Endo-Repro L27 Fetal Organ System Flashcards Preview

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Flashcards in Endo-Repro L27 Fetal Organ System Deck (38):
1

The intrauterine environment relieves foetal organs of the need to perform certain functions:

1. Placenta
2. Weightless state of foetus
3. Isothermal environment

2

Foetus is not dormant →

→ Foetal systems must develop and mature to sustain life immediately after birth.

3

Adaptations of the fetal cardiovascular system: Ventricles

Two fetal ventricles pump in parallel, not series.

4

Adaptations of the fetal cardiovascular system: Four foetal shunts

1. Placenta
2. Ductus venosus - liver
3. Foramen ovale
4. Ductus arteriosus → pulmonary artery to aorta

5

Adaptations of the fetal cardiovascular system: Foetal shunts ensure

Optimal distribution of oxygenated blood to head and body

6

Changes in foetal circulation at birth:

At birth, the four fetal shunts close to replace the placental circulation with the pulmonary circulation:
1. Placenta ceases to deliver oxygenated blood to newborn
2. Pulmonary vascular resistance falls dramatically
3. Pressure on the right side of the heart decreases
4. Pressure on the left side of the heart increases
5. Flap valve closes foramen ovale
6. Ductus venosus ceases to carry blood to the heart
7. Ductus arteriosus contracts and close

7

Respiratory System: fetal breathing

2. Fetal breathing movements:
a. Are Rapid and irregular
b. Occur only during REM sleep
c. Are diaphragmatic
d. Move amniotic fluid in and out of the lungs

8

Functions of fetal breathingh

a. Practice
b. Distend the lungs and stimulate growth

9

Maturation of Lung function:

1. Fetal lungs undergo major structural changes during pregnancy
2. Near birth, the pressure required to expand the lung decreases

10

3. Surfactant:

a. Phospholipid synthesized in lung
b. Defiency causes respiratory distress syndrome

11

4. Water reabsorption: in fetus

a. Switch from Cl- secretion to Na+ absorption

12

Foetus salt and water reabsorption

CFTR-driven salt and water secretion.

13

Neonate salt and water reabsorption

Neonate:

14

Gastrointestinal activity during pregnancy

1. The feotus swallows large volumes of amniotic fluid daily.
2. Swallowed salt, water, and small molecules are absorbed in the small intestine

15

Meconium formed from

Swallowed debris and large molecules accumulate in the large intestine to form

16

Defecation occurs

Post utero

17

Function:
Of Process of gastrointestinal

1. Practise
2. Contributes to fetal nutrition
3. Control of amniotic fluid volume

18

The Renal System:

1. During pregnancy, the placenta, not the kidney, is the organ of excretion

19

2. Renal agenesis (Potter’s syndrome) causes:

a. Foetal growth and developmental defects the virtual absence of amniotic fluid

20

3. Function: of renal system

a. Regulation of amniotic fluid volume

21

Water in amniotic fluid turnover

At least once per day

22

Amniotic Fluid production

Renal excretion (~75%)
Pulmonary secretions (~25%)

23

Amniotic Fluid removal

Gastrointestinal tract (~55%)
Amnion (~30%)
Lungs (~15%)

24

Diagnostic Value of Amniotic fluid:

Neural tube defects

Lung maturation
Chromosome abnormalities and genentic diseases

25

Neural tube defects

Elevated levels of alpha-fetoprotein in amniotic fuid are diagnostic of spina bifida or anencephaly

26

Lung maturation

Monitor the lecithin/sphingomyelin ratio of amniotic fluid (ratio >2, surfactant production normal; ratio <2, suggestive of respiratory distress syndrome)

27

Chromosome abnormalities and genentic diseases

Fetal cells recovered in amniotic fluid can be used for karyotyping to detect Downs syndrome or to amplify fetal DNA for mutation screening (e.g. Duchenne muscular dystrophy)

28

The Nervous System:

1. Sensory organs of the fetus are highly developed
2. Fetal movements occur early in pregnancy
3. The fetus shows periods of slow-wave and REM sleep between periods of wakefulness
4. Drugs from the maternal circulation profoundly effect the developing brain of the fetus

29

Relationship between foetal and maternal endocrine systems:

1. Foetal hormones profoundly influence the mother
2. Maternal hormones do not directly influence the fetus except in disease
3. The Foetal endocrine system is autonomous
4. The Foetal endocrine system has specialized functions not present in the adult


30

Hypothalamus

Co-ordinates the activities of endocrine organs

31

Anterior pituitary

Regulates the activity of other endocrine organs

32

Thyroid Gland

Thyroxine is essential for normal foetal development

33

Pancreas

Insulin regulates the rate of glucose utilization

34

Gonads

Ovaries → inactive
Testis: Essential for male sexual differentiation

35

The Fetal Adrenal Gland: Medulla

Adrenaline and noradrenaline

36

The Fetal Adrenal Gland: Cortex

Glucocorticosteroids
DHEA

37

Functions of Glucocorticosteroids:

1. Renal maturation
2. GIT maturationInsulin secretion
3. Glucose storage
4. Thryoxine
5. Lactogenesis
6. Haemoglobin
7. Parturition
8. Adrenaline
9. Lung maturation

38

Preparation for birth:

1. Successful transition from intrauterine to extrauterine life depends on events that preceed birth:
a. Maturation of the lungs
b. Accumulation of carbohydrate and fat reserves
c. Onset of lactation
2. Glucocorticosteroids control the maturation of foetal physiology and its timing
3. Critical anatomical and functional changes occur at birth

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