Female reproductive system + pregnancy

Question 1

What are the main functions of the female reproductive system?

Answer 1

Produce haploid gametes
Facilitate fertilisation
Site for implantation of the embryo
Provide physical and nutritional needs to nurture the neonate after birth

Question 2

What is the structure of the ovaries?

Answer 2

Cortex- outer zone with germinal epithelial layer that contains oocytes
Inner medulla- blood vessels and lymph
Oocytes are enclosed in follicle, follicular cells secrete steroid hormones

Question 3

What are the three layers of the uterine wall?

Answer 3

Perimetrium
Myometrium
Endometrium

Question 4

What is the structure of the endometrium?

Answer 4

Simple columnar epithelial cells
Compound tubular glands
Spiral arteries

Question 5

Neuroendocrine control of the menstrual cycle

Answer 5

Hypothalamic-pituitary-gonadal axis drives the menstrual cycle
Hypothalamic neurons release gonadotropin-releasing hormone (GnRH)
Hypophyseal portal system connects hypothalamus to anterior pituitary

Question 6

What is the effect of GnRH binding to receptors?

Answer 6

Binds to G protein coupled receptor activating PLC, leading to the formation of DAG, IP3 and an increase in Ca2+
Leads to exocytosis of gonadotropins FSH and LH

Question 7

Action of FSH and LH on the ovaries

Answer 7

Stimulate ovaries to secrete progesterone from the theca and oestrogen, inihibin and activin from the granulosa

Question 8

What do oestrogen and progesterone do?

Answer 8

Develop ovum
Maintain corpus luteum
Maintain pregnancy

Question 9

What happens during the follicular phase of the endometrial cycle in terms of hormones?

Answer 9

Oestrogen forms channels to propel sperm

Question 9

What happens in the proliferative phase of the endometrial cycle?

Answer 9

Secretion of oestrogen increases

Stimulated growth of endometrium, glands, stroma, spiral arteries elongate

Question 10

What happens in the secretory phase of the endometrial cycle?

Answer 10

Following ovulation and is dominated by progesterone, endometrial proliferation slows and thickness decreases
Glands are tortuous with accumulated glycogen vacuoles, increased mucus
Stroma is oedamatous, ending in menses

Question 11

How do hormonal contraceptives work?

Answer 11

Feedback to hypothalamus decreasing secretion of GnRH
Negative feedback on anterior pituitary gonadotropins to inhibit FSH/LH
Low FSH insufficient to stimulate folliculogenesis, low LH insufficient for ovulation
Progestin affects cervical mucus, fallopian tube motility, endometrial glycogen

Question 12

How does the hormonal ‘morning after pill’ work?

Answer 12

Higher dose preparations inhibit ovulation and interfere with implantation
So therefore can be used as a postcoital contraceptive

Question 13

How does fertilisation occur?

Answer 13

Sperm acrosomal reaction- penetration
Oocyte activation leads to cortical reaction: second meiotic division and prevents polyploidy
Fusion of haploid pronuclei to form diploid zygote

Question 14

How does implantation occur?

Answer 14

Endometrium reception of blastocyst, which promotes endometrial stromal cells to predecidualize
Invasion of the endometrium is in 4 stages- hatching, apposition, adhesion and invasion

Question 15

What are the two types of blastocyst trophoblastic cells?

Answer 15

Inner cytotrophoblast

Outer syncytiotrophoblast

Question 16

What is the function of the intervillous space of the placenta?

Answer 16

Spaces between the mother’s blood vessels and fetal chorionic villi
Reduces force and velocity for exchange

Question 17

What is the function of the syncytiotrophoblast lacunae?

Answer 17

Placental barrier between maternal and fetal blood

Merge and fill with maternal blood

Question 18

In the mature placenta what is maternal and fetal blood seperated by?

Answer 18

Fetal capillary endothelium
Mesenchyme
Syncytiotrophoblast
Cytotrophoblasts

Question 19

What substances are transported from maternal to fetal blood and how?

Answer 19

Glucose- facilitated diffusion
Amino acids- secondary active transport
Vitamins- active transport

Question 20

What substances are transported from fetal to maternal blood and how?

Answer 20

Waste urea and creatine- diffusion

Question 21

How are large molecules such as antibodies, hormones and LDL transported?

Answer 21

Receptor mediated endocytosis

Question 22

Hormonal changes during trimester 1

Answer 22

In the trophoblast and then placenta- human chorionic gonadotropin HCG ‘rescues’ corpus luteum
Corpus luteum- continues secretion of progesterone and oestrogen to support endometrium

Question 23

Hormonal changes during trimesters 2-3

Answer 23

Placenta becomes the primary hormone source
Human placental lactogens (hCS)- coordinate fuel economy of glucose to FA, ketone storage for neonate and development of mammary glands
Progesterone synthesised from circulatory progesterone
Oestrogen- placenta-foetal synthesis

Question 24

What is stage 0 of parturition?

Answer 24

Quiescence- prelude to birth form conception to initiation of parturition, 95% of gestation
Uterus is relaxed and insensitive to uterotonic hormones
Progesterone suppresses myometrial contractions
Braxton-Hicks contractions in preparation

Question 25

What happens during stage 1 of parturition?

Answer 25

Preparation for birth prior to labour
Foetal-H-P-adrenal axis increases in cortisol which increases oestrogen:progesterone, leads to an increase in contractility
Oestrogen stimulates prostaglandin release

Question 26

What does the release of prostaglandin during stage 1 of parturition lead to?

Answer 26

Promotes formation of gap junctions

Softening, thinning and dilation of the cervix

Question 27

What happens during stage 2 of parturition?

Answer 27

Increased prostaglandin and oxytocin levels lead to myometrial contraction and cervical dilation
Increased myometrial connectivity and responsiveness
Positive feedback using Ferguson reflex
Stages of delivery- dilation, expulsion and placental

Question 28

What is the Ferguson reflex?

Answer 28

Neuroendocrine regulation of oxytocin

Uterine contraction stimulates prostaglandin

Question 29

What happens during stage 3 of parturition?

Answer 29

Haemostasis- vasoconstriction of spiral arteries to decrease haemorrhaging
Decrease in placental oestrogen which leads to myometrial atrophy adn regression of uterine vasculature
Cervix remodelling

Question 30

How long does it take to reestablish the endometrial cycle?

Answer 30

3-5 months

Question 31

What structures are important for lactation?

Answer 31

Alveoli- secretory unit of breasts

Contractile myoepithelial cells and adipose tissue

Question 32

What is colostrum?

Answer 32

First milk

High in fat, proteins and antibodies

Question 33

How are hormones for lactation controlled during pregnancy?

Answer 33

Oestrogen + progesterone stimulate breast growth and development
Oestrogen stimulates anterior pituitary prolactin (PRL), the major milk production hormone and also stimulates breast development
In pregnancy oestrogen + progesterone inhibit PRL activity on breast

Question 34

What is mammogenic hormone action?

Answer 34

Promotion of cell proliferation

Question 35

What is lactogenic hormone action?

Answer 35

Promotion of initiation of milk production by PRL

Question 36

What is galactokinetic hormone action?

Answer 36

Promotion of myoepithelial contraction by oxytocin

Question 37

What is galactopoietic hormone action?

Answer 37

Maintenance of milk production by PRL + cortisol