week 12 Flashcards
Hormonal regulation, maternal changes pregnancy + birth
Where is Oxycontin is produced and secreted
produced: hypothalamus
secreted: posterior pituitary
SERTOLI cells MALE
• ‘Nursing cells’ • Protect developing/maturating sperm • Assist their maturation • Make sure that the immune system does not destroy them (Blood–Testis barrier) • In fact, sperm develop and mature inside the Sertoli cells
LEYDIG cells MALE
- ‘Interstitial cells’
* Produce testosterone
ENDOCRINE CONTROL IN MALES
Negative feedback
- GnRH stimulates LH and FSH secretions
- FSH stimulates Sertoli cells
- They become better ‘nurses’ spermatogenesis
- They produce inhibin
- Inhibin is a peptide hormone
- LH stimulates Leydig cells
- The produce testosterone spermatogenesis
- Testosterone is a lipid (steroid) hormone
- The produce testosterone spermatogenesis
- Inhibin inhibits GnRH and FSH secretions
- Testosterone inhibits GnRH and LH secretions
Effects of testosterone
- Responsible for the development of male genitalia
- Essential for spermatogenesis
- Secondary male characteristics
- Powerful anabolic hormone
- Behavioural effects (??)
- Libido (there is a catch here)
- Inhibits GnRH, LH (and probably FSH) productions
ENDOCRINE CONTROL IN FEMALES
Both negative and positive feedback
Effects of oestrogens
Prepares the body for intercourse and conception
• Essential for the development and maturation of female sexual organs
(primary female sexual characteristics)
• Essential for egg production
• Produce secondary female characteristics
• Essential for regeneration and proliferation of endometrium
• Increase uterine motility
• Essential for breast development and maturation
• Anabolic effects (i.e., promote growth of muscle and bones)
• Effects on the central nervous system (libido and related behaviours)
• Inhibit GnRH, LH, and FSH productions
• With some positive feedback thrown in
Effects of progesterone
Prepares the body for pregnancy and helps maintain it
• Stimulates endometrial secretion (secretory phase)
• Stimulates secretion of the Fallopian tubes (egg/zygote survival…)
• Decreases uterine contractions (helps implantation and then
keeping the pregnancy)
• Also necessary for breast development
• Inhibits GnRH, LH, and FSH productions
• With some positive feedback thrown in
Day 1
first day of bleeding
Day 14
Ovulation
Pre-ovulation phase
- Oestrogen phase
- Follicular phase (Follicle is developing)
- Proliferative phase (endometrium)
Post-ovulation phase
- Progesterone phase
- Lutein phase (corpus luteum)
- Secretory phase (endometrium)
LH surge
When the body’s levels of luteinizing hormone (LH) rise, it triggers the start of ovulation, and the most fertile period of the menstrual cycle occurs.
Pregnancy
Oestrogen and progesterone levels continuously increase
• First trimester
• hCG production (by the developing placenta)
• hCG maintains the activity of the corpus luteum
-> Progesterone and oestrogen production
• After the first trimester
• Corpus luteum disappears
• Buts this is OK
• By this time, the placenta is capable of taking care
of oestrogen and progesterone productions
fertilization
• oocyte ovulated • uterine tube • 12 to 24 hours • outer layer follicular cells attached • sperm live for about 5 days • ‘capacitation’ – become fully functional – exposure to seminal gland secretions • gain motility – exposure to female tract • able to fertilise • single successful sperm • triggers cortical reaction – zona pellucida hardens • prevents polyspermy
Twins
- fraternal = dizygotic
- two separate oocytes ovulated and fertilised
- same relatedness as any two siblings
• identical = monozygotic
• single oocyte released and fertilised
• division early in
development
Implantation
Day 2-12: Trophoblasts
Stages of intrauterine development
pre-embryonic stage = from 0 – 2 weeks
embryonic stage from 3 – 8
weeks foetal stage = from 9 weeks – birth
Trimesters
- first trimester
- major organ systems appear
- embryonic and early foetal
- second trimester
- development organs and organ systems
- third trimester
- rapid growth
- most organ systems fully functional
Blood volume increases: Pregnancy
- blood flow to placenta reduces blood volume in systemic circulation
- foetal metabolic activity reduces PO2 & increases PCO2
- Stimulates erythropoietin from kidney
- maternal volume increased by 30 – 50% by term
Kidneys: Pregnancy
• GFR increases 50% • because blood volume increased • wastes from foetal metabolism excreted • pregnant women need to urinate frequently – extra urine – foetus pressing on bladder
Respiratory: Pregnancy
- increased tidal volume, deeper breathing
- higher O2 demand as metabolic rate increases
- also, mum more sensitive to CO2
- progesterone
- breathing adjusts so CO2 in blood is lower
- lower PCO2 aids diffusion of foetal CO2
Mammary Glands: Pregnancy
- development involves many hormones
- oestrogen, progesterone, prolactin…
- colostrum
- 1st 2 to 3 days
- antibodies: passive immunity
Gastrointestinal tract
- nausea & vomiting
- heartburn
- enlarging uterus pressing upwards on stomach, causing reflux
- constipation
- reduced intestinal motility from steroids of pregnancy (progesterone) relax smooth muscle
- pressure from enlarging uterus on rectum and lower portion of colon
Metabolic Rate
- requirements for nutrients climb 10 to 30%
- BMR may climb 15%
- may feel overheated
- also effort of carrying extra weight
Key female hormones
- oestrogen
- prostaglandin
- stimulates smooth muscle contractions
- oxytocin
- stimulates smooth muscle contractions
- cortisol
- ‘stress’ hormone
- from foetus
Preparation for pregnancy
- oestrogen:
- increases sensitivity myometrium
- increases sensitivity to oxytocin
- relaxin:
- relaxes pelvic articulation
- dilates cervix
Birth
- foetus: may trigger birth
- cortisol
- oxytocin: causes prostaglandin release
- stretching
- cervix and myometrium
- any stretching of smooth muscle increases its contractility
- mother also releasing oxytocin
Three stages of labour/ birth
- first: dilation (of cervix)
- second: expulsion (of baby)
- third: placental stage
Dilation
- variable time; usually 8 or more hours
- contractions begin about 30 minutes apart
- periodic relaxation allows blood flow
- ‘water’s break’: foetal membrane ruptures
- cervix dilates (widens), stretches, and thins
- engagement: foetal head enters pelvis
- until cervix = 10 cm open
Expulsion
- from full dilatation till birth of baby
- 10 to 30 mins or longer (variable)
- contraction of myometrial smooth muscle
- every 2–3 minutes
- lasting 1 minute
- crowning at vulva
- head extension
- baby born; umbilical cord clamped & cut
Placental
• 5 to 30 mins
• expulsion of placenta, umbilical cord & membranes
• uterus continues to contract – oxytocin
• blood vessels(umbilical, placental) constrict
• placenta begins to separate from uterine wall
• uterine blood vessels tear, bleed
• uterine contractions help compress vessels &
restrict blood flow
