What do spermatogonia mature into?
Where do spermatogonia mature into spermatozoa?
In the seminiferous tubules of the testis
How long does maturation of spermatogonia into spermatzoa take?
Up to 74 days
How much of maturation of spermatogonia to spermatozoa occurs in the testis?
Up to 74 days
How much does maturation of spermatongonia to spermatozoa take in the epididymis?
From what stages in life does spermatogenesis occur?
Starts at puberty, continues until death, there is no male menopause
How many sperm to the testes produce each day?
How many of the sperm produced by the testes become viable?
What happens to the sperm produced with age?
Slight decrease in quality and quantity
What is spermatogenesis controlled by?
What produces LH?
What does LH act on in males?
Leydig cells of the testis
What is the result of the action of LH on the Leydig cells of the testes?
Stimulates them to produce testosterone, which is a direct stimulant of spermatogenesis
What does FSH act on in the male?
Androgen binding protein in the Sertoli cell
What is formed when FSH acts on androgen binding protein in Sertoli cells?
The blood-testis barrier
What is the result of the formation of the blood-testis barrier?
Increases testosterone concentration, which is a further stimulant for spermatogenesis
What can spermatogenesis be initated with if the pituitary gland is removed?
FSH and testosterone alone, bypass the need for LH
What is the effect of oestrogen from Leydig cells?
It can increase sperm viability
How is hormonal control of spermatogenesis in itself controlled?
By a negative feedback loop
How does the negative feedback loop controlling the hormonal control of spermatogenesis work?
The release of inhibin from stimulated Sertoli cells decreased FSH, and so decreases spermatogenesis
What happens in spermiogenesis?
The spermatid matures to spermatozoon
What forms the head of the spermatozoon?
The acrosome and nucleus
What happens in the maturation to a spermatazoon?
- The head undergoes nuclear condensation
- The acrosome forms
What happens in nuclear condensation?
The nucleus becomes much smaller
What are the features of the acrosome?
- Golgi apparatus
- Lysosome like, in that it has hydrolytic enzymes
What is the function of the acrosome?
Enable sperm to penerate ovum
What is the midpiece of the sperm made of?
Mitochondria packed around contractile filaments
What is the tail of the sperm?
It is a flagellum produced by microtubules growing from centriole to form axoneme
What happens to the spermatozoon?
It matures to spermatozoa
What happens in the maturation to spermatozoa?
Cytoplasm and organelles stripped under influence of testosterone
What is true of sperm once they have matured into spermatozoa?
They are now mature, but lack motility, so are infertile
Where are spermatozoa released from?
Where are spermatozoa released from Sertoli cells into?
The lumen of seminiferous tubules
What is the process of releasing spermatozoa into the lumen of the seminiferous tubule called?
Where do spermatazoa go from the seminiferous tubules?
How are spermatozoa transported to the epididymis?
In testicular fluid, by peristaltic contraction
What produces testicular fluid?
What happens to spermatozoa in the epididymis?
They gain motility and become fertile in the epididymis
How long can sperm be stored in the epididymis with no loss of fertility?
What happens to the epididymis during sexual arousal?
There is contraction of the epidiymal wall muscle
What does contraction of the epididymal wall do?
Expels spermatozoa into ductus (vas) deferens, and then out through penis in ejaculation
What happens to the spermatozoa if they are not expelled?
They are eventually phagocytosed by the epididymal epithelial cells
What are the phases of coitus?
- Excitement phase
- Plateau phase
- Orgasmic phase
- Resolution phase
What happens in the excitement phase of the male sexual response?
Sensory and psychological stimulation needs to the activation of the sacral parasympathetic neurones, and inhibition of the thoracolumbar sympathetic neurones
What is the affect of activation of the sacral parasympathetic neurones?
ACh acts on M3 receptors on endothelial cells, leading to an increase in intracytoplasmic Ca2+, leading to activation of eNOS, and thus increasing nitric oxide production
What does nitric oxide production cause in the male sexual response?
Arteriolar vasodilation in the corposa cavernosa
What does arteriolar vasodilation in the corposa cavernosa cause?
Increased penile blood flow, and then penile filling (latency) to penile tumesence (erection)
What is true of the erection at the excitement phase?
It is reversible
What happens to the testes in the excitement phase?
They begin to elevate and engorge
What happens to the scrotum in the excitement phase?
Scrotal skin thickens and tenses
What happens in the plateau phase in the male sexual response?
- Activation of the sacrospinous reflex
- Stimulation of secretion from accessory glands
- Corona may become further engorged
What does activation of the sacrospinous reflex lead to in the plateau phaes of the male sexual reponse?
Contraction of the ischiocavernosus
What is the result of the contraction of the ischiocavernosus?
Compresses the crus penis and impedes venous return, leading to venous engorgement
What happens to intracavernous pressure in the plateau phase of the male sexual response?
What does the rise in intracavernous pressure lead to?
Decreased arterial inflow
What accessory glands are stimulated in the plateau phase of male sexual excitement?
Cowpers and Littre's glands
What is the function of the stimulation of secretion from Cowpers and Littre's glands?
- It lubricates distal urethra
- Neutralise acidic urine in urethra
What % of the ejaculate do the secretions from the Cowpers and Littres glands in the plateau phase constitute?
What happens to the testes in the plateau phase?
They become completely engorged and elevated
What happens to the scrotum in the plateau phase?
It maintains its thickened and tensed state
What is true of the erection in the plateau phase?
Loss is unlikely
What is the orgasm phase of the male sexual response split into?
What happens in the emission phase of the male sexual response?
Stimulation of thoracolumbar sympathetic reflex
What does stimulation of the thoracolumbar sympathetic reflex cause?
- Contraction of smooth muscle in ductus deferens, ampulla, seminal vesicle, and prostate
- Internal and external urethral sphincters contract
What is the result of the contraction of the smooth muscle in the ductus deferens, ampulla, seminal vesicle, and prostate?
Semen is pooled in the urethral bulb
Why do the internal and external urethral sphincters contract in the emission stage of the male sexual response?
So don't get retrograde ejaculation into the bladder
What happens in the ejaculation stage of the male sexual response?
Spinal reflex (with corticol control) stimulates sympathetic nervous system (L1, 2)
What does L1 and 2 stimulation in the ejaculation phase of the male sexual response cause?
- Contraction of the glands and ducts
- Internal urethral sphincter contracts
What does filling of the urethra stimulate in the ejaculation phase?
Pudendal nerve, which stimulates the contraction of the genital organs, the ischiocavernosus, and the bulbocavernosus muscles
What does contraction of the genital organs, ischiocavernosus, and bulbocavernosus muscles lead to?
Expulsion of semen
What happens to the anal sphincter during ejaculation?
What happens in the resolution phase of male sexual excitement?
Activation of the thoracolumbar sympathetic pathway
What does the activation of the thoracolumbar sympathetic pathways lead to in resolution of the male sexual response?
- Contraction of arteriolar smooth muscle in the corporta cavernosa
- Increased venous return
- Detumescence and flaccidity
Is there a refractory period in the male sexual response?
What happens to the testes in the resolution phase of the male sexual response?
Testes descend and return to unstimulated size
What happens to the scrotum in the resolution phase?
Thins and resumes wrinkled appearance
What happens in the excitement phase of the female sexual response?
- Same neuronal responses as male
- Vaginal lubrication begins
- Clioris engorges with blood
- Uterus elevates
- Increase in muscle bone, heart rate, and BP
- Inner 2/3 of vagina lengthens and expands
What causes vaginal lubrication?
What happens in the plateau phase of the female sexual response?
- Further increase in muscle tone, heart rate, and BP
- Labia minora deepens in colour
- Clitoris withdraws under its hood
- Bartholin glands secretions lubricate vestible
- Orgasmic platform forms in lower 1/3 of vagina
- Inner 2/3 of vagina fully distended
- Uterus is fully elevated
What happens in the orgasmic phase of the female sexual response?
- Orgasmic platform (outer 1/3 of vagina) contracts rhythmically 3-15 times, inner 2/3 remains motionless
- Uterus contractions beginning at top (fundus) and moving down towards cervix
- Anal sphincter contracts
- Clitoris remains retracted under hood
Is there a refractory period in the orgasmic phase of the female sexual response?
No, multiple orgasms possible
What happens in the resolution phase of the female sexual response?
- Clitoris descends and engorgement subsides
- Labia returns to unaroused size and colour
- Uterus descends to unaroused position
- Vagina shortens and narrows back to unaroused state
What happens to the breasts in the excitement phase of the female sexual response?
- Breast size increases
- Nipple becomes erect
- Veins become more distinct
What happens to the brests in the plateau and orgasm phase of the female sexual response?
- Greater size increase
- Areola increases in size, and causes nipple to appear less erect
- Sex flush may appear on breasts and upper abdomen
What causes the sex flush in the female sexual response?
Increase in arterial inflow
What happens to the breats in the resolution phase of the sexual response?
- Detumesence of areola
- Disapperance of sex flush
- Reutrn to unaroused size
What is the result of detumescene of the areola?
Nipple appears more erect
What is the G-spot?
An area of erotic sensitivity located along the anterior wall of the vagina
What is the sexual relevance of the G-spot?
Some women are able to experience orgasm and possibly ejaculation from G-spot stimulation
What is G-spot tissue similar too?
Similar to the male prostate
What is the result of the G-spot tissue being similar to the prostate?
Therefore, fluid may be similar to prostatic component of semen
What evidence is there that the G-spot fluid is similar to the prostatic component of semen?
Research has showed the presence of enzyme in female ejaculate is characteristic of prostate secretions
How does orgasm from G-spot stimulation differ from clitoral stimulation?
It is the same, though intensity may vary depending on method of stimulation
What effect does age have on sexual response in females?
- Some women report reduced desire
- Vaginal and urethral tissue loose elasticity
- Length and width of vagina decrease
- Number of orgasmic contractions is often reduced
- More rapid resolution
Why does sexual desire decrease with age in women?
- Psychological factors, e.g. body changes
- Reduced vasocongestion response
What does the reduced vasocongestion response cause in females?
Reduced vaginal lubrications
What is the result of the length and width of the vagina decreasing with age?
Reduced expansile ability of inner vagina during arousal
What % of married couples report in engaging in sexual intercourse a few times a year?
What % of married couples report having sexual intercourse of 2-3 times a week?
What is the most common sexual dysfunction?
Problems with desire
What is happening to the incidence of sexual desire problems?
It is increasing
What are the potential problems with sexual desire?
- Kluver Bucci syndrome
What is hypoactive sexual desire?
Little or no interest in sex
What is sexual aversion?
Revulsion or fear of one or all aspects of sex
What is sexual aversion often a result of?
Abuse or assault
How common is sexual aversion?
How is sexual aversion treated?
Intensive psychological therapies
What causes Kluver Bucci syndrome?
Bilateral medial temporal lobe lesions
What can cause bilateral medial temporal lobe lesions?
- Head injury
- Multiple cerebral metastases
What are the symptoms of Kluver Bucci syndrome?
- Visual agnosia
What are arousal disorders defined as in females?
Persistent, recurrent, inability to maintain lubrication-swelling response, leading to lack of lubrication
When are arousal disorders especially prevalent in females?
What are arousal disorders called in males?
What is impotence caused by?
- Tears in fibrous tissue of corpora cavernosa
How do psychological factors cause impotence?
Descending inhibition of spinal reflexes
What can cause a tear in the fibrous tissue of the corpora cavernosa?
Trauma sustained with erection
How is a tear in the fibrous tissue of the corpora cavernosa treated?
- Try to treat with surgical stitches
- If this fails, penile implant
What vascular problems can cause impotence?
What drugs can cause impotence?
- Antihypertensives - ß-blockers, diuretics
How is impotence treated?
What is the mechanism of action of viagra?
Inhibits cGMP breakdown in corpus cavernosum, which increases nitric oxide-stimulated vasodilation and increases penile blood flow leading to erection