Session 6: Human Sexual Response Flashcards
Phases of human sexual response found in both women and men.
Excitement phase
Plateau phase
Orgasm phase
Resolution phase
What stimuli causes the excitement phase in men?
Psychogenic stimuli
Somatogenic stimuli
Explain the psychogenic stimuli of the excitement phase in men.
Looking/hearing/smelling something causing a somatic and parasympathetic response.
Explain the somatogenic stimuli of the excitement phase in men.
Touching.
Causes tactile afferents of the penis to signal via the spinal reflex to cause a somatic and parasympathetic response.
Explain the excitement phase in men.
Somatogenic and psychogenic stimuli feeding afferents to the somatic and parasympathetic efferents.
The somatic efferents are via the pudendal nerve.
Parasympathetic efferents are via the pelvic nerve.
The parasympathetic nerves release ACh which will bind to the M3 receptors. Along with cGMP this causes an increase in intracellular Ca2+ concentrations which causes the release of NO (nitrous oxide).
Nitrous oxide causes vascular smooth muscle relaxation and arterial and venodilation. Sinusoids within the corpora cavernosa also dilate. All of this dilation leads to an erection by subsequent increased blood flow to the corpora cavernosa against the tough tunica albuginea. This also compresses venous drainage.
This is all important in order to maintain an erection.
Explain the plateau phase in men.
Minor involuntary vasocongestion
Penile erection increase slightly
A rise in heart rate
What can the orgasm phase in men be divided into?
Emission and ejaculation
Explain the emission part of the orgasm phase in men.
Smooth muscle contraction of the prostate, vas def and seminal vesicle.
This pushes semen into the prostatic urethra.
Explain the ejaculation part of the orgasm phase.
Contraction of the glands and ducts.
Contraction of the IUS to prevent retrograde flow.
Rhythmic contraction of the muscles of the pelvic floor.
This leads to expulsion of the semen.
Explain the resolution phase of men.
2 steps:
1 - Penile involution and decrease in penile erection and size. This is an absolute refractory period. During this time the cycle cannot keep going.
2 - Penis return to normal size. This is the relative refractory period. During this time it is possible to start the excitement phase again.
Explain the differences in the human sexual response between men and women.
Men have an absolute refractory period
Causes of erectile dysfunction.
Psychological input
Vascular disorders
Anti-hypertensives
Drugs
Neurological disorders
Tears in fibrous tissue of corpora cavernosa (Tunica albuginea)
Explain the mucus changes produced by the cervix over the course of the menstrual cycle.
Oestrogen - thin and stretchy mucus
Oestrogen + progesterone - Thick, sticky and forms a plug of the cervix to prevent further sperm getting in. Also prevents pathogens to enter to protect a potential fertilisation
Explain capacitation.
Further maturation of the sperm inside of the female reproductive tract.
The sperm membrane changes in order to be able to fuse with the oocyte.
Also the tail changes from a beat to a whip-like action.
Also allows acrosome reaction by the sperm.
Fertile window of the spermatozoa.
Can survive for 48-72 hours