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203: Theme 1: The Endocrine System > Nuts and bolts of the endocrine system - part 2 > Flashcards

Nuts and bolts of the endocrine system - part 2 Flashcards

1
Q

Endocrine glands

A

No duct system

Hormones are released at specific times in small amounts into the tissue fluids or blood vessels

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2
Q

Endocrine definition

A

Action of the hormone on a target organ away from the secreting cell

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3
Q

Autocrine definition

A

Action of the hormone on the secreting cell

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4
Q

Paracrine definition

A

Action of the hormone on the adjacent cell

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5
Q

Neuroendocrine definition

A

Neural stimulation of endocrine cells to secrete hormones

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6
Q

Overall structure of endocrine glands

A

Functional unit consist of cuboidal secretory cells with a lumen at the centre

Secretory cells supported by myoepithelial cells

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7
Q

Clinical manifestations of endocrine diseases

A

Hormone overproduction

Hormone underproduction

Tumour/ mass lesion which can be

  • non-functional so has pressure effect
  • associated with over production of hormones
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8
Q

Pituitary gland divided into

A

Adenohypophysis/ anterior lobe

Neurohypophysis/ posterior lobe

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9
Q

Cells of the anterior pituitary gland

A

Acidophils

Basophils

Chromophobe

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10
Q

Acidophils

A

Take up acidic dyes

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11
Q

Basophils

A

Take up basic dyes

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12
Q

Chromophobe

A

No specific staining feature

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13
Q

Somatotroph

A

Secretes growth hormone

Target organ: bones

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14
Q

Lactotroph

A

Secretes prolactin

Target organ: breasts

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15
Q

Corticotroph

A

Secretes adrenocorticotrophic hormone

Target organ: adrenal glands

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16
Q

Gonadotroph

A

Secretes follicle stimulating hormone and luteinising hormone

Target organ: ovary and testis

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17
Q

Thydrotroph

A

Secretes thyroid stimulating hormone

Target organ: thyroid gland

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18
Q

Hormones from the posterior pituitary

A

Antidiuretic hormone
- facilitates absorption of water in kidneys

Oxytocin
- promotes contraction of smooth muscle in the uterus during childbirth and myoepithelial cells in the breast during breast feeding

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19
Q

Pathology of the pituitary gland

A

Pituitary adenomas (benign tumours)

  • arise from anterior lobe
  • can be functional or non-functional
  • constitute 10% of intra cranial neoplasms
  • productive adenomas cause hyperpituitarism
  • pressure effect causing hypopituitarism

Space occupying effect of functional or non-functional adenomas
- headaches, vomiting, nausea and diplopia, impaired vision

20
Q

Thyroid gland

A

Synthesises T4 (thyroxine) and T3 (triiodothyronine) which stimulates metabolic rate

Synthesis of T4 and T3 requires iodine

Lack of iodine leads to an enlarged thyroid gland termed goitre

Gland expands to absorb maximum concentration of iodine

21
Q

Normal thyroid gland

A

Weight = 35-45g

2 lobes and isthmus

Thyroid tissue is composed of follicles with variable sized lumina

Follicles contain colloid with eosinophilic or pink appearance

22
Q

Features of the thyroid gland

A

Very vascular

Endothelial cells lining the capillaries are fenestrated

Fenestration allows passage of hormones into the circulation

Para- follicular cells or clear (C) cells are found between the follicles

C cells secrete calcitonin which promotes reduction of calcium concentration in the blood

23
Q

Pathology of the thyroid gland

A

Goitre- euthyroid

Grave’s disease- hyperthyroid

Hashimoto’s disease- hypothyroid

Adenoma- euthyroid

Cancer- euthyroid

24
Q

Multi-nodular goitre

A

Lack of iodine leads to an enlarged thyroid gland

Due to hyperplasia and hypertrophy of thyroid cells

Gland enlarges to maximise amount of iodine absorbed

The increase in size overcomes the hormone deficiency and the patients are euthyroid

25
Q

Grave’s disease

A

Auto-antibodies stimulate TSH receptors

Diffuse enlargement of the thyroid due to hyperplasia of thyroid cells

Infiltrative opthalmopathy

Infiltrative dermopathy

26
Q

Infiltrative opthalmopathy

A

Accumulation of soft tissue and inflammatory cells behind the eye leading to proptosis

27
Q

Infiltrative dermopathy

A

Thickening and induration of the skin on the anterior shin

Pre-tibial myxoedema

28
Q

Hashimoto’s thyroiditis

A

Most common cause of hypothyroidism in areas where iodine is readily available

An auto-immune disease- immune system destroys its own thyroid tissue

Progressive depletion of thyroid cells by inflammation and replaced by fibrosis

  • decreased T3 and T4
  • increased TSH
29
Q

Thyroid tumours

A

Follicular adenoma- benign tumour of the thyroid follicular cells

Four main types of carcinoma

  • pappilary (75-85%): increased risk of lymph node metastasis
  • follicular (10-20%): increased mets to bone, lung and liver
  • medullary (5%): arise from C cells
  • anaplastic (<5%): older patients, poor prognosis
30
Q

Para-follicular cells

A

C cells secrete calcitonin which promotes reduction of calcium concentration in the blood

Para- follicular cells (C cells) are found between the follicles

C cells are the origin of medullary carcinoma of the thyroid

31
Q

Parathyroid glands

A

Secrete parathyroid hormone

Controls the levels of calcium in the blood

Decrease in blood calcium stimulates PTH secretion

Chief cells with no lumen

32
Q

Pathology of parathyroid glands

A

Adenoma- involves one gland

Hyperplasia- involves all four glands

Both cause hypercalcaemia

33
Q

Adrenal glands

A

Paired glands

Upper poles of the kidneys

Consist of adrenal cortex and adrenal medulla which are embryologically, morphologically and functionally distinct

34
Q

Adrenal cortex derived from

A

The mesoderm

35
Q

Adrenal medulla derived from

A

The neural crest

36
Q

Normal adrenal gland

A

Characteristically orange/ yellow in colour because cells are rich in lipids

37
Q

Adrenal cortex

A

Divided into three distinct zones

  • zona glomerulose
  • zona fasciculata
  • zona reticularis

Cells appear pale on histology becuase the lipids are cleared by chemicals during processing

38
Q

Functional zonation of the adrenal cortex (salt, sugar, sex)

A

Zona glomerulosa

  • minerlocorticoid
  • aldosterone
  • for absorption of sodium

Zona fasciculata

  • glucocorticoids
  • cortisol and corticosterone
  • sex hormones

Zona reticularis

  • 17 ketosteroids
  • sex hormones
39
Q

Pathology of the adrenal glands

A

Adrenocortical hyperactivity

Adrenocortical insufficiency

40
Q

Adrenocortical hyperactivity

A

Due to hyperplasia, adenoma or cancer

Cushing’s syndrome (excess cortisol)

Conn’s syndrome (excess aldosterone)

Adrenogenital syndrome (excess androgens)

41
Q

Adrenocortical insufficiency

A

Addision’s disease

42
Q

Adrenal cortex adenoma

A

Non-functional cortical adenoma

Incidental finding on abdominal imaging

Functional adenomas can cause Cushing’s or Conn’s syndrome

43
Q

Adrenal medulla

A

Compact cells which secrete adrenaline and noradrenaline

Fight or flight hormones

Secretion results in vasoconstriction, increased heart rate, increased blood sugar levels

44
Q

Adrenal medulla cells

A

Neuroendocrine

Darker staining than the adrenal cortex cells

45
Q

Phaechromocytoma

A

Tumour of the adrenal medulla

0.1-0.3% cause of treatable hypertension

10% tumour

  • familial as part of MEN2
  • extra adrenal
  • bilateral
  • malignant
  • arise in childhood
46
Q

Cause of phaechromocytoma

A

Due to high levels of catecholamines

47
Q

Phaechromocytoma leads to

A

Precipitois increase BP and tachycardia

Palpitations

Headache

Sweating

Tremor

Sense of apprehension

203: Theme 1: The Endocrine System (22 decks)

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