male reproductive system

Question 1

what is the biosynthetic precursor of steroids?

Answer 1

cholesterol

Question 2

what hormonesa re needed for male reproductive function?

Answer 2

estrogen and progesterone

Question 3

why are estrogen and progesteron needed within a male?

Answer 3

sustain spermiogenesis = production of mature and motile spermatozoa

Question 4

what is the main parts of the male reproductive tract/

Answer 4

testes is the site of sperm production
epididmysis is where the sperm pass through on their way to the vas deferens
the prosate semi vesicles and rhe bulbourethal gland are the three accessory glands within the male - they give the fluid in the ejaculation

Question 5

what happens in the anterior cutaway of the male reproductive tract?

Answer 5

the prostate gland adds secretions

- little bit of the fluid goes through the ves deferens but majority of ejaculate comes from the 3 accessory glands

Question 6

what causes an erection?

Answer 6

tissue within the penis becoming filled with blood

Question 7

what are the male reproductive tract functions?

Answer 7

 Testis – sperm production, steroid hormone production
 Epididymis – sperm collection and maturation
 Ductus deferens – transport and storage
 Accessory glands – contributions to seminal fluid
 Urethra – transport

Question 8

what is the testicular anatomy?

Answer 8

Seminiferous tubles is where the sperm are produced and from here, they pas through some tubes to get to the efferent ducts into the epididmyus.
As a male you have about 600 m of tubes, so there is a lot fo tubes concentrated into one space.

Question 9

what do blue dots show on a histological section of a testes seminiferous tubules?

Answer 9

The larger round dots = resident epithelial cells of the tubules – nurse cell provide an environment where sperm production can occur.
Smaller dots are more conc in the center of the tubules – nuclei are smaller. These are moving upwards through the nurse cell environment and conc near the top side of the inner suface of the cell. From here they are extruded and transported.

Question 10

where is sperm produced?

Answer 10

the sperm from precursor as they mature move towards the lumen.
produced in the seminiferous tubule.

Question 11

where does steroid production start?

Answer 11

beginning of the step from cholestreol to androgen is in the leydig cell.
they need to be then transprotted to the sertoli cell

Question 12

where are androgens produced?

Answer 12

mostly in LEYDIG CELLS

Question 13

why is DHT important?

Answer 13

if men have mutations it impeded the function of alpha 5 reductase, so you will get developmental abnormalties.
dht is needed for maturation of testerone (more active then testerone itself)

Question 14

what are the common properties of the receptors superfamily for steroid hormones?

Answer 14

• they are a protein which has TWO binding sites, one for the steroid and one for the DNA
• binding to the steroid ligand produces a compled that acts on DNA
• this alters the gene expressed

Question 15

what is the androgen receptor?

Answer 15

• androgens are defined as compunds which interact with the androgen receptor.
• all major cell populations of testis, epididymis and accessory glands express androgen receptor.
• the receptors are also found in tissues where secondary sexual characterstics appear

Question 16

what is a target tissue for androgens, estrogen and progesterone?

Answer 16

the brain

Question 17

what is more likely to lead to male pattern baldness?

Answer 17

having a higher endogenous androgen level

Question 18

what happens in the HPG axis?

Answer 18

• GnRH arises in the hypothalmus and is transported down small blood vessels to the anterior pituiatry
• the anterior pituitary produced two important polypeptide hormones LH and FSH.
• these control sperm production and maturation

Question 19

what is LH and FSH?

Answer 19

LH = luteninsing hormone
FSH = follicle stimulating hormone

Question 20

where do polypeptide hormones need receptors?

Answer 20

on the membrane so they can signal as they are macromolecules.

Question 21

are steroid hormones lipid soluble?

Answer 21

yes

this means they can pass across cell membranes and reach the cytoplasm

Question 22

what does the sertoli cell produce?

Answer 22

androgen binding protein

ABP

Question 23

what does ABP do?

Answer 23

has the steroid isnt very water soluble
so it binds to the steroid hormone and is released as a complex to get from one organ to another.
it helps to impive the capacity of the system to transport the steroid which isnt very water soluble

Question 24

what does ABP bind to?

Answer 24

T and DHT and concentrates them in the luminal fluid of the seminiferous tubule

Question 25

what does the binding of ABP stimulate?

Answer 25

• spematogenesis in the seminiferous tubule
• sperm maturation in the epididymis
• accessory gland secretions
• myoid cell contractile actibity to propel sperm along the tract

Question 26

how is feedback controlled in male?

Answer 26

much easier in male then female
- the feedback of testosteron is both at the anterior pituitary and the hypothalamus. thus means there is a system in place so you cannot overproduce.

Question 27

how is feedback controlled within the female?

Answer 27

in female there is a specific time window in menstrual cycle where estrogen stimulates positive feedback - short time period.
there is also a pulsatile release of GnRH within a female where in a male there is just a constant frequency

Question 28

what happens during spermatogenesis?

Answer 28

1. sperm move from the base of the cell upwards this then leads to them undergoing two miotic divisions.
2. after this they begin to acquire characterstics which allow us to recognise them as sperm
3. sperm exit from the inner suface tail first
4. they grow a tail from the lumen
5. later stages you get maturation which is androgen dependent

Question 29

when do sperm become motile?

Answer 29

when sperm are released into the lumen they are not yet motile.
they gain the ability to swim in the epididymis (DHT dependent)

Question 30

what is the volume of an ejaculation?

Answer 30

1.5-5mL

Question 31

what is the sperm count within an ejaculation?

Answer 31

40-250 million per mL

Question 32

what is the sperm motility 1 hour and 3 hours after ejaculation?

Answer 32

1 hour = 70%

3 hours = 60%

Question 33

what is the leukocyte count of an ejaculation?

Answer 33

0-2000 per mL if there are lots then this needs to be addressed

Question 34

what is the pH of semen/

Answer 34

7.2-7.8 - slightly alkali of neutral as vagina is acidic so accessory glands need to protect the sperm

Question 35

what is the fructose content of sperm?

Answer 35

150-600mg per 100mL - metabolic substrate for the motility

Question 36

what are the contributions of accessory glands within the compostion of the ejaculate/

Answer 36

• Epididymis & Ductus deferens (sperm-rich fraction):5 % of the ejaculate volume
• Prostatic secretion: 13-33% of the ejaculate volume
• Seminal vesicle secretion: 46 – 80% of the ejaculate volume
• Bulbo-urethral gland secretion: 5% of the ejaculate

Question 37

what is an erection?

Answer 37

erectile tissues become engorged with blood, arterioles dilated as a result of parasympathetic nervous system activity.

Question 38

what are the erectile tissues?

Answer 38

corpus cavernosum and corpus spongiosum

Question 39

what is erectile dysfunction`?

Answer 39

unable to always get an erection when needed / wanted?

Question 40

what are the pathological bases which may cause erectile dysfunction?

Answer 40

psychogenic
neurogenic
vascular
endocrine

Question 41

what else may cause erectile dysfunction?

Answer 41

many drugs including tricyclics and SSRIs ; antihypertensives including beta blockers and calcium antagonists

Question 42

how can you manage erectile dysfunction?

Answer 42

• PGE1 – alprostadil
• PDE5 inhibitors – eg sildenafil
• Look up what can be prescribed on NHS

Question 43

what are the risk factors of prostate cancer?

Answer 43

• age
• ethinicity
• family history

Question 44

what are the symptoms of prostate cancer?

Answer 44

• Urgent and frequent urination
• Nocturnal enuresis (involuntary urination)
• Difficulty starting or emptying the bladder
• Urine flow weak, interrupted or difficult to control
• Back or pelvic pain

Question 45

what is the pharmacological management of prostate cancer?

Answer 45

• Gonadorelin (GnRH) agonists and antagonists. Block so you don’t get the gondatropins so you won’t get the steroids oR agonist= high levels the receptor will downregulate and the pituitary gland becomes deaf to action of the gondatropins
• Androgen antagonist – cyproterone acetate could be affected provided the tumour retains normal androgen state of the prostate but tumours mutate and they can become independent to normal control.
• 5-a-reductase inhibitors – dutasteride & finasteride. More subtle option as you still have testerone acting but you are blocking DHT which is the more active progesterone

Question 46

what is the new way of have contraception for a male?

Answer 46

exogenous testosterone

• decrease LH and FSH and therefore decreases fertility
• needs to be given in HIGH doses
• this causes loss of sperm production
• this may lead to hypogonadotropic hypogonadism
• but you produce that much sperm it might not affect them all