Topic 95 - The endocrinology of parturition; birth Flashcards

1
Q

Words to include in birth

A

Phases of parturition

  • Before parturition (initial phase)
    • Edema of vulva
    • Mucous hanging out of vagina
    • Edematous udder
    • Dripping of colostrum
    • Loosening of lig. sacroiliaca (effect of relaxin)
  • Preparatory phase
    • Opeining of cerix
    • 0.5-1.0 ˚C decrease in body temperature
    • Uterus reaches tonic status
    • No labor pains
    • Opening
      • Tonicity of uterus is replaced with rhytmical contraction
        • Labor pains
      • Fetal and maternal placenta connection loosens
      • Preparsatory pains (dolores preparantes)
  • Phase of contraction
    • Rhytmical uterine contractions increased by oxytocin
    • Most severe pain (dolores ad partum)
  • After phase
    • After-pains
      • Expelling membranes
    • Morphological recovery of uterus (puerperium)
      • Reach pre-gravid status (involution)
  • End of parurion
    • Contraction of uterine muscles
      • Separation of allantochorion from endometrium
    • Allantochorion
      • Inside out transferred to environment

Normal birth positions of a fetus

  • Presentation
    • Position of fetus in birth canal
    • Longitudinal
    • Head/bottom first
      • Head first: normal in large animals
  • Position
    • Location of fetal vertebral column
    • Abdominal position
      • Abdomen up: eq
      • Abdomen down: ru
  • Deportment
    • Position of fetal limbs and head
    • Stretched limbs
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2
Q

Words to include in the endocrinology of parturition

A
  • End of pregnancy:
    • P4 high
    • E2 low
    • Uterus is insensitive to contracting effect of
      • E2
      • Oxytocin
  • Intiator of changes
    • Fetal stress
      • Mechanical stress
      • Chemical stress
      • High environmental temperature
      • Maturation of hypothalamus
      • Maturation of fetal adrenal cortex
  • Fetal hypoth-hypophysis (ACTH)-adrenocortex axis
    • Synthesized:
      • Glucocorticoids
      • C19 steroids (androgens)
    • Glucocorticoid inhibits P4 syntheis in placenta and ovary
    • P4 → E2
      • Due to activity of 17-α-hidroxylase
    • Andorgens → E2
      • Phosphorylase A2 activated
        • Prostaglandin synthesis stimulated in uterus and placenta
    • ↑ Prostaglandin stimulate:
      • Luteolysis
      • Oxytocin secretion
    • Myometrium sensitive to oxytocin
      • Contraction phase: fetus puts pressure on birth canal
        • Ferguson reflex
          • Relasing oxytocin from posterior pituitary
          • Abdominal pressure

Regulators of parurition

  • Labor onset
  • Strectch stimulus
  • Oxytocin
  • Prostaglandins
  • Positive feedback
    • Cervical stretch →
    • Oxytocin ↑
    • Parutition
  • Positive feedback loop of parturition
    • Fetus drops lower in uterus
    • Cervical stretch
    • Uterine contractions
    • Oxytocin from posterior pituitary
    • Prostaglandins from uterine wall

Endocrionlogical changes in hors

  • Parturition → prostaglandin & oxytocin ↑
    • Uterine contractions ↑

Role of hormones

  • AC steroids
  • Activation of 17-α-hydroxylase
  • Progesterone
  • Estrogens
  • Level of estrogens high +
  • Levels of progesterone low ÷
  • Contractions of uterus
  • Cervix is pushed (and stretched) by the head of the foetus
  • Ferguson reflex
  • Oxytocin secretion
  • PGF, PGI2
  • Luteolysis
  • Development of gap junctions in myometrium

Can include:

  • Sexual period and breeding maturity
  • Pregnancy duration
  • Size of litter
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3
Q

Parturition

Give the phases of parturition

A
    1. Initial phase: Before parutition
    1. phase: Preparatory phase
    1. phase: Phase of contraction
    1. phase: After-phase

0. Initial phase: Before parutition

  • Signals of coming parurition:
    • Edema of vulva
    • Mucus is hanging out of vagina
    • Edematous udder
    • Dripping of colostrum
    • Relaxin effects:
      • Uneasiness
      • Bending of back
      • Loosening of lig. sacroiliaca

1. phase: Preparatory phase​:

  • Opening of cervix
  • Infiltration and swelling of birth canal
  • Cervical plud is dissolved and appears in vagina
  • Pelvic ligament relaxed
  • Abdominal wall lowered
  • 0.5-1.0 ˚C decrease in body temperature
  • Uterus reaches tonic status
  • Opening (dilation):
    • Rhytmical contractions of uterus
      • Labor pains
    • Connection between fetal and maternal parts of placenta gets looser
    • Preparatory pains begin
    • Upper limbs of foetus may already be out

2. phase: Phase of contraction

  • The rhytmic uterine contractions increased by:
    • Oxytocin
    • Increased abdominal pressure
  • Head is pushed out
  • Most intensive stage with the most severe pain (dolores ad partum)
  • Following is a short break for gathering of strength

3. phase: After-phase

  • After-pains
  • Expelling the fetal membranes to the environment
  • Morphological recovery of uterus (purperium), in order to rach pre-gravid status (involution)
  • Ovary is reactivated, new cycle

End of parurition

  • Contraction of the uterine muscles result in the separation of the allantochorion from the endometrium
  • Allantochorion is inside out transferred to the environment
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4
Q

Parturition

Normal birth positions of a fetus

A
  • Presentation
    • Position of fetus in birth canal
    • Longitudinal
      • Head or bottom first
        • Head first: normal in large animals
  • Position
    • Location of fetal vertebral column and birth canal
    • Abdominal position
      • Abdomen up: horse
      • Abdomen down: cow
  • Deportment
    • Position of fetal limbs and head in relation to the birth canal
    • Stretched limbs
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5
Q

The endocrinology of paturition

A
  • End of pregnancy:
    • High P4
    • Low E2
    • Uterus is insensitive to contracting effects of E2 and oxytocin
  • Intiator of changes:
    • Fetal stress
      • ​Mechanical stess
      • Chemical stress
      • High environmental temperature
      • Maturation of hypothalamus
      • Maturation of fetal adrenal cortex
  • Activaiton of fetal hypthalamus-hypophysis (ACTH)-adrenocortex axis
    • Synthesized:
      • Glucocorticoids
      • C18 steroids (androgens)
    • Glucocorticoids inhibits P4 synthesis in the placenta and ovary
    • P4 is converted to E2
      • Due to activity of 17-α-hidroxylase
    • Androgens are converted to E2
      • Activate phsphorylase A2, which stimulates prostaglandin synthesis in the uterus and placenta
  • Increasing prostaglandin stimulate:
    • Luteolysis
    • Oxytocin secretion
  • Myometrium is getting sensitive to oxytoxin
    • During contraction phase, the fetus puts pressure on the birth canal → Ferguson reflex
    • Ferguson reflex leads to
      • Oxytocin secretion from posterior pituitary
        • Intensive uterinal contractions
        • Depolarization
        • AP ↑
      • Abdominal pressure
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6
Q

The endocrinology of parturation

Give the graph of hormonal changes during parturation

A

Except the horse pregnancy, where P4 increase and E decrease (unlike in others)

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7
Q

The endocrinology of paturition

Regulators of parurition

A
  • Labor onset
  • Strectch stimulus
  • Oxytocin
  • Prostaglandins
  • Positive feedback
    • Cervical stretch →
    • Oxytocin ↑
    • Parutition

Figure: the positive feedback loop of paturition

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8
Q

The endocrinology of parturition

Endocrinological changes in horse

A
  • Parturition is leads to large increases in prostaglandin and oxytocin concentrations
    • Induce uterine contractions and delivery of the foal
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