Page 253 - Biology_F5

Biology for Advanced Level Secondary Schools

Table 4.2: Endocrine glands, hormones they produce and their functions
Endocrine gland Hormone(s) produced Functions
Regulate vital body functions. Stimulates
Thyroid Thyroxine, and maintains metabolism, growth and
Triiodothyronine
development
Calcitonin Reduction of blood Ca levels
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Parathyroid Hormone Controls calcium concentration or levels
Parathyroid
(PTH) within the blood
Increases blood Na levels; increase K
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Aldosterone secretion
Adrenal (Cortex)
Cortisol,
Corticosterone, Regulates blood pressure. Increases blood
glucose levels; anti-inflammatory effects
Cortisone
Stimulates fight-or-flight response, increases
Adrenal Epinephrine (Adrenaline) blood glucose levels and increase metabolic
(Medulla) Norepinephrine
activities
Insulin Reduces blood glucose levels
Pancreas
Glucagon Increases blood glucose levels
Regulates some biological rhythms and protect
Pineal gland Melatonin
CNS from free radicals
Regulates, promotes, increases or maintains
Testes Androgens sperm production and male secondary sexual
characteristics
Promotes uterine lining growth and female
Ovaries Oestrogen
secondary sexual characteristics
Properties of hormones
Hormones are produced by specific cells glucose. Another factor is the presence of
of endocrine system. They are transported another hormone in the blood. Majority
through the blood, and show their effect of the hormones released from the
to the site away from its source. Hormones anterior pituitary gland are stimulating
are specific for a particular target. They hormones, which direct other glands to
are soluble organic molecules and are secrete their hormones. For instance,
effective even at low concentration. thyroid stimulating hormone (TSH)
causes the release of the thyroxine
Feedback mechanisms for hormonal hormone. Stimulation by neurones from
coordination the autonomic nervous system can also
The release of hormones by glands is cause secretion of hormones. Under the
controlled by several factors, including condition of stress, fear or danger, the
the presence of specific metabolites in body secretes hormones to combat the
the blood. For example, excess glucose situation.
in the blood triggers the pancreas to The timing of hormone release and the
release insulin to lower the level of blood amount of hormone to be released are

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