Thyroid Gland

Question 1

Is the colloid considered “inside” the thyroid cell

Answer 1

no

Question 2

Synthesis of thyroid hormone is initiated…. and completed…..

Answer 2

inside the cell….outside the cell

Question 3

Is thyroid hormone stored in secretion granules

Answer 3

no- in follicles

Question 4

What are the advantages to storing thyroid hormone in colloid verses secretion granules

Answer 4

it allows the organ to store more hormone (this was very useful when your diets were such that Iodine levels were low)

Question 5

What organ is closely associated with the thyroid gland

Answer 5

parathyroid gland

Question 6

What are the 3 major components of the parathyroid gland

Answer 6

oxyphil cells, chief cells, and fatty tissue

Question 7

Oxyphil cell morphology

Answer 7

Large cells (nuclei far apart), acidophilic (due to large amounts of mitochondria),

Question 8

Chief cell morphology

Answer 8

Poorly stained (due to glycogen), small (nuclei close together, resembles lymphocytes

Question 9

Chief cell function in parathyroid gland

Answer 9

Synthesis and secretion of Parathyroid hormone (PTH).

Question 10

Function of PTH

Answer 10

stimulates osteoclast to increase blood calcium concentrations

Question 11

The hormone that is antagonistic to PTH is…

Answer 11

calcitonin

Question 12

Do follicles hold active thyroid hormone

Answer 12

no- its prohormone

Question 13

Colloid is (acidophilic/basophilic) and (electron lucid/electron dense)

Answer 13

Acidophilic….electron dense

Question 14

What cells secrete calcitonin

Answer 14

parafollicular cells

Question 15

other names for parafollicular cells

Answer 15

clear cells (c-cell)

Question 16

Function of calcitonin

Answer 16

• inhibit osteoclasts

- Inhibit Ca uptake by the small intestine and kidney

Question 17

Do parafollicular cells touch colloid

Answer 17

no

Question 18

T/F: Parafollicular and follicular cells are simple cuboidal/columnar epithelium?

Answer 18

T

Question 19

What is the principle (chief) cell for the thyroid

Answer 19

follicular cell

Question 20

If the epithelium around the follicle is columnar the organ is (more/less) active

Answer 20

more

Question 21

If epithelium around the follicle is cuboidal the organ is (Less/more) active

Answer 21

less

Question 22

Is the parafollicular cell a secreting cell

Answer 22

yes

Question 23

What organelles do you expect to find in a secreting cell

Answer 23

golgi, RER, secretion granules

Question 24

EM of parafllicular cell

Answer 24

• Follicular cells overlap the parafollicular cells to prevent it from touching the colloid
• Secretion granules (small) located at the base of the cell near the capillary beds.
• RER and golgi present

Question 25

What structures are located between the follicles

Answer 25

Collagen fibers containing BV, nerves (sympathetic and parasympathetic) and lymphatics

Question 26

Voids (white colored vacuoles) in the colloid are present due to...

Answer 26

artifacts (NOT reabsorption!)

Question 27

Why might we see nuclei in the colloid?

Answer 27

Epithelium is being regenerated

Question 28

Why might we see more heavily stained colloid in certain follicles verses others

Answer 28

More intensely stained colloid= more heavily concentrated with thyroglobulin

Question 29

Know the pathway for thyroid hormone synthesis

Answer 29

ok (slide 17)

Question 30

The apical surface of the follicular cell faces...

Answer 30

the colloid

Question 31

The basal surface of the follicular cell sits...

Answer 31

on the basement membrane

Question 32

The lateral surface of the follicular cell...

Answer 32

binds to adjacent cells

Question 33

Characteristics of the basal surface of follicular cells

Answer 33

- LOTS of mitochondria - Sits on basement membrane (lucida (2), densa, and reticular layer). - Capillary is under the basement membrane (fenestrated with diaphragms)

Question 34

Would we expect to see lysosomes in follicular cells? Why?

Answer 34

Yes because the phagosome with iodine modified thyroglobulin is attacked by primary lysosomes

Question 35

Primary lysosome morphology

Answer 35

electron dense with membrane

Question 36

phagosome morphology

Answer 36

similar to primary lysosome only is less electron dense and lacks a membrane

Question 37

Secondary lysosome morphology

Answer 37

heterogenous matrix

Question 38

Important cell structures on apical surface of follicular cell

Answer 38

- RER with dilated cisterns | - Short stubby microvilli

Question 39

Important cell structures on lateral surface of follicular cells

Answer 39

- Terminal bar (ZO, ZA, MA) - Transport and secretion vesicles - Golgi (will be found near the vesicles)

Question 40

(ZO,ZA,MA) is a tight junction

Answer 40

ZO

Question 41

(ZO,ZA,MA) is a gap junction

Answer 41

ZA

Question 42

(ZO,ZA,MA) is a desmosome

Answer 42

MA

Question 43

Purpose of the terminal par in the follicular cell (2)

Answer 43

- Holds cells together | - Prevents colloid from leaking into circulation

Question 44

Why does it make sense to find vesicles and golgi near the lateral/apical surface of the cell

Answer 44

Thyroglobulin is being exocytosed into the colloid

Question 45

Slide 30 is a nice pathway

Answer 45

ok

Question 46

T/F The thyroid gland does not have a CT capsule

Answer 46

F

Question 47

What makes up the lobules of the thyroid gland

Answer 47

Septa from the capsule

Question 48

Activity of the thyroid gland is controlled by...

Answer 48

``` Pituitary gland (TSH) Hypothalymus (thyroid releasing factor) ```

Question 49

T/F Follicles are always round

Answer 49

F: Compressible

Question 50

What is the function of the oxyphil cell

Answer 50

nobody knows

Question 51

There are two types of chief cells in the parathyroid (light and dark) what makes these two differe

Answer 51

Amount og glycogen (light= more glycogen because glycogen doesn't stain)

Question 52

There is (more/less) fatty tissue in a younger individual

Answer 52

less

Question 53

T/F The parathyroid hormone ONLY contains chief cells until childhood

Answer 53

true

Question 54

What regulates the parathyroid gland

Answer 54

blood Ca levels