Flashcards · Biology · The Endocrine System
Hormones and the Endocrine System
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What is a hormone?
A chemical messenger carried in the blood.
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What is an endocrine gland?
A gland that releases hormones into the blood.
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How are hormones carried around the body?
In the blood.
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What is a target organ?
An organ that has receptors for a particular hormone.
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Which gland is the master gland?
The pituitary gland.
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Which gland releases thyroxine?
The thyroid gland.
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Which gland releases insulin and glucagon?
The pancreas.
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Which glands release adrenaline?
The adrenal glands.
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Which hormones do the ovaries release?
Oestrogen and progesterone.
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Which hormone do the testes release?
Testosterone.
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Is hormonal control faster or slower than nervous control?
Slower.
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Do hormones last for a longer or a shorter time than nerve impulses?
Longer.
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What does thyroxine control? (Higher tier)
The basal metabolic rate.
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What is negative feedback? (Higher tier)
A change causes a response that reverses the change.
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What does adrenaline do? (Higher tier)
Prepares the body for fight or flight: faster heart rate, more glucose and blood to the muscles.
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Name the gland marked X and the hormone it releases. The thyroid gland. It releases thyroxine, which controls the metabolic rate.
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Name the endocrine glands. 
Pituitary gland, thyroid gland, pancreas, adrenal glands, ovaries (female) and testes (male).
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Describe how thyroxine is controlled. 
The pituitary tells the thyroid to release thyroxine. A high level of thyroxine stops the pituitary, so the level falls. This is negative feedback (Higher tier).