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Flashcards in Formation of Body Systems Deck (15)
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1

Folding of Embryo

1) folding of flat trilaminar disc into cylindrical embryo
2) Head region fold bc brain growth
3) Tail region fold bc spinal cord growth
4) Spinal cord and somites cause the future ventrolateral body walls to fold towards midline

2

Cardiovascular System

1) Blood vessels form initially in extra embryonic mesoderm of Secondary umbilical vesicle, future umbilical cord, and chorion
2) Development of vessels in embryo 2 days later
3) Primordial Heart & great vessel differentiate from mesoderm
4) Heart starts to beat @ beginning of 4th week
5) FIRST MAJOR SYSTEM TO FUNCTION

3

Nervous System

1) Neuralation (neural tube formation)
-4th week
-forms primordial brain and spinal cord

4

Brain
-different portions form what

1) Forebrain becomes:
-Cerebrum
-thalamus
-Hypothalamus
2) midbrain-->Midbrain
3) Hindbrain becomes:
-pons
-cerebellum
-Medulla

5

Skeleton: Bones
-arise from

1) Skull bones
-neural crest cells
2) Axial Skeleton
-vertebrae, sternum, ribs
-selerotome part of somites (Paraaxial mesoderm)
3) Limbs:
-Lateral mesoderm

6

Bones form directly from:

1)Mesoderm/neural crest cell
-intramembranous ossification
2) Cartilage Precursor
-endochondrial ossification
3) Ossification begins in 7th-8th week but continues into fetal period and beyond

7

Muscles:
-arise from

1) muscles of trunk, limbs, eyes, and tongue
-dermomyotome part of somites
-paraxial mesoderm
2) Muscles of Head/neck
-Mesoderm associated pharyngeal arches

8

how does the Primitive Gut form:

1) Forms during folding of embryo
-consists of endodermal tube surrounded by mesoderm

9

GUT Tube characterized as:

1) Foregut
2) Intermediate Midgut
3) Hindgut (caudal)

10

Development of Midgut:

1) Herniation of GUT tube into extra embryonic coelom
-6th week
2) Returns to abdominal cavity during 10/11th week
-becomes most of small intestine, appendix, and 1/2 large intestine

11

Development of Foregut:

1) Outgrowth of the Gut tube during 4th week
2) Largest outgrowth=stomach
3) Liver/Gallbladder= ventral outgrowth
4) Pancreas= Dorsal/Ventral outgrowth

12

Development of Hindgut:

1) Urorectal septum separates lower part from urinary system
2) Remainder of Large intestine

13

Respiratory System

1) First indication of Lower respiratory system
Evagination from the foregut
-week 4
-trachea, bronchi, lungs
2) Endodermal Lung Bund grows into mesoderm and divides into 2 bronchial buds
-Forms primary bronchi of 2 lungs
3) FOLLOWING weeks
-bronchial bud divides into secondary bronchi
-then divide to form tertiary (segmental) bronchi

14

Urogenital System

1) Divided Functionally
-Urinary
-Genital
2) Kindey & Ureter & Gonads
-intermediate mesoderm
-5th week

15

Endocrine System

1) Most develop during 4th week
2) Thyroid
-1st endocrine gland to develop
-from diverticium of foregut
3) Pancreas/Parathyroid/Thymus
-endoderm
4) Pituitary
-ectodermal upgrowth near mouth (ant lobe)
-downgroth from brain (posterior lobe)
5) Gonads/Suprarenal glands
-5th/6th week
-dual origin
-mesoderm (cortex
-Neural crest cells (medulla)