CARDIO AND RESPIRATORY EMBRYOLOGY Flashcards

1
Q

What is the first major system to function in the embryo?

A

The CVS

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2
Q

What week does the CVS start to develop ?

A

Week 3 and 4

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3
Q

Why does the cardiovascular system have to develop?

A

Because the embryo gets to big for diffusion along to support all the cells.

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4
Q

How do blood vessels form?

A

Little islands of blood vessel form in the yolk sac, allantois and chorion creating an cardiogenic field.

Blood vessels in the splanchnic mesoderm from two heart tubes.

Heart tubes fuse and join with blood vessels to from the primordial CVS.

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5
Q

How do the pericardium form?

A

Folding moves the pericardium so that it is dorsal to the pericardial cavity.

Fibrous and parietal layer of the pericardium from from the somatic mesoderm.

The visceral layer forms from the splanchnic mesoderm.

The pericardial cavity forms from the intra-embryonic coelom.

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6
Q

How do heart tubes form?

A

From the heart bundle heart tubes start to budge and form arterial and venous ends.

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7
Q

How do heart tubes form loops?

A

The heart tube grows in the pericardium but then gets to big and so forms a loop. This is called the bulboventriclar loop.
The bulbus cordis and ventricle enlarge and loop to the right. This pushes the ventricle left and down and the atria up and back.

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8
Q

What abnormality can occur in the looping of the privative heart tube?

A

Dextrocardia - Heart tube goes to the left so the ventricles come to lie facing the right.

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9
Q

How is the atrioventricular canals formed?

A

An endocardial cushion develops to separate the left and right side of the heart

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10
Q

How is the interatrial septum formed?

A

The septum primum and septum secundum both grow down to separate the two atrium however they leave a hole called the foramen ovule which is essential for circulation before birth. After birth the Forman ovule closes as the septum primitive and the septum secundum fuse to form the fossa ovalis.

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11
Q

What is a common congenital defect with the formation of the interatrial septum?

A

Can cause a hole in the heart

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12
Q

How is the interventricular septum formed?

A

Muscular ventricular septum forms. It has a hole called the interventricular foramen.

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13
Q

Parts of primitive heart

A
Truncus arteriosus 
Bulbus cordis 
Ventricle 
Atrium 
Sinus venosus
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14
Q

How are the aorta and pulmonary trunk differentiated?

A

Aorticopulmonary septum divides the bublis cordis and the truncus arteriosus into the aorta and the pulmonary trunk.
The aorticopulmonary septum fuses with the muscular ventricular septum and endocardial cushion and the interventricular foramen is closed.

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15
Q

What are VSDs?

A

Ventricular septal defects are ‘holes on the heart’ small once’s will close naturally. Very common especially the membranous type/

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16
Q

How are the heart valves formed?

A

Develop from the ventricular wall from the subendocardial valve tissue.

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17
Q

What is cyanotic disease ?

A

Where there has been transposition of the great vessels. It allows gas exchange from the systemic to pulmonary circulation.

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18
Q

How is the conducting system of the heart established?

A

cardiomyocytes are early pacemaker cells and are found in the atrium and sinus venosus. SA node develops during week 5

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19
Q

What causes SIDS?

A

Abnormalities in the conducting tissue

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20
Q

When does the aortic sac develop?

A

Same time blood vessels start to appear.

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21
Q

How do the arteries from?

A

Ventral aorta and dorsal aorta combine and from the aortic sac which then becomes an extension of the truncus arteriosus.

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22
Q

What happens to the aortic sac during week 4 and 5 ?

A

6 Pairs of aortic arches are formed from the aortic sac.

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23
Q

What two ways can blood vessels develop in ?

A

Vasculogenic - the formation of new vascular networks

Angiogenesis - The formation of new vessels from pre-existing vessels

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24
Q

What happens to the 1st and 2nd pair of aortic arches?

A

Disappear

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25
Q

What happens to the 3rd pair of aortic arches?

A

Forms the common carotid arteries

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26
Q

What happens to the 4th right aortic arch?

A

Right subclavian artery

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27
Q

What happens to the 4th left aortic arch?

A

Aortic arch

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28
Q

What happens to the 5th arch ?

A

Disappears

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29
Q

What happens to the right 6th arch?

A

Right arch forms the right pulmonary artery

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30
Q

What happens to the left 6th arch?

A

Left arch forms the left pulmonary artery and ductus arteriosus (closes shortly after birth)

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31
Q

What are the abnormalities of the arch

A

right subclavius artery arises from the left and constricts the trachea and oesophagus
Double aortic arch where non-regression of the right arch forms the vascular ring around the trachea and oesophagus which causes difficulties in breathing and swallowing.
Patient ductus arteriosus (PDA) where the muscular wall fails to develop and so gas exchange occurs.
Cortication of the aorta where the aorta is severely narrowed.

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32
Q

By what processes do embryonic vessels become adult vessels ?

A

Vitelline vessels supply the yolk sac and become adult gut vessels
Umbilical vessels that supply the placenta becomes the internal iliac arteries
The cardinal vessels supply the rest of the body and becomes the SVC and IVC

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33
Q

When does the lymphatic system begin to develop ?

A

Week 6

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34
Q

How does the lymphatic system develop?

A

6 lymph sacs from.
Lymph vessels join the lymph sacs.
2 Thoracic duct develop from the to vessels anterior to the aorta.
The left one becomes the adult thoracic duct.

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35
Q

What are the three foetal circulation shunts ?

A

Ductus venous
The foramen ovule
The ductus arteriosus

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36
Q

How does the ductus venous close?

A

The ductus venous becomes the ligamentum venosum of the liver, the foramen ovule closes after birth to form the fossa ovalis of the heart

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37
Q

What is the Ductus venous

A

Ductus venous shunts blood in the left umbilical vein directly to the IVC bypassing the liver.

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38
Q

What is the foramen ovule

A

The foramen ovule shunts blood from the right atrium to the left atrium bypassing the lungs.

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39
Q

What is the ductus arteriosus

A

The ductus arteriosus shunts blood from the right ventricular and pulmonary arteries to the aorta bypassing the lungs

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40
Q

How does the foramen ovule close?

A

foramen ovule closes after birth to form the fossa ovalis of the heart,

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41
Q

How does the ductus arteriosus close?

A

the ductus arteriosus becomes the ligamentous arteriosum between the left pulmonary artery and the aorta and the umbilical arteries become the medial umbilical ligaments of the anterior abdominal wall.

42
Q

What is the cardiogenic field?

A

What is created when the blood vessels begin to from in the yolk sac, allantois an chorion.

43
Q

What is the bulboventriclar loop ?

A

Created when the tunicus arteriosus grows into the pericardium runs out of room and loops round.

44
Q

What is the intra-embryonic coelm

A

What the pericardial cavity forms from

45
Q

What are three parts of the primitive heart which are hard to remember?

A

Bulbus cordis
Truncus ateriosus
Sinus venosus

46
Q

What is the other membrane besides the septum primum ?

A

Septum secundum

47
Q

What is the septum that grows up into the tube?

A

Aorticopulmonary septum

48
Q

What is the subendocardial valve tissue?

A

What the valves grow from

49
Q

What separates the left and right side of the heart?

A

endocardial cushion

50
Q

What type of cell make up the conducting heart?

A

cardiomyocytes

51
Q

What is the name given to the parent gametes and the gametes they develop into ?

A

spermatogonium into sperm

oogonium into ovum

52
Q

What does the process of meiosis produce in males and females?

A

Males - 4 sperm

Females - 1 egg + 3 polar bodies (which degenerate)

53
Q

Where does fertilisation occur?

A

The ovum

54
Q

What is a morula ?

A

The zygote undergoes mitosis to form a solid ball of cells called the morula.

55
Q

What is a blastocyst?

A

The morula divides into two forming the trophoblast and an inner mass of cells. It also have an blastocyst cavity which nutrition can move into helping the cells to get nutrition.

56
Q

What do the layers in the blastocyst go on to form?

A

Trophoblast - Placenta

Inner ball of cells – Baby

57
Q

What is implantation ?

A

When the blastocysts buries itself in the endometrial lining. Controlled by the trophoblast which divides into two forming the chorion.

58
Q

What hormone does the chorion produce?

A

HCG (Human chorionic gonadotropins)

59
Q

At what week does the placenta start supplying the baby with nutrients?

A

12

60
Q

What is the name given for the endometrial lining once’s the blastocyte has implanted?

A

Decidua basalis

61
Q

What is a bilaminar disc?

A

Formed during week 2
During implantation the inner call ball forms two layers which is called the bilaminar disc. This forms an upper cavity called the amniotic cavity and a lower cavity called the yolk sac.

62
Q

What are the two layer in the bilaminar disc called?

A

Epiblast and hypoblast

63
Q

What is a primitive streak?

A

The groove that is created which runs down the top of the bilaminar disc. (Epiblast)

64
Q

What are the three layers that are formed during gastrulation?

A

Ectoderm
Mesoderm
Endoderm

65
Q

Describe gastrulation

A

Cells from the epiblast migrate to lie between the epiblast and hypoblast forming the mesoderm.

66
Q

Describe neurulation

A

Cells of the ectoderm descend down and form a ball of cells which disconnects under the mesoderm and is called the notochord.
The primate chord thickens and forms a neural tube under the surface of the ectoderm.

67
Q

What happens after neurulation?

A

Mesoderm thickens and forms a paraxial mesoderm intermediate plate mesoderm and lateral plate mesoderm.

68
Q

What happens to the paraxial mesoderm ?

A

It divides into 3- the dermatome (Skin), myotome (muscles) and sclerotome (bones)

69
Q

Describe the folding that then takes place in the embryo?

A

In week 3/4 The three layers fold round each other to create a tube.

70
Q

What layer will form the respiratory system?

A

The endoderm

71
Q

What is teratology ?

A

The study of things that go wrong in development

72
Q

Describe how the endoderm forms the respiratory system

A

Endoderm gives rise to the privative gut tube which has a hindgut, midgut and foregut. The trachea and lung buds form from the ventral wall of primitive foregut.The lung bud then is separated off from the foregut when a septum (the oesophagotracheal septum) develops between the oesophagus and trachea.

73
Q

How does the pleura form?

A

As the lung bud forms it pushes the splanchnic mesoderm towards the somatic mesoderm so that the lung bus is surrounded by both layers.
However the pleural cavity and membrane is not complete as the space between these two layers of mesoderm around the lungs is continuous with the heart in front and the peritoneal cavity below. This continuity is called the pericardioperitoneal canal (which separates the pericardial and peritoneal cavities). This continuity ends when a lateral plate of somatic mesoderm grows in from the periphery and completely closes off the pleural cavity from the heart. This fold is called the pleuropericardial fold and will become the pericardium of the heart. around the lungs becomes a closed cavity forming the pleural cavity.

74
Q

Name the stages in the development of the respiratory system ?

A
Embryonic 
Pseudoglandual 
Canalicular 
Saccular 
Alveolar
75
Q

What happens in the Pseudoglandual phase (Respiratory)?

A

7-17 weeks

development of all lung structures except respiratory part

76
Q

What happens in the Canalicular phase (Respiratory)?

A

17-27 weeks
There is the formation of the respiratory part. Alveolar ducts form and epithelium starts to differentiate into Type 1 and type II pneumocytes

77
Q

What happens in the saccular phase (Respiratory)?

A

27 weeks - 40 weeks
Formation of the alveolar sacs, primitive alveoli and surfactant. Gas exchange begins.
What happens in the alveolar phase (Respiratory)?

78
Q

What happens in the alveolar phase (Respiratory)?

A

32 weeks - 8 years

proliferation of alveoli form alveolar sacs. 95% of adult alveoli are formed postnatally.

79
Q

From what does the diagram develop?

A

Mesoderm

80
Q

The diagram develops from 4 mesodermal structures, they are …

A

Septum transversum - forms the central tendon
Pleuroperitoneal folds - grown in from peripheries and fuse with septum
Skeletal muscle - Cover the pleuroperitoneal folds and forms the muscular part
Doral mesentery of the oesophagus - Forms the crura

81
Q

Name a few congenital lung conditions

A
  • TOF or oesophageal atresia. The oesophagus has not correctly disconnected from the trachea.
  • IRDS - Lack of surfactant
  • Lung agenesis. Failure of lung development.
  • Diagram isn’t completes closed (hernias) and hypoplasia (lack of growth).
82
Q

What is meiosis?

A

production of haploid gametes which unique genetic information from parental diploid cells

83
Q

What is fertilisation? And what does it from?

A

When the ovum and sperm pronucleus combine. Only the genetic information from the sperm enter the ovum.
It forms the zygote.

84
Q

Which parent does cytoplasmic genetic information come from? i.e. mitochondrial DNA

A

the mother

85
Q

Describe the path of the zygote / blastocyte before implantation?

A

Ovum released from ovary
Fertilisation in the fallopian tube creating a zygote
zygote moves down fallopian tube becoming a morula
Morula moves into the uterus becoming a blastocyte

86
Q

How does an ectopic pregnancy occur?

A

Failure of the cilia in the fallopian tube to move the morula and so implantation occurs in the tube rather than in the uterus.

87
Q

How many days does it take for the morula to travel down the fallopian tube?

A

6-7 days

88
Q

How many days before her period starts does a women start to ovulate?

A

14

89
Q

What is the role of the chorion?

A

Develops chorionic villi which burry into the endometrium lining

90
Q

When does HCG hormone stop being produced?

A

when the placenta starts supplied the baby with nutrients

91
Q

What are the different types of twins

A

Fraternal (Non-identical) there are two ova

Identical there is one ova which splits into two

92
Q

What does the trophoblast develop to form?

A

Chorion
Umbilical chord
Foetal blood vessels
Placenta

93
Q

What is the role of the placenta ?

A

Provides foetal nutrition
Transports waste + gases
Helps provide immunity

94
Q

At what week is the placenta fully mature ?

A

18-20 weeks

95
Q

What does the ectoderm go and from?

A

epidermis of the skin and neural tube

96
Q

What does the mesoderm go and from?

A

The paraxial mesoderm (somite’s) will form the dermatome (dermis of the skin) myotome (muscles) and sclerotome (bone). The intermediate plate mesoderm will form the urogenital system (kidneys and reproductive) and the lateral plate mesoderm will form the peritoneum, pleura and body cavities.

97
Q

What is teratogens?

A

Environmental factors which can cause abnormal development

98
Q

What are examples of teratogens ?

A
Drugs 
Alcohol 
Tobacco 
Infectious agents 
radiation 
genetic actors
99
Q

What is the risk of teratogenesis dependant on?

A

Period of exposure
Dosage of drug
Genetic constitution of the embryo

100
Q

What methods can be used to detect a teratogenesis?

A

Bloods (AFP)
Ultrasound
Invasive tests

101
Q

Summary of the tissues which from the respiratory system

A

Endoderm forms the trunk of the lungs and respiratory system
Mesoderm forms the tissues of the lung