Thyroid Hormonal System Flashcards Preview

RUSVM Physiology II > Thyroid Hormonal System > Flashcards

Flashcards in Thyroid Hormonal System Deck (50):
1

Functional unit of the parathyroid gland

Parathyroid Cells (Chief Cells)

2

Congenital hypothyroidism occurs in _________.

Congenital hypothyroidism occurs in foals.

3

Percursors of thyroid hormone synthesis

Tyrosine Amino Acids

Iodide

4

_____________ is synthesized and secreted by parathyroid glands and is stimulated by decreased [calcium]

Parathyroid Hormone (PTH) is synthesized and secreted by parathyroid glands and is stimulated by decreased [calcium]

5

The primary clearance organs for thyroid hormone are

liver and kidney

6

_____________ is characterized by decreased thyroid horomone and thus decreased metabolic rate.

Hypothyroidism is characterized by decreased thyroid horomone and thus decreased metabolic rate.

7

When T3 binds _________ receptors it activates oxidative phosphorylation and ATP synthesis

When T3 binds mitochondrial receptors it activates oxidative phosphorylation and ATP synthesis

8

______________ blood samples are taken before and after administration of TSH.

TSH Stimulation Test blood samples are taken before and after administration of TSH.

________________

Expect to see increased T4 after administration

Was Gold Standard at one time

9

____________: located between thyroid follicles, produce calcitonin.

Parafollicular Cells (C Cells): located between thyroid follicles, produce calcitonin.

10

Cold temperatures (increases/decreases) [T3]

Cold temperatures (increases/decreases) [T3]

11

Etiology of Hypothyroidism

Lymphatic thyroiditis (autoimmune)

Idiopathic atrophy

12

Control of Thyroid Hormone homeostasis is maintained by the ____________.

Control of Thyroid Hormone homeostasis is maintained by the Hypothalamic - Pituitary - Thyroid- Axis.

13

___________ is synthesized and secreted by parafollicular cells and is stimulated by increased [calcium]

Calcitonin is synthesized and secreted by parafollicular cells and is stimulated by increased [calcium]

14

Calcitonin effects on target tissues

@ Bone - inhibits osteoclast activiyt

@ Kidney - inhibits reabsorption of calcium

@ GI - inhibits absorption of calcium

15

Increased [T3] and [T4] (increases/decreases) the release of TRH and TSH

Increased [T3] and [T4] (increases/decreases) the release of TRH and TSH

16

__________: epithelial cells in spherical arrangement that produce thyroid hormones.

Thyroid Follicles: epithelial cells in spherical arrangement that produce thyroid hormones.

17

____________ disease in which excessive amounts of PTH produced leading to increased blood [calcium]

Hyperparathyroidism disease in which excessive amounts of PTH produced leading to increased blood [calcium]

18

_____________ binds to anterior pituitary and signals the release of TSH

Thyroid Releasing Hormone (TRH) binds to anterior pituitary and signals the release of TSH

19

High carbohydrate diet (increases/decreases) [T3] causing an (increased/decreased) metabolic rate.

High carbohydrate diet (increases/decreases) [T3] causing an (increased/decreased) metabolic rate.

20

___________ are provided by thyroglobulin and secreted into the colloid.

Tyrosine Amino Acids are provided by thyroglobulin and secreted into the colloid.

21

____________: densely arranged near capillaries and produce parathyroid hormone (PTH)

Parathyroid (Chief) Cells: densely arranged near capillaries and produce parathyroid hormone (PTH)

22

__________ is the most common feline endocrine disorder.

Hyperthyroidism is the most common feline endocrine disorder.

23

Diagnosis of Hyperthyroidism

tT4

fT4

tT3 or fT3

TSH Stimulation Test

T3 Suppression Test

24

______________ test for hyperthyroidism where T3 is administered to inhibit the release of TSH and decrease T4 secretion.

T3 Suppression Test test for hyperthyroidism where T3 is administered to inhibit the release of TSH and decrease T4 secretion.

25

Thyroid hormones are _______ soluble.

Thyroid hormones are fat soluble.

 

___________________

Must be bound to protein in order to circulate

26

Explain the process of secretion of thyroid horomones

Epithelial cells ingest colloid by endocytosis

Endosomes fuse whith lysosomes to liberate thyroglobulin

Free thyroid hormones diffuse out

 

27

Explain thyroid hormone mechanism of action

Free T3 and T4 taken up by target cell

In cytoplasm T3/T4 bound to transport proteins

T4 → T3 by deiodinase

T3 binds mitochondrial or nuclear receptors

28

_____________ : enzyme that brings precursor molecules together

Thyroxoid Peroxidase (TPO) : enzyme that brings precursor molecules together

29

_____________ disease in which C cell production of calcitonin may be impaired leading to increased blood [calcium]

Thyroid Parafollicular Cell Dysfunction disease in which C cell production of calcitonin may be impaired leading to increased blood [calcium]

30

________ is the bioactive thyroid hormone.

T3 is the bioactive thyroid hormone.

31

Hypothyroidism is more common in ______ 

Hypothyroidism is more common in dogs 

______________________

Can occur in cats after bilateral thyroidectomy

32

Etiology of Hyperthyroidism

Thyroid Adenoma/ Benign Adenomatous Hyperplasia

Thyroid Carcinoma

33

________ is most abundant thyroid hormone

T4 is most abundant thyroid hormone

34

DIT + DIT = 

T4

35

When T3 binds _________ receptors it increases mRNA transcription leading to increased protein synthesis.

When T3 binds nuclear receptors it increases mRNA transcription leading to increased protein synthesis.

36

________ measures only free T4

fT4 measures only free T4

_______________

Used to corraborate tT4

37

Parathyroid hormone effects on target tissues

@ Bone - stimulate osteoclast activity

@ Kidney - inhibit excertion of calcium, promote reabsorption of calcium

@ GI - stimulate uptake of calcium

38

Explain the process of thyroid hormone synthesis

Iodide → Iodine

Iodine +Tyrosine → MIT or DIT

Coupling process 

Thyroid hormone stored bound to thyroglobulin in colloid until stimulated to be released

39

__________ disease in which insufficient PTH is produced leading to decreased blood [Calcium]

Hypoparathyroidism disease in which insufficient PTH is produced leading to decreased blood [Calcium]

40

________ measures both free and bound T4

tT4 measures both free and bound T4

41

Functional units of the thyroid gland

Thyroid Follicles

Colloid

Parafollicular Cells

42

T4 undergoes glucuronidation by _________ in order to increase its solubility to bile.

T4 undergoes glucuronidation by T4 UDP-Glucuronyl Transferase in order to increase its solubility to bile.

43

Endocrine system

Collection of ductless glands that secrete hormones directly into the circulatory system

44

_______________ stimulates T3/T4 synthesis and secretion.

Thyroid Stimulating Hormone (TSH) stimulates T3/T4 synthesis and secretion.

45

Diagnosis of Hypothyroidism

tT4

fT4

TSH Stimulation Test

46

________: intrafollicular fluid rich in thyroglobulin

Colloid: intrafollicular fluid rich in thyroglobulin

47

T3 has a (higher/lower) affinity for binding protien than T4.

T3 has a (higher/lower) affinity for binding protien than T4.

48

MIT + DIT =

T3 or reverse T3

49

___________ is obtained from the diet and secreted into the colloid 

Iodide is obtained from the diet and secreted into the colloid 

______________________

Process called iodide trapping

50

__________ binds 70-80% of all circulating thyroid hormones.

Thyroid Binding Globulin (TBG) binds 70-80% of all circulating thyroid hormones.