Topic 95 - The endocrinology of parturition; birth Flashcards
Words to include in birth
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)
- Tonicity of uterus is replaced with rhytmical contraction
-
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)
-
After-pains
-
End of parurion
-
Contraction of uterine muscles
- Separation of allantochorion from endometrium
- Allantochorion
- Inside out transferred to environment
-
Contraction of uterine muscles
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
Words to include in the endocrinology of parturition
-
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 stress
- 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
- Phosphorylase A2 activated
- ↑ 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
- Ferguson reflex
- Contraction phase: fetus puts pressure on birth canal
- Synthesized:
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
- PGF2α, PGI2
- Luteolysis
- Development of gap junctions in myometrium
Can include:
- Sexual period and breeding maturity
- Pregnancy duration
- Size of litter
Parturition
Give the phases of parturition
- Initial phase: Before parutition
- phase: Preparatory phase
- phase: Phase of contraction
- 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
-
Rhytmical contractions of uterus
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
Parturition
Normal birth positions of a fetus
-
Presentation
- Position of fetus in birth canal
-
Longitudinal
-
Head or bottom first
- Head first: normal in large animals
-
Head or bottom first
-
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
The endocrinology of paturition
- 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
-
Fetal stress
- 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
-
Synthesized:
- 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
-
Oxytocin secretion from posterior pituitary
The endocrinology of parturation
Give the graph of hormonal changes during parturation
Except the horse pregnancy, where P4 increase and E decrease (unlike in others)
The endocrinology of paturition
Regulators of parurition
- Labor onset
- Strectch stimulus
- Oxytocin
- Prostaglandins
-
Positive feedback
- Cervical stretch →
- Oxytocin ↑
- Parutition
Figure: the positive feedback loop of paturition
The endocrinology of parturition
Endocrinological changes in horse
- Parturition is leads to large increases in prostaglandin and oxytocin concentrations
- Induce uterine contractions and delivery of the foal