Pathology of the Endocrine System 1&2 Flashcards
What are the seven components which make up the classic endocrine system?
Pineal Gland Hypothalamus Pituitary Gland Thyroid Gland Adrenal Glands Parathyroid Glands Pancreas
What is hyperplasia of endocrine organs?
Increased number and change in activity of the secretory activity of cells
What is atrophy in endocrine organs?
Diminution of cells due to a lack of stimulation
What are the two types of tumour which may cause neoplasia in endocrine organs?
Adenoma
Carcinoma
Which hormones is the thyroid gland responsible for?
Thyroxine T4
Triiodothyronine T3
- both responsible for regulating basal metabolic rate
Calcitonin - regulates calcium homeostasis
Does T3 or T4 have a longer half life?
T4 by far and there is much more of it in the tissues
Which of T3 and T4 is more potent?
T3 - but there is less of it
What are found within thyroid follicular cells?
Colloid
What is the function of thyroid C-cells?
Secrete calcitonin
What two things are required to allow the epithelial cells of the thyroid to synthesise thyroglobulin?
Iodine and tyrosine
What type of epithelial cells are found surrounding the follicular cells of the thyroid?
Cuboidal epithelial cells
What external factors stimulate TRH release from the hypothalamus?
Cold and stress
What may cause thyroid enlargement excluding hyper and hypothyroidism?
Goitre
Isolated nodule/mass
Are the vast majority of thyroid diseases primary or secondary?
Primary
What is the main cause of hyperthyroidism?
Grave’s disease
Is TSH elevated in primary hyperthyroidism?
No
Which gender is more susceptible to Grave’s disease?
Females
What is the autoimmune pathology of Grave’s disease?
Production of anti-TSH receptor antibodies - they stimulate activity, growth and inhibit TSH from binding
Is there a visible increase or decrease in cell number and activity on histological visualisation of thyroid tissue in hyperthyroidism?
A visible increase in both
What is the main cause of hypothyroidism?
Hashimoto’s disease
What are some other causes of hypothyroidism?
Iatrogenic - surgery/drugs
Iodine deficiency
Congenital hypothyroidism
Which gender is more commonly affected by Hashimoto’s thyroiditis? Is this a hyper or hyposecreting condition?
Females -(genetic, predisposition) hyposecreting
What is the autoimmmune pathology of Hashimoto’s thyroiditis?
Autoimmune destruction of thyroid epithelial cells - cytotoxic T cells, cytosine and antibody mediated
There is a loss of tolerance and and malfunction of regulatory T cells due t o exposure to hidden antigens - cytotoxic T cells, T cell mediated cytokines and antibodies
What is the change that affects thyroid cells in hypothyroidism called?
Hurthle cell change
What is the most common cause of multi nodular goitre?
Iodine deficiency - most commonly affects the elderly
What is the physiological pathway of multi nodular goitre caused by iodine deficiency?
Iodine deficiency to Impaired synthesis of T3 and T4 to Increased TSH synthesis to Hypertrophy and hyperplasia of the epithelium
What is the dominant nodule in a multinodular goitre known as?
The thyroid nodule
What may be causing the thyroid nodule?
Multinodular goitre
Cyst
Follicular adenoma
Carcinoma - most commonly differentiated thyroid carcinoma
Are the majority of thyroid follicular adenomas functioning?
No, the majority are non-functioning
What is relevant about the borders of a follicular adenoma in the thyroid?
It is encapsulated, often by a thick margin which can prevent the cells leaking out and causing local spread, however this may eventually happen and cause local invasion and possible metastasis, commonly to the blood and bone
What are the two gene abnormalities linked with papillary carcinoma?
BRAF mutation
RET/PTC rearrangement
What is the general prognosis of papillary carcinoma?
Very good prognosis, 99% 1 yr survival
What cells are affected in thyroid medullary carcinoma?
C-cells of the thyroid
Are thyroid medullary carcinomas secretory? If so what do they secrete?
Yes, calcitonin
What hormone is produced by parathyroid glands?
Parathyroid hormone (PTH)
What is the action of PTH?
Regulating plasme Ca2+
Which hormone opposes the action of PTH?
Calcitonin from the thyroid
What is the main cause of hypoparathyroidism?
Secondary to thyroid surgery
What is the most common cause for primary hyperthyroidism?
Adenoma (85-95%)
What are some other causes of hyperparathyroidism?
Hyperplasia
Carcinoma
An increase in what is commonly seen in patients with hyperparathyroidism?
Calcium - hypercalcaemia
And subsequent loss of phosphorus
What is another name for the anterior pituitary?
Adenohypophysis
What hormones are secreted by the anterior pituitary?
ACTH TSH GH Prolactin FSH/LH
What is another name for th posterior pituitary?
Neurohypophysis
What hormones are secreted by the posterior pituitary?
Vasopressin/ADH
Oxytocin
What are the three main cell types of the posterior pituitary?
Adicophils
Basophils
Chromophobes
Which hormones are secreted by the acidophils of the anterior pituitary?
GH
Prolactin
Which hormones are secreted by the basophils of the anterior pituitary?
ACTH
TSH
FSH
LH
What is the most common cause of primary hyperfunciton of the pituitary? (hyperpituitarism)
Pituitary adenoma
What is unusual about the histology of pituitary adenomas?
They have the same appearance as the normal gland
What is a prolactinoma?
A prolactin secreting pituitary adenoma
What hormones may a pituitary adenoma secrete?
Prolactin - prolactinoma
GH
ACTH = cushing’s disease
What is the mass pressure effect associate with some pituitary adenomas?
If the adenoma is large enough, regardless of whether it is secreting or not, may have mass effects on the surrounding structures, and may cause visual field defects - often bitermporal hemianopia and caused raised ICP and common cranial symptoms such as headaches, nausea, vomiting
What effect may a large pituitary adenoma exerting mass effect have on the pituitary gland?
It may cause compression damage which results in hypopituitarism
What percentage of the pituitary glands mass must be lost for there to be pituitary hypofunciton?
75%
What are the most common causes of pituitary hypofunction?
Compression damage from tumours
Trauma
Infection (rare)
Which hormones are produced by the adrenal cortex?
Mineralocorticoids
Glucocorticoids
Sex steroids
What part of the adrenal gland secretes mineralocorticoids? Which is the most significant of these hormones?
The bona glomerulosa of the adrenal cortex
Aldosterone
What is the function of aldosterone?
To maintain plasma volume via secretion at the kidney tubules
Which part of the adrenal gland produces glucocorticoids? Which of these hormones is the most significant?
The zona fasiculata of the adrenal cortex
Cortisol
What is the function of cortisol?
Increasing blood glucose levels by increasing gluconeogenesis, supressing the immune system, aiding in the metabolism of fat, protein and lipolysis, as well as decreasing bone formation
What is produced by the zona reticularis?
Sex steroids - oestrogen, androgens
What is produced by the adrenal medulla?
Adrenaline/noradrenaline in response to stress
What is the main cause of adrenal cortical hyperfunction? What specifically does this cause in terms of hormones?
Cushing’s syndrome
Hypercortisolism
What is the main cause of hyperaldosteronsim?
Conn’s syndrome
