Male Reproductive System Flashcards Preview

Anatomy and Physiology > Male Reproductive System > Flashcards

Flashcards in Male Reproductive System Deck (32):


Production of androgens
Production, nourishment, storage of male gametes
Introduction of male gametes into female reproductive tract



- epididymal
- vas deferens
- urethra
- seminal vesicles
- prostate
- bulbourethral


Testes & scrotum

4cm long, 2.5cm diameter
Enclosed in sac = scrotum
Scrotal septum seperates scrotum in 2 parts
Each testes is suspended from spermatic chord
Passes through inguinal canal to/from abdominal cavity
--> Testes:
Contains.. Vas deferens, testicular artery, cremasteric artery, testicular venous plexus, lymph vessels, nerves


What are the 2 tissue layers covering the testes?

Tunica vaginalis
- thin serous outer layer
Tunica albuginae
- white coat
- tough fibrous inner layer (divides testes into testicular lobules)


Testicular lobules

Each testes is divided into 300 by each tunica albuginea
Each lobule contains 1-4 seminiferous tubules
Site of spermatogenesis


What are seminiferous tubules?

Walls formed of sertoli cells
Sertoli cells secrete nutrients for developing spermatozoa
Spermatogenic cells are in the walls(most immature by basement membrane)
At maturity, sperm released into the lumen


What is mitosis?

Division of parent cell into 2 daughter cells that are genetically identical
Diploid (2n)


What is meiosis?

Division of parent cells into 4 daughter cells with half the number of chromosomes
Haploid (n)
Forms gametes



1. Diploid spermatogenia duplicte --> diploid primary spermatocytes
2. Primary spermatocytes divide into 2 haploid daughter cells --> secondary spermatocytes
3. Secondary spermatocytes divide into 4 haploid daughter cells = spermatids
4. Development of spermatids into mature spermatozoa


Structure of sperm

Head ---- acrosome (outer) nucleus (inner)
Middle piece ---- spiral mitochondria, axoneme
Tail (flagellum)


What are the 2 cells in seminiferous tubules called?

Sertoli cells - required for maturation of spermatozoa
- form 10% of cells in testes
- necessary for spermatogenesis
- support and nourishment
- more developing sperm towards lumen
- produce fluid for transport
- forms blood-testes barrier
- prevents immune response
- secrete testicular fluid:
> inhibin
> androgen-binding protein
> Mullerian-inhibiting substance
Leydig cells - secrete androgenic steroids near capillaries


How does the endocrine system control the male reproductive system?

1. release of GnRH from anterior pituitary gland
2. Stimulates release of FSH and LH
3. FSH travels to the seminiferous tubules and sustentacular cells, which cause the secretion of inhibin, synthesis of androgen-binding protein and stimulation of spermatogenesis
4. LH travels to the interstitial cells, causing the secretion of testosterone, causing the stimulation of sustentacular cells to release inhibin, ABP and spermatogenesis
5. the release of testosterone also has affects on the CNS, causes stimulation of bone and muscle growth, establishes and maintains male secondary sex characteristics, and maintenance of accessory glands and organs


What happens if sperm count is too high?

Inhibin release is increased, negative feedback on FSH and GnRH by hypothalamus


What happens if sperm count is decreased below 20 million?

Inhibin release is decreased


Temperature control of testes

Testes kept just below body temperature at 35c
Testes are drawn closer to the body by the cremaster muscle in response to cold
Dartos muscle decreases SA and assists cremaster
Testes cooled by heat exchange at pampiniform plexus


Describe the duct system

Straight seminiferous tubules
Rete testis
Efferent ductules
Epididymal duct
Vas deferens
Ejaculatory duct



Attached to posterior surface of testes
Spermatozoa are matured and stored in the tail
Continuous with bas deferens


Vas deferens

45cm long fibromuscular tube-
narrow lumen surrounded by thick smooth muscle layer
Ascends posterior to testis along spermatic chord
Enters abdominal cavity through inguinal canal
Dilated terminal portion (ampulla) joins the ejaculatory duct
Stores and conveys spermatozoa (expelled by peristalsis)
VASECTOMY = sperm still produced but deteriorates and are phagocytosed, success of reversal depends on patient eg age


What are the accessory glands and what do they do

Seminal vesicles
Prostate gland
Bulbourethral gland
These glands produce the majority of semen (sperm + accessory gland secretions)


Seminal vesicles

Convoluted muscular glands 5-7cm long
Posterior to bladder
Joins vas deferens to form ejaculatory duct when sperm and seminal fluid mix
Yellowish viscous alkaline fluid containing fructose, ascorbic acid, prostaglandins, coagulating enzymes
- 60% semen volume


Prostate gland

Lies inferior to bladder
Surrounds prostatic urethra
Milky, slightly acid fluid containing citrate and enzymes, and prostate-specific antigen
Role in activating sperm
- 30% semen volume
Has tubular-alveolar glands
Main prostatic glands in outermost ring


Problems with prostate gland

Often enlarged in older males: benign prostatic hyperplasia
- lower urinary tract symptoms:
- increased frequency, nocturia, weak stream
- alpha adrenergic blockers eg. tamsulosin - reduce smooth muscle tone
- 5-alpha reductase inhibitors eg. finasteride - blocks conversion of testosterone to dihydrotesterone
- acute or chronic
- pain when urinating and ejaculating, general discomfort in pelvic area
- acute = antibiotics and painkillers
- chronic = antibiotics, analgesics


Prostate cancer

To do with levels of prostate-specific antigen
- during coughing and sneezing prostatic blood may enter vertebral veins
- lower vertebral and pelvic metastases


Bulbourethral glands

Pea-sized glands inferior to the prostate gland
Lined by mucus-secreting epithelium
Mucus-like secretion enters urethra during sexual arousal
Drains into spongy part of urethra
Neutralised urine residue



Common path for urine and semen
Approx. 20cm long in males
> Prostatic part
> Membranous part: passes through urogenital diaphragm
> spongy part: passes through penis



Divided into 3 regions:
- root: bulb in midline attached to inferior surface of urogenital membrane (become corporus spongiosum), crura attach the root of penis to pubic arch (becomes corpora cavernosa)
- shaft (body): spongy urethra + 3 cylindrical bodies of erectile tissues - corpora cavernosa (paired) and corporus spongiosum, dense network of connective tissue, smooth muscle and blood vessels, bound by tunica albuginea
- glans penis: tip of corporus spongiosum expanded to form glans penis


Histology of the penis

Vascular spaces in erectile tissue
Lined with endothelium
Spongy urethra lined with pseudo-stratified columnar epithelium



1. Arteries dilate (parasympathetic impulses: endothelial cells produce nitric oxide and relax smooth muscles)
2. Corpora cavernosa and corpus spongiosum become distended
3. Compression of veins reduces outward blood flow


Emission and ejaculation

Sympathetic control
1. Contraction in smooth muscles of epididymal duct, vas deferens, prostate and seminal vesicles
2. Bladder sphincter muscle constricts
3. Emission: the release of a small volume of seminal fluid before ejaculation
4. Ejaculation: contraction of bulbospongiousus muscle


Describe the functions and constituents of semen

2-5ml per ejaculation
- transport medium
- nutrient provision
- has chemicals which protect and activate the sperm
- 20-150 million sperm per ml
- seminal fluid (secretions of seminal vesicles, prostate and bulbourethral glands)
> fructose, prostaglandins, relaxin, enzymes, seminal plasmin, fibrinogen, fibrinolysin


What is oligospermia?

Less than 15 million sperm per ml = conception may be difficult


If man has inability to ejaculate, low sperm count, poor motility etc what can he do to increase chances of pregnancy?

-intracytoplasmic sperm injection
- intrauterine insemination
- donor insemination
- gamete intra-fallopian transfer