Physiology

Question 1

How long after ovulation must fertilisation occur?

Answer 1

within 24 hours

Question 2

What does the ovum differentiate into after fertilisation?

Answer 2

blastocyte

Question 3

what are the two parts of the blastocyst?

Answer 3

• trophoblast - accomplishes implantation and develops into the fetal portion of the placenta
• inner cell mass - destined to become the foetus

Question 4

where is the site of implantation?

Answer 4

the endometrium of the uterus

Question 5

what feature of the blastocyst penetrates the endometrium?

Answer 5

cord of the trophoblastic cells

Question 6

the inner mast cells give rise to what?

Answer 6

the developing embryo

Question 7

what are the 3 most important placental hormones?

Answer 7

• human chorionic gonadotropin (hCG)
• estrogen
• progesterone

Question 8

what is the role of human chorionic gonadotropin (hCG)?

Answer 8

acts to prolongue the life span of the corpus luteum

Question 9

what hormones does the corpus luteum produce increasingly greater amounts of (for 10 weeks post implantation)?

Answer 9

progesterone and oestrogen

Question 10

what hormone does pregnancy tests detect?

Answer 10

hCG

Question 11

In a male foetus, hCG stimulates what cells which masculinise the developing reproductive tract?

Answer 11

Precursor leydig cells in the fetal tests to secrete testosterone which masculinises the developing reproductive tract

Question 12

What secretes oestrogen and progesterone in the 1st semester and the 2/3rd semester?

Answer 12

1st semester = corpus luteum
2nd and 3rd = the placenta

Question 13

what is the role of oestrogen?

Answer 13

• stimulates growth of the myometrium, which increases in size throughout pregnancy. The stronger uterine musculature is needed to expell the fetus during labour
• also promotes development of mammary gland ducts, through which milk will be ejected during lactation

Question 14

what is the role of progesterone during pregnancy?

Answer 14

• main role - to prevent miscarriage by supressing contractions of the uterine myometrium
• also promotes formation of a mucus plug in the cervical canal to prevent vaginal contaminants from reaching the feotus
• progesterone stimulates development of the milk glands in the breast in preparation for lactation

Question 15

what is required for parturition (labour)

Answer 15

• dilation of the cervical canal
• contraction of the uterine myometrium

Question 17

what hormone largely causes cervical softening?

Answer 17

relaxin

Question 18

what is it called when any part of the body but the head approaches the birth canal first

Answer 18

a breech birth

Question 19

after deliver, the uterous shrinks to its pregestational size, what is this called?

Answer 19

involution

Question 20

what induces involution?

Answer 20

a fall in oestrogen and progesterone when the placenta is lost at delivery

Question 21

what hormone promotes myometrial contractions that help maintain uterine muscle tine, inhancing involution?

Answer 21

oxytocin

Question 22

what is the third stage of labour

Answer 22

delivery of the placenta

Question 23

what is the second stage of labour?

Answer 23

delivery of yhe baby

Question 24

what is the first stage of labour?

Answer 24

cervical dilation

Question 25

what is oestrogens role in development of the breast during pregnancy?

Answer 25

promotes extensive duct development

Question 26

what is progesterones role in development of the breast during pregnancy?

Answer 26

stimulates abundant alveolar-lobular formation

Question 27

what induce the synthesis of enzymes needed for milk production?

Answer 27

prolactin (anterior pituitary hormone) and human chorionic somatomammotropin (hCSl placental hormone)

Question 28

prolactin also stimulates milk production after parturition, how does it not stimulate during pregnancy?

Answer 28

stimulatory action of prolactin is blocked in later stages of pregnancy by oestrogen and progesterone but after parturition oestrogen and progesterone levels dropping allowing prolactin to induce milk production

Question 29

where is prolactin produced?

Answer 29

anterior pituitary gland

Question 30

where is oxytocin produced?

Answer 30

posterior pituitary gland

Question 31

what is the role of prolactin?

Answer 31

stimulates milk production

Question 32

what is the role of oxytocin?

Answer 32

stimulates milk ejection

Question 33

how does oxytocin stimulate milk ejection?

Answer 33

oxytocin stimulation contraction of myoepithelial cells in the mammary ducts

Question 34

what is the breast milk in the first 5 days called?

Answer 34

colostrum