Exam 1 Ch. 4.1-4.2

Question 1

List & describe 3 trimesters of gestation

Answer 1

1st tri:
-ovulation to implantation
-bi & trilaminar
2nd tri:
-organegesis done
3rd tri:
-baby continues to grow

Question 2

Process that creates blastocyst

Answer 2

-Fertilization occurs when sperm and egg meet in Fallopian tube
-Results in zygote w/ zona pellucida prevents more sperm from entering
-Holoblastic cleavage occurs through mitosis zygote divides
- Results in Morula(32 cells)
-Morula cells move to one side(embryoblast)creating hollow center(blastocoele)

Question 3

Layers of bilaminar embryo

Answer 3

Epiblast: becomes ectoderm
Hypoblast:becomes endoderm

Question 4

Process that turns bilaminar into trilaminar embryo

Answer 4

Through Gastrulation, epiblast thickens & moves toward primitive groove.
Cells then move to hypoblast creating 3 tissues

Question 5

What is holoblastic cleavage?

Answer 5

Mitosis, one cell divides into 2 after zygote is surrounded by zona pellucida

Question 6

Describe how amniotic cavity is created. What bilaminar issue is it derived from?

Answer 6

Epiblast cells migrate dorsally coming together
creating the a. c. Derived from trophoblasts

Question 7

Purpose of trophoblast

Answer 7

-Allows embryo to be invisible
-helps form placenta

Question 8

Describe process of neuralation, what does this process create?

Answer 8

Lateral edges of primitive streak thickens elevates creating neural folds and then elevates coming together as the neural plate ectoderm bends downward forming the DHNT.

Question 9

Where does neuralation start to end?

Answer 9

Starts where edges come together fold and eventually zip

Question 10

What does ecto, meso, and endoderm become as embryo continues to develop?

Answer 10

Ecto-epidermal ectoderm: hair, skin, nails
Meso-Somites: dermatome, myotome, skleratome
Intermediate Mesoderm: urogenital system
Lateral Plate Mesoderm: Coelom
Somatic Mesoderm: body wall and limbs
Splachnic Mesoderm: gut linings (organs)
Endoderm- fore, mid, hind gut

Question 11

Where does neural crest come from? What structures arise from this?

Answer 11

At junction of where DHNT rolls up, the cells that stick together become neural crest. Creating PNS, ganglia of nervous system, dentine of teeth, much of head skeleton, melanocytes and meninges.

Question 12

Describe formation and organization of gut tube

Answer 12

during the splitting
of the L.P.M. Lateral
edges pinch together closing becoming tube inside tube

Question 13

For the gut tube to be divided into 3 sections, what is happening during embryonic development?

Answer 13

Cephalocaudal, which gives fetal position. The embryo moves to head down position creating fore and midgut and then the tail moves down too, creating mid and hindgut positions.

Question 14

Segmental & Trans-segmental structures

Answer 14

Segmental: somites, intermediate mesoderm, dorsal aortae
Trans-segmental: notochord, dhnt, lateral plate mesoderm, dorsal aorta, gut tube, coelom,