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Rob's RDA > Embryology parts 5-8 > Flashcards

Embryology parts 5-8 Flashcards

1
Q

The formation of the heart tube occurs through fusion of what

A

Endocardial tubes

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2
Q

State the structures in heart tube

A

Truncus arteriosis

Bulbus cordis

Primative ventricles

Primative atrium

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3
Q

Just look at the folding of the heart, the diagram is excellent

A

…… figure 5.5.1

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4
Q

Give a brief overview of the development of the heart tube

A

The cardiogenic cells develop in a U (or horseshoe) pattern outside the embryo proper.

These form a pair of heart tubes (endocardial tubes), which fuse to form a single heart tube by ~21 days post-fertilisation.

This tube is already able to pump blood unidirectionally.

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5
Q

T/f, vessels attached to the correct heart region following the looping and septation of chambers

A

F… during looping and septation

the vascular connections are maintained, so that the major veins are connected to the atria, and major arteries to the ventricles.

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6
Q

3 key steps in heart development

A
  1. Looping.
  2. Septation
  3. Valves develop
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7
Q

What is the reason for the difference between heart in utero and after delivery

A

The provision of oxygen to the embryo and fetus from the placenta is linked to the main structural difference between the heart in utero, and after delivery.

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8
Q

Blood returning to the right atrium in utero can be described as

A

Well oxygenated

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9
Q

Differences between heart in utero and in life

A
  1. Little blood flow to the lungs is needed, there is a gap between the atria, the foramen ovale.
    Blood returning goes striaht into left atrium, then left ventricle then aorta to the rest of body
  2. Main artery from right ventricle (i.e. pulmonary artery) connected to aorta via ductus arteriosis. Any blood that got into pulmonayr circulation goes through this into the aorta
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10
Q

What changes should occur to the heart following birth

A

ductus arteriosus and foramen ovale should close, converting the circulation to the ‘figure of 8’ system and allowing oxygenation within the lungs

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11
Q

What usually corrects cardiac abnormalities

A

As most abnormalities are structural, surgical procedures have been developed to correct some abnormalities

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12
Q

Why does surgery have to occur shortly after delivery in babies with cardiac defects

A

As these complications may become clinically significant at the time of birth (as the blood flow needs to be changed to include the lungs), surgery may need to be done shortly after delivery.

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13
Q

2 important conditions in the tetraology of fallot

A
  1. Pulmonary artery stenosis (decreasing blood flow to the lungs)
  2. Septal defect between ventricles (allow deoxygenated blood into the left ventricle)

other 2 are

thickened right ventricle wall
and
aorta overriding septal defect

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14
Q

Outline a case of transposition of blood vessels

A
  1. Aorta attached to right ventricle
  2. Pulmonary arteries attached to left

Blood comes from body deoxygenated into right side of heart, then back through aorta to body
Blood goes from left side of the heart to the pulmonayr arteries to lungs, then back through pulmonary veins to the left atrium again, so oxygenated blood just passing between heart and lungs and not getting to rest of body

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15
Q

Why is transposed blood vessels not a problem before birth . What happens after birth

A

the foreman ovale and ductus arteriosus allow mixing of the blood flows sufficiently to sustain fetal growth and development. The closure of these connections after delivery separates the blood flows, so the infant becomes cyanotic (‘blue baby syndrome’).

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16
Q

What is treatment for transposed blood vessels leading to cyanosis

A

Administering prostaglandins to keep the ductus arteriosus open (PGE2)

perhaps opening of a link between the atria

Definitive treatment would usually involve the switching of the two arteries, to restore the normal blood flows

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17
Q

T/f spina bifida is very rare

A

The incidence of spina bifida is 1-2 per 1000 pregnancies, with variation between study populations. This makes it one of the most common developmental defects.

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18
Q

T/f surgery is a cure for spina bifida

A

F…. skin can be placed to protect the neural tissue instead of exposed spinal cord,

however

it will not address any functional problems

defects in the spinal cord often lead to damage to the nerves supplying associated tissues

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19
Q

Most effective treatment for spina bifida

A

folic acid; if the maternal diet is low in folate, then the risks of spina bifida increase

The timing of spinal development is early, so folate needs to be given before conception, preferably about 3 months beforehand.

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20
Q

T/f low maternal folate accounts for all spina bifida

A

F t has been calculate that about 70% of cases of spina bifida are due to low maternal folate, so this does not explain all of this developmental abnormality.

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21
Q

T/f spina bifida occurs on the lower back

A

F…
spina bifida refers to two spines (the unclose neural tube)…

not necessarily a single defect, not necessarily on lower back

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22
Q

When does formation of neural tube occur

A

Formation of the neural tube, the precursor of the central nervous system occurs early in pregnancy, about 3 weeks after fertilisation (Figure 5.6.2). Fusion should occur through the neural tube, but in spina bifida this process is not completed.

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23
Q

What is anencephaly

A

compromised development of the head and skull

General aetiology is thought to be similar to spina bifida, though the result of a lack of closure of the anterior neuropore.

24
Q

T/f anencephaly linked to low folate

A

Some studies have suggested that folic acid can also decrease the incidence of anencephaly, although the smaller numbers make it difficult to determine the scale of the benefit.

25
Q

Why must the folate be taken 3 motnhs before conception to reduce spina bifida incidence

A

Because the maturation of the oocyte is happening at this stage

26
Q

3 types of spina bifida with increasing severity

A

Occulta
Meningocele
Myelomeningocele

The bottom 2 likely to involve nerves and have functional implications below the level of the lesion

27
Q

What does the malformation of bone tell us in spina bifida

A

That it is the nerves in spinal cold controlling development of the vertebral body

There is nerve defect and results in bone defect

28
Q

Where does neural tube closure usually start

A

Starts in the middle of the neural tube and spreads from there up to head and down to tail

29
Q

Differentiate the structural defect in anencephaly and spina bifida

A

An= anterior neiuropore

spina= posterior neuropore

30
Q

Taking folic acid when you realise you are pregnant will help

A

F….

it’s too late

it’s porbbaly already 2 weeks PF…

you need folate from maturation of the egg 3 months before

31
Q

Anencaphy happens in which babies most commonly

A

Girls

32
Q

Where can eyes and other primary features of the dace be found during development

A

primary structures of the face form on the sides of the head – for example the eye. This pattern persists until at least 5 weeks post-fertilisation

33
Q

When are precursors of nose, cheeks, lips, mouth and chin formed

A

Also around 5 weeks PF (like eyes)

34
Q

When do the face structures move from the side of head to central

A

structures then move over a period of about 5 weeks until the reach the expected positions, with the nose centrally placed, and the eyes facing forwards on the face

35
Q

Why is facial development not completely understoof with regard to eyes

A

requires the movement of pre-existing structures (e.g. eyes) through the tissues of the developing face, a process that is not fully understood.

36
Q

How is the nose formed

A

There are medial and lateral nasal prominences on each side of the head which merge in the midline

Nasal pit in between these becoes nostril

37
Q

How do tissues move to the correct place in the face

A

It seems that repeated formation of clefts in the face, and then filling in of the clefts, leads to sequential loss of tissue from the centre of the face, and the movement of tissues to the correct places.

38
Q

Outline a structual process leading to clef lip

A

There is a groove create where the medial and lateral nasal prominences have not yet fused

Groove filling occurs on one side (normal)

On the other side, there is a persistance labial groove. The medial nasal prominences fuse fine, but there is a seaparate lateral part of the lib

=complete unilateral cleft lip

39
Q

T/F development of the facial tissues on the separate sides of the head is distinct to humans

A

The development of the facial tissues on the separate sides of the head is common in vertebrate development; most fish and birds retain this arrangement, with the eyes remaining on the side of the head into adult life.

40
Q

What clefting may occur and why

A

need to form the face from two separated halves

May give rise to cleft lip, cleft palate or both

41
Q

Outline the symmetrical or asymmetrical nature of cleft lip and palate

A

Clefting in both lip and palate may also be found. Note that cleft lip is often asymmetric, as only one of the two clefts does not function correctly, whereas cleft palate is usually symmetric as the halves of the palate do not meet and fuse correctly.

42
Q

Why is surgery to correct facial congenital defects often successful

A

The turnover of cells in infants is normally very rapid, and healing often occurs with little or no scarring, so surgical outcomes can be very impressive.

43
Q

When does it occur that the eyes don’t remain on the side of the head

A

Binocular vision

44
Q

When does surfactant production begin

A

early in the third trimester of pregnancy (Figure 5.8.1) and gradually increases

45
Q

Why is lung surfactnat important to be produced

A

Adequate production of surfactant is necessary for normal lung function at birth.

46
Q

What is respiratory distress syndrome

A

Preterm infants often suffer from lung complications due to low levels of surfactant (Respiratory Distress Syndrome, RDS).

47
Q

What can you do if the baby is likely to be born very early, crreating problems due to reduced surfactatn

A
  1. Delaying the birth of a preterm infant may give more time for surfactant to be produced
  2. injection of glucocorticoid to the mother, which also increases surfactant production in the infant’s lungs
48
Q

When is a glucocorticoid injection to the mother useful to increase foetal surfactant?

A

Optimal timings are not fully established, although 24-48 hours between administration and delivery of the infant or infants is often the aim.

49
Q

What can be given to preterm babies with low surfactant

A

Artificial surfactant has also been developed, and this can be administered to preterm infants while their lungs develop sufficiently to produce enough surfactant to allow normal function.

50
Q

State the 5 stages of lung development

A
  1. Embryonic (3-8 weeks PF)
  2. Pseudoglandulat (5-17)
  3. Canalicular (16-26)
  4. Saccular (24-38)
  5. Alveolar (36-38)
51
Q

When are alveolar produced in utero

A

Only last two weeks PF (i.e. from 36 weeks PF which is actually 4 weeks before term)

52
Q

From when is surfactnat produced

A

25-27 weeks

53
Q

What distinguishes conducting and respiratory zones

A

In the conducting zone, all branches of the bronchial tree, the walls of which contain cartilage tissue and seromucous glands, are bronchi. As soon as cartilage and glands are no longer present, bronchioli are involved.

54
Q

What proporton of babies will have RDS, who are born at:

24 weeks

26-28 weeks

30-31 weeks

A

100%, 50%, 25%

55
Q

What is surfactant made of

A

lipids, proteins and glycoproteins

56
Q

Which organs complete development at a very late stage

A

Brain completes late, as do lungs and digestive system

Rob's RDA (10 decks)

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