Neurultion & Organ Formation

Question 1

When do organs begin to form?

Answer 1

During weeks 3-8, the 3-layer embryo will soon become. body w/ separate organs

Question 2

What does the Mesoderm develop to form?

Answer 2

During week 3, a thickened band of Mesoderm cell develop along the back of the ED
The form the baby’s back and the notochord - which will provide the basic framework of the skeleton

Question 3

Organs and Body Systems that Develop from the Mesoderm (9)

Answer 3

Dermis of skin
Muscle Tissues
Adrenal Cortex
Heart
Internal Reproductive Organs
Cellular lining of blood vessels & body cavities
Connective Tissue
Kidneys and Uterus
Spleen

Question 4

What does the Ectoderm develop to form?

Answer 4

The nervous system
Cells along the surface above the notochord begins to thicken
Folds develop on each side of a groove along this surface
When the folds fuse, they become the neural tube, which devs. into the brain/SC
The process of forming the NT is called Neurulation, and it marks the start of organ formation
Soon after neurulation, the heart forms (day18)

Question 5

What happens during the 4th week?

Answer 5

Blood cells star to form and fill BVs
Lungs/Kidneys start to take shape
Small bud, which will dev. Into arms/legs appear
Head is visible, early evidence of nose/eyes/ears

Question 6

What happen during the 5th week?

Answer 6

Large head, small body
Eyes open, but they don’t have eyelid or irises
Bran cells are differentiating

Question 7

What happens in the 6th week?

Answer 7

Brain continues to develop
Limbs lengthen and flex slightly
Gonads begin to produce hormones that will influence development of external genitalia

Question 8

What happen in the 7th & 8th weeks?

Answer 8

Embryo has distinct human characteristics
Organs are formed and nervous system begins coordinating body activity
A skeleton of cartilage has formed (not bone)
Eyes well developed but lids are closed
Nostrils developed but plugged with mucus - not end or breathing while in utero

Question 9

Organs and Body Systems that Develop from the Ectoderm (6)

Answer 9

Outer skin & associated structures
Pituitary Gland
Adrenal Medulla
Nervous Tissue and Sense Organs
Tooth Enamel
Eye Lens

Question 10

Organ and Body Systems that Develop from the Endoderm (8)

Answer 10

Cellular lining of the respiratory tract, digestive tract, urinary bladder, urethra
Tonsils
Pancreas
Thyroid Gland
Liver
Gall Bladder
Parathyroid Gland
Thymus