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Equine Endocrine System - Horse Anatomy (view source)
Revision as of 13:54, 19 November 2012
, 13:54, 19 November 2012→Thyroid Gland
==Thyroid Gland==
==Thyroid Gland==
The thyroid gland lies in the neck, on either side of and ventral to the trachea. Two types of hormones are produced, which are the iodine containing hormones; '''tri-iodothyronine'''(T3) and '''thyroxine''' (T4). Thyroid hormones regulate the basal metabolic rate and are important in the regulation of growth of tissues, particularly nervous tissue. Release is stimulated by thyroid stimulating hormone (TSH) from the pituitary. The second type of hormone produced from the thyroid gland is '''[[calcitonin]]''', which regulates blood calcium levels along with parathyroid hormone and acts to reduce blood calcium by inhibiting its removal from bone.
The thyroid gland lies in the neck, on either side of the second and third tracheal rings on their ventral aspect. It consists of left and right lobes, which are connected at their caudal aspect by a strand of connective tissue known as the '''isthmus'''. In the horse, the two lobes of the thyroid are oval in shape and roughly the size of a plumb.
Two types of hormones are produced by the thyroid gland. This first type is the iodine containing hormones; '''tri-iodothyronine'''(T3) and '''thyroxine''' (T4), which are produced by '''follicular cells'''. These thyroid hormones regulate the basal metabolic rate and are important in growth, regulation of body temperature and carbohydrate metabolism. Their release is stimulated by thyroid stimulating hormone (TSH) from the pituitary. The second type of hormone produced from '''parafollicular (C-cells)''' of the thyroid gland is '''[[calcitonin]]''', which regulates blood calcium levels along with parathyroid hormone and acts to reduce blood calcium by inhibiting its removal from bone.
===Vasculature===
The main blood supply is via the '''cranial thyroid artery''', which is a branch of the '''common carotid artery'''. There is a minor contribution from the '''caudal thyroid artery'''. Venous drainage is via the '''cranial and middle thyroid veins''', which drain into the '''external jugular vein'''.
===Lymphatics===
The thyroid drains to the '''deep cervical thoracic lymph node''' or the '''tracheal trunk'''.
===Innervation===
*Sympathetic: Supply from the cranial cervical ganglion.
*Parasympathetic: Supply from branches of cranial and caudal laryngeal nerves, which themselves branch from the vagus nerve.
==Parathyroid Glands==
==Parathyroid Glands==
==Adrenal Glands==
==Adrenal Glands==
==Pineal Glands==
==Pineal Glands==