Thyroid lecture Flashcards
What is a blastula?
Name for what forms when an egg and sperm combine. An embryo at the early stage of development.
Name the 3 cellular layers which develop when an embryo forms. List them in order, from outermost to inner most.
Ectoderm (out), Mesoderm (middle), Endoderm (inner)
What does the Ectoderm develop into?
Skin, nervous tissue, hair
What does the Endoderm develop into?
Gut, Lungs, Liver, pancreas, thyroid
List the 3 regions of the Mesoderm and what is formed in each layer?
Paraxial- Muscle
Intermediate- Gonads, Kidneys
Lateral plates- Body wall, body cavity, cardiovascular, GIT structures
At which week does the thyroid being to properly develop?
Week 4-5
What develops in pouch 1 and 2 of the pharyngeal arches?
The thyroid diverticulum
Where does the thyroid diverticulum develop? (not the pouchs)
The foramen secum
Where is the foramen secum located?
Between the anterior 2/3 and posterior 1/3 of the tongue
What is the function of the thyroglossal duct?
It pulls the thyroid from the formen secum to its final position infront of the first two tracheal rings
After how many weeks or months will the thyroid begin to function? Name the substance it produces first?
3 months
Colloids
What do the colloids contain?
Pro-hormone thyroglobulin
What is formed by the 3rd pharyngeal arches?
Inferior- parathyroid and thymus
What is formed by the 4th pharyngeal arches?
Superior-parathyroid and ultimobranchial body
What is found at the ultimobranchial body?
Para-follicular cells (C cells)
What is the function of Para-follicular cells (C cells)?
produce calcitonin
What are the pharyngeal pouches?
Endodermal out pouches of the pharynx
What produces the pyramidal lobe?
Reminiance from the thyroglossal duct
What are the origins of the superior and inferior thyroid arteries?
Superior- external carotid
Inferior - thyrocervical trunk from the subclavian artery
Name all three thyroid veins and where they drain?
Superior, middle and inferior.
Superior and middle- jugular vein
Inferior- brachiocephalic vein
