Physio 8

Question 0

where does fertilization usually take place

Answer 0

ampulla of the fallopian tube

Question 1

steps of fertilization process

Answer 1

1. sperm binds zona pellucida
2. acrosomal reaction is triggered by sperm binding. leads to fusion of acrosome with sperm cell plasma membrane
3. hydrolytic enzymes released from acrosome penetrate zona pellucida
4. cell membranes of sperm and oocyte fuse. cytoplasm of sperm head and tail enter oocyte
5. oocyte undergoes cortical reaction, preventing entry of other sperm
6. oocyte completes its second meiotic division and 2nd polar body expelled
7. sperm head condenses and becomes male pronucleus. cytoplasmic portion of tail degenerates
8. male and female pronuclei fuse, forming zygote.

Question 2

what transports the sperm?

Answer 2

flagella motility of the sperm tail. contractions of uterus, cervix, and fallopian tubes in response to oxytocin released during female orgasm and prostaglandins in the male seminal fluid also help

Question 3

hCG (human chorionic gonadotropin)

Answer 3

produced in the syncytiotrophoblasts by the blastocyst. closely related to LH, and sustains corpus luteum in the face of declining levels of maternal LH. acts as immunosuppressant agent, has growth promoting activity, and promotes placental development. can be measured in urine and is basis for pregnancy tests. stimulates testes of male fetus to make testosterone

Question 4

where does fetus get nutrition from during early and late pregnancy?

Answer 4

gets nutrition from the endometrial decidua early on. later on in pregnancy, gets it through diffusion through the placenta

Question 5

what hormones are supplied by the placenta?

Answer 5

steroid hormones
hCG: most important placental peptide hormone
somatomammotropins: coordinate fuel economy by contributing to the conversion of glucose to fatty acids and ketones. also promote mamary gland development in the pregnant mother

Question 6

what happens to steroid hormones during pregnancy?

Answer 6

steroid hormones rise rapidly and remain elevated during pregnancy

Question 7

what does placenta need to make steroid hormones?

Answer 7

needs assistance of both mother and fetus. referred to as the maternal-fetal-placental unit. placenta cannot make enough cholesterol on its own, and lacks two key enzymes needed for synth of estrone and estradiol. placenta lacks a third enzyme needed for synth of estriol

Question 8

production of steroid hormones in the maternal-placental-fetal unit

Answer 8

mom is the major source of cholesterol. placenta can form progesterone and this returns to the mother. baby has a fairly developed adrenal gland and liver, and it can make DHEA, a precursor for estrogen. the placenta is a sink for the DHEA, so it doesnt accumulate in the fetus.

Question 9

maternal response to pregnancy

Answer 9

1. increased blood volume
2. MAP usually decreases due to vasodilating effect of steroid hormones, then rises during 3rd trimester
3. increased cardiac output mainly in first trimester.
4. increased alveolar ventilation
5. increased demand for dietary protein, folic acid, and iron
6. uterus increased from 50 to 1100 grams and breasts double in size
7. weight gain from 25-35 pounds
8. BMR increases, especially in the latter half of pregnancy

Question 10

parturition

Answer 10

birth of the baby. combination of endocrine, mechanical stretching and paracrine factors are involved. uterus is quiet during pregnancy due to progesterone. prostaglandins initiate contractions, and are sustained by oxytocin and more prostaglandins made by fetal membranes, placenta, and uterus. estrogen increases number of oxytocin receptors on myometrial tissue, and maternnal oxytocin is released in response to distension of cervix. positive feedback happens to sustain the loops

Question 11

oxytocin and prolactin

Answer 11

released in response to suckling. oxytocin promotes milk let-down and uterine contractility. prolactin promotes milk synthesis

Question 12

lactation

Answer 12

breast responds to multiple hormones both during and after pregnancy. mammogenic promote cell proliferation. lactogenic promote initiation of milk production. galactokinetic promote milk ejection or ‘let down’. galactopoietic maintain milk production

Question 13

alveolus

Answer 13

functional secretory unit of the breast. organized into lobules which drain into a ductule. contractile myoepithelial cells surround each alveolus and adipose cells and promote milk let down in response to oxytocin. secretory epithelial cells comprise alveolus and secrete milk in response to prolactin and cortisol

Question 14

milk

Answer 14

emulsion of fats in an aqueous solution containing sugar, proteins and electrolytes

Question 15

colostrum

Answer 15

concentrated, low volume form of nutrition for the neonates immature GI tract during first few days of life. contains protective antibodies. newborns cant handle cow milk due to high protein and sugar

Question 16

effects of suckling

Answer 16

1. stims sensory nerves which carry signal to brain
2. afferent input from nipple inhibits neurons that release dopamine, leading to increased prolactin release
3. in supraoptic and paraventricular nuclei of hypothal, input from nipple triggers making and release of oxytocin
4. in preoptic area and arcuate nucleus, input inhibits GnRH release, therefore inhibiting LH and FSH, inhibiting ovarian cycle in lactating women