Lecture 12: Parturition (Kelleman) Flashcards Preview

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Flashcards in Lecture 12: Parturition (Kelleman) Deck (48):
1

Clicker Q: Which of the following are polyestrus and thus have repeated estrous cycles throughout the entire year? A's: Queens, mares, bitches, cows, or wes

Ewes

2

Clicker Q: Is progesterone high or low in diestrus?

high

3

Clicker Q: Melatonin suppresses GnRH in which animal?

Mares

4

Clicker Q: Luteinizing hormone (LH) causes:

ovulation

5

Ferguson Reflex

Neuro-endocrine loop causing oxytocin release

6

Main hormone for maintaining pregnancy

progesterone

7

cervical closure fx. Maintained by which hormone?

Keeps contents from falling out and infection from getting in during preg. Progesterone

8

Where is progesterone produced?

CL and placenta

9

Which species have high progesterone throughout most of pregnancy?

ewe, sow, cow. Decreases in late-gestastion with estradiol peak

10

rising estradiol --> progesterone

decreases

11

HPA axis stands for

hypothalamic-pituitary-adrenal axis

12

Activation of fetal HPA axis increases what 3 hormones

1) Corticotrpoin releasing hormone (CRH)
2) Adrenocorticotropin Hormone (ACTH)
3) Cortisol***

13

Types of fetal stress

hypoxia, overcrowding, nutritional compromise

14

Fetal HPA axis:
Name the 3 organs involved

hypothalamus --> anterior pituitary --> adrenal gland (cortex)

15

Fetal HPA axis:
what hormone is released by the hypothalamus to stimulate the anterior pituitary?

CRF

16

what hormone is released by the anterior pituitary to stimulate the adrenal gland?

ACTH

17

Name the 3 functions of cortisol on the fetus:

1. induce enzymatic changes in the placenta ie "communicates" with mom
2. promotes prostaglandin synthesis
3. fetal maturation

18

main action of progsterone

"pro-gestational"
"hormone of pregnancy"

19

main function of estrogen

increased uterine "responsiveness"

20

main function of PGF2-alpha

luteolysis and contractions

21

main function of oxytocin

contractions

22

main function of relaxin

genital tract softening

23

Upon stimulation, what hormone can progesterone be converted to?

estradiol

24

what hormone induces placental enzymes which convert progesterone to estradiol?

fetal cortisol

25

what hormone is progesterone converted to before its final conversion to estradiol?

testosterone

progesterone --> testosterone --> estradiol
21 carbons --> 19 carbons --> 18 carbons

26

3 ways in which progesterone falls

1: enzymatic - fetal cortisol induces placental conversion of progesterone to estrogen
2: luteolysis - via PGF2-alpha and uterine contractions
3: removal of "progesterone block" (keeps fetus quiet during gestation)

27

"progesterone block"

- keeps fetus quiet during gestation
- during the removal of the "progesterone block" cortisol release induces progesterone to estrogen thereby decreasing progesterone and increasing estrogen.

28

what way can estrogen can be increased (during parturition)

enzymatic - fetal cortisol induces placental conversion of progesterone to estrogen

29

what are the three functions of estrogen?

1. increases uterine sensitivity to oxytocin
2. increases lubrication and sofening
3. promotes release of PGF2-alpha

30

2 main functions of prostaglandin in parturition

1. causes luteolysis if CL is still present
2. will cause uterine (myometrial) contractions

31

what is the main function of oxytocin

myometrial contractions

these contractions can subsequently promote more oxytocin and PGF2-alpha release.

32

what is the main function of relaxin in parturition?

encourages pelvic, genital tract and cervical softening to facilitate parturition

- this can be externally assessed as parturition nears: vulva, perineum and pelvic ligaments

33

The Ferguson reflex

the sensation of distension of the cervix, uterus and vagina by the fetus results in a neuroendocrine reflex which causes the release of oxytocin (from posterior pituitary).

oxytocin causes uterine contractions resulting in further distension, which increases oxytocin, causing further distension and contraction and so on.....

34

Name the 3 stages of parturition

Stage I: "preparation"
Stage II: fetal expulsion with "true labor"
Stage III: expulsion of the fetal membranes

35

what happens in stage I of parurition

- cervical dilation, myometrial contractions, some fetal positioning
- behavior: nest building behaviors in dog & cat. cattle and sheep isolate themselves. mare shows colic-like signs (poor appetite and restlessness)

36

what happens in stage II of parturition

start: rupture of the chorioallantois
finish: complete expulsion of the fetus
- myometrial and abdominal contractions.

1.chorioallantois breaks (1st fluid expulsion).
2. fetus is seen within the amnion. amnion breaks and amniotic fluid is released (2nd fluid expulsion).

37

Stage III of parturition

expulsion of fetal membranes

in species that are polytocus (more than one fetus), phase II and phase III often follow each other with each fetal passage.
- mom experiences vasoconstriction and inflammation

38

typical position of fetus upon actual parturition

anterior, dorsosacral, forelimbs extended.

39

species variability in length of each stage of parturition
(general - no specific numbers)

cow - slow
heifer - even slower

horse - fast, "explosive"

40

define: Lochia

the normal fluid which is passed from the uterus during the purerperium. it consists of cellular (RBC, WBC, bits of tissue, etc) and noncellular debris (fetal fluids, lysed blood, mucus, etc).
- time varies by species
minimal odor!

41

type of contractions throughout parturition

uterine myometrial (smooth muscle) contractions

abdominal contractions:
- straining against closed glottis
- additive with smooth muscle contractions

42

time from fetal delivery until complete uterine involution is defined as:

Puerperium

43

Complete Uterine Involution varies by species. cow? mare? bitch?

uterine involution = transformation from pregnant to non-pregnant state

mare = ~ 2 weeks
cow = 1 - 1.5 months
bitch = about 2 months or more

44

Retained Fetal Membranes (RFM)

aka "retained placenta" - when placenta is not expelled in its entirety within a given time for each species.
- incomplete expulsion
- autolysis (rotting)
- minor to serious health problems may result depending upon species
- involution is delayed by RFM

45

dystocia

"difficult birth"

46

Equine RFM is how much time after fetal delivery?

3 hours - considered a true emergency - potentially life threatening

47

Bovine RFM - how much time after fetal delivery?

> 12 hours

48

General parturition summary

1. Fetal HPA activation
2. decreased Progesterone
3. increased estrogen
4. increased oxytocin and PGF2-alpha
relative uterine quiescence changes to dramatic uterine activation!

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