Physiology of Parturition - Dr. da Silva

Question 1

What is essential for the maintenance of pregnancy?

Answer 1

Progesterone

Question 2

What 2 species don’t have the P4 fall prior to parturition?

Answer 2

Primate and Guinea Pig

Question 3

In what species is the placenta the progesterone source?

Answer 3

Sheep, Cow, Mare, Primate, Guinea Pig

Question 4

(T/F) Most studies of parturition is in sheep, primates, lab animals

Answer 4

True

Question 5

What are the Three functions of P4?

Answer 5

• Development/function of the placenta through gestation
• Myometrial quiescence, keeps uterine “quiet”
• Closure of cervix, keeps it tight

Question 6

(T/F) Fetus triggers parturition

Answer 6

True

Question 7

What is the stress that the fetus undergoes, that then triggers the hypothalamic-pituitary-adrenal axis?

Answer 7

hypoxia

Question 8

Events of Parturition
Increased Cortisol increases __________ and __________

Answer 8

Estrogen and PGF2alpha

Question 9

• Increase Oxytocin receptors
• Increase GAP junctions uterus
• Relax cervix

Answer 9

Increased estrogen

Question 10

• Luteolysis
• Stimulate Relaxin synthesis
  - Cervix/ Ligaments
• Myometrial contractions

Answer 10

Increased PGF2alpha

Question 11

What is the most common cause of equine dystocia?

Answer 11

Fetal malposture

Question 12

Fill in the blanks:
Events of Parturition
- Increased pressure + open cervix
- Rupture of ________________
- Release of ____________ fluid
- Further lubrication of the birth canal
- Fetus enters the birth canal
- Stretch of cervix / cranial vagina
- Increase oxytocin release
- Fergusson’s Reflex

Answer 12

chorioallantois, allantoic fluid

Question 13

What stage of parturition is this?
- Myometrial contractions begin
- Cervical relaxation
- Fetus adopts birth posture / position
- Chorioallantois rupture

Answer 13

Stage I

Question 14

What stage of parturition is this?
- Fetus enters the birth canal
- Strong uterine / abdominal contractions
- Fetus is delivered

Answer 14

Stage II

Question 15

What stage of parturition is this?
- Placental expulsion

Answer 15

Stage III

Question 16

(T/F) During parturition, stretching of the cervix stimulated Ferguson’s reflex and causes a major release of prostaglandin from the uterus

Answer 16

False

Question 17

What event determine the end of the first stage of parturition and the initiation of the second stage?

Answer 17

Rupture of the allantochorion and release of allantoic fluid

Question 18

During parturition, fetal stress causes the secretion of cortisol by the fetal adrenal glands. The increased cortisol causes:

Answer 18

• Increased secretion of PGF2alpha
• Decrease in progesterone and increase in estradiol secretion by the placenta
• Maturation of fetal lungs, kidney,s and brain
• Increase in the reproductive tract secretion

Question 19

During parturition in cows, increased levels of fetal ____________ act in the placenta and uterus resulting in a rapid decrease in _____________levels and an increase in both ________________ and _____________ levels.

Answer 19

cortisol, progesterone, estradiol, prostaglandin