MNSR 36 - Human Reproduction: embryological origins; Male System

Question 1

reproduction

Answer 1

for species to survive they must multiply and produce new individuals to replace those lost to predators, parasites and old age
implies transfer of genetic material from one partner to another

Question 2

hermaphroditism

Answer 2

possessing both male and female sex organs in the same individual

Question 3

examples of organism that feature aphroditism

Answer 3

lower invertebrates e.g. Platyhelminthes (i.e. flat worms),

Question 4

parthenogenesis

Answer 4

reproduction from a female gamete without fertilisation by a male gamete
unfertilized egg develops to maturity via asexual reproduction

Question 5

terrestrial tetrapods

Answer 5

repitles, birds and mammals - developed a mechanism of internal fertilization as they live in a terrestrial environment

Question 6

oviparous

Answer 6

laying eggs

Question 7

vviparous

Answer 7

producing live young

Question 8

gonads

Answer 8

reproductive organs e.g. testis and ovaries

Question 9

where do both the testis and ovary develop from

Answer 9

mesodermal genital ridge of the embryo

Question 10

where is mesodermal genital ridge

Answer 10

medial to the mesonephros - nearby developing intermediate kidney

Question 11

____ or ___are gradually taken over for reproductive purposes in males

Answer 11

1. mesonephric

2. wolffian ducts

Question 12

1.___ or2. ___ are taken over for reproduction in

females

Answer 12

1.paramesonephric or Mullerian

Question 13

in males how are sperm conducted to the outside

Answer 13

in all male vertebrates, sperm are conducted to the outside via the closed tubes of the excretory system

Question 14

in females how do ova shed coelom

Answer 14

ova are shed into the coelom and then pass into a special tube, the fallopian tube or Müllerian duct

Question 15

where are the testes

Answer 15

upper lumbar region of coelomic cavity

Question 16

how does the position of scrotal sacs change through fetal development

Answer 16

However, in most mammals the testes descend into scrotal sacs during foetal development passing through the inguinal canal

Question 17

what also descends with the testes in fetal development

Answer 17

with the testes descends the sperm duct,

Question 18

gubernaculum

Answer 18

testes and sperm duct with their nerve and blood supply and a fold of mesentery called the gubernaculum

Question 19

how many seminiferous tubules are in each testis

Answer 19

1,000 highly coiled seminiferous tubules

Question 20

function of seminiferous tubules

Answer 20

are open at both ends and produce spermatozoa into the rete testis which acts as a reservoir

Question 21

vasa efferentia

Answer 21

A series of fine ciliated tubes the vasa efferentia (or efferent ducts), that connect the rete testis with the epididymis

Question 22

epididymus

Answer 22

a single long convoluted duct lined with pseudostratified columnar epithelium with stereocilia (microvilli);

Question 23

how are immobilised spermatoza transported

Answer 23

transported through the epididymis by peristalsis of the layer of smooth muscle in the wall

Question 24

function of epididymus

Answer 24

Functionally the epididymis is the site of sperm maturation (acquire motility and ability to fertilize)

Question 25

how does the spermatoza transported prior to ejaculation

Answer 25

epididymis (by peristalsis of the smooth muscle) the vas deferens bladder prostate gland urethra in males the urethra is a common urino-genital duct.

Question 26

vas deferens

Answer 26

a muscular tube, which brings them back into the abdominal cavity;

Question 27

2 cavernous bodies in penis

Answer 27

corpora cavernosa - outer corpus spongiosum - inner surround the urethra

Question 28

how are blood supplied from arteries

Answer 28

Essentially helicine arteries supplying the cavernous bodies dilate filling the cavernosa with blood while at the same time the veins are compressed

Question 29

pH of semen

Answer 29

7.5

Question 30

average volume of semen per ejaculation

Answer 30

3.5ml

Question 31

normal amount of spermatoza per ml

Answer 31

120 million spermatazoa/ml

Question 32

sperm count of infertile men

Answer 32

less than 20 million spermatozoa

Question 33

accessory sex glands of male reproductive system

Answer 33

seminal vesicles prostate gland cowpers glands

Question 34

function of seminal vesical

Answer 34

produce viscous fluid into vas deferens makes up to 60% of semen volume provides fructose for ATP production and enables sperm to swim

Question 35

function of prostate gland

Answer 35

produces a thin milky alkaline fluid containing citric acid (used for ATP production by sperm) acid phosphatase neutralise acidity of vagina which has pH of 3.5

Question 36

function of cowpers gland/bulbourethral

Answer 36

(bulbo-urethral) produces a viscous mucous secretion for lubrication

Question 37

path of secretions from accessory glands

Answer 37

Cowper’s secretions -> prostatic fluid --> spermatozoa -->seminal vesicle secretions

Question 38

how does consistency change and what enzyme contributes to this change

Answer 38

the semen initially coagulates into a gelatinous mass and then dissolves over the next 15 to 20 minutes; this is helped by a prostatic proenzyme

Question 39

histology of testis - seminiferous tubules

Answer 39

germinal epithelium - undergoes meiosis those cells sit on a basement membrane - outside that membrane have fibroelastic connectice tissue and myoid cells that are muscle like cells can contract

Question 40

describe cells resting on basement membrane

Answer 40

type A1 spermatogonia - divide by mitosis to make type B spermatogonia diploid cells

Question 41

Type B spermatagonia divide to make..

Answer 41

these type B spermatogonia now undergo a series of mitotic divisions to produce primary spermatocytes (2N);

Question 42

primary spermatocytes (2N); divide

Answer 42

and these divide by meiosis (‘SPERMATOGENESIS’) to produce two secondary Spermatocytes (N);

Question 43

why are secondary spermatocytes rarely seen

Answer 43

they rapidly undergo the second meiotic division to produce the haploid spermatids (N). these by a process of SPERMIOGENESIS differentiate into spermatozoa, which are stored in the epididymis;

Question 44

what hormone controls process of spermatogenesis

Answer 44

FSH from pituitary gland

Question 45

leydig cells

Answer 45

between the seminiferous tubules are the Leydig cells, which secrete testosterone

Question 46

testicular descent

Answer 46

the descent of the testis but the scrotal sac is high up or inguinal canal or abdomen This is especially serious where the spermatic cord is not long enough to travel the complete journey can lead to malignancy if elft intreated

Question 47

testicular malignancy

Answer 47

Malignancy may quickly spread to Inguinal nodes | Males should examine themselves regularly as do women their breasts

Question 48

inguinal hernia

Answer 48

The internal structures (intestines or fat) are forced out through the weakness in the abdominal wall (inguinal canal)

Question 49

what gender is inguinal hernia more common and why

Answer 49

This is more common in males as the canal is larger

Question 50

main cause of erectile dysfunction

Answer 50

insufficient release of nitric oxide which relaxes the smooth muscle of the penile arterioles and erectile tissue.