Pathology of Endocrine System 1 Flashcards

1
Q

What is the endocrine system?

A

Integrated network of glands that secrete chemical messengers (hormones) into the bloodstream

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2
Q

What do hormones act on?

A

Target cells distant to site of synthesis, binding to receptors and changing their activity

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3
Q

What are some examples of effects that hormones may have?

A

Regulation of metabolism, growth and development, tissue function

Maintain functional balance (homeostasis)

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4
Q

Where are hormones synthesised and stored?

A

In glands, which are packets of cells with secretory granules that are vascular and ductless

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5
Q

How are levels of hormones maintained?

A

Negative feedback

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6
Q

What are examples of organs in the endocrine system?

A
  • Pineal gland
  • Hypothalamus
  • Pituitary gland
  • Thyroid gland
  • Parathyroid gland
  • Adrenal glands
  • Pancreas
  • Includes other organs, such as ovary, testes and kidneys, and also diffuse endocrine cells such as those in the lungs and GIT
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7
Q

Endocrine organs are linked by feedback axis, what are some major systems?

A
  • TRH -> TSH -> T3/4
  • GnRH -> LH/FSH -> sex hormones
  • CRH -> ACTH -> cortisol
  • Renin -> angiotensin -> aldosterone
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8
Q

What are examples of classificaitons of endocrine disease?

A
  • Dysregulated hormone release
    • Hyperfunction
    • Hypofunction
  • Effect of a mass lesion
  • Hyperplasia
    • Increased number and secretory activity of cells
  • Atrophy
    • Diminution of cells due to lack of stimulation
  • Tissue damage
    • Inflammation, autoimmune disease, compression, trauma, infarction
  • Neoplasia
    • Adenoma, functioning or non-functioning (benign)
    • Carcinoma (malignant)
  • Congenital abnormality
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9
Q

What is hyperplasia in terms of the endocrine system?

A

Increased number and secretory activity of cells

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10
Q

What is atrophy?

A

Diminution of cells due to lack of stimulation

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11
Q

What are examples of causes of tissue damage?

A

Inflammation

Autoimmune disease

Compression

Trauma

Infarction

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12
Q

How can diseases on one endocrine gland have multiorgan clinical effects?

A

Due to hormones acting on several tissues

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13
Q

What is the thyroid responsible for the release of?

A

Thyroxine (T3) and triiodothyronine (T3)

Calcitonin

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14
Q

What is the function of T4 and T3?

A

Regulates basal metabolic rate

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15
Q

What is the function of calcitonin?

A

Regulates calcium homeostasis

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16
Q

What is T3 also known as?

A

Triiodothyronine

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17
Q

What is T4 also known as?

A

Thyroxine

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18
Q

What can be seen in the histology of the thyroid gland?

A
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19
Q

What are the epithelial cells of the thyroid gland resonsible for?

A

TG synthesis

Iodination

Resorption and release of T3 and T4

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20
Q

What cells in the thyroid gland secrete calcitonin?

A

C-cells

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21
Q

How are epithelial cell of the thyroid gland arranged?

A

Follicles filled with colloid (contains thyroglobulin)

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22
Q

What is contained in the colloid of the thyroid gland?

A

Thyroglobulin

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23
Q

Explain the process of the hypothalamus-pituitary-thyroid axis?

A
  • TRH from hypothalamus stimulated by cold, stress
  • Stimulates TSH leading to stimulation of thyroid to produce T3 and T4 (increase the number, size and activity of thyroid follicular cells)
  • TSH/TRH levels feedback of T3 and T4 respond to circulating
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24
Q

What is TRH from hypothalamus stimulated by?

A

Cold

Stress

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25
Q

How does TSH lead to stimulation of thyroid to produce T3 and T4?

A

Increases the number, size and activity of thyroid follicular cells

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26
Q

What supplies the feedback of TSH/TRH?

A

T3 and T4

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27
Q

What are some manifestations of thyroid disease?

A
  • Hyperthyroidism
    • Thyrotoxicosis
  • Hypothyroidism
    • Myxoedema, cretinism, subclinical
  • Thyroid enlargement
    • Goitre, isolated nodule/mass
  • Thyroiditis
    • Autoimmune
  • Gland destruction
  • Multinodular goitre
  • Tumours
    • Benign, malignant
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28
Q

What does hyperthyroidism lead to?

A

Thyrotoxicosis (excess thyroid hormone in the body)

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29
Q

What does hypothyroidism lead to?

A

Myxoedema

Cretinism

Subclinical hypothyroidism

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30
Q

What is myxoedema?

A

Severely advanced hypothyroidism

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31
Q

What is cretinism?

A

Condition characterised by deformity and learning difficulties due to congenital hypothyroidism

32
Q

What does thyroid enlargement lead to?

A

Goitre

Isolated nodule/mass

33
Q

What is thyroiditis?

A

Inflammation of the thyroid gland

34
Q

What are some causes of hyperthyroidism?

A

Diffuse toxic hyperplasia (Grave’s disease) 70%

Toxic multinodular goitre 20%

Toxic adenoma

35
Q

What is the most common cause of hyperthyroidism?

A

Grave’s disease

36
Q

What is Grave’s disease also known as?

A

Diffuse toxic hyperplasia

37
Q

Does Grave’s disease impact more males or females?

A

Females > males

38
Q

What is the pathogenesis of Grave’s disease?

A
  • Autoimmune production of anti-TSH receptor antibodies
    • Stimulate activity, growth, inhibit TSH binding
    • Ophthalmopathy immune mediated, ocular fibroblasts have TSH receptor
  • Affects the thyroid by causing diffuse hyperplasia and hyperfunction
39
Q

What are some causes of hypothyroidism?

A

Hashimoto’s thyroiditis

Iatrogenic

Iodine deficiency

Congenital hypothyroidism

40
Q

What is Hashimoto’s thyroiditis?

A
  • Autoimmune destruction of thyroid epithelial cells
    • Cytotoxic T cells, cytokine and antibody mediated destruction
    • Circulating autoantibodies to thyroglobulin and thyroid peroxidase
41
Q

What is the commonest cause of hypothyroidism?

A

Hashimoto’s thyroiditis

42
Q

Does Hashimoto’s thyroiditis affect more males or females?

A

M>F

43
Q

What age group is most affected by Grave’s disease?

A

20-40

44
Q

What age group is most affected by Hashimoto’s thyroiditis?

A

45-65

45
Q

What impact does Hashimoto’s thyroiditis have on the thyroid?

A

Causes diffuse enlargement and gradual failure

46
Q

What is seen in the histology of Hashimoto’s thyroiditis?

A

Intense infiltrate of lymphocytes and plasma cells

Hurthle cell change

47
Q

What is goitre?

A

Enlarged thyroid

48
Q

Explain the pathogenesis of goitre?

A
  • Iodine deficiency, goitrogens -> impaired synthesis of T3 and T4 -> increased TSH concentration -> hypertrophy and hyperplasia of thyroid epithelium (simple epithelium becomes multinodular)
49
Q

What is the most common cause of goitre?

A

Iodine deficiency

50
Q

What is seen in the histology of goitre?

A

Crowded follicles

Distended colloid filled follicles

Haemorrhage

Fibrosis

Cystic change

Nodular appearance

51
Q

What is the thyroid nodule?

A

The dominant nodule in multinodular goitre

52
Q

What can the thyroid nodule be?

A

Cyst, follicular adenoma or carcinoma

53
Q

What are the different kinds of thyroid carcinoma?

A
  • Differentiated thyroid carcinoma
    • Papillary carcinoma 75-85%
    • Follicular carcinoma 10-20%
  • Anaplastic carcinoma <5%
  • Medullar carcinoma (lymphoma) 5%
54
Q

What can the thyroid nodule be investigated by?

A

TFTs

Ultrasound

FNA - cytology

55
Q

What are risk factors for thyroid carcinoma?

A

Family history

Chrominc inflammatory conditions

Radiation exposure

Obesity

56
Q

What is a neoplasm?

A

A new and abnormal growth of tissue in a part of the body, especially as a characteristic of cancer

57
Q

Are most thyroid neoplasms functioning or non-functioning?

A

Non-functioning

58
Q

What does DTC stand for?

A

Differentiated thyroid cancer

59
Q

What are 2 kinds of differentiated thyroid cancer (DTC)?

A

Follicular carcinoma

Papillary carcinoma

60
Q

Where does follicular carcinoma often metastasis to?

A

Blood or bones

61
Q

Does follicular carcinoma have a genetic predisposition?

A

RAS mutation

or PAX8/PPARG translocation

62
Q

What age group usually gets papillary carcinoma?

A

<50

63
Q

Is there a genetic predisposition to papillary carcinoma?

A

BRAF mutation

or RET/PTC gene rearrangement

64
Q

What is papillary carcinoma associated with?

A

Ionising radiation

65
Q

What is seen in the histology of papillary carcinoma?

A
  • Papillary projections, empty nuclai, psammoma bodies, may be cystic
66
Q

What is thyroid medullar carcinoma?

A

Malignant tumour of C-cells

Produces calcitonin

67
Q

Does thyroid medullar carcinoma have a genetic predisposition?

A

RET proto-oncogene

68
Q

What does thyroid medullar carcinoma produce?

A

Calcitonin (with or without production of other polypeptides)

69
Q

What is the treatment of thyroid carcinoma?

A
  • Surgery
    • Follicular and PTC, medullary (with external radiotherapy)
  • Radioactive iodine
    • Unsafe during pregnancy
  • External radiotherapy
  • Chemotherapy
70
Q

When is it unsafe to use radioactive iodine as a treatment for thyroid carcinoma?

A

During pregnancy

71
Q

How many parathyroid glands do most people have?

A

4

72
Q

What do parathyroid glands produce?

A

PTH which regulates plasma calcium

73
Q

What is the function of PTH?

A

Regulate plasma calcium

74
Q

What are the different classifications of hyperparathyroidism?

A
  • Primary hyperparathyroidism
    • Often asymptomatic hypercalcaemia
    • Sporadic or familial (MEN-1)
      • Adenoma 85-95%
      • Hyperplasia 5-10%
      • Carcinoma rare
  • Secondary hyperparathyroidism
75
Q

Is there a genetic predisposition to primary hyperparathyroidism?

A

MEN-1

76
Q

What is secondary hyperparathyroidism?

A

Physiological response to decreased calcium in renal failure