(7.1) Coitus & Conception Flashcards
Describe the phases of Coitus in a male. How is it different from female?
- Excitement: desire of sex
- Plateau: sexual activity
- Orgasmic: ejaculation
- Refractory (Resolution): period before next ejaculation can take place
- Female: +/- Orgasm & - Refractory
Describe the physiological changes during Erection.
- Stimulation of AFFERENT fibres: Pudenal (somatic)
- Inhibition of SNS to prevent vasoconstriction
- Pelvic PNS EFFERENT fibres: Pelvic (S2-S4) release ACh -> M3 receptors on endothelium -> NO production
- Direct production of NO from non-adrenergic/cholinergic receptors
- NO -> smooth muscle cells -> cGMP -> uptake of Ca2+ into sacroplasmic reticulum -> vasodilation of central arteries in Corpus Caverosum (more) & Sponginosum
- Tensed Bulbosponginosus & Ischiocaverosus muscles contract -> Compressing venous drainage
What structures aid to maintain erection?
- Dilation of Central A of Corpus Cavernosus
- Bulbosponginosus & Ischiocaverosus muscles contract -> Compressing venous drainage
- Corpus Cavernosus remains engorged and erected
What may cause erectile dysfunction?
- Psychological
- Tearing of the fibrous tissue of Corpora cavernosa
- Haemodynamic problem
- Factors blocking NO: alcohol, anti-hypertensive, diabetes
What is the most common cause of erectile dysfunction? What is its treatment and how does it work?
- Vascular
- Viagra: inhibit breakdown of cGMP -> constant removal of Ca2+ -> vasodilation
What is Emission in male?
Before ejaculation, the secretions into the Prostatic Urethra, including products from Vas deferens & Seminal Vesicles
State the volume and constituents in a normal Semen. What is it called if it is abnormal?
- 2-4 ml
- from Testis: 20-200x10^6 sperms per ml (Sertoli cells)
- from Seminal Vesicles (60%): Alkaline, Coagulatory factors (fibrinogen), Fructose
- from Prostate Gland (25%): Citric acid, Proteolytic enzymes
- from Bulbourethral Glands: Alkaline, mucus
- Abnormal: Oligozoospermia
What are the secretions from the Seminal vesicles into the semen? What are their purpose?
- Alkaline: neutralise acidic vagina
- Coagulatory factors: holds sperms in place after ejaculation
- Fructose: provide energy for sperms
State three factors inside the female reproductive tract that affect the transportation of sperms.
- Vaginal Mucus: Oestrogen - watery
- Cervical Mucus: Oestrogen + Progesterone - sticky plug
- Uterine Tube: Psudostratified columnar ciliated epithelium
Why may an infection of the female reproductive tract reduce the ability of her to become pregnant?
Infection -> reduced cilia in uterine tube -> reduced sperms transport to Fallopian Tube
What changes occur when sperms travel through the female reproductive tract?
- Undergo Capacitation
- Become motile, beating of tails
- Removal of glycoprotein coat
Where is the normal site of fertilisation?
Ampulla of Fallopian Tube
What happens when a Sperm reaches an Oocyte?
Acrosome Reaction:
- Fusion of membrane
- Acrosome release proteolytic enzymes via exoctytosis
- Break down of Zona Pellucida
- Two nuclei fuse to form Zygocyte
What happens to the Oocyte after fertilisation?
- Primary Oocyte -> complete Meiosis II -> Secondary Oocyte (haploid chromosomes + rest of cell) & Polar Body (rest of haploid chromosomes)
- Zygocyte -> Cleavage -> totipotent Morula -> Blastocyst losses totipotency
- Outer Trophblasts -> Plancenta
- Inner Blastomeres -> Embryo
Describe the innervations and actions of emission and ejaculation.
- Emission: SNS Hypogastric N (L1-L2) -> contractions of seminal vesicles & prostatic glands & ducts -> into Prostatic Urethra
- Ejaculation: SNS Pelvic N (S2-S4) -> contractions of Corpus cavernosus and sponginosus & pelvic floor and anal muscles & internal bladder sphincter
