(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
How many chromosomes are in the secondary oocyte?
Haploid chromosomes (23 unpaired) + the corresponding in the Polar Body
Which hormone provides evidence that ovulation has occurred? When relative to the onset of menstrual bleed should you measure it, and in what bodily fluid?
- Progesterone
- Day 21
- In the blood
