Lecture 9 - Getting Pregnant, Sex And Fertilisation

Question 1

Where is sperm produced?

Answer 1

Seminferous tubules by germ cells

Question 2

Where do spermatozoa travel to following the Seminferous tubules?

Answer 2

Epididymis
Vas deferens
Ejaculatory duct
Prostatic urethra
Membranous urethra
Spongy urethra
External urethral meatus

Question 3

Where do spermatozoa first start to mature once produced?

What is needed to support this?

Answer 3

Epididymis

Androgens

Question 4

What are the 2 main components of semen?

Answer 4

Spermatozoa + Seminal plasma

Question 5

Where is seminal plasma produced?

Answer 5

Accessory glands of male repro tract

Question 6

What are the general functions of the seminal plasma?

Answer 6

Transport medium for sperm
Nutrition to sperm

Question 7

What are the 3 main accessory glands that produce seminal plasma?

Answer 7

Seminal vesicles
Prostate gland
Bulbourethral glands

Question 8

Which of the accessory glands produce the majority of the volume of seminal plasma?

Answer 8

Seminal vesicles

Question 9

Describe the composition of the seminal plasma made by the seminal vesicles:

Acidic?
Contents?

Answer 9

Alkaline (neutralises acidic male urethra and female repro tract)

Fructose (energy)
Prostaglandins (move sperm along female tract)
Clotting factors (needed to move sperm)

Question 10

Describe the composition of the seminal plasma made by the prostate gland:

Acidic?
Contents?

Answer 10

Milky and slightly acidic
Contains proteolytic enzymes (breaks down clotting proteins re-liquefying semen
Citric acid and acid phosphatase

Question 11

Describe the composition of the seminal plasma made by the bulbourethral glands:

Acidic?
Contents?

Answer 11

Very small volume
Alkaline
Mucous that lubricates the end of the penis and urethral lining

Question 12

What is the reference volume of semen?

Answer 12

Between 1.4 to 1.7ml

Question 13

What percentage of spermatozoa need to look normal?

Answer 13

4%

Question 14

What percentage of sperm need to be moving?

Answer 14

38 - 42%

Question 15

Where does fertilisation take place?

Answer 15

Ampulla

Question 16

What are the 4 stages of the human sexual response?

Answer 16

Excitement phase
Plateau phase
Orgasm phase
Resolution phase

Question 17

What occurs in the excitement phase of the sexual response?

Answer 17

Psychological or somatogenic stimuli (touching)

Question 18

What changes occur in the orgasm phase and then resolution phase?

Answer 18

Orgasm phase = lots of heamodynamic changes

Resolution phase = return to normal haeodynamics
Contains refractory period

Question 19

What is the refractory period?

Answer 19

The time period in men where they cannot orgasm

Question 20

What is Point and Shoot used to remember?

Answer 20

Point (erection) = parasympathetic

Shoot (ejaculation) = sympathetics

Question 21

What are the important efferent nerves in obtaining an erection?

Answer 21

Pudendal nerve
Pelvic nerve
Somatic and autonomic efferent

Question 22

What are the spinal nerve roots of th pundenal nerve?

Answer 22

S2 - S4

Question 23

What part of the penis receives an increased blood flow to achieve an erection?

Answer 23

Corpus cavernosum

Question 24

What it’s the blood supply like in the flaccid penis?

Answer 24

Arterio-venous anastomoses allows blood to bypass the corpus cavernosum

The helicine arteries stay coiled

Question 25

How does the penis change during erection, blood supply?

Answer 25

Smooth muscle in helicine areties relaxes, straightens and dilates allowing blood into corpus cavernosum Bulbspongiosus compresses venous plexus keeping more blood in penis

Question 26

What neurophysiological changes occur during an erection? What substance is produced?

Answer 26

Inhibiton of sympathetic arterial vasoconstrictor nerves Nitrous Oxide produced

Question 27

What is the effect of Nitrous oxide on blood vessels?

Answer 27

Potent vasodilator

Question 28

What is the process to producing NO to cause vasodilation?

Answer 28

Post ganglionic make ACh ACh binds to M3 receptors Levels of NO rise Diffuses into vascular smooth muscle causing relation

Question 29

What can causes erectile dysfunction>

Answer 29

Psychological Vascular (Cardiovascular disease, diabetes Mellitus) Anatomical Neurogenic - peripheral neuropathy Diabetes , spinal cord lesion, multiple sclerosis) Hormonal Drugs

Question 30

How does viagra work to treat Erectile dysfunction?

Answer 30

Is a phosphodiesterase inhibitor preventing break down of cGMP so the effects of NO last longer (vasodilation and erection)

Question 31

What are the 2 parts of of ejaculation?

Answer 31

Emission Expulsion

Question 32

What occurs in the emission stage of ejaculation?

Answer 32

Deposition of seminal plasma into the prostatic urethra

Question 33

What occurs in the expulsion stage in ejaculation?

Answer 33

Expulsion of semen through the urethra and out the urethral meatus

Question 34

What is the name of the sphincter joining the bladder to the urethra?

Answer 34

Internal Urethral Sphincter

Question 35

What happens to the internal urethral sphincter ini ejaculation? Why’s this important?

Answer 35

Closes during ejaculation Prevents retrograde ejaculation (stops Ejaculate entering bladder)

Question 36

What hormone is responsible for making the cervical mucus thin and stretchy? What stage of the menstrual cycle is this relevant to?

Answer 36

Oestrogen Thin and Stretchy around ovulation

Question 37

What hormone is responsible for making the cervical mucus thick and sticky? What stage of the menstrual cycle is this relevant to?

Answer 37

Progesterone Produced in the luteal phase and is still present but decreases as menstruation occurs

Question 38

What are the changes that occur during teh female sexual response?

Answer 38

Vaginal lubrication occurs Clitoris enlarges Uterus contractions Rhythmic contraction in orgamsic platform

Question 39

What part of the femal repro tract is sperm deposited?

Answer 39

Cervix

Question 40

What is capacitation?

Answer 40

Further maturation of the sperm when its in the female reproductive tract

Question 41

What changes occur to the sperm in capacitation?

Answer 41

Sperm loses outer layer of its head so can interact with egg Tail movement more whip like

Question 42

What is the acrosome reaction?

Answer 42

When the head of the sperm produces enzymes which break down the outer layer of the egg called the zona pellucida

Question 43

What is the layer surrounding the outside of the zona pellucida that sperm must push through?

Answer 43

Corona radiata

Question 44

What happens once a sperm manages to fuse with the plasma membrane of the oocyte leading to fertilisation?

Answer 44

Cortical reaction

Question 45

What is the cortical reaction?

Answer 45

The process that occurs once a single sperm has fused with the egg to block other sperm from accessing the egg preventing polyspermy

Question 46

What stage of the cell cycle is resumed for the oocyte once fertilisation has occured?

Answer 46

Meiosis II

Question 47

What is the Morula?

Answer 47

What forms once fertilisation occurs, all cells totipotent, contains 16 cells before it becomes the blastocyst

Question 48

What stage of development is an embryo when its implanted in Assisted Reproductive Technolgy?

Answer 48

Morula

Question 49

What’s the benefit of Pre-implantation Genetic diagnosis?

Answer 49

Ensure no chromosomal abnormalities

Question 50

What needs to happen before the blastocyst can implant in the uterine wall?

Answer 50

Zona pellucida needs to break down so the blastocyst can hatch from the zona pellucida

Question 51

What is the order of the accessory glands in the male reproductive tract from most proximal (closest to the Seminiferous tubules) to most distal (closest to the external urethral meatus)?

Answer 51

Seminal vesicles Prostate gland Bulbourethral gland