Anatomy and Control of Parturition

Question 1

What is stage one of parturition?

Answer 1

positioning of the foestus
- myometrium contracts

Question 2

What is stage two of parturition?

Answer 2

• initiated by release of allantoic fluid/cervical star breakage (mare)
• uterine myometrium contraction
• voluntary straining forces

Question 3

What is stage three of parturition?

Answer 3

• birth of placenta
  -uterine involution
  -uterine myometrial contraction

Question 4

How are myometrial contractions stimulated and controlled?

Answer 4

• high progestrone levels
  -foetal stress trigger
  -removal of progestrone block

Question 5

How does foetal stress initiate parturition?

Answer 5

• foetal stress increases
  -hypoxia caused
• physical confinement
  -nutritional stress
• stress activates hypotholomo-pituitary- axis (coricotrophin/ adrenocorticotophin/adrenal cordiciods released)

Question 6

How is the progesterone block removed?

Answer 6

• progesterone is converted into oestradiol
• foetal corticoids drive this
• lutolysis of the corpus luteum

Question 7

How does oestrodial help partuition?

Answer 7

• increases myometrial activity
• increases female tract secretions (lubrication/ washes cervical seal out)

Question 8

How does oxytocin have an impact on parturition process?

Answer 8

-released in response to pressure on the cervix
- further drives contractions

Question 9

What is stage 2 controlled by?

Answer 9

• oestrogens
• oxytocin
  -prostaglandin

Question 10

What is stage 3 controlled by?

Answer 10

• prostiglandin
• oxytocin