Grade 12 Human Reproduction Part 1 Male reproductive organs Flashcards
What makes up the male reproductive organs?
- Primary sex organs - the testis / testes in scrotum
- Ducts - epididymis, sperm duct (vas deferens) and urethra
- Accessory glands e.g. prostrate
- External genitalia - penis
To simplify: Testes, Tubules for the transport of sperm, accessory glan
What is the scrotum and what is its function?
**A sac of skin that ecloses the testis.
**Functions: **
* Temperature regulator - keeping testis 2 - 3 degrees lower than body temperature ( for formation of fertile sperm).
* Protects the testis
What is the testis?
- Primary male sex organs - pair of **testes **
- Two oval structures, suspended outside the body in the scrotum
- Oval shaped gland, about 5cm in length
- Divided internally into compartments or small lobules
- Each lobule contains several closely packed, convoluted seminiferous tubules - 250m in each testis
- Tubules - lined with special cells, namely germinal epithelium.
- Epithelium cells can divide and give rise to sperm (male gametes) in a process called - spermatogenesis
- Between the tubules (connective tissue) are groups of endocrine cells - the interstitial cells / cells of Leydig = Produce male hormone testosterone
- A few germinal epithelium cells develop into l**arger columnar cells - Sertoli cells = provide food for sperm
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Discuss the function of the testis:
- Sperm production
- Testosterone - male sex hormone - development of secondary sexual characteristics
List the tubules for the transport of sperm (4)
- Epididymus
- Vas deferens (sperm duct)
- Ejaculatory duct
- Urethra
What is the epididymus?
Seminiferous tubules join to form the epididymis where they:
* mature to become motile and fertile
* are stored for several months (after which they are broken down by the epithelial cells of the epididymis and re-absorbed into the body
* situated at the back of the testes and lined with a mucous membrane
Explain the function of the epidiymis: (2)
- Stores sperm produced in testes - mature inside until ready to become motile and fertile and fertilise ovum
- Mucous membrane lining epididymis secretes a substance that, together with peristaltic movements of tubule walls, facilitate movement of sperm
What is the sperm duct / vas deferens?
- Muscular sperm duct = continuation of epididymis, which passes through abdominal cavity and opens in urethra
- Forms a swelling just before it joins the urethra = ampulla
What is hte function of the sperm duct / vas deferens?
- Transports sperm - by means of peristaltic movements, from epididymis to urethra
- Ejaculation
What is the ejaculatory duct?
The ampulla of the vas deferens leads to a muscular tubule, the ejaculatory duct.
What is the function of the ejaculatory duct?
The smooth muscle fibres in the duct contract, forcing the contents of the duct (semen) along the urethra to the exterior.
I.e. to ejaculate
What is the urethra?
The duct at the end of the uro-genital system leading to the exterior.
What is the function of the urethra?
- Forms a common duct for the transportation of semen and urine.
- These two processes never occur together.
LIst the accessory glands:
- Seminal vesicles
- Prostate gland
- Cowper’s glands
Explain seminal vesicles:
- Two sac-like structures connected by a tubule to the lower end of the ampulla.
- Lined with a mucous membrae that secretes a yellow-ish, sticky substance.
What is the function of the seminal vesicles?
Secretion of mucous membrane provides fructose, main source of food for sperm.
What is the prostrate gland?
- **Plumb-sized **
- Surrounds urethra at the base of the bladder - where ejaculatory ducts join the urethra
- Conical gland
- Secretes a milky alkaline liquid, the prostrate fluid, which gives semen its characteristic smell
Discuss the function of the prostrate gland:
Secretes prostrate fluid - that:
1. ensures maximum sperm motility (certain enzymes)
1. protects sperm against low pH (acidity) in the urethra and vagina
What are Cowper’s glands?
**Two small glands on either side of the urethra - just below the prostrate gland.
What are the functions of Cowper’s glands?
- Secretion = greater motility of sperm
- Clears the urethra of urine residue - neutralise acidic urine
- Lubricates the head of the penis - prevents mechanical damage during ejaculation
Explain what the penis is:
- Male sex organ
- Consists of shaft + head region
- Cone-shaped head - glans penis
- Partially covered by foreskin - remove through circumcision
- Shaft is divided up into three columns of erectile tissue - Corpus carvernosa (2 columns) , corpus spongiosum
- Erectile tissue in these columns become filled with blood during arousal due to increased blood pressure and blood flow = erection
Explain the three columns that the shaft of the penis is divided into:
- **Corpus cavernosa **- 2 columns of erectile tissue that form the upper part of the penis
- Corpus spongiosum - 1 smaller column of erectile tissue that surrounds the urethra on the lower part of the penis. Ensures that the urethra remains open during erection for the passage of semen.
What mechanism brings about an erection of the penis?
- Dilation of the dorsal and central arteries supplying blood to the penis.
- This allows more blood to fill the three spongy erectile tissue chambers (columns), causing the penis to lengthen and stiffen.
What is the function of the penis?
- **Deposits semen with sperm **into the female’s vagina during copulation.
- Sperm are brought **closer to the egg **for fertilisation - increases chances of fertilisation.
