Male reproductive system

1. gametogenesis (spermatogenesis)

2. delivery of sperm to female tract

3. secretion of sex hormones (androgens- esp testosterone)

Gonads: Testes

Reproductive tract: Epididymis, ductus (Vas) deferens, urethra, external genitalia

external genitalia: penis, corpora cavernosa, corpus spongiosum

accessory glands: prostate, seminal vesicles, bulbourethral glands

key roles: sperm and hormone production

Lobules, seperated by septums

lobules contain seminderous tubules which feed into the ductus epididymas

1. leydig cells- outside tubules which are tesosterone producing

2. sertoli cells- within tubules

3. germ cells at different stages

produce testosterone

blood-testes barrier, nourishment for sperm, ABP

anterior and posterior

gonadotroph cells in Anterior pituitary

GnRH- gonadotrophin releasing hormone

ley dig cells to make testosterone

sertoli cells to make inhibin

e.g. if testosterone/inhibin levels are high, sends signals to AP/GnRH to reduce FSH and LH secretion

T is synthesised by foetal leydig cells in response to maternal hCG

T masculinizes the external genitalia (T conversion to DHT by 5alpha reductase enzyme)

T promotes descent of testes into scrotum

low production until puberty

around puberty- LH production by pituitary is iniated

- penis scrotum enlargement,
- scrotum darkening, enlargement of epididymis, prostate, seminal vesicles
- essential for spermatogenesis
- maintains reproductive tract through adulthood

- development of libido-sex drive

- control of gonadotrophin secretion- via negative feedback

- Promotes muscle growth responsible for male body conformation
o increases protein synthesis
odecreases protein degradation
o increases lean:fat ratio
- Promotes bone growth at puberty and then closure of epiphyses
- Induces male pattern of hair growth (i.e. beard)
- deepening of voice
- Skin thickens & sebaceous glandsthicken

- decrease testosterone production
reduced testicular androgen response to LH
physical changes
- loss of muscle mass
- shrinking of reproductive organs, - loss of libido
- harder to get erection
- osteoporosis

mental changes- depression, reduced energy

pool shaped blood vessels that fill with blood during an erection

erectile tissue

Spongy muscle, surrounds urethra

- hypothalamus releases GnRH, which acts on anterior pituitary (AP)
- AP releases LH and FSH
- LH stimulates Leydig cells to produce testosterone which stimulates spermatogenesis
- FSH also stimulates spermatogenesis in semininferous tubules

sympathetic and parasympathetic nerves innervate blood vessels and sinusoids in erectile tissues

psychogenic and tactile stimulation triggers increased acetylcholine (para) and decreased noradrenaline (sympa) release ---> increased eNOS ---> increased NO

dilation of smooth muscle of aterioles and sinusoids within erectile tissue,

increase in blood flow into corpus cavernosum and corpus spongiosum = erection

cavernous sinuses contract- less blood

smooth muscle surrounding sinuses relaxes- causing sinusoidal dilation
Tissue engorgement flattens the surrounding veins 'trapping' blood => erection

•Neurotransmitters (Ach) and neuronal nNOS released from the cavernous nerve, stimulate production of eNOS within the vascular endothelial cells
•NO diffuses into surrounding vascular smooth muscle
•NO binds to and activates guanylyl cyclase which converts GTP into the second messenger cGMP
•cGMP activates its dependent protein kinase - protein kinase G (PKG)
PKG activation promotes vascular smooth muscle relaxation= erection

Results in smooth muscle relaxation = erection

nervousness, guilt, relationship problems, depression, exhaustion

- Deterioration of arteries
- diabetes
- obese
- smoking
- alcohol
- certain drugs- anti depressants, anti hypertensives

sildenafil citrate. it was first for hyper tension and angina, but found out it also treats ED

inhibits enzyme responsible for degradation of cGMP to GMP. this enzyme is PDE5

stabilization of cGMP= prolonged action

more sustained dilation of sinusoidal smooth muscle via PKG dependent reduction in free cytosolic calcium ion conc

engorgement of erectile tissue with blood

flushing, headache, nasal congestion, stomach pain after meals

possibly: blur vision loss of hearing bladder pain dizziness pain on urine

Persistent, painful erection lasting longer than 4 hours - in absence of sexual stimulation/desire

-ischemic (no flow): obstruction in venous drainage

-non ischemic(high flow): excess arterial supply

for pulmonary arterial hypertension, under the name REVATIO

reduces the blood pressure- by widening blood vessels in lungs

walnut sized gland that surrounds urethra just below bladder .

a milky slightly alkaline prostatic fluid

muscular contractions of gland propel prostatic fluid into urethra.

the prostatic fluid mixed with sperm and secretions from other glands = ejaculation

large with age.

enlarged prostate.

symptoms: hesitant weak urine
- urgency or dribbling leaking urine
- more frequent urine esp at night

Alpha adrenoceptor blockers- relax muscle fibres within prostate- reduce obstruction to urine flow
eg tamsulosin, terazosin

viagra should be used w caution when taking alpha blockers as may cause fall in bp = dizziness fainting
- 5-alpha-reductase inhibitors
- surgery

eg Finasteride (proscar) - inhibits growth of prostate and reduce the size of gland

transurethral resection

or

laser resection

- increasing age
- family history- 2.5x likely to get if father or bro got
- ethnicity- afro carribeans 3x likely than whites
- diet

similar to bph:

hesitant weak urine, leaking, urgency, dribbling, more frequent

test by gp: first urine test to rule out infec

then blood test- measure prostate specific antigen

DRE- digital rectal examination


hospital tests:
-TRUS guided biopsy
-CT, MRI, Bone scan

depends on localized, locally advanced and advanced

active surveillance, radiotherapy, surgical prostatectomy

hormone therapy

tumour growth is often androgen dependent so aim is to block androgen production

can also surgical castration

1. down regulate GnRH receptors- to block LH and androgen secretion

2. block androgen synthesis directly

3. block androgen receptors

- block production of androgen
Goserelin
Buserelin acetate

Abiraterone
Finasteride

taken orally either alone or together with GnRH agonists

Bicalutamide
Flutamide
Cyproterone acetate