Pathology of Endocrine System 1 Flashcards
What is the endocrine system?
Integrated network of glands that secrete chemical messengers (hormones) into the bloodstream
What do hormones act on?
Target cells distant to site of synthesis, binding to receptors and changing their activity
What are some examples of effects that hormones may have?
Regulation of metabolism, growth and development, tissue function
Maintain functional balance (homeostasis)
Where are hormones synthesised and stored?
In glands, which are packets of cells with secretory granules that are vascular and ductless
How are levels of hormones maintained?
Negative feedback
What are examples of organs in the endocrine system?
- 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
Endocrine organs are linked by feedback axis, what are some major systems?
- TRH -> TSH -> T3/4
- GnRH -> LH/FSH -> sex hormones
- CRH -> ACTH -> cortisol
- Renin -> angiotensin -> aldosterone
What are examples of classificaitons of endocrine disease?
- 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
What is hyperplasia in terms of the endocrine system?
Increased number and secretory activity of cells
What is atrophy?
Diminution of cells due to lack of stimulation
What are examples of causes of tissue damage?
Inflammation
Autoimmune disease
Compression
Trauma
Infarction
How can diseases on one endocrine gland have multiorgan clinical effects?
Due to hormones acting on several tissues
What is the thyroid responsible for the release of?
Thyroxine (T3) and triiodothyronine (T3)
Calcitonin
What is the function of T4 and T3?
Regulates basal metabolic rate
What is the function of calcitonin?
Regulates calcium homeostasis
What is T3 also known as?
Triiodothyronine
What is T4 also known as?
Thyroxine
What can be seen in the histology of the thyroid gland?
What are the epithelial cells of the thyroid gland resonsible for?
TG synthesis
Iodination
Resorption and release of T3 and T4
What cells in the thyroid gland secrete calcitonin?
C-cells
How are epithelial cell of the thyroid gland arranged?
Follicles filled with colloid (contains thyroglobulin)
What is contained in the colloid of the thyroid gland?
Thyroglobulin
Explain the process of the hypothalamus-pituitary-thyroid axis?
- 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
What is TRH from hypothalamus stimulated by?
Cold
Stress
How does TSH lead to stimulation of thyroid to produce T3 and T4?
Increases the number, size and activity of thyroid follicular cells
What supplies the feedback of TSH/TRH?
T3 and T4
What are some manifestations of thyroid disease?
- Hyperthyroidism
- Thyrotoxicosis
- Hypothyroidism
- Myxoedema, cretinism, subclinical
- Thyroid enlargement
- Goitre, isolated nodule/mass
- Thyroiditis
- Autoimmune
- Gland destruction
- Multinodular goitre
- Tumours
- Benign, malignant
What does hyperthyroidism lead to?
Thyrotoxicosis (excess thyroid hormone in the body)
What does hypothyroidism lead to?
Myxoedema
Cretinism
Subclinical hypothyroidism
What is myxoedema?
Severely advanced hypothyroidism