Thyroid Flashcards
What does the Thyroid Gland produce?
Thyroid hormones T3 and T4, also Calcitonin
Describe the structure of the thyroid gland.
- dense connective tissue capsule - follicules surrounded by single layer of secretory follicular cells on basement membrane - cell free follicle that store thyroid hormone - parafollicular cells that store calcitonin
What does Calcitonin do?
Acts on bone by increasing osteoblast activity; increases Calcium storage but decreases Calcium serum levels.
Who produces Calcitonin?
parafollicular cells / “C” cells
Identify A and B
A = Thyroid glandB = Parathyroid gland
A = calcitonin
Thyroid
What do Follicular cells produce?
Thyroglobulin, it is iodinated and stored within the follicles.
In response to TSH, the thyroglobulin is endocytosed, processed into T3 and T4 and secreted into the blood. T3 and T4 are important regulators of metabolic activity.
What do parafollicular cells do?
Make calcitonin (thyrocalcitonin), a peptide hormone that inhibits bone resorption by osteoclasts, thereby lowering calcium concentrations in blood.
identify
How is Thyroid hormone produced?
- Iodine pump transports and concentrates iodide into colloid
- & 3. Epithelial cells secrete thyroglobulin and thyroid peroxidase into colloid
- Thyroglobulin becomes iodinated after thyroid peroxidase converts iodide to iodine
- Proteolysis of iodothyroglobulin after uptake of colloid droplets and fusion with lysosomes
- Release of thyroid hormones triiodotyrosine (T3) and thyroxine (T4) into the circulation
Identify the structure
Describe the function of thyronines
- increase the basal metabolic rate
- affect protein synthesis
- help regulate long bone growth
- neuronal maturation
- increase the body’s sensitivity to catecholamines.
- essential for proper development and differentiation of all cells of the human body.
- Thyroid hormone stimulates heat generation.
What are the thyroid hormones?
The thyroid hormones (thyronines) are:
- thyroxine (T4)
- triiodothyronine (T3)
What is needed to produce the thyroid hormones?
They are produced using iodine
What is thyroid hormone T4 converted to?
T4 is converted to T3 by deiodinases and further processed by decarboxylation and deionidation to produce T1a (iodothyronamine) and thyronamine (T0a).
Describe the function of calcitonin
Parafollicular (C) cells secrete calcitonin which binds to receptors on osteoclast and inhibits bone resorption.
What are Hyperthyroidism symptoms?
Symptoms:
- nervousness
- irritability
- increased perspiration
- heart racing
- hand tremors
- anxiety
- difficulty sleeping
- muscular weakness (main-upper arms)
Why does Hyperthyroidism occur?
Excess thyroid hormones overstimulate metabolism and enhance the effect of the sympathetic nervous system, causing “speeding up” of various body systems and symptoms resembling an overdose of epinephrine (adrenaline).
What is Graves Disease?
- It’s the most common form of hyperthyroidism.
What is this disease?
Graves Disease
What is Hypothyroidism?
- is a Iodine deficiency
- In the US the most common cause is Hashimoto’s thyroiditis.
- B cells produce autoantibodies against thyroid antigens
What is this disease?
Hashimoto’s Thyroiditis
