Week 3 Flashcards
describe the hormonal changes in parturition of the cow in pregnancy?
late pregnancy - oestradiol rises gradually to reach peak
progesterone begins to decline + drops before parturition (CLs still produce progesterone)
describe the hormonal changes in sheep during parturition?
progesterone rises considerably from mid=pregnancy
oestrdial remains low until peak before parturition.
describe the hormonal changes in mare during parturition?
oestragrens reach peak in mid-pregnancy while progesterone declines
CLs progesterone conc declines dramatically
what else occurs in mare during partursition with cortisol and myometrial activity?
a rise in cortisol occurs during days of parturition
Myometrial activity increase at night in peripoant mare, thus mares feed predominantly at night
why must progesterone decline for parturition?
reduces functions to occur - increased oestrdiol
decreased progesterone
leads to onset of labour
describe how the fetal hypothalamus has a effect on fetal cortisol levels rising?
fetal hypothalamus release CRF
fetal Ant. Pititaru release ACTH
Feta; adrenal glands release cortisol levels that rise and travel to placenta.
describe how sheep fetal cortisol crosses the mature placenta and causes oestradiol synthesis?
cortisol diffuses across mature placenta membrane via PGE2 - 17a hydrolase aromatase which causes pregnenolone to covert into oestrdiaol synthesis.
oestradiol induces contractility active proteins in the myometrium, such as PGF2a and oxytocin receptors
describe how cow fetal cortisol induces PGF2a and causes luteolysis?
fetal cortisol crosses membrane increases levels of oestradiol and PGF2a causes CL regression in ovary leading to lowered progesterone levels.
what else does PGF2a cause in parturition?
uterine contractions, cervical dilation and aids fetal expulsion via relaxin release and oxytocin responsiveness.
relaxin levels increase in mare/bitch.
how does cortisol achieve the increase in oestriaol and decline in progesterone which is essential for parturition?
in placenta?
placenta responsible for progesterone production at the end of pregnancy - fetal cortisol induces 17a Hydroxylase + aromatase in the placenta
leads to C21 steroids used as a precursor for oestrdiaol production
oestradiol rises and progetsone falls.
how does cortisol achieve the increase in oestriaol and decline in progesterone which is essential for parturition?
in CLs?
corpus luteum (or CLs) is responsible for progesterone production at the end of pregnancy
Fetal cortisol induces placental PGF2a synthesis -
Luteolysis of the CL -
Acute prepartal progesterone decline -
Placental oestradiol synthesis is increasing
describe labour stage 1?
preparation - fetus changes position in uterus + enters birth canal
mother becomes restless, vomiting, sweating
mammary gland changes - oedema in mammary gland
- dripping colostrum
- expulsion of cervial plug
describe labour stage 2?
expulsion of foetuses (mins)
abdominal contractions viable - foetus delivered though birth canal in the aminon.
escape of allantoic fluid, strong uterine contractions. amino may rupture
explain the Ferguson + Pudendal reflex?
1) vaginal = cervical stretching leads to oxytocin release causing smooth muscle contractions
2) N.pudendus reflexes: vaginal stretching leads to strong abdominal contractions
describe labour stage 3?
placenta expulsion of first ducklings/standing up
after birth delivered.
repute of umbilical cord
expulsion of fetal membrane 1-12 hours post partum
beginning of puerperium (post partum blood)
name the basic neonate adaptations?
cortisol rise thyroid T3 hormone rise Cord Clamping Cold shock neonate breathing fetal lung fluid secretion thermoregulation (non-shivering thermogenesis)
explain the cortisol rise before birth and what its functions for?
lung anatomical devopelment, maturation + sue faction synthesis
clearance of fetal lung fluid
matyrationof thyroid axis + more conversions of T4 - T3 leading to rise in thyroid hormone
what does increasing thyroid hormone T3 do afterbirth?
stimulates thermogenesis
regulates maturation of the repsiratory, nervous system
discuss what cord clamping is?
leads to catecholamine surge within minutes of delivery
the NA + A surge is a response to hypoxia leads to = large increase in B.P
thermogenesis from brown adipose tissue (lipolysis = heat)
these hormones place neonate into âCatabolic stateâ
glycolysis + lipolysis occur which elevate glucose + free FA depleted by 2-3hours
insulin rises after colostrum feed intake to ensure nutrient uptake
explain the stages of neonate breathing?
1) cleansing of fetel lung fluid - reversal of fluid secretion + reabsodprption
Areation of the alveoli + INNITAION OF O2 + CO2 exchange between pulmonary capillary blood + gas.
2) surfactant secretion - new alveolar lining layer on liquid hypophase
3) continuous breathing pattern devoplment ex-utero when umbilical cord is calmed to hypoxia leading and cold stimuli
describe fetel lung fluid secretion?
1) high secretion in late gestation
2) decline in airspace fluid volume during birth
3) sodium pump responsible for reabsorption of lung fluid into blood vessels + lymphatics
what occurs when new-born takes first breath?
air enters bronchi - alveoli move fluid into distal airspace where it is absorbed, O2 can now move in
alveolar fluid is absorbed through the intertsiutm.
O2 transports form alveoli to blood vessels - increasing pO2
in 3 breaths = 50% of the lungs become aerated.
what must happen when neonate lungs are breathing?
neonate lungs must allow gas exchange by surfactant production + function.
surfactant reduces inflation resistance + ensures alveoli do not collapse after expiration.
what considerations occur when the fetal circulation oxygen and flow occur?
left shift - causes loads of O2 to low O2 tension
High pulmonary vascular resistance in fetal lungs due to low oxygen tension
umbilical vein O2 saturation is 80% with some flow bypassing liver enters caudal vena cava via DUCTUS VENOSUS
what is the ductus Venous?
shunts a portion of umbilical vein blood flow directly to the inferior vena cava. allows oxygenated blood from placenta to bypass the liver
where does the caudal vena cava flow direct too?
to right atrium + foramen ovale to left atrium P ventricle pumped into aorta.
what is the foramen ovale?
small hole located in the septum, which is the wall between the two upper chambers of the heart (atria). Before a baby is born, it does not use its lungs to get blood rich in oxygen.
what is the ductus arteiosus?
blood vessel that connects the pulmonary artery (main vessel supplying the blood to the lungs) to the aorta This connection is present in all babies in the womb, but should close shortly after birth.
what does the ductus arteiosus join too?
joins aorta downstream of arteries to heal and fix - aortic blood O2 saturation is reduced to 58%
what controls the transition of fetal circulation to adult circulation?
cortisol + catecholamines - leads to increased lung perfusion + O2 pressure.
what changes occur from transition of fetal circulation to adult circulation?
2x cardiac output with rise in O2 consumption due to increased metabolism, breathing effort, thermogenesis.
increased B.P
blood flow - lungs, heart, kidneys, GIT etc
what do the changes in B.P causes in the atria + aorta + pulmonary artery?
cause closure of foramen ovale + ductus arteriousus = aortic pressure causes back flow through PA into pulmonary cirulaiton, muscle wall sown restrictions flow + DA closes.
describe thermoregulation in neonate?
brown adipose tissue - responsible for non-shivering thermogenesis on hypothalamus neonates in first 5 hours
colostrum - source of energy in first 12 hours
energy expandable via attempting to stand
desicbe brown adipose tissue and its advantages?
1-2% of fetal wight at term - but can be repsosiable for 100% of heat generation post naturally
formed near kidney - activation of non-shivering thermogenesis at birth due to sympatahtis signals
describe the anatomy of mammary glands?
modified skin glands (sweat)
both sexes but develop in females after birth/
Age related structure - rudimentary duct system = secretary alveoli develop.
name and number the mammary glands of diffenrt species?
bitch = 8-10 - thoracic-abdominal-the groin area (inguinal) Mare = 2-4 - udder, 1 pair, inguinal sheep = 2 - 1 pair, inguanil Pig = 8-12 - 6-7 pairs, thoracic-abdonomal-inguinal Cow = 2-4 - 50Kg!! hind quater, fore quieter
describe the bovine udder?
purpose = lactation- supermammroy teats common on hind quarters.
suspensory apparatus supports the weight of lactating udder
consists of: medial + lateral laminae, aponeurosis of external adom.oblique muscle
what does the bovine udder consist of?
tunica flava, linea abla, medial laminae, Lateral laminae inter-mammary groove
name the internal features of bovine glands?
glandular parenchyma - simple cuboidal secretary epithelium near capillary bed.
myoepithelial cells surround alveoli + eject milk into branching duct system.
teat canal or papillary duct - closed in-between milking
describe the anatomy of the bovine teat gland?
milk duct
Teat cistern / gland cistern
lactiferous sinus
describe how the closure of the teat occurs?
for defence to microbial influx
mucosa in region involved in immuno-survallance.
1) smooth muscle sphincter - closure of teat
2) teat canal and teat sphincter close
mucosal surface of teat seals and folds.
