Parturition

Question 0

What are the three stages of labor?

Answer 0

1) dilation of the cervix
2) expulsion of the fetus
3) expulsion if the placenta

Question 1

Parturition?

Answer 1

Expulsion of the fetus and placenta from the uterus

Question 2

What labor stage is the longest?

Answer 2

Stage one: dilation of the cervix

Question 3

What are the 2 requirements for the expulsion of the fetus?

Answer 3

Myometrium contractions, dilation of the cervix

Question 4

What hormones stimulate the myometrium contractions?

Answer 4

PGF-2a: contractions of myometrium and luteal regression

Oxytocin: myometrial cintractions itself and stimulates PGF production

Question 5

Which hormones stimulate the dilation of the cervix?

Answer 5

Relaxin

PGF-2a

Question 6

What three things occur in the stage of dilation of the cervix?

Answer 6

1) loss of collagen
2) loosening or separation of collagen fibers
3) stage of labor that takes the longest ad also associated with distocia

Question 7

What two things comprise the endocrinology of parturition?

Answer 7

1) removal of the progesterone block

2) estrogen to progesterone ratio

Question 8

What steps must take place for the progesterone block to be removed?

Answer 8

P4 blocks E2 receptor and oxytocin receptor formation and PGF synthesis. Removal of P4 permits receptor formation and PGF synthesis

Question 9

A __ estrogen:progesterone ratio promotes myometrial excitability (contractions).

Answer 9

High

Question 10

Ferguson reflex?

Answer 10

A neuroendocrine reflex in which the head of the fetus presses on cervix stimulating release of oxytocin from posterior pituitary gland

Question 11

What is the ferguson reflex facilitated by?

Answer 11

A high E:P ratio

Question 12

What is the function of oxytocin in the ferguson reflex?

Answer 12

Stimulate myometrial contractions and PGF release from uterus

Question 13

Oxytocin receptors ___ 40-100 fold at term in women.

Answer 13

Increase

Question 14

Oxytocin concentrations change little during ___ but increase greatly during ___.

Answer 14

Initial stages of labor

Expulsion of the fetus

Question 15

In the ewe, what is parturition initiated by?

Answer 15

The fetus

Question 16

How does the fetus stimulate parturition in the ewe?

Answer 16

1) maturation of the fetal hypothalamus.
2) fetal corticotropin releasing hormone (CRH) stimulates anterior pituitary to release adrenocorticotropic hormone (ACTH)
3) ACTH stimulates fetal adrenal gland to release cortisol
4) fetal cortisol induces placental production of enzymes that metabolize P4 to E2
5) increased E2 and cortisol stimulate increased PGF production by uterus

Question 17

What 2 things remove the P4 block?

Answer 17

1) CL regression (PGF)

2) placental conversion of P4 to E2

Question 18

Which hormone increases elasticity of cervix and birth canal? Where is it found and stimulated by?

Answer 18

Relaxin: from CL or placenta; stimulated by PGF

Question 19

What 4 factors cause myometrial contractions?

Answer 19

E:P
Ferguson Reflex
Oxytocin
PGF

Question 20

In women, which hormone does not decline at parturition?

Answer 20

P4

Question 21

What are the two earliest identifiable events of parturition?

Answer 21

Increase PGF

Increase oxytocin receptor

Question 22

Which hormone increases cervical, vaginal secretions-lubrication?

Answer 22

Estrogen

Question 23

Water breaks?

Answer 23

Head and feet of fetus push on amnion/allantois rupturing membranes-lubrication

Question 24

Fetal hypoxia?

Answer 24

Fetus deprived of oxygen in birth canal - stimulates uterine contractions

Question 25

Uterine contractions are accompanied by ___ contractions.

Answer 25

Abdominal

Question 26

What is one way pressure is reduced in parturition?

Answer 26

By the release of chorionic villi facilitated by vasoconstriction of villi arterioles

Question 27

Hemochorial placenta?

Answer 27

Maternal vasoconstriction reduces hemorrhaging

Question 28

Three reasons for distocia?

Answer 28

1) large fetus 2) abnormal presentation of the fetus (breach), abnormal limb presentation 3) multiple birth

Question 29

Skunk cabbage?

Answer 29

Sheep had prolonged gestation and congenital hypoplasia of anterior pituitary gland

Question 30

Gene defects?

Answer 30

Recessive gene in Holsteins had prolonged gestation due to pituitary hypoplasia

Question 31

How can parturition be induced in cattle and sheep?

Answer 31

By injecting corticosteroids

Question 32

What 6 things do hormonal changes cause?

Answer 32

1) final maturation of fetus 2) expansion of birth canal 3) maternal behavior 4) synthesis and ejection of milk 5) initiation of uterine contractions 6) termination of pregnancy

Question 33

Which hormone completes final mammary development and milk secretion?

Answer 33

Prolactin

Question 34

Fescue toxicity problems?

Answer 34

Ergot causes inhibition of prolactin release and thus milk production

Question 35

Which hormone stimulates lung surfactant?

Answer 35

Cortisol

Question 36

Which hormone initiates parturition and lung development?

Answer 36

Fetal cortisol