BSI 2 Lecture 59-60: Pregnancy and Lactation Flashcards
What happens to the ovum just prior to ovulation?
It undergoes meiosis with the release of the first polar body
When the ovum is released and makes it into the fallopian tube, what is responsible for its movement?
Estrogen-activated cilia
What stimulates the contractions that aids the travel of sperm?
Prostaglandins and oxytocin
What must the sperm do to begin the process of fertilization?
Penetrate several layers of granulosa cells and then bind to the zona pellucida
What happens when a sperm cell makes it through the zona pellucida and binds to the membrane of the egg?
The egg releases contents of secretory vesicles, and these contents enter the zona pellucida preventing multiple sperm from entering the cell
What happens as soon as the sperm is inside the egg cell?
The ovum undergoes the second round of meiosis and ejects the second polar body which allows the sperm and egg to unite
Why is the ovum trapped in the fallopian tube for about 3 days after fertilization?
So it has time to become the blastoid
What is responsible for relaxing the contractions at the isthmus once the ovum has become a blastoid?
An increase in progesterone from the corpus luteum
Once in the uterus, how long does it take for the ovum to implant?
About 1-3 days (5-6 days after ovulation) in order to create an environment necessary for survival
What causes actual implantation?
Trophoblast cells of the blastocyst secreting proteolytic enzymes that allow it access and form a secure connection to the endometrium
As soon as the blastocyst attaches, what cells rapidly divide, and what do they form?
The trophoblast and other cells divide to form the placenta and uterine membranes
What provides nourishment until the placenta takes over?
Progesterone release from the corpus luteum causes endometrial proliferation and release of nourishment
When does the placenta start to provide nourishment?
At about 8 weeks until birth
When does the embryonic heart start to beat?
After about 16 days
Fetal hemoglobin has a higher affinity for oxygen, but how does the amount of hemoglobin in the blood compare to that of the mother?
Fetal blood contains about 50% more Hb per unit voume
How does the Bohr effect enhance oxygen delivery to the fetus?
There is an increase in CO2 diffusing from fetal blood which lowers the pH of the mother’s blood. The causes the Bohr effect and a rightward shift in the Hb-O2 curve. This causes a decreased affinity between hemoglobin and oxygen allowing the fetus to receive more oxygen
What produces human chorionic gonadotropin?
Trophoblast cells surrounding the fertilized egg
What does human chorionic gonadotropin act like?
A gonadotropin (specifically LH)
What is the purpose of chorionic gonadotropin?
To maintain the corpus luteum until the placenta can take over
What does the corpus luteum secrete?
Progesterone and estrogens to prevent menstruation and to stimulate endometrium growth
What is pregnancy test looking for?
Presence of hCG in the urine
When does the placenta take over and allow the corpus luteum to degenerate?
About the 12th week (1st trimester)
What does hCG do in the male fetus?
Stimulates the testes to secrete testosterone which causes growth of male sex organs instead of female
What do estrogens do?
They cause growth of the uterus but also produce enlargement of the breasts and female genitalia
What is a negative aspect to estrogens?
They may have proliferative effects which can promote cancer
What does progesterone do?
It stimulates development of decidual cells which are involved in fetal nutrition, they inhibit uterine contractility and spontaneous abortion, and stimulate uterine and fallopian secretions that maintain the early implanting embryo, and facilitate estrogen’s effects on breast development
When and from what is hCS secreted?
It is secreted from the placenta after the 5th week
What is the function of hCS?
- May include breast development
- Preparation for lactation (similar to prolactin)
- Metabolic coordination with mother
What happens to the anterior pituitary of the mother during pregnancy?
Enlarges 50% and increases production of TSH, ACTH, prolactin, and T4/T3 and cortisol
What happens to the thyroid?
Enlarges 50% to produce more thyroid hormones
What happens to the parathyroid gland?
Enlarges because of poor calcium levels in the mother. This causes increased production of PTH, and increased bone reabsorption
What happens to FSH and LH?
They are suppressed by steroid feedback
What happens to aldosterone?
Increased secretion leading to increased sodium and water retention which can cause pregnancy-related hypertension
What secretes relaxin?
The corpus luteum
What does relaxin do?
causes relaxation of the symphsis ligaments at the connection of the 2 halves of the pelvis it also helps soften the cervix prior to birth
What physical effect does pregnancy have on the mother?
increase in size of sex organs, edema, acne, and slight masculinizing of features
What is the average weight gain during pregnancy?
24 pounds (7 pound fetus, 4 pounds in amniotic fluid, and the rest due to edema, fat, etc.)
Name the response: placenta
secretion of…
1) estrogen
2) progesterone
3) hCG
4) inhibin
5) human placental lactogen
Name the response: anterior pituitary
increased secretion of prolactin, very little FSH and LH secretion
Name the response: adrenal cortex
Increased aldosterone and cortisol secretion
Name the response: posterior pituitary
increased secretion of vasopressin
Name the response: parathyroids
increased secretion of PTH
Name the response: kidneys
increased secretion of renin, erythropoietin, and vitamin D. Also salt and water retention
Name the response: breasts
enlarge and develop mature glandular structure
Name the response: blood volume
increase because of red blood cell production and water retention
Name the response: body weight
increase because of PTH and vitamin D
Name the response: circulation
increased CO and decreased peripheral resistance
Name the response: respiration
hyperventilation due to effects of increased progesterone
Name the response: metabolism
increased plasma glucose, gluconeogenesis, and fatty acid metabolism because of hypo-responsiveness to insulin
Name the response: appetite and thirst
increased after first trimester
Name the response: nutritional RDAs
increased
How do you treat eclampsia?
rapid acting vasodilators and immediate delivery of the baby
What produces expression of oxytocin receptors in the uterus?
Estrogen
What completes breast development into a milk-secreting organ?
progesterone
