thyroid and parathyroid histology

Question 1

what connects sides of thyroid gland

Answer 1

isthmus

Question 2

thyroid follicle is ___ when active and ___ when inactive

Answer 2

columnar when active

cuboidal when inactive

Question 3

what protein helps transport T3 and T4 from follicle to the capillary

Answer 3

thyroxine binding protein

Question 4

what is an endemic goiter caused by

Answer 4

iodine deficiency

• body doesn’t get enough T3 or T4 so hypothalamus tries to simulate AP to make more TSH
• TSH sent out but gland can only respond by hypertrophying

Question 5

congenital hypothyroidism

Answer 5

can be endemic, genetic, sporadic

• sporadic and geneti from abnormal development or fucntion of the fetal thyroid gland
• been almost eliminated by early screening detection and thyroid hormone supplementation

Question 6

what does the follicular epithelium contain

Answer 6

parafollicular cells (c cells)
-secrete calcitonin

Question 7

how does calcitonin work

Answer 7

decrease calcium concentration by inhibiting bone resorption

-binds to receptor on osteoclast

Question 8

parathyroid glands originate from interaction of what

Answer 8

endoderm of 3rd and 4th pouch

• 3rd = inferior
• 4th = superior

Question 9

2 cells of parathyroid gland and function

Answer 9

1) chief cell or principal cell secretes PTH

2) oxyphil cells function unkown

Question 10

what other type of cell will you see abundant in parathyroid glandsq

Answer 10

adipose cells

Question 11

what is associated with chief cells to sense calcium levels

levels of calcium effect

Answer 11

Ca2+ sensing receptor (CASR)

• increased calcium in blood, decreases
• decreased calcium in blood, increases

Question 12

Vitamin D stimulates the synthesis of ___ carrier protein

Answer 12

calbindin

• formed when calcitrol binds receptor on enterocyte
• transports calcium across enterocyte into bloodstream through calcium ATPase

Question 13

steps in formation of osteoclast

Answer 13

1) monocyte from bone marrow has M-CSF receptor
2) PTH binds osteoblast an induces M-CSF ligand to be released
3) M-CSF ligand binds M-CSF receptor and monocyte becomes macrophage, expresses RANK
4) osteoblast has RANKL which binds RANK and cell becomes osteoclast

Question 14

what blocks RANKL binding to RANK

Answer 14

osteoprotegrin binds RANKL to block

Question 15

hypoparathyroidism symptom

Answer 15

calcium deficiency results in spontaneous depolarization of neurons and muscle fibers resulting in tetany

Question 16

hyperparathyroidism symptoms

Answer 16

qresults in bone loss, osteomalacia (soft bones), and osteitis fibrosa cystica (bones with open cysts)
-causes abnormal calcium deposition in arteries and kidneys

Question 17

rickets

Answer 17

vitamin D deficiency

• bone remodeling defective
• end of bones bulge (rachitic rosary at costochondral jnctions)
• bending of long bones

Question 18

besides Vitamin D deficiency what else causes rickets or osteomalacia

Answer 18

chronic renal railure or lack of 1a hydroxylase