7. Coitus & Conception (workbook)

Question 1

what is coitus?

Answer 1

the act of sexual intercourse that results in the deposition of sperms in the vagina at the level of the cervix

Question 2

from the cervix, where do the sperm travel?

Answer 2

a proportion of sperm enters the uterus and reaches the uterine tubes (fallopian tubes) where they may encounter an ovum (oocyte) released from the ovary

Question 3

what is conception?

Answer 3

fertilisation of the ovum by a sperm and the subsequent establishment of pregnancy

Question 4

what does sexual excitement that leads to the act of coitus involve in both sexes?

Answer 4

genital and systemic (e.g. raise in BP) changes in both genders

Question 5

what are the different phases of genital and systemic changes leading to the act of coitus?

Answer 5

EPOR (like explore)
excitement phase
plateau phase
orgasmic phase
resolution phase

Question 6

what is the climax of sexual excitement in males accompanied by?

Answer 6

ejaculation

Question 7

immediately after ejaculation, what happens to the semen?

Answer 7

the semen first coagulates due to the action of clotting factors (fibrinogen and vesiculae)

Question 8

why is the semen required to coagulate>

Answer 8

to prevent the sperms from being physically lost from the vagina

Question 9

what happens to the semen after coagulation by clotting factors?

Answer 9

it then liquifies by the action of enzymes derived from prostatic secretions (fibrinolysis)

Question 10

what happens to the majority of the sperms?

Answer 10

doesn’t enter the cervix of uterus - are lost by leakage from the vagina

Question 11

what happens to the sperm which enter the uterus?

Answer 11

travel a distance of 15-20cm to reach the uterine tube

Question 12

how long does it take the sperm to enter the uterus (15-20cm uterine tube)?

Answer 12

a few hours

Question 13

what is transport of sperms to the uterine tube a result of?

Answer 13

probably the result of their own propulsive capacity and the fluid currents caused by the action of ciliated cells in the uterine tract

Question 14

during the passage of sperms through the uterus to the uterine tube, what happens to the sperm?

Answer 14

the sperm undergo a further series of maturational changes

Question 15

what are the further maturational changes that a sperm undergoes through its passage in the uterine tube?

Answer 15

capacitation and acrosomal reaction

Question 16

what does capacitation and acrosomal reaction result in?

Answer 16

results in sperm acquiring a full capacity to fertilise the ovum

Question 17

where do the sperm maturation changes first begin?

Answer 17

during their transport from the testis to the epididymis

Question 18

where do sperm maturation changes continue after transport from testis to epididymis?

Answer 18

during their storage at epididymis until ejaculation

Question 19

can newly ejaculated spermatozoa fertilise an oocyte? why?

Answer 19

newly ejaculated spermatozoa cannot fertilise an oocyte until capacitation has occurred

Question 20

where does capacitation normally occur?

Answer 20

within the female genital tract, but it can be induced in vitro

Question 21

what promotes the change in the sperm cell membrane?

Answer 21

removal of a glycoprotein coat

Question 22

what happens to the tail of the sperm? (the changes)

Answer 22

from waves to whip-like thrashing movement

Question 23

why does the tail of sperm have to change to whip-like thrashing movement?

Answer 23

to propel the sperm along and the spermatozoa also become responsive to signals from the oocyte

Question 24

how long does capacitation take?

Answer 24

several hours

Question 25

what does a capacitated sperm comes into contact with?

Answer 25

oocyte zona pellucida

Question 26

what happens when a capacitated sperm comes into contact with oocyte zona pellucida?

Answer 26

the membranes fuse and this marks the commencement of the acrosomal reaction

Question 27

what happens during acrosomal reaction?

Answer 27

the acrosome swells and liberates its contents by exocytosis

Question 28

what facilitates the penetration of zona pellucida by the sperm?

Answer 28

proteolytic enzymes

Question 29

how long does it take for proteolytic enzymes to penetrate the zona pellucida?

Answer 29

about 15mins

Question 30

what are both capacitation and acrosomal reactions induced by?

Answer 30

an influx of calcium and rise in cAMP in the spermatozoa