Thyroid Physiology Flashcards
What hormone are secreted by the thyroid gland
thyroxine (T4)
tri-iodothyronine (T3)
calcitonin
What hormones are secreted by the parathyroid gland
parathyroid hormone
What are colloids
tyrosine containing thyroglobulin filled spheres enclosed by follicular cells
What secretes calcitonin
parafollicular C cells
Where is T3 and T4 stored until required
in colloid thyroglobulin
What drugs inhibit the attachment of iodine onto tyrosine residues
carbimazole
propylthiuracil
How are T3 and T4 transported in the blood?
bound to plasma proteins because they are hydrophobic
Name the plasma proteins which bind T3 and T4
thyroxine binding globulin (70%)
thyroxine binding prealbumin
albumin
What effect does an increase or decrease of TBG have on the free T4
no effect- only effects the total T4
How do thyroid hormones increase basal metabolic rat
increased number and size of mitochondria
increase oxygen use and rates of ATP hydrolysis
Increased synthesis of respiratory chain enzymes
What are the effects of thyroid hormones
Increased metabolic rate- increased carb, lipid and protein metabolism Increased thermogenesis growth faetal and neonatal brain development normal CNS activity
What stimulates thyroid releasing hormone
Thyrotropin releasing hormone
What gland released TRH
the hypothalamus
What gland releases TSH
the anterior pituitary
What is the major stimulant for release of thyroid hormones
TSH
