UNIT 5 - EARLY HUMAN DEVELOPMENT

Question 1

How long is the pre-embryonic period?

Pre-embryonic period

Answer 1

First 2 weeks

Question 2

What is the first stage in the pre-embryonic period?

Pre-embryonic period

Answer 2

The zygote

1 cell, diploid

Question 3

Where does the zygote form?

Pre-embryonic period

Answer 3

In the uterien tube

Question 4

What are the 4-5 divisions the zygote goes through called?

Pre-embryonic period

Answer 4

Cleavage divisions

Question 5

What do the divisions of the zygote form?

Pre-embryonic period

Answer 5

The morula

Question 6

What is the second stage in the pre-embryonic period?

Pre-embryonic period

Answer 6

The morula

Question 7

What determines the morula?

Pre-embryonic period

Answer 7

If it consists of AT LEAST 16 cells

16-32

Question 8

True or False:

The Morula is bigger than the zygote.

Pre-embryonic period

Answer 8

• FALSE
• It is the SAME size

Question 9

What does the morula develop into?

Pre-embryonic period

Answer 9

The Blastocyst

Question 10

What is the third stage in the pre-embryonic period?

Pre-embryonic period

Answer 10

The Blastocyst

Question 11

How long does the Blastocyst last?

Pre-embryonic period

Answer 11

5 days

Question 12

What is the fluid filled cavity in the blastocyst called?

Pre-embryonic period

Answer 12

The Blastocoel/Blastocyst cavity

Question 13

What is the inner mass of cells called in the blastocyst?

Pre-embryonic period

Answer 13

The embryoblast

Question 14

What does the embryoblast eventually differentiate into?

Pre-embryonic period

Answer 14

The Embryo

Question 15

What is the outside ring of cells in the blastocyst called?

Answer 15

The Trophoblast

Question 16

What is the trophoblast made of?

Pre-embryonic period

Answer 16

Trophoblast cells

Question 17

What will the trophoblast defferentiate into?

Pre-embryonic period

Answer 17

The Chorion

Question 18

What does the chorion do?

Pre-embryonic period

Answer 18

Provide nurtients to the developing embryo

Question 19

What is Implantation?

Pre-embryonic period

Answer 19

When the blastocyst moves from the uterine tube and attaches to the endometrium of the uterine wall

Question 20

What occurs after implantation?

Pre-embryonic period

Answer 20

The embryoblast differentiates into a bilayered embryonic disc

Question 21

What are the 2 divisions of the embryoblast after differation?

After implantation

Pre-embryonic period

Answer 21

• Epiblast
• Hypoblast

Question 22

What does the epiblast form?

Pre-embryonic period

Answer 22

• The Amnion - With a fluid filled amniotic cavity
• The 3 germ layers of the embryo

Question 23

What does the Hypoblast form?

Pre-embryonic period

Answer 23

• The Yolk Sac
• The ubilical cord

Question 24

When do the extraembryonic membranes start to form?

Pre-embryonic period

Answer 24

After implantation

Question 25

How long is the Embryonic period? ## Footnote Embryonic period

Answer 25

3rd -> end of 8th week

Question 26

What are the 3 germ layers? ## Footnote Embryonic period

Answer 26

1. Ectoderm 2. Mesoderm 3. Endoderm

Question 27

What does the **Ectoderm** form? | (2) ## Footnote Embryonic period

Answer 27

* The nervous system * Epidermis of skin

Question 28

What does the **Mesoderm** form? | (4) ## Footnote Embryonic period

Answer 28

* Muscles * Cardiovascular system * Dermis * Most bones

Question 29

What does the **Endoderm** form? ## Footnote Embryonic period

Answer 29

The Epithelial linings of: * DIgestive * Respiratory * Urinary * Reproductive systems And their associated glands

Question 30

What occurs during the Embryonic period? | (4) ## Footnote Embryonic period

Answer 30

* Major organ systems almost completely formed * Heart begins to beat * Limb buds differentiate * Extraembryonic membranes continue forming

Question 31

What is the Chorion derived from? ## Footnote Embryonic period

Answer 31

Trophoblast cells

Question 32

What does the chorion do? ## Footnote Embryonic period

Answer 32

Surrounds all embryonic membranes

Question 33

What are the **Chorionic Villi?**

Answer 33

**Projections** of the chorion **containing** the **blood vessels** that will form the **fetal part** of the **placenta** ## Footnote Wh/ nutrients, wastes, oxygen/carbon dioxide move between fetal & maternal blood

Question 34

Where is the **Amnion** derrived from? ## Footnote Embryonic period

Answer 34

The Epiblast

Question 35

What does the Amnion form? ## Footnote Embryonic period

Answer 35

Amniotic cavity that surrounds embryo/fetus with amniotic fluid

Question 36

What does the fuction of amniotic fluid? ## Footnote Embryonic period

Answer 36

Shock absorption & Temperature regulation

Question 37

Where is the yolk sac derrived from? ## Footnote Embryonic period

Answer 37

The Hypoblast

Question 38

What does the yolk sac form? ## Footnote Embryonic period

Answer 38

Part of digestive tract

Question 39

What is the source of reproductive germ cells & embryonic blood cells? ## Footnote Embryonic period

Answer 39

The yolk sac

Question 40

What is the allantosis? ## Footnote Embryonic period

Answer 40

A projection off the yolk sac

Question 41

What does the allantosis form? ## Footnote Embryonic period

Answer 41

The umbilical cord and urinary bladder

Question 42

When does the fetal period begin?

Answer 42

9th week -> 40th week

Question 43

What occurs during the fetal period?

Answer 43

Growth and maturation of organs