BIOL124 - Lecture 5 - Mammalian Endocrien System II

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  • Created by: Katherine
  • Created on: 11-03-16 11:16
Name the human endocrine glands:
Hypthalamus, pineal gland, pituitary gland, thyroid gland, parathyroid gland, thymus, adrenal glands, pancreas, ovary, testis
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What are the hormones secreted by the thyroid?
T4 (Thyroxine) and T3 (Triiodothyronine)
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What is included in the fine structure of the thyroid?
Thyroid follicle, composed of follicle cavities and follicle cells. There are C cells, capillaries and capsules.
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What is within the follicle cavities?
The colloid - this contains thyroglobulin
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How does synthesis of thyroid hormone occur?
There is gradual release and diffusion into peripheral tissues throughout the body of iodine. The iodine
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What is the first step of synthesis of thyroid hormones?
Iodide ions are pumped through a TSH sensitive pump into the follicle cell.
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What is the second step of synthesis of thyroid hormones?
The iodide ions diffuse across the follicle cell.
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What is the third step of synthesis of thyroid hormones?
The iodide ions attach to thyroid peroxidase and package thyrogloblin containing T3 and T4. It goes into the follicle cavity.
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What is the fourth step of synthesis of thyroid hormones?
Endocytosis is the thyroglobulin back into the follicle cell.
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What is the fifth step of synthesis of thyroid hormones?
Lysosomal digestion
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What is the sixth step of synthesis of thyroid hormones?
Diffusion of the T3 and T4 into the capillary.
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What controls thyroid hormone production?
Low levels of T3/T4 stimulates release of TRH. TRH, carried by hypophseal portal veins to anterior pituitary, stimulates release of TSH by thyrotrophs. TSH in blood stimulates thyroid follicular cells. T3/T4 released into blood. High T3 inhibits TRH
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What are the functions of thyroid hormones in development?
Metamorphosis in frogs, bone formation, brain.
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Which is more active, T3 or T4?
T3
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What are the functions of thyroid hormones in metabolism?
To increase metabolic rate, to increase ATP production, to timulate glycolysis, to increase heart rate and blood pressure
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What is it called when you have a thyroid deficiency?
Cretinism
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What are the symptoms of cretinism?
Poor skeletal and nervous system development, low metabolic rate - it affects around 1 in 500 births.
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What is hypothyroidism?
f
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What are the symptoms of hypothyroidism?
Lethargy, low body temperature, muscle weakness, subcaneous swellings, dry skin, hair loss, enlarged thyroid.
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What is hyperthyroidism?
f
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What are the symptoms of hyperthyroidism?
High metabolic rate, high body temperature, sweating, high heart rate and high blood pressure, central nervous system effects (excitability, restlessness, mood swings)>
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What is the purpose of the thyroid c cells?
To release Calcitonin - it is a hormone that regulates the level of calcium and phosphate in the blood.
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What happens when there is a falling blood Ca2+ level?
The parathyroid releases PTH which stimulates Ca2+ uptake in kidneys and increases Ca2+ uptake in intestines. PTH stimulates Ca2+ release from bones. Ca2+ in blood rises.
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Where is the parathyroid found?
Behind the thyroid gland.
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What kinds of epithelial cell are found in the parathyroid gland?
Principal (chief) cells which produce PTH. And Oxyphil cells which have unknown function.
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What is secreted by the medulla?
Adrenaline and noradrenaline
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What is secreted by the cortex?
Corticosteroids
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The adrenal cortex contains...
Androgens, glucocorticoids and mineralocorticoids.
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Give an example of androgens:
Testosterone
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Give an example of glucocorticoids:
Cortisol
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Give an example of mineralocorticoids:
Aldosterone
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What does aldosterone do?
It increases Na+ and H2O reaborption in distal tubules.
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What do glucocotricoids do?
Stimulate glucose and glycogen synthesis. Stimulate release of fatty acids. Cause tissues to break down fatty acids and proteins. Immunosuppressive. Anti-inflammatory.
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What do the hormones secreted by the adrenal medulla do?
They increase heart and respiratory rate. They increase energy use by all cells.
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What is the effect of stress on the adrenal gland?
Stress activates the hypothalamus which activates the adrenal medulla via nerve impulses. This secretes epinephrine and norepinephrine (short term). The arenal cortex secretes mineralcorticoids and glucocorticoids (long term).
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Card 2

Front

What are the hormones secreted by the thyroid?

Back

T4 (Thyroxine) and T3 (Triiodothyronine)

Card 3

Front

What is included in the fine structure of the thyroid?

Back

Preview of the front of card 3

Card 4

Front

What is within the follicle cavities?

Back

Preview of the front of card 4

Card 5

Front

How does synthesis of thyroid hormone occur?

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