Modules 2.1 - 2.3 Male Reproductive Physiology Flashcards
What are the major accessory reproductive organs, gonads and ducts in the Male reproductive system?
External:
- Penis
- Scrotum
Internal:
- Ducts for sperm storage and transport:
- Epididymis
- Vas deferens
- Associated Glands
- Prostate
- bublbourethral
- seminal vesicles
Where is the anatomical location of the urethra? What surrounds it?
Ventral aspect of the penile shaft
Surrounded by corpus spongiosum (erectile tissue)
What is the glans?
Enlarged tip of penis
Covered in foreskin (prepuce)
What makes up the penile erectile tissue?
Corpus spongiosum and corpus cavernosa
What surrounds the corpus cavernosa and corpus spongiosum?
Tunica albuginea - dense tissue (effected in penile fracture)
What is notable about a ventral rupture in the tunical albuginea?
Because the urethra is at the ventral side of the penis, a rupture may effect the urethra
- requires surgical intervention
What are 5 physiological benefits of circumcision?
- Reduced rate of UTI’s
- Reduced rate of foreskin-related complications
- inflammation, odor, infection
- Reduced rate of sexually transmitted infections
- Hiv because foreskin can tear easily (blood to blood transmission)
- Foreskin has lots of langerhans cells to which HIV readily attaches
- syphilis
- genital herpes
- Lower rates of penile and cervical cancer (95-99%
- Lower rates of prostate cancer
What are risks of circumcision?
- Infection (0.4%)
- Bleeding
- Higher risk with adult circumcision compared to newborn
When do the testes descend from the abdomen into the scrotum?
~7th month of pregnancy
What is important about the countercurrent organization of the spermatic cord?
Allows blood temp to decrease/increase when going to testes/body respectively.
Spermatogenesis requires cooler temperature
What is cryptorchidism?
undescended testes
- must be corrected before puberty or pt may become sterile
- prone to cancer
Where does spermatogenesis occur?
In the seminiferous tubules
What is featured in the interstitial tissue of the testes?
Blood vessels and leydig cells
What is the path sperm take through the testes?
Seminiferous tubules
Rete testis
Efferent ductules
Epididymis
Vas deferens
The spermatic cord includes:
The vasculature and the vas deferens
The spermatic cord passes to the testis through the ____________
The spermatic cord passes to the testis through the inguinal canal
Each vas deferens extends behind the _______ and join the _______
Each vas deferens extends behind the bladder and join the seminal vesicles
The vas deferens and seminal vesicals join to form the _______
The vas deferens and seminal vesicals join to form the ejaculatory ducts
The ejaculatory ducts enter the ______ and join the ______
The ejaculatory ducts enter the prostate and join the urethra
Where do the glands secrete their fluids?
Prostate
Bulbourethral
Seminal vesicals
Prostate:
- Urethra
Bulbourethral (Cowper’s) Glands:
- Cowper’s glands secrete a thick, alkaline fluid into urethra at its junction with the prostate
Seminal Vesicals:
- When the vasa deferentia travel through the center of the prostate gland, each widens to form the ampulla of the ductus. It is here that the seminal glands empty their contents.
For each component of sperm give the function and source:
Sperm
Function:
Gametes
Source:
Seminiferous tubules
For each component of sperm give the function and source:
Mucus
- Function:
- lubricant
- Source:
- Bulbourethral glands (cowpers)
For each component of sperm give the function and source:
Water
- Function:
- Provides liquid medium
- Source
- All accessory glands
For each component of sperm give the function and source:
Buffers
- Function
- Neutralize acidic environment of the vagina
- Source
- Prostate, bulbourethral glands
For each component of sperm give the function and source:
Nutrients
- Fructose
- Citric acid
- Vitamin C
- Carnitine
- Function:
- Nourish Sperm
- Source
- Fructose - seminal vesicles
- Citric acid - prostate
- Vitamine C - seminal vesicles
- Carnitine - epididymis
For each component of sperm give the function and source:
enzymes
- Function:
- Clot semen in vagina then liquefy clot
- Source
- Seminal vesicles and prostate
For each component of sperm give the function and source:
Zinc
Function:
- Unknown, possible association with infertility
- Low zinc = low fertility
Source
- Unknown
For each component of sperm give the function and source:
Prostaglandins
- Function:
- Smooth muscle contaction;
- May aid sperm transport
- Source:
- Seminal vesicles
Each seminiferous tubule is surrounded by a basement membrane containing which two types of cells?
- Developing sperm
- Sertoli cells
In the center of each seminiferous tubule is a fluid-filled ______ containing _______ cells
In the center of each seminiferous tubule is a fluid-filled lumen containing mature sperm cells
The tubular wall (of the seminiferous tubules) is composed of _______ and _______ cells
The tubular wall (of the seminiferous tubules) is composed of developing germ cells (sperm) and Sertoli (supporting) cells
Which cell type synthesizes and releases testosterone?
Leydig cells
How long does spermatogenesis take?
64-74 days
30-300 million sperm formed/day
>300 million released in a single ejaculation
Which hormone freely enters sertoli cells?
Testosterone
Sertoli cells in the seminiferous tubules extend from the ______ to the ______
Sertoli cells extend from the basment membrane to the lumen
Sertoli cells are joined together by ________ which forms an unbroken ring around the outer circumference of the seminiferous tubule = _________
Sertoli cells are joined together by tight junctions which forms an unbroken ring around the outer circumference of the seminiferous tubule = blood-testis barrier/ sertoli-cell barrier
Where are leydig cells located?
in connective tissue (interstitial) spaces between tubules
Function of leydig cells?
Activity throughout life?
- Synthesize and release testosterone
- Convert testosterone into estradiol via enzyme aromatase (one source of estrogen)
Active in fetus
Quiescent following birth
Reactivated at puberty
Describe the hormonal control of spermatogenesis:
- Hypothalamus releases GnRH which acts on the anterior pituitary to release LH and FSH
- FSH acts on Sertoli cell
- Increases activity of sertoli cells
- Inhibin - inhibits FSH release
- Androgen-binding protein (ABP) binds testosterone (from leydig cells)
- Increases activity of sertoli cells
- LH acts on leydig cells (aka interstitial cells)
- stimulate testosterone production
- some T goes into circulation (via venous drainage of testes) for secondary effects
- some T goes to seminiferous tubules for spermatogenesis
- Testosterone acts as an inhibitor of LH (ant pit) and GnRH (hypothalamus)
Where does mitosis (of spermatogenesis) occur?
in the basal compartment of the seminiferous tubules - continuously creating additional germ cells
Sperm cells remain bound to _________ until transformation is complete; final maturation occurs in the ________
Sperm cells remain bound to apical membrane of Sertoli cells until transformation is complete; final maturation occurs in the epididymis (lose cytoplasm and develop flagellum)
Describe the three regions of sperm:
Head; midpiece; tail
- Head
- almost entirely nucleus
- contains genetic information
- Acrosome covers tip of nucleus
- protein filled vesicle
- contains enzymes necessary for fertilization
- almost entirely nucleus
- Midpiece
- formed by mitochondria
- provides energy (ATP) for movement
- Tail
- Mostly flagellum
- propels sperm: 1-4mm/min
What happens if sperm has a defect that alters structure/function, energy generation and/or motility?
Fertility is impaired
What can cause mutation/abnormal forms of sperm?
Causes range from genetic to stress and health status
Where is sperm stored prior to ejaculation?
Vas deferens and epididymis
Fluid is absorbed from ________ to concentrate sperm
epididymis lumen
Summarize the process that leads to penile erection
Begin: 3 cylindrical vascular compartments - flaccid (corpus spongiosum and 2 corpus cavernosum)
- Central stimulation -> hypothalamus -> sexual excitation
- Leads to dilation of small arteries + passive compression of adjacent veins (reduce blood drainage)
- Increased blood flow and engorgement of vascular compartments
- Erection
Which muscles contract to contribute to penile tumescence (erection)
Ischiocavernosus muscles - conract to increase pressure
At rest, the dominant input to small penile arteries is _____
At rest, the dominant input to small penile arteries is sympathetic (norepinephrine)
During erection, what happens to the sympathetic input to associated arteries
Sympathetic input is inhibited during erection => net vasoconstriction
Which autonomic neurons to arteries are activated during erection
Non-adrenergic, non-cholinergic autonomic neurons
(No NE of Ach)
Nitric oxide (NO) is released during erection, what is it’s role?
Vasorelaxation
Central neural input that initiates vascular dilation:
Begin ->
- > _________ pathways triggered by thoughts, emotions and sensory inputs such as sight and smell
- > neurons to penis:
- increase activity of neurons that release ______
- decrease activity of __________
-> Penis:
- _________ (vasculature)
- __________
- _________(vasculature)
- __________
Central neural input that initiates vascular dilation:
Begin ->
- > descending CNS pathways triggered by thoughts, emotions and sensory inputs such as sight and smell
- > neurons to penis:
- increase activity of neurons that release nitric oxide
- decrease activity of sympathetic neurons
-> Penis:
-
dilation of arteries (vasculature)
-
erection
-
compression of veins (vasculature)
- reinforces erection
-
compression of veins (vasculature)
-
erection
Ejaculation is a _______ reflex mediated by _______ pathways from _________
Ejaculation is a spinal reflex mediated by afferent pathways from penile mechanoreceptors
What are the two phases of ejaculation?
- Emission:
- Sympathetically mediated contraction of epididymis, vas deferens, ejaculatory ducts, prostate and seminal vesicles
- Empties sperm and secretions into urethra
- Ejaculation
- ~3ml semen (300million sperm) expelled from urethra by rapid contractions of urethral smooth muscle and skeletal muscle at base of penis (bulbospongiosus and ischiocavernosus)
- Sphincter at the base of bladder is closed to prevent semen from entering bladder
- ~3ml semen (300million sperm) expelled from urethra by rapid contractions of urethral smooth muscle and skeletal muscle at base of penis (bulbospongiosus and ischiocavernosus)
- Emission:
- _________ mediated contraction of _______, ________, _________, _______ and _______
- Empties sperm and secretions into _______
- Ejaculation
- ~3ml semen (300million sperm) expelled from ______ by ______________
- What prevents sperm from entering into the bladder
- ~3ml semen (300million sperm) expelled from ______ by ______________
- Emission:
- Sympathetically mediated contraction of epididymis, vas deferens, ejaculatory ducts, prostate and seminal vesicles
- Empties sperm and secretions into urethra
- Ejaculation
- ~3ml semen (300million sperm) expelled from urethra by rapid contractions of urethral smooth muscle and skeletal muscle at base of penis (bulbospongiosus and ischiocavernosus)
- Sphincter at the base of bladder is closed to prevent semen from entering bladder
- ~3ml semen (300million sperm) expelled from urethra by rapid contractions of urethral smooth muscle and skeletal muscle at base of penis (bulbospongiosus and ischiocavernosus)
What is orgasm?
Muscular contractions, pleasure and systemic physiological changes (eg increased HR and BP)
Followed by latent period - erection is not possible
