Endocrine disorders Flashcards
How can we measure hormone levels to see if they are appropriate?
- Compare with reference range
2. Always interpret with respect to controlling variable
What is the function of the thyroid gland
The thyroid gland makes thyroid hormone which consists of T3 and T4.
T3 is Triiodothyronine (more active form)
T4 is Thyroxine
Most of it is T4.
T4 is activated into T3 by deiodinase enzymes in peripheral tissue
What is the function of Thyroid hormone ?
- Normal growth and development
- Congenital hypothyroidism can lead to developmental problems
2.Upregulator of metabolism
Can increase metabolic rate , heat production, ATP production and is metabolically active and can lead to increased glucose release
What are the two main categories of thyroid disorders ?
Underproduction -Hypothyroidism
Overproduction-
Hyperthyroidism
What is the Hypothalamic-pituitary-thyroid control of the thyroid gland?
In the hypothalamus there are neurosecretory cells located in specific nuclei called parvocellular neuron in specific thalamic nuclei synthesise thyrotropin releasing hormone.
These neurons have short axons and terminate on the capillary bed at the base of the hypothalamus where they release TRH into local capillaries.
These collect in the pituitary portal vein carrying TRH to the anterior pituitary gland which activates TSH synthesising cells which binds to receptors on thyroid gland =T4 and T3 release
There is a negative feedback loop
What are the aspects which can result in thyroid disorders?
Problems with the actual thyroid gland making it produce too much /little hormones
(Primary problem)
If there is a problem in the pituitary this can also affect the thyroid gland.
(Secondary problem)
Disease involving hypothalamus
How can primary hypo/hyper thyroidism be diagnosed ?
Primary disorders are more common
-You can measure T4/T3
-Measure circulating TSH in blood (can rule out primary hypothyroidism).
In primary hypothyroidism there is high TSH levels due to lack of negative feedback.
In primary hyperthyroidism there is low TSH as there is too much negative feedback
In secondary hypothyroidism , the TSH levels will be low
In secondary hyperthyroidism , the TSH level will H.
Describe the structure of adrenal glands
The adrenal glands are found on top of the kidney
The adrenal gland consists of outer layer called cortex and inner called the medulla. The cortex is divided into thee zones :
Outer zone
-Zona glomerulosa - Mineralocorticoids
-Zona faciculants Glucocorticoids (cortisol)
-Zona reticulates
Adrenal androgens
There is also blood supply from the outer cortex to the inner medulla which affects the pattern of steroid synthesis. Its due to the carrying of the precursors
What are the two types of adrenocortical disorders ?
Adrenal hyperfunction :
Too much cortisol =excess
(Cushings syndrome )
Excess aldosterone (Conn's syndrome)
Adewnal insufficiency
Hypocorticolism
Lack of aldosterone and cortisol
(Addisons)
What is primary hyperadosteronism ?
This is when the adrenal gland is producing an excess of aldosterone.
(Conn’s syndrome
