Endocrinology- Thyroid hormone
Terms in this set (34)
What is colloid?
A protein rich viscous fluid
Where is Thyroglobuline stored?
In colloid of thyroid gland follicles
What are the two thyroid hormones?
What is the difference between T3 and T4?
T3 has 3 iodines
T4 has 4 iodines
What is the sole source of iodine?
How is iodide transported into a follicular cells?
Sodium Iodide co-transport
Where is Iodine added to thyrogobuline?
In the colloid
Where in the thyroid gland are T3 and T4 separated from thyroglobulin?
Inside the follicular cell but and intracellular enzyme.
What proportion of hormones produced from the thyroid gland is T3?
What proportion of hormones produced from the thyroid gland is T4?
Which hormone (T3 or T4) has the greatest receptor affinity?
T3 (5 times more)
Do thyroid hormones circulate freely or bound to a protein?
Which hormone (T3 or T4) is bound tightest to its carrier protein?
What is the half life of T3?
What is the half life of T4?
Which hormone stimulates thyroid release?
Thyroid stimulating hormones
Where is thyroid stimulating hormone released?
Anterior pituitary gland
What happens to 40% of T4?
It is converted to T3
Which cells in the anterior pituitary gland produce thyroid stimulating hormone?
What is release by the hypothalamus which causes thyroid release indirectly?
Thyrotropin releasing hormone
What can increase the release of thyrotropin releasing hormone from the hypothalamus?
What can decrease the release of thyrotropin releasing hormone from the hypothalamus?
Where does Thyroid releasing hormone bind?
To a receptor on the thyroid follicular cell
What does thyroid releasing hormone binding to the follicular cell caused?
Re-uptake of colloidal thyroglobulin
An increased size, number and secretory activity of thyroid cells
What shape are the epithelial cells of thyroid tissue which has been stimulated by thyroid stimulating hormone?
Why are the follicles depleted/ collapsed when TSH has stimulated the tissue?
Colloid had been taken up by follicular cells for T3 and T4 production.
Where do T3 and T4 have there negative feedback action?
On the hypthalamus and anterior pituitary
How does thyroid hormone impact the cardiovascular system?
Increases manufacture and incoporation of beta-1 adrenergic receptors (Increasing cardiac output)
How does thyroid hormone impact growth?
Essential for normal growth in childhood
Critical for CNS growth ( No. neurons and myelination)
How does thyroid hormone affect basal metabolic rate?
Increased basal metabolic rate (increased oxidative metabolism)
Stimulates catabolic and anabolic reactionsin pathways affecting fats, cards and proteins.
Stimulates synthesis of enzymes and structural proteins
More glucose made available
Increased lipid metabolism
How is T4 converted to T3?
It is deiodinated by 3'/5' monodeiodinase
How does T3 act on target cells?
It enters them and their nuclei and binds to thyroid hormone receptor, which can bind to dna leading to transcription.
What is grave's disease?
Thyroid gland enlargement caused by continual thyroid hormone production due to an autoimmune disease which produces and antibody which binds to the TSH receptor on follicular cells.
What is hypothyroidism often caused by?