Male Reproductive System Flashcards
What are the functions of the male reproductive system?
1) To produce male andrgoens (sex hormones)
2) To produce, store and nourish male gamates (sex cells)
3) To introduce gamates into the female reproductive tract
Where are the testes located and what is produced inside them?
The testes are located within the scrotum. Sperm is produced within the testes and sperm will then travel through a series of ducts.
Where is the scrotum located and what is the benefit of this?
The scrotum is located just outside the abdominal/pelvic cavity. This allows for the sperm within the testes (inside the scrotum) to be stored at a temp. lower than body temp.
What muscles are responsible for determining how close the scrotum is to the body?
Cremasteric muscles
Where is the spermatic cord’s location?
Passes into the abdominal cod via the inguinal canal
What does the spermatic cord contain?
Blood vessels, lymphatic vessels and nerves
What is the function of the spermatic cord?
To suspend the testes in the scrotum
Length and width of the testes:
L: 4cm
W: 2.5cm
What are the 7 contents of the testes?
1) Blood vessels
2) Lymphatic vessels
3) Cremaster muscle
4) Cremaster artery
5) Testicular artery
6) Testicular venous plexus
7) Vas deferens
What is the function of the scrotal septum?
To seperate the scrotum into 2 compartments
What are the fasical layers that surround the testes?
1) Outer layer = Tunica Vaginalis
- Double layer
- Thin
- Derived from the peritoneum
2) Inner layer = Tunica Albuginea
- Thick
- “white coat”
- Seperates the testes into testicular lobules
How many testicular lobules does the tunica albuginea divide EACH testes?
250 - 300 testicular lobules
How many seminiferous tubules come from each testicular lobule?
1 to 4
What happens in mitosis and what is produced?
The parent cell is divided into 2 daughter (diploid) daughter cells. The daughter cells are identical to the parent and to each other.
What happens in meiosis and what is produced?
The parent cell is divided into 4 daughter (haploid) cells. These form the gametes.
Which cells undergo meiosis?
Germ cells
Where in the testes is the sperm produced?
Seminiferous tubules
What is the term used for the production of sperm?
Spermatogenesis
What cells form the walls of the seminiferous tubules and what do they secrete?
Sertoli cells secrete:
1) Nutrients that well help the development of the spermatogonium.
2) Testicular fluid - helps to transport the developed spermatids to the lumen of the seminiferous tubules.
Where are the spermatogonium cells stored?
Inside the walls of the seminiferous tubules. At the basement membrane the spermatogonium cells are immature and they will develop and become more mature the further towards the lumen of the seminiferous tubules they get.
When they are fully matured (spermatids) = they can be released into the lumen.
Where are the leydig cells located and what do they secrete?
Leydig cells are found near the capillaries and secrete androgenic steroids near the capillaries.
What % does the sertoli cells take up of the overall cells in the testes?
10%
What are the 3 substances that are contained in the testicular fluid (secreted from the Sertoli cells)?
1) Inhibin (protein hormone) = This is secreted due to a high sperm count to reduce spermatogeneisis.
2) Androgen-binding hormone = Encourages the developing sperm to bind to the androgens which will encourage spermatogenesis.
3) Mullerin - inhibiting substance
The structure of the sertoli cells?
Tall and columner
The 2 compartments of the sertoli cells?
1) Adluminal compartment
2) Basal compartment
What is the function of the tight junction that separates the 2 compartments of the sertoli cells?
It acts as a blood-testis barrier. Sperm isn’t produced at birth so the body doesn’t recognise it as a self cell. The tight junction prevents any sperm from entering the blood so that the body doesn’t carry out an immune defence on its own sperm.
Steps of the life cycle:
1) 2 multicellular diploid adults
2) Germ cells from both adults undergo meiosis to form gamates (haploid)
3) The 2 haploid gametes fuse at fertilisation
4) Zygote is formed
5) The zygote develops into the foetus via mitosis
Zygote
Fused cell which develops into the foetus
How long does it take for spermatogenesis to take place?
62-74 days
What are the 2 types of germ cells?
Type A = stay within the basal membrane of the seminiferous tubules Type B (spermatogonium) = undergo spermatogenesis
Spermatogonium
Type B germ cells (diploid) and they undergo spermatogenesis
What are the steps of spermatogenesis?
1) Spermatogonium (Type B diploid germ cells) will undergo mitosis.
2) Primary spermatocytes and formed (diploid)
3) Meiosis 1: Primary spermatocytes undergo meiosis and form 2 daughter haploid cells (secondary spermatocytes)
4) Meiosis 2: Secondary spermatocytes undergo meiosis to form overall 4 daughter haploid cells (spermatids)
5) Spermiogenesis: Spermatids develop into the mature spermatozoa.
What are the final mature sperm cells called?
Spermatozoa
In what part of the sperm’s structure are the enzymes?
Acrosome
In what part of the sperm’s structure is the genetic material?
Inside the nucleus inside the head
Why is the middle part important of the sperm’s structure?
Contains spiral mitochondria
GnRH
Gonadotropin - releasing hormone
Endocrine functions on the male reproductive system:
1) Hypothalamus releasing GnRH
2) Stimulates the anterior pituitary gland to secrete LH and FSH
What does FSH stimulate and what are the 3 effects?
Stimulates: Seminiferous tububle which then stimulates the Sertoli cells
3 effect of this:
1) Stimulates the synthesis of androgen-binding protein
2) Stimulates spermatogenesis and spermiogenesis
3) Stimulates the sertoli cells to secrete inhibin.
4) Inhibin will have a negative feedback effect on the anterior pituatory gland - to stop releasing FSH.
What does LH stimulate and what are it’s 5 effects?
Stimulates: Leydig cells.
4 effects of this:
1) Acts on the CNS.
2) Stimulates the growth of muscles and bones
3) Establishes and maintains the secondary male sex characteristics.
4) Maintains the accessory organs and glands
Stimulates: Sertoli cells (directly)
(same 3 effects as FSH)
What 3 things are involved in temperature control of the testes:
1) Heat exchange with the pampiniform plexus (a network of veins surrounding the arteries going into the testes).
2) Cremaster muscles will contract to bring the testes closer to the body (to warm them in the cold)
3) Dartos muscles will contract which wrinkles the skin which lowers the surface area of the scrotum so that less heat is exchanged with the env (in the cold)
What does the duct system do?
Allows for the mature sperm (created during spermatogenesis in the seminiferous tubules) to escape.
What is the escape route for the mature sperm out of the testes?
1) Straight tubules
2) Rete testis (gaps in between the seminiferous tubules)
3) Efferent ductules
4) Epididymis
5) Vas deferens
6) Ejaculatory duct
7) Urethra
Where is the epididymis?
Attached to the posterior surface of the testes
What does the epididymis consist of?
highly coiled tubules
How long does it take for sperm to travel through the epididymis?
20 days
What is the epididymis seperated up into and where are the spermatozoas stored?
1) Head
2) Body
3) Tail - where the spermatozoas are stored (continuous with the Vad Deferens)
Description of the Vas Deferens?
45 cm long tube.
Narrow lumen - surrounded by a thick layer of smooth muscle.
What is the position of the Vas Deferens?
Extends from the tail of the epididymis, passes the middle of the uthera, continues through the abdominal cavity via the inguinal canal, passes the bladder superior to posterior, at the end of the vas deferens it will dilate t become the AMPULLA.
Function of the Vas Deferens:
Through peristalsis will transport the sperm from the tail of the epididymis to the ampulla
Where does a vasectomy take place?
The Vas Deferens is cut near to the epididymis
What happens to sperm after a vasectomy has taken place?
The sperm is still produced in the seminiferous tububles. However, as it is not being lost through ejaculation, the sperm will deteriorate and phagocytosed
What 2 factors make it more likely for a successful vasectomy reversal to take place?
1) Under 30 years
2) It is under 7 years post operation
What are the 3 accessory glands?
1) Seminal vesicle
2) Prostate Gland
3) Bulbourethral gland
What is the overall function of the accessory glands?
Produce the majority of the semen.
What best describes the seminal vesicle?
Convoluted muscular gland
Where is the seminal vesicle located?
Posterior to the bladder
What is the function of the seminal vesicle?
1) To join together the 2 ampulla’s in order to form the ejaculatory duct
2) To secrete semen into the ejaculatory duct, in order to mix with the sperm
What % of overall semen production does the seminal vesicle produce?
60%
What is contained in the fluid produced from the seminal vesicle?
1) Viscous
2) Fructose
3) Asorbic acid
4) Prostaglandins
5) Coagulating enzyme (keeps the semen sticky)
What best describes the prostate gland?
Doughnut-shaped gland. Size of a peanut
Where is the prostate gland located?
Inferior to the bladder and surrounds the urethra
What is the function of the prostate gland?
To activate the sperm
What % of overall semen production does the prostate gland produce?
20%
What is contained in the fluid produced from the prostate gland?
1) Milky
2) Citrate
3) Slightly acidic
4) PSA (prostate-specific antigen)
What are the components of the prostate gland?
The prostate gland contains tubular-alveoli glands that are concentrated into 3 area (outside-in)
1) Peripheral zone glands
2) Outer mucosal glands
3) Inner mucosal glands (surround urethra)
How many tubular-alveoli glands are contained in the prostate gland?
20-30
Smooth muscle surrounding the prostate gland:
Contracts so the fluid produced in the prostate gland can mix with the sperm in the urethra
What are the 3 problems associated with the prostate gland?
1) UTI’s
2) Prostatitis
3) Prostate cancer
What are UTI’s in the prostate gland caused by?
The prostate gland enlarges and pushes onto the urethra making it harder to urinate
Who in the population is more likely to be affected by UTI’s?
1) 50% of over 60’s
2) Older males
What is prostatitis?
Inflammation of the prostate gland
What are the causes of prostatitis?
Acute - bacterial cause
Chronic - unknown cause
Which of the 2 prostatitis is most common?
Chronic
What is the cause of prostate cancer?
The Prostate-Specific Antigen in the fluid secreted from the prostate gland increases
What is the complication of prostate cancer?
Metastases
Definition of metastases
Cancer forming elsewhere in the body other than the primary cancer site
What is the best way to describe the bulboural gland?
pea sized and lined with mucus secreting membrane
Where is the bulboural gland located?
Inferior to the prostate gland
What is the function of the bulboural gland?
(during sexual arousal) To secrete the mucus from the mucus-secreting epithelial layer in the spongy part of the urethra in order to neutralise the urine.
Description of the urethra
- Appox. 20cm long.
- Forms a pathway for urine and sperm
- Divided into 3 parts
What are the 3 parts of the urethra?
1) Prostatic part
2) Membranous part
3) Spongy part
Prepuce
Foreskin covering the glans penis and external urethra
3 divisions of the penis:
1) Root
2) Shaft (body)
3) Glans Penis
2 parts of the root of the penis
1) Bulb
2) Crus
What is the bulb of the penis attached to?
Inferior part of the urogenital membrane
What does the bulb of the penis become?
Corpus spongiosum penis (single)
What is the crus of the penis attached to?
Pubic arch
What does the crus of the penis become?
Corpora Cavernosa penis (paired)
What do both the corpus spongiosum penis and the corpora cavernosa penis contain?
1) Dense network of connective tissue
2) Blood vessels
3) smooth muscle
What layer bounds the corpus spongiosum penis and the corpora cavernosa penis?
Tunica albuginea
What runs through the corpus spongiosum penis?
Urethra
What forms the glands penis?
The tip of the corpus spongiosum expands to form the glans penis
Where are the dorsal arteries of the penis located?
Outside the corpora cavernosa penis (inside the tunica albuginea layer)
Where are the deep arteries of the penis located?
Inside the corpora cavernosa layer
How does an erection occur?
1) Dorsal artery and deep artery dilate due to parasympathetic impulses.
2) This causes the endothelial cells to release nitric oxide.
3) This causes the smooth muscles inside the corpora cavernosa and corpus spongiosum to relax.
4) More blood is able to enter the penis.
5) The corpora cavernosa and corpus spongiosum swell.
6) They push on the veins.
7) This reduces the outward blood flow from the penis.
Which erectile body contributes more to the erection?
Corpora cavernosa (as it contains the deep artery)
How does Viagra work?
By increasing the release of nitric oxide from the artery endothelial cells for longer, so smooth muscle relaxes for longer.
What part of the ANS controls the erection?
Parasympathetic
What part of the ANS controls ejaculation?
Sympathetic
What muscle is involved in ejaculation?
Bulbospongiosus muscle
What causes ejaculation?
1) The smooth muscle of the epididymis, Vas Deferens, seminal vesicle and prostate gland.
2) Sphincter of the bladder constricts.
3) Emission: A small volume of seminal fluid is released before ejaculation.
4) Ejaculation: occurs due to the contraction of the bulbospongiosus muscle.
What is the function of semen?
1) A transport medium for sperm
2) The nutrients and chemicals it contains protects and activates sperms
How much semen per each ejaculation?
2-5 ml
How many sperm cells per ml of semen?
20-15 of million
What is the problem called if you have less sperm per ml semen and how much less is a problem?
Less than 15 million sperm cells per ml.
Problem is called = OLIGOSPERMIA
What are the 2 constitutes of semen
1) Seminal fluid (from the seminal vesicle, prostate gland and bulbourethral gland)
2) Sperm
How long is the embryo in a sexually indifferent stage for?
For up to 7/8 weeks the embryo is sexually indifferent as it will contain both male and female ducts.
When/how does a female embryo develop?
After 8 weeks the Mullerian ducts will develop a uterus and the Wolfarian ducts will degenerate
When/how does a male embryo develop?
After 7 weeks the Wolfarian ducts will develop in testes. The Sertoli cells will secrete Mullerian-inhbiting substance and the Mullerian ducts will degenerate.
The Leydig cells will secrete androgens and the male genitalia will develop.
