T1 L5: Pathology of the endocrine system Flashcards
Is the pancreas an endocrine or exocrine gland?
Both
It releases insulin straight into the blood and proteases through a duct into the intestines
What is the meaning of endocrine?
Action of a hormone on a target organ away from a secreting cell
What us the meaning of autocrine?
Action of the hormone on the secreting cell
What is the meaning of paracrine?
Action of the hormone on the adjacent cell
What is the meaning of neuroendocrine?
Neural stimulation of endocrine cells to secrete hormones
What type of cell is the functional unit of endocrine cells consist of?
cuboidal secretory cells with a lumen in the centre
What is the function of myoepithelial cells in endocrine glands?
They contract to facilitate secretion
Which endocrine glands don’t have a functional unit with a lumen?
The pituitary and parathyroid gland
What is the adenohypophysis?
The anterior pituitary gland lobe
What is the neurohypophysis?
The posterior pituitary gland lobe
What do acidophils?
They take up acidic dyes
What are Basophils?
They take up basic dyes
What are Chromophobes?
They have no specific staining features
What hormone do Somatotrophs secrete and what is the target organ?
They secrete growth hormone and target bones
What hormone do lactotrophs secrete and what is the target organ?
They secrete Prolactin and target breasts
What hormone so Corticotrophes secrete and what is the target organ?
They secrete Adrenocorticotropic hormone (ACTH) and target the adrenal glands
What hormone do Gonadotrophs secrete and what is their target organ?
They secrete Follicle stimulating hormone (FSH) and Luteinising hormone (LH) which target the ovaries and testes
What hormone do Thyrotrophs secrete and what is the target organ?
They secrete thyroid stimulating hormone (TSH) which targets the thyroid gland
What are the 2 hormones secreted by the posterior pituitary gland?
ADH and Oxytocin
What are pituitary adenomas?
Benign tumours that arise from the anterior lobe
What are some clinical presentations of pituitary adenomas and why?
Headaches, vomiting, diplopia, impaired vision
Because the adenoma occupies space and puts pressure on the optic chiasm and surrounding structures
What is diplopia?
Double vision
Which element is needed to produce the thyroid hormones T3 and T4?
Iodine
Why does the thyroid gland enlarge during an iodine deficiency?
So it can absorb as much iodine as possible
How much does the thyroid gland weigh?
35-45g
Describe the structure of the thyroid gland?
2 lobes linked together by the isthmus
What type of capillaries line the thyroid gland?
Fenestrated capillaries
This allows easy movement of hormones between the layers
What is meant by Euthyroid?
Normal function of the thyroid even if pathology is present
What is a Goitre?
An enlarged thyroid gland
What is Graves disease?
When auto-antibodies stimulate TSH receptors and cause hyperplasia of thyroid cells.
It can cause Infiltrative ophthalmopathy and infiltrative dermopathy
What is Hashimoto’s disease?
An Autoimmune condition of the thyroid the system to destroy it’s own thyroid tissue leading to a progressive depletion of thyroid cells by inflammation and replaced by fibrosis
What is the pathophysiology behind a multi-nodular goitre?
Lack of iodine leads to an enlarges thyroid gland due to hyperplasia and hypertrophy of the thyroid cells. The increase in size overcomes the hormone deficiency and the patients are therefore euthyroid
What is Hyperplasia?
Enlargement
What is Hypertrophy?
Increase in growth
Why may a multi-lobar goitre need to be removed?
It will be compressing the surrounding structures Eg. Trachea
What is tracheomalacia?
When the cartilage of the trachea is soft, weak and floppy
What is infiltrative ophthalmopathy?
Accumulation of soft tissue and inflammatory cells behind the eye leading to proptosis
What is infiltrative dermopathy?
Thickening and induration of skin on the anterior caused by a deposition of hyaluronic acid
What is proptosis?
Protruding of the eyes
Why do thyroid colloids have a soap-like appearance with Grave’s disease?
Due to the hyperactivity
What is the most common type of hypothyroidism where iodine is widley available?
Hashimoto’s disease
How does Hashimoto’s thyroiditis appear histologically?
The gland is irregular and there will be prominent lymphocytic infiltrate
What is Follicular adenoma?
A benign tumour of the thyroid follicular cells
What is a papillary thyroid tumour?
The most common type of thyroid carcinoma. It appears as an irregular solid or cystic mass or nodule in a normal thyroid parenchyma
Where does a papillary thyroid tumour metastisise?
Into the lymph nodes
What is a follicular thyroid tumour?
2nd most common type of thyroid cancer.
Tumours consist of a microfollicular architecture with follicles lined by cuboidal epithelial cells
Where do Follicular thyroid tumours most commonly metastasise?
To bones, lung, and liver
What is a medullary thyroid tumour?
A tumour that arises from C cells and is associated with MEN 2 syndrome
What is an Anaplastic thyroid tumour?
An aggressive form of thyroid cancer characterized by uncontrolled growth of cells in the thyroid gland. Most common in older patients and has a poor prognosis
What are C cells for?
They secrete Calcitonin and are found between follicles in the thyroid
What do Parathyroid glands do?
They secrete Parathyroid hormone (PTH)
What is the function of parathyroid hormone?
It controls the levels of calcium in the blood
How is the release of parathyroid hormone stimulated?
A decrease in blood calcium
How many glands does an adenoma of the parathyroid gland affect?
1
How many glands does hyperplasia of the parathyroid gland affect?
All 4
Which embryological layer is the adrenal cortex derived from?
The mesoderm
Which embryological layer is the adrenal medulla derived from?
The neural crest
What colour is a normal adrenal gland?
Characteristically orange/yellow in colour because the cells are rich in lipids
Which 3 layers is the adrenal cortex divided into?
Zona Glomerulosa
Zona Fasciculata
Zona Reticularis
What is the zona Glomerulosa for?
It secretes mineralocorticoids and aldosterone for the absorption of sodium (Salts)
What is the zona Fasciculata for?
For Glucocorticoids, cortisol, corticosterone, and sex hormones (Sugars)
What is the zone Reticularis for?
17 Ketosteroids and sex hormones (Sex)
What is Cushings syndrome?
Excess cortisol
What is adrenogenital syndrome?
Excess androgens
What is Addison’s disease?
Adrenocortical insufficiency
Which diseases can functional adrenal cortex adenomas cause?
Cushing’s syndrome or Conn’s syndrome
Which cells comprise the adrenal medulla?
Compact cells that secrete adrenaline and noradrenaline in response to intense reactions which results in vasoconstriction, increased heart rate, and increased blood sugar levels
What is a 10% tumour?
A phaeochromocytoma because:
10% are familial as part of MEN2 syndrome 10% are extra-adrenal 10% bilateral 10% malignant 10% arise at childhood