Pregnant Physiology Flashcards
What is the site of fertilization?
upper third of oviduct
What is the site of implantation?
endometrium of uterus
What is a blastocyst?
Fertilized ovum becomes blastocyst.
- Inner cell mass: becomes fetus
- trophoblast: establishes implantation, then becomes fetal portion of placenta.
How are placental villi formed?
finger like projection of chorionic tissues
what happens at the inter-villus spaces?
exchange between fetal and maternal blood
what are the functions of the placenta?
- kidneys, digestive and respiratory yet NOT USED because mothers system does this.
- becomes TEMPORARY ENDOCRINE ORGAN
what 3 endocrine systems interact during pregancy? why?
maternal, fetal and placental hormones interact to enhance growth and development, coordinate time of birth and prepare mammary glands.
what hormones are released by the placenta? what is their critical role?
human chorionic gonadotropin (hCG), estrogen, progesterone.
MAINTAIN PREGNANCY
why is the placenta unique? (2 reasons)
- transient
- hormones controlled by STAGE OF PREGNANCY (not EXTRINSIC CONTROL).
what is the main function of human chorionic gonadotropin (hCG)? What are 3 additional functions?
prolong the life of CORPUS LUTEUM (CL).
- stimulate LEYDIG CELLS in male tested to secrete testosterone.
- used in pregnancy diagnostic testing in urine (about 2 weeks after missed period).
- may cause morning sickness
What is the corpus luteum? what is its function?
Ovarian endocrine organ, produces ESTROGEN and PROGESTERONE until about 10 WEEKS POST IMPLANTATION
What hormones does maintenance of pregnancy depend on? Why?
Estrogen and progesterone and they maintain THICK, PULPY ENDOMETRIAL TISSUE and CEASE MENSTRUATION
(indirectly hCG as it maintains corpus luteum which releases these)
when does peak hCG secretion occur? when does it start to decline?
- PEAK: 60 DAYS after last menstrual period
- Decline: by 10th week post implantion
why doesnt placenta secrete estrogen in tjhe first trimester and instead produced hCG to stimulate corpus luteum?
Because placenta does not have the required enzymes for ESTROGEN SYNTHESIS in first trimester. Has them for PROGESTERONE yet does not produce enough in first 10 weeks.
does placenta secrete progesterone in first 10 weeks?
Placenta produces progesterone soon after implantation yet this is too small in FIRST 10 WEEKS to produce ENOUGH PROGESTERONE TO MAINTAIN PREGNANCY.
What is the key role of estrogen and progesterone?
High levels necessary to MAINTAIN PREGANCY
What structures release estrogen and progesterone in 1st, 2nd and 3rd trimester?
1st: Corpus luteum
2nd and 3rd: placenta
What are the 2 main roles (specific) of estrogen?
- stimulate growth of myometrium –> help EXPEL FETUS during LABOUR
- development of mammary gland DUCTS.
What are the 3 main roles (specific) of progesterone?
- PREVENT MISCARRIAGE (prevent contraction of uterine myometrium)
- mucus plug
- development of MILK GLANDS
what leads to weight gain in pregnant patients?
- uterine enlargment (20 times its size)
- 30% increase in blood volume
what is parturition?
birth/ labour/ delivery
what are two requirements for parturition?
- dilation of the cervical canal
- contractions of the uterine myometrium
what are two changes that occur in the late gestation period that prepare for parturition?
- Braxton - Hicks contractions (last trimester)
- softening of the cervix (and birth canal) via relaxin from CL
what is gestation?
pregnancy
What is a breech birth?
any part of the body other than head approach birth canal first.
what type of contractions can be seen when there is onset of parturition/ true labour?
rhythmic, coordinated contractions.
