corona radiata)
- Acrosome reaction when sperm interacts with zona pellucida. Sperm loses outer membrane so it can penetrate ovum and fuse with ova membrane
- Cortical reaction in the oocyte to stop more sperm entering and then this triggers meiosis II to finish via calcium wave
- Fusion of pronuclei and formation of morula by mitotic spindle and cleavage
What is assisted reproductive technology?
- Medical procedures that are used to tackle infertility
- Can do pre-implantation genetic diagnosis by taking one cell from morula before implanted in uterus
- Implanted at 4-8 cell morula
What has to happen to the blastocyst for implantation to occur?
Hatching from zona pellucida so outer cell mass (trophoblasts) can interact with endometrium where secretory glands and increased vasculature are
