Thyroid Flashcards

1
Q

Which gland is most important for basal metabolic regulation?

A

Thyroid gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the isthmus?

A

Connecting tissue between the lobes of the thyroid. Hard to find in dogs and cats

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the effect of thyroid hormone on oxygen?

A

Increase consumption of oxygen in target cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are some functions of thyroid hormone?

A
  • Maintain function of organs
  • Consumption of )2
  • Lipid and carb metabolism
  • Normal growth and maturation
  • Regulation of calcium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the location of the thyroid gland?

A

Bilateral around trachea. Carotid sheath is lateral. Medial retropharyngeal is cranial. Deep to sternothyroideus muscle. and larynx is cranial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where is the parathyroid gland?

A

Usually 4 and embedded in and is not normally palpable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are follicular cells?

A
  • Traps iodide and transport
  • Synthesize and secrete thyroglobulin
  • Remove and secrete T3 and T4
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are parafollicular cells?

A

In the thyroid.

  • secrete calcitonin
  • neural crest derivative
  • decrease calcium levels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is in follicles of the thyroid?

A

Colloid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What organ has the greatest blood flow per gram of tissue?

A

Thyroid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which cells in the thyroid are pituitary independent?

A

Parafollicular cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Were is iodine found in the body?

A

In the intestinal tract from feed and are trapped by follicular cells and through active transport enter the follicle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens to iodine when it enters the follicle?

A

Attached to Tyrosine by thyroperoxidase and makes either MIT (1 iodine) or DIT(2 iodines)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is thyroglobulin?

A

In the colloid with many tyrosine residues and gets released to form T3 and T4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the ultimate effect of T3?

A

Increase basal metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How do you get T3?

A

1 MIT + 1 DIT + thyroglobulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Where does formation of MIT and DIT happen?

A

in the lumen???

18
Q

How do you get T4?

A

DIT +DIT + thyroglobulin

19
Q

What is reverse T3?

A

Order of addition of tyrosine is opposite. 3, 3’, 5’ tyrosines

20
Q

Which thyroid hormone exists in the most amount?

A

T4

21
Q

Where are receptors for thyroid hormone?

A

In the nucleus

22
Q

How is thyroid hormone liberated from thyroglobulin?

A
  1. Endocytosis by thyroid epithelial cells
  2. Lysosomes fuse with endocytotic vesicles
  3. Free thyroid hormones diffuse from lysosomes into the blood.
23
Q

What can transport thyroid hormones

A
  1. Thyroxine binding globulin (TBG) (70%)
  2. Transthyretin (10-15%)
  3. Albumin (20%)
24
Q

What animals do not have TGB?

A

Rodents and cats

25
Q

What cells produce calcitonin?

A

Thyroid parafollicular cells

26
Q

What does calcitonin do?

A

Lower blood Ca and phosphorus

  • Blocks osteoclasts action so it is stored in bones
  • BLocks renal reabsorption of Ca and P
27
Q

What it the antagonistic hormone to parathyroid hormone?

A

Calcitonin

28
Q

What 3 hormones regulate calcium?

A
  • Calcitonin (lower)
  • Vitamin D (raise)
  • Parathyroid hormone (raise)
29
Q

What is a goiter?

A

Gross enlargement of the thyroid usually nonneoplastic and non-inflammatory

30
Q

What animal is hyperthyroidism most common in?

A

Cats. Very rare in dog

31
Q

How many months worth of thyroid hormone is stored in the thyroid?

A

6months

32
Q

What is a primary hyperthyroidism?

A

Thyroid adenoma or enlargement

33
Q

What is a secondary cause of hyperthyroidism?

A

Pituitary tumors or adenoma

34
Q

What is a tertiary cause of hyperthyroidism?

A

Hypothalamic legion

35
Q

What are some clinical signs of hyperthyroidism?

A
  • increased metabolic rate (heat intolerance)
  • Goiter
  • Weight loss, polyphagia, PU
  • Hyperactivity
  • Tachycardia
  • Cardiac murmur
  • Diarrhea
  • Serum enzymes elevated
  • Low plasma cholesterol
  • Bulging eyes in humans (sympathetic drive)
36
Q

How can you diagnose hyperthyroidism?

A
  • Serum T4
  • TSH stimulation test
  • Thyroid scan
  • Needle biopsy
37
Q

What is the treatment of hyperthyroidism?

A
  • Antithyroid drugs (inhibit thyroperoxidase)
  • Radioactive iodine
  • Surgery
  • Propanolol for tachycardia
38
Q

What is hypothyroidism?

A

Deficiency of thyroid follicular hormones

39
Q

What is cretinism?

A

Irreversible growth and metabolic retardation due to lack of thyroid hormones

40
Q

Why is it important to catch hypothyroidism in young animals?

A

Without treatment there can be permanent growth damage and retardation

41
Q

What are the signs of hypothyroidism?

A
  • Elevated thyroglobulin antibodies
  • Poor response to TSH
  • High serum cholesterol
  • Alopecia
  • Lethargy
  • Cold intolerance
  • Obesity
  • Bradycardia
42
Q

What is treatment for hypothyroidism?

A

Thyroid replacement therapy