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Structure & Function 5 > Pregnancy and Parturition > Flashcards

Pregnancy and Parturition Flashcards

1
Q

what is pregnancy?

A

the carrying and supporting of a developing embryo until it can survive in the outside world

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2
Q

what is the ‘embryo’?

A

it is essentially a parasite as it derives sustenance from the ‘host’ without contributing anything itself

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3
Q

what does the uterus serve as during pregnancy?

A

serves as an incubator for the developing embryo

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4
Q

inner cell mass of embryo becomes?

A

becomes the foetus (allantois and yolk sac)

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5
Q

remainder of blastocyst (after inner cells mass has turned into foetus) becomes?

A

the remainder of the blastocyst forms amnion and chorion placental membranes

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6
Q

what does the embryo contribute to?

A

contributes to a transient organ that enables it to take oxygen and nutrients from the mother - the placenta

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7
Q

role of the placenta?

A

allantois functions as depot for excretory products
transport of metabolic substances
glucose is a high priority to the foetus (even in ruminants compared to adulthood)

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8
Q

describe the role of placenta in the transport of metabolic substances:

A

lipid-soluble substances including oxygen and CO2 diffuse across the epithelial barriers
Glucose, AA, Ca2+ and other ions are actively transported
concentrations are greater in foetal blood compared to maternal blood
free fatty acids –> important for horses and very little used in ruminants
water soluble vitamins are actively transported
steroid hormones and catecholamines diffuse across to foetus easily
peptide hormones and proteins are transported to the foetus only to a limited extent
Immunoglobulins in some species (not ruminants)

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9
Q

what are the roles of the placental hormones?

A

assist in parturition
stimulate mammary function
stimulate ovarian function
maintain pregnancy
influence foetal growth

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10
Q

what type of major organ is the placenta?

A

a major endocrine organ

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11
Q

placental hormones of pregnancy - role of it?

A

progesterone: important to maintain pregnancy and prevent uterine contractions during pregnancy
always produced by the corpus luteum during early pregnancy, however the role of the CL to maintain pregnancy will vary among species
In some species, the placenta will take over

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12
Q

placental lactogen?

A

peptide hormone closely related to Growth Hormone
Also called chorionic somatomammotropin (CS)
stimulates growth of alveoli in mammary glands during pregnancy

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13
Q

what does relaxin placental hormone do?

A

produced in both placenta and ovaries
secreted throughout pregnancy
prevents uterine contractions during pregnancy alongside progesterone
Also loosen connective tissue in cervix and ligaments in pelvis prior to parturition

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14
Q

anterior longitudinal?

A

head facing the bottom of mum

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15
Q

posterior longitudinal?

A

head is facing head of mum in cervix

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16
Q

equine chorionic gonadotropin? (eCG)

A

produced by the endometrial cups of the placenta
acts as a luteotropin and provides stimulus for maintenance of the primary corpus luteum
controls and maintains supplementary corpora lutea and therefore increases the ability of the ovary to produce progesterone

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17
Q

when is eCG produced?

A

produced from 2nd to 5th month of pregnancy

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18
Q

human chorionic gonadotropin (hCG)?

A

originates from the trophoblastic cells of the chorion in humans and primates
can be detected in the blood and urine as early as 8 days of pregnancy

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19
Q

what does parturition involve?

A

relaxation + softening of the cervix, pelvic ligaments and perineum
repositioning of the foetus
dilation of the cervix
myometrial and abdominal contractions
expulsion of the foetus and foetal membranes

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20
Q

what is a progesterone block?

A

high levels of progesterone inhibit contractions of uterine muscle cells
prevents premature expulsion of the foetus

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21
Q

what is the primary trigger for parturition?

A

foetal stress

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22
Q

describe how foetal stress is the primary trigger for parturition:

A

lack of space + high metabolic demands
foetal stress
ACTH released from foetal pituitary
Cortisol secreted from foetal adrenal glands

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23
Q

once foetal cortisol has been secreted - what happens?

A

synthesis of placental enzymes
enzymes convert progesterone to oestradiol
progesterone decreases
oestradiol increases

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24
Q

increased oestrogens (oestradiol is one) leads to?

A

increased synthesis of myofilaments in uterine smooth muscle
increases in the number of gap junctions between the muscle cells
which facilitates more action potentials and greater forces and coordination of uterine contractions

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25
oestrogen concentrations also... endocrinology of parturition
increase the numbers of calcium channels and uterine receptors for oxytocin stimulates glandular cells in the cervix and vagina to secrete watery mucous --> softens the mucous plug
26
how is prostaglandin PGF2α also important for the endocrinology of parturition?
stimulated by cortisol and released in placenta causes luteolysis and contributes to the removal of the progesterone block ceases production of progesterone in placenta in species with placental takeover
27
what are the different types of presentation a lamb can be in - obstetric terminology?
presentation - longitudinal, transverse of vertical
28
what are the different types of position of a lamb - obstetric terminology?
position - dorsal, ventral, right, left
29
what are the different types of posture a lamb can be in - obstetric terminology?
posture - flexion, extension
30
what is presentation of the foetus?
the relationship between the longitudinal axes of foetus and birth canal and the foetal surface directed toward the cervical canal
31
presentation for monotocous species?
anterior presentation
32
presentation of polytocous species? (dog and pig)
45% are in a posterior position
33
longitudinal presentation?
the axes are parallel
34
anterior longitudinal?
cranial end directed toward the birth canal
35
posterior longitudinal?
caudal end directed toward the birth canal
36
what is the transverse presentation of the foetus?
transverse --> the foetus lies transversely in relation to the direction of the birth canal
37
Dorsotransverse presentation?
dorsum is directed toward the birth canal
38
Ventrotransverse presentation?
ventral surface is directed toward the birth canal
39
vertical presentation?
very rare
40
what are the types of positions the baby can take up - obstetric terminology?
dorsal, ventral, left, right
41
position - obstetric terminology?
the relationship of the foetal back to the dorsal surface of the birth canal
42
dorsal positioning?
dorsum of the foetus directed dorsally
43
ventral positioning?
ventral surface of the foetus is directed dorsally
44
left positioning?
left lateral surface of foetus directed dorsally
45
right positioning?
right lateral surface of foetus directed dorsally
46
what is the posture - obstetric terminology?
Disposition of moveable appendages e.g. foetal neck, limbs within the birth canal (lateral or ventral neck flexion, extended forelimbs and hindlimbs, carpal flexion, hip flexion)
47
how many stages can parturition be divided into?
into 3 stages
48
what are the 3 stages that parturition can be divided into?
Stage 1 --> prep of the reproductive tract and foetus for delivery Stage 2 --> Delivery of the foetus Stage 3 --> Expulsion of the foetal membranes
49
in which species do stage 2 and stage 3 of parturition overlap?
In polytocous species
50
stage 1 of parturition time period for bitch?
6-12 hours
51
stage 1 of parturition time period for sow?
2-12 hours
52
stage 1 of parturition time period for cow?
2-6 hours
53
stage 1 of parturition time period for mare?
1-4 hours
54
stage 2 of parturition time period for bitch?
6 hours 0.5 -2 hour interval
55
stage 2 of parturition time period for sow?
2.5 - 3 hours intervals 16 minutes
56
stage 2 of parturition time period for cow?
0.5-1 hour
57
stage 2 of parturition time period for mare?
12-30 mins
58
stage 3 of parturition time period for bitch?
foetal membranes pass attached to the neonate or within 15 mins of birth
59
stage 3 of parturition time period for sow?
1-4 hours
60
stage 3 of parturition time period for cow?
6-12 hours
61
stage 3 of parturition time period for mare?
1 hour
62
contraction of the myometrium continues - what does this result in?
reduces the size of the uterus (involution)
63
what happens during involution of the uterus?
the smooth muscle cells decrease in size and the glands in the endometrium are degraded
64
when granulocytes enter, what happens and when do granulocytes enter?
they decompose tissue remnants and kill remaining microorganisms - these enter once the smooth muscle of the uterus has involuted
65
What are the stages of stage 1 of parturition?
Connective tissue remodelling Pelvic ligaments relax Due to PGF2α --> relaxin production (from CL/placenta) Increased cervical mucoid secretion Myometrial contractions Removal of the progesterone block Action
66
Describe the connective tissue remodelling step of the stage of parturition?
Dilation of the cervix Extracellular matrix remodelling so there is separation of collagen fibres and increase in water content
67
what is the external os and what is it also known as?
it is the opening between the cervix and the vagina - AKA external uterine orifice
68
describe the movement of the cervix when connective tissue remodelling occurs during parturition:
the external os dilates, cervix shortens, internal os dilates, cervix dilates and mucoid plug is lost, distended chorioallantoic sac enters the cervical canal
69
what is PGF2α?
prostaglandin E2 (PGE2) and F2α (PGF2α) are the two most prominent prostanoids in parturition.
70
what are prostanoids?
these are eicosanoids which consist of prostaglandins
71
what are eicosanoids and give example?
lipid-based signalling molecules e.g. prostanoids which consist of the prostaglandins
72
what do prostaglandins do during parturition?
the uterine cells produce prostaglandins to help dilate the cervix and cause uterine contractions (myometrium contractions)
73
why is there increased cervical mucoid secretion during stage 1 of parturition?
due to increased levels of oestrogen
74
describe the myometrial contractions that occur during the first stage of parturition:
They become regulated and coordinated Prior to stage 1 of parturition these are weak + uncoordinated they increase in duration, frequency + amplitude
75
Describe the nature of myometrial contractions during stage 1 of parturition:
they are peristaltic in nature
76
Describe what happens after the removal of the progesterone block:
--> activation of enzymes: progesterone --> oestrogen Synthesis of PGF2α leads to regression of the CL
77
Describe what happens when the 'action' part of stage 1 of parturition occurs:
vasoconstriction on maternal side of the placenta --> increases blood return to the foetus and loosening of the placental attachment commences
78
what happens to the foetal positioning during stage 1 of parturition?
rotation of foal + puppy: from ventral --> dorsal position AND extension of limbs and head
79
what part of the foetal movement is unnecessary in calf and lamb and why?
Rotation from ventral to dorsal position THIS IS UNNECESSARY in CALF + LAMB as they are already in dorsal position
80
the extension of the limbs during stage 1 of parturition doesn't occur in which animal?
limbs aren't extended in the pig
81
the rotation of foal and puppy (foetus) is associated with what?
associated with myometrial contractions and spontaneous foetal movement
82
what may rupture at the end of stage 1?
the chorioallantois
83
What are the behavioural changes associated with stage 1 of parturition?
restlessness nesting activity Towards the end of the stage, the mare may crouch, straddle her hindlimbs and go down on her sternum then rise again
84
What are the physiological changes associated with stage 1 of parturition?
increase in pulse and respiratory rates decrease in body temp in mares: patchy sweating behind elbows and about the flanks
85
Describe stage 2 of parturition for monotocous species:
Stage 2 is delivery of the foetus Stage 2 involves expulsion of the foetus but not the foetal membranes
86
Describe stage 2 of parturition for polytocous species:
stage 2 and 3 are inseparable because one foetus follows another and the membranes are expelled throughout this process
87
What steps does stage 2 of parturition consist of?
Abdominal wall contractions commence Myometrial contractions increase Rupture of the chorioallantois Then structures appear at the vulval cleft
88
Describe what happens when the abdominal wall contractions commence during the delivery of the foetus stage (stage 2) of parturition:
myometrial contractions move the foetus toward the pelvic inlet, this activates the 'pelvic reflex' and stimulates straining Contractions increase as the foetus passes through the pelvic canal
89
When myometrial contractions increase - describe what happens - this is part of stage 2 of parturition:
due to the foetal pressure on the cervix and cranial vagina --> oxytocin is released
90
describe the rupturing stage of stage 2 of parturition?
rupture of the chorioallantois (if this hasn't ruptured earlier) Release of 'urine like' allantoic fluid escapes from the vulva Placental attachments still present
91
During delivery of the foetus - describe what structures appear at the vulval cleft?
As straining continues, the amnion traverses the vagina + appears at the vulva as a 'water bag' Foetal limbs appear contained in bag Amnion expelled + may rupture Foetal head occupies the vulva + contractions climax
92
When foetal limbs appear at the vulval cleft - they appear in a bag, describe what may happen at this stage in monotocous species?
one limb may slightly precede the other
93
When are contractions maximal during the delivery of the foetus?
the contractions are maximal w/ appearance of the head if nostrils are exposed to air, breathing will commence and rest period may ensue for the mother
94
After the rest period for the mother - what happens during stage 2 of parturition?
abdominal contractions will resume foetal thorax and pelvis are then delivered Amnion rupture (if intact) The umbilical cord ruptures
95
when the foetal thorax and pelvis are delivered - what is different for large animals?
the hind limbs may remain in the vagina until freed by movement of the neonate or the mother
96
when the foetal thorax and pelvis are delivered - what is different for pigs and small animals?
the limbs immediately follow the body
97
how does the amnion ruptures - if intact?
this is associated with movement of the neonate or mother stimulus to breathe - impact of air on the nostrils
98
what happens during the rupture of the umbilical cord?
if animal is in lateral recumbency - the umbilical cord may remain intact umbilical arteries and urachus then retract associated w/ movement of the neonate and/or mother
99
when does the rupturing of the umbilical cord occur?
occurs shortly after delivery or thereafter
100
if the animal is in lateral recumbency, the umbilical cord may remain intact: what does this allow for?
allows time for large volume of blood from placenta to return to young
101
what often happens to the foetal membranes that are expelled?
they are often eaten by the mother
102
what is stage 3 of parturition?
expulsion of foetal membranes
103
describe stage 3 of parturition - (expulsion of foetal membranes) in monotocous species?
it is a distinct stage and involves only the delivery of the foetal membranes (occurs 30mins - few hours after stage 2)
104
describe the 3rd stage of parturition - expulsion of the foetal membranes:
abdominal contractions largely cease Endometrium secretes pulses of PGF2, which (w/ oxytocin) cause myometrial contractions to persist This disrupts the physical contact between the foetal membranes and the endometrium allowing expulsion
105
what is stage 2 of parturition?
delivery of the foetus
106
what is stage 1 of parturition?
preparation of the reproductive tract and foetus for delivery
107
what is a monotocous species?
they produce a single offspring at birth
108
what is a polytocous species?
where the female produces multiple offspring at birth

Structure & Function 5 (24 decks)

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