Thyroid Hormonal System Flashcards Preview

RUSVM Physiology II > Thyroid Hormonal System > Flashcards

Flashcards in Thyroid Hormonal System Deck (50)
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1
Q

Functional unit of the parathyroid gland

A

Parathyroid Cells (Chief Cells)

2
Q

Congenital hypothyroidism occurs in _________.

A

Congenital hypothyroidism occurs in foals.

3
Q

Percursors of thyroid hormone synthesis

A

Tyrosine Amino Acids

Iodide

4
Q

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

A

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

5
Q

The primary clearance organs for thyroid hormone are

A

liver and kidney

6
Q

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

A

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

7
Q

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

A

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

8
Q

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

A

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
Q

____________: located between thyroid follicles, produce calcitonin.

A

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

10
Q

Cold temperatures (increases/decreases) [T3]

A

Cold temperatures (increases/decreases) [T3]

11
Q

Etiology of Hypothyroidism

A

Lymphatic thyroiditis (autoimmune)

Idiopathic atrophy

12
Q

Control of Thyroid Hormone homeostasis is maintained by the ____________.

A

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

13
Q

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

A

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

14
Q

Calcitonin effects on target tissues

A

@ Bone - inhibits osteoclast activiyt

@ Kidney - inhibits reabsorption of calcium

@ GI - inhibits absorption of calcium

15
Q

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

A

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

16
Q

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

A

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

17
Q

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

A

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

18
Q

_____________ binds to anterior pituitary and signals the release of TSH

A

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

19
Q

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

A

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

20
Q

___________ are provided by thyroglobulin and secreted into the colloid.

A

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

21
Q

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

A

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

22
Q

__________ is the most common feline endocrine disorder.

A

Hyperthyroidism is the most common feline endocrine disorder.

23
Q

Diagnosis of Hyperthyroidism

A

tT4

fT4

tT3 or fT3

TSH Stimulation Test

T3 Suppression Test

24
Q

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

A

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

25
Q

Thyroid hormones are _______ soluble.

A

Thyroid hormones are fat soluble.

___________________

Must be bound to protein in order to circulate

26
Q

Explain the process of secretion of thyroid horomones

A

Epithelial cells ingest colloid by endocytosis

Endosomes fuse whith lysosomes to liberate thyroglobulin

Free thyroid hormones diffuse out

27
Q

Explain thyroid hormone mechanism of action

A

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
Q

_____________ : enzyme that brings precursor molecules together

A

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

29
Q

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

A

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

30
Q

________ is the bioactive thyroid hormone.

A

T3 is the bioactive thyroid hormone.

31
Q

Hypothyroidism is more common in ______

A

Hypothyroidism is more common in dogs

______________________

Can occur in cats after bilateral thyroidectomy

32
Q

Etiology of Hyperthyroidism

A

Thyroid Adenoma/ Benign Adenomatous Hyperplasia

Thyroid Carcinoma

33
Q

________ is most abundant thyroid hormone

A

T4 is most abundant thyroid hormone

34
Q

DIT + DIT =

A

T4

35
Q

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

A

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

36
Q

________ measures only free T4

A

fT4 measures only free T4

_______________

Used to corraborate tT4

37
Q

Parathyroid hormone effects on target tissues

A

@ Bone - stimulate osteoclast activity

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

@ GI - stimulate uptake of calcium

38
Q

Explain the process of thyroid hormone synthesis

A

Iodide → Iodine

Iodine +Tyrosine → MIT or DIT

Coupling process

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

39
Q

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

A

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

40
Q

________ measures both free and bound T4

A

tT4 measures both free and bound T4

41
Q

Functional units of the thyroid gland

A

Thyroid Follicles

Colloid

Parafollicular Cells

42
Q

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

A

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

43
Q

Endocrine system

A

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

44
Q

_______________ stimulates T3/T4 synthesis and secretion.

A

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

45
Q

Diagnosis of Hypothyroidism

A

tT4

fT4

TSH Stimulation Test

46
Q

________: intrafollicular fluid rich in thyroglobulin

A

Colloid: intrafollicular fluid rich in thyroglobulin

47
Q

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

A

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

48
Q

MIT + DIT =

A

T3 or reverse T3

49
Q

___________ is obtained from the diet and secreted into the colloid

A

Iodide is obtained from the diet and secreted into the colloid

______________________

Process called iodide trapping

50
Q

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

A

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