embroyonic development :)

Question 1

what does human development start out as

Answer 1

oocyte (single cell)

Question 2

how long does human development take

Answer 2

38 wks

3 trimesters

Question 3

what are the 3 trimester stages called

Answer 3

pre-embryonic period
embryonic period
fetal period

Question 4

what occurs in pre embroyonic period and time

Answer 4

embryonic germ layers formed(make the basic tissues needed to form the organism)
0-2.5 wks

Question 5

embryonic period and time

Answer 5

2.5-8wks

rudiments of most organims and tissues develop

Question 6

fetal period and time

Answer 6

8wk to 9mn
rudiments grow and mature
called a foetus

Question 7

what has to form early on

Answer 7

heart and CVS system to push nutrients around the body

Question 8

what can embroyonic cells do

Answer 8

divide
death (remove cell by apotosis)
fixed/motile (chemical gradients may cause movements)
shape change(may be needed to form polarised cells)
specilalise

Question 9

what is cleavage

Answer 9

series of cell divisions that subdivides the cytoplasm

Question 10

what occurs in pre embryonic development

Answer 10

cleavage
morula formation
blastocyte formation

Question 11

during cleavage…

Answer 11

size of the blastomere stays the same

no cells increases

Question 12

what is a morula

Answer 12

ball of 16 cells

Question 13

what happens to the morula

Answer 13

takes up fluid and hollows out to form a blastocyte

Question 14

what forms the extra emmbryonic structres

Answer 14

trophoblast

Question 15

what surrounds the blastocyte after 5/6 days and purpose

Answer 15

zona pallucida

prevent sperm entering early

Question 16

what is found in the blastocyte

Answer 16

inner cell mass (figure of 8 shape)

form the embyro

Question 17

what does the pre embryo appear as

Answer 17

bilaminar disk (2 cell layers)

Question 18

what are the 2 layers of the pre embryo

Answer 18

epiblast (upper layer, columnar cells)

hypoblast (lower layer, cuboidal cells)

Question 19

what occurs after the pre embryo is formed

Answer 19

gastrulation

Question 20

what is gastrulation

Answer 20

where the 3rd germ layer is formed

Question 21

gastrulation process steps

Answer 21

epiblast cells move towards the primitive streak(accross the embryonic disk) and invaginate to displace the hypoblast cells
some epilast cells detach and move betwee the epiblast and hypoblast layer
notochord fomration

Question 22

what does the primitive streak do

Answer 22

estavlished the cranial/caudal ends and the right/left of embryo

Question 23

what are the three embryonic layers

Answer 23

ectoderm (outer)
mesoderm (middle)
endoderm (inner)

Question 24

what are the three embryonic layers in terms of abilty to speclise

Answer 24

mulipotent

Question 25

what does gastrulation allow

Answer 25

basic framework of embryo formed | all adult systems reconisable at 8wks

Question 26

what happens after gastrulation

Answer 26

organonesis | 1st step within that is neuralation

Question 27

what happens in neuralation

Answer 27

formation of neural tube grt the CNS

Question 28

as the CNS develops what else develops

Answer 28

another germ layer (ectomesoderm)

Question 29

neuralation steps

Answer 29

ectoderm thickens in midline(above the notochord) and grows caudally a crease develops along the axis of the neural plate by invagination neural folds move together and fuse to form neurla tube neural crest ells detatch to form the neural crest

Question 30

where are neural crest cells and what does the neural crest contibute to

Answer 30

on the crest of the neural groove migrating to the mesoderm | formation of peripheral NS

Question 31

what do crainial neural cells differentaite into

Answer 31

craniofacil cartialge and bones

Question 32

what do ectoderm cells form

Answer 32

epidermis hair mucus epithelium (ie nose mouth)

Question 33

what do mesoderm cells form

Answer 33

skeletal/musular components

Question 34

what do endoderm cells form

Answer 34

mucus epithelium (digestive and respiratory)

Question 35

what do neuroderm cells form

Answer 35

CNS and peripheral nerves

Question 36

what does the embryo have at 3.5 wks

Answer 36

cranial and caudal ends | pharyngeal arches

Question 37

how many pairs of pharyngeal arches are there

Answer 37

6 pairs in neck 5 never forms 456 fuse separated by cleft (externally)

Question 38

what are the arches called

Answer 38

1 - mandibular 2 - hyoid 3 - glossopharyngeal

Question 39

what are arches separated by internally

Answer 39

pouches

Question 40

what is found in each arch

Answer 40

``` cartilage artyer mesoderm component cranial nerves skeletal component ```

Question 41

what does the Hox gene do

Answer 41

each of muscle derived from the arch is innervated by the nerve that arises from the arch

Question 42

pharyngeal arch nerves

Answer 42

1 - trigeminal V 2- facial VII 3 - glossopharyngeal IX 4- vagus X

Question 43

what forms the external ear, iddle ear and auditory tube

Answer 43

first cleft - external | corresponding pouch - middle and tube

Question 44

where do arch deformities mainly occur

Answer 44

1st arch

Question 45

deformities of 1st arch symptoms

Answer 45

``` underdeveloped mandible (class II occlusion) malformed external ears absent/reduced malleus/incus ```

Question 46

muscle derivaitves 1st arch

Answer 46

muscles of mastication - myelohyoid - anterior belly of digastric and tensor veil palatini

Question 47

muscle derivatives 2nd arch

Answer 47

stylohyoid | posterior belly of digasttic and stapedius

Question 48

muscle derivatives 3rd arch

Answer 48

stylopharyngeus

Question 49

muscle derivatives 4th arch

Answer 49

pharyngeal constricutors soft palate LTP intrinsic muscles of larynx

Question 50

skeletal derivatives 1st arch

Answer 50

meckels cartilage (until mandible forms) malleus incus

Question 51

skeletal derivatives 2nd arch

Answer 51

stapes | styloud process

Question 52

skeletal derivatives 3rd

Answer 52

hyoid bone

Question 53

skeletal derivatives 4th

Answer 53

laryngeal cartilages | epiglottis