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ENDOCRINE SYSTEM - Coggle Diagram
ENDOCRINE SYSTEM
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Neuro-Endocrine Control
Actions of hypothalamic peptides include:
- binding to plasma membrane receptors.
- release of stored target hormones (in pituitary) via exocytosis.
- increase of transcription of target hormones.
- modulation of their receptor activity (up regulation; down regulation).
Hypothalamic hormones are:
- peptides called releasing factors.
- secreted in an episodic and pulsatile manner.
- present at high concentrations at target cell.
- present at very low concentration in systemic blood.
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Pathology
Hyper-secretion. Excess secretion of GH results in acromegaly. Acromegaly before puberty results in a giant. After puberty, acromegaly results in a thickening of the hands and feet and coarsening of facial features.
Hypo-secretion. Insufficiency of IGF-1 alone results in pygmies (found in Africa and Australia). Receptor resistance for GH results in Laron Dwarfism.
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Synthesis, Secretion and Storage of Thyroid Hormone
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In the absence of iodide, thyroid hormones are not made.
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Pathophysiology
Hypothyroidism leads to weight gain due to decreased metabolism, hair loss, mental
sluggishness, and decreased tolerance to cold.
Hyperthyroidism leads to muscle wasting, nervousness, weight loss due to increased metabolism and decreased tolerance for heat. A common sign of hyperthyroidism is a rapid heart rate.
Iodine deficiency can lead to an enlarged gland called a goiter. Frank iodine deficiency has been virtually eliminated by iodine supplementation of salt.
Grave’s disease is an autoimmune disease in which circulating antibodies (IgG) bind to and activate the TSH receptor on the thyroid gland follicular cells. This leads to increased secretion of T3 and T4.