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Unit 6 > Embryology > Flashcards

Flashcards in Embryology Deck (45):
0

What does a blastocyst consist of?

Embryoblast
Trophoblast

1

The Embryoblast splits into which two layers?

Epiblast
Hypoblast

2

What does the trophoblast split into? And at what stage does this happen?

Cytotrophoblast
Syncytiotrophoblast
In week to when in invades the endometrium

3

What are the two cavities formed in week 2?

Yolk sac
Amniotic cavity

4

What happens to the syncytiotrophoblast in week 2?

It becomes vascularised in maternal blood

5

At what stage is the embryo known as en bilaminar embryonic disc?

Week 2

6

Where does the primitive streak form from and in which week?

Week three from the Epiblast

7

What is gastrulation? When does this occur?

Week three
It's the formation of the three germ layers from the Epiblast

8

What are the three layers that the Epiblast forms?

Endoderm
Mesoderm
Ectoderm

9

Where does the notochord form from and when?

Week 3 from the mesoderm

10

What is derived from the ectoderm?

Epidermis of skin
Brain, spinal cord, peripheral nerves and nervous tissue

11

What is derived from the mesoderm?

Skeleton
Connective tissue
Cartilage
Muscle, tendons and ligaments
Vessels and blood
Urogenital system

12

What is derived from the endoderm?

Epithelial of organ systems
Glands
Digestive organs

13

What cells are in the primitive node?

Notochord cells

14

What are the three main steps of gastrulation?

First, cells proliferate and begin to migrate and displace the hypoblast layer, this forms the endoderm
Secondly, cells migrate and settle above endoderm to form the mesoderm
Remaining Epiblast cells form the ectoderm

15

What is neurulation and when does it happen?

Transformation of neural plate into neural tube week 3 + 4

16

What is the notochord?

A column of midline cells vital for induction of neural plate, motor region of the brain and spinal cord and vertebral formation.

17

At the end of week four when neural tube closure is complete, what are the 3 primary brain vesicles that are formed?

Forebrain
Midbrain
Hindbrain

18

How is the mesoderm split up?

Lateral plate
Intermediate mesoderm
Paraxial mesoderm (somites-form tissues of back)
Notochord

19

When is the umbilical cord formed?

Around 5 weeks

20

What are the four factors that affect placental transfer

Placental size
Maternal-placental blood flow
Concentration or electrochemical gradient
Presence of transporters

21

What are the two main types of transport across the placenta?

Passive diffusion (simple or facilitated)
Active transport (enzymatic reaction or pinocytosis)

22

What are neural crest cells?

Cells that are pinched off during the formation of the neural tube
They migrate to diff locations

23

The lateral plate of the mesoderm forms......

Pleura
Pericardium
Peritoneum
Heart
Blood
Blood vessels

24

The intermediate mesoderm forms.....

Urogenital system

25

Describe neuralation

It's the formation of the neural tube (cns)
Neural crest cells also created and pinched off
A thickening of the ectoderm folds and closes
Notochord is needed to induce the formation

26

Neural crest cells can develop into......

Teeth
Schwann cells
Pia and arachnoid mater
Dorsal root ganglion
Adrenal medulla

27

What happens in week four?

Lateral and longitudinal folding
Beginning of organogenesis
Formation of limb buds

28

Describe brain formation

It's the dilation, thickening and folding of the neural tube
The central canal widens to form the ventricles
The brain then forms around the ventricles

29

How is the liver formed?

Liver bud forms from endoderm gut tube and grows into septum transversum
Endoderm forms hepatocytes
Mesoderm forms blood vessels
Connection with duodenum narrows forming the bile duct

30

Which arteries supply the diff parts of the gut?

Forgut- celiac artery
Midgut- superior mesenteric
Hindgut- inferior mesenteric

31

Describe the development of the pancreas

It develops from dorsal and ventral buds of the Forgut
Dorsal buds grow largest
Dorsal and ventral buds fuse after midgut rotation

32

How is the heart formed?

Wk 3- blood islands form in mesoderm
Vasculogenic endothelial growth factor- angiogenesis
Wk 4- 2 heart tubes form from lateral mesoderm
They unite and dilate forming atria and ventricles
Heart tubes fold upwards
R. Sinus venosum forms SVC
L. Sinus venosum forms IVC
Wk 8- neural crest cells form spiral valve which splits bulbus cordis into pulmonary trunk and aorta

33

What is cardiac looping?

The process where the heart tube folds to create typical heart shape and location

34

What is the ductus venosus?

A channel that bypasses the liver
It regulates blood flow from placenta to IVC

35

What is the ductus arteriosus?

Ductus that connects pulmonary artery to aorta so most blood coming fro might ventricle can bypass the lungs which are non functional

36

What is atrial septation?

It involves the growth of two overlying septa to create an opening with a valve
The opening is the foramen ovale
Heart septation is done by week 8

37

What happens at birth to the ductus venosus?

The cord is clamped stopping blood flow from placenta
The ductus venosus becomes the ligamentum venosum

38

What happens to the foramen ovale at birth?

Increased blood flow from lungs causes more pressure in left atrium
The pressure change closes the flap forming the fossa ovale

39

What happens to the ductus arteriosus after birth?

Bradykinin is secreted by the lungs and causes it to close
It then becomes the ligamentum arteriosum

40

The two dorsal aorta have how many arches coming off them?

6 pairs

41

Pair three of the aortic arches form......

Common carotids

42

Pair 4 of the aortic arches form........

Aorta and subclavian artery

43

What does pair 6 of the aortic arches form?

The pulmonary arteries and ductus arteriosus

44

How does the respiratory system develop?

Wk 4- bud develop from endoderm of Forgut
Bud bifurcates into left and right primary bronchial buds
Wk 8- bronchial buds divide into two or three divisions (lobes)
Wks 16-28- bronchioles begin to form
Wk 36- alveoli start to form