Embryology II Flashcards

0
Q

Early CV system: development of primitive heart:

A

Before 3rd week first blood cells arise in yolk sac and spaces in mesoderm > gaps in endothelial cells along with mesoderm spaces

By 3 weeks there is a system of paired blood vessels > swellings of these vessels merge together to form primitive heart

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1
Q

Early CV system: how does embryo initially receive O2?

A

Diffusion from nearby maternal blood

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2
Q

First heart beat?

A

21-22 days

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3
Q

Development of the heart: first blood flow

A

Occurs inferiorly to superiorly

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4
Q

Development of the heart: heart tubes bend creating three areas:

A

Bulbous cordis (superior)
Ventricle
Atrium (inferior)

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5
Q

Development of the heart: continued folding results in:

A

Atrium moved superiorly towards BC dividing in to two parts
Ventricle moves inferiorly deciding in to two parts
BC becomes truncheon arteriosis then aorta

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6
Q

Development of the heart: what are the ‘cushions’

A

Thickening so between atria and ventricles that separate them allowing unidirectional bood flow. Eventually become the valves

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7
Q

Development of the heart: Umbilical vein

A

Return from placenta and empty in to inferior vena cava via ductus venosis

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8
Q

Development of the heart: Umbilical artery

A

Extends from internal iliac artery through the umbilical cord to placenta

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9
Q

Development of the heart: Ductus venosis

A

S a vascular shunt from umbilical vein to inferior vena cava

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10
Q

Development of the heart: foraman ovale

A

Hole in the atrial septum allowing blood flow directly between atria

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11
Q

Development of the heart: ductus arteriosis

A

Vascular shunt from pulmonary trunk to aorta bypassing pulmonary circulation

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12
Q

Respiratory development WEEK 4

A
  • Laryngotrachial diverticum arises from foregut
  • lung bud arises from laryngotrachial tube
  • bronchial buds lengthen and become primary bronchi
  • RHS = 3 secondary bronchi
  • LHS = 2 secondary bronchi
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13
Q

Repiratory system WEEK 5

A
  • Secondary bronchial buds continue to generate successive branches
  • surrounding mesoderm will become surrounding CT, cartilage, muscles, blood, lymphatic system
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14
Q

GI Tract development

A
  • Wk 4 primordial gut (foregut, midgut, hindgut) forms from endoderm folding as it creates endoderm tube
  • surrounding mesoderm will create muscles and CT tissue of GI tract
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15
Q

Forgut develops in to:

A
Pharynx
Esophagus 
Lower respiratory tract
Stomach
Duodenum
Liver and bilary apparatus 
Pancreas
16
Q

Midgut develops in to:

A
Duodenum
Jejunum and ilium
Appendix
Ascending colon
First part of transverse colon
17
Q

Hindgut develops in to

A
Remaining transverse colon
Descending colon
Sigmoid colon 
Rectum 
Anal canal
18
Q

Renal system development:

A

(Wk 3)Development of epithelial cords > mesonephric tubules (which empty in to mesonephric ducts) > mesonephric ducts form ureteric bud > develops in to ureters and kidneys.

19
Q

Reproductive system: gonads

A

Sex is determined at conception by presence of Y chrom

20
Q

Reproductive system: genital ducts

A

Mesonephric ducts become part of reproductive system

Paramesonephric ducts develop alongside

21
Q

Reproductive system: external genitalia

A

Mesoderm forms genital eminence near cloaca which becomes genital tubercle, genital folds flank genital tubercle and urogenital sinus

22
Q

Differentiation of genital tract occurs when:

A

Testes produce MIH and testosterone:
Mesonephric stimulated under presence of testosterone
Para mesonephric ducts are suppressed by MIH

23
Q

Skeletal system:

A

Cartilage preform skeleton is developed from mesoderm, some ossification occurring

24
Q

Limb development

A

4th week: limb buds are present

8th week: regions are distinct and fingers/toes are developed

25
Q

Integumentary system development:

A

Out of single layer of epidermal cells have connected with a loose dermis tissue by end of 8th week