4.11: The reproductive system (part 2 of 3) Flashcards
What does tubular fluid reabsorption result in
Concentration (induced by oestrogen)
What does the epididymis secrete into the epididymis fluid
Nutrients and glycoproteins
(Induced by androgens)
How far does the sperm travel from the testis to fallopian tube
100,000 x it’s length
What does Semen contain (3)
Spermatozoa 15-120 million/ml
Seminal fluid 2-5ml
Leuococytes
(Potentially viruses: hep B, HIV)
How many spermatozoa in ejaculate enter the cervix
1/100
How many sperm enter the ovum from the cervix
1/10,000
Overall how many sperm reach the ovum
1/1 million
Where does seminal fluid mainly arise from (3)
Seminal vesicles
Prostate
Bulbourethral glands
(Small contribution from epididymis/ testis)
Capacitation of sperm
Achieve fertilising capability in the female reproductive tract
3 ways sperm becomes capacitance
Loss of glycoprotein coat
Change in surface membrane characteristics
Develop whiplash movement of tail
Where does sperm capacitation occur
Ionic and proteolytic environment of the fallopian tube
What 2 things is sperm capacitation dependent on
Oestrogen
Ca2+
What is the sperm receptor on the egg
ZP3
In the acrosome reaction
Ca2+ influx into sperm - Stimulated by progesterone
Release of hyaluronidase and proteolytic enzymes (from acrosome)
Spermatozoon penetrates the zona pellucida
Where does fertilisation occur
Within the fallopian tube
What does fertilisation trigger
Cortical reaction
What happens in the cortical reaction
Cortical granules release molecules which degrade Zona Pellucida
Preventing further sperm binding as no receptors
Haploid -> Diploid
What is the conceptus
Embryo in the uterus, especially during early stages of pregnancy
Development of conceptus
Continues to divide as it moves down fallopian tube to uterus (3-4days)
What does the conceptus receive nutrients from
Uterine secretions
How long can the conceptus free living phase last for
9-10 days
Two phases of Implantation
Attachment phase
Decidualisation phase
In the attachment phase
Outer trophoblast cells contact uterine surface epithelium
What does the attachment phase trigger
Decidualisation phase
What occurs in the Decidualisation phase
Changes in underlying uterine stromal tissue (within a few hours)
What does implantation require
Progesterone domination in the presence of oestrogen
What two hormones aid implantation
LIF - leukaemia inhibitory factor
IL11 - interleukin-11
How does LIF aid implantation
LIF from endometrial cells stimulates adhesion of blastocyst to endometrial cells
How does IL11 aid implantation
IL11 from endometrial cells is released into uterine fluid, and may be involved
4 endometrial changes due to progesterone
Glandular epithelial secretion
Glycogen accumulation in stromal cell cytoplasm
Growth of capillaries
Increased vascular permeability (-> oedema)
Factors involved in Decidualisation
Interleukin 11
Histamine
Prostaglandins
TGF B -> promotes angiogenesis
Progesterone and oestrogen production in the first 40 days
Produced in corpus luteum (maternal ovary) and stimulated by hCG which acts on LH receptors
Essential for developing fetoplacental unit
Inhibits maternal LH and FSH ( negative feedback )
Progesterone and oestrogen production from day 40
Placenta takes over
What 4 hormones does DHEAS stimulate the placenta to produce
Progesterone
Oestradiol
Oestrone
Oestriol
What 6 maternal hormones increase during pregnancy
ACTH
Adrenal steroids
Prolactin
IGF-1 (stimulated by placental GH- variant
Iodothyronines
PHT related peptides
What 6 maternal hormones decrease during pregnancy
Gonadotropins
Pituitary GH
TSH
3 functions of oxytocin
Uterine contraction
Cervical dilation
Milk ejection
Endocrine control of lactation
Suckling on the nipple (stimulus)
Neural pathways travel to hypothalamus
Hypothalamus signals to pituitary
Neurohypophysis - oxytocin - milk ejection
Adenohypophysis - prolactin - milk synthesis
