HORMONES
Definitions
Hormones: A chemical substance produced by a gland, carried by the blood,
which alters the activity of one or more specific target organs and is then
destroyed by the liver
Endocrine gland or ductless gland: The gland, which has no duct for secretion and
they secreted their chemical substances directly into the bloodstream is called
endocrine or ductless gland.
E.g. Thyroid gland, adrenal gland, pituitary gland etc.
Exocrine gland or duct gland: The gland which secret its chemical substances
through a duct is called exocrine or duct gland.
E.g. Salivary gland, lacrimal gland, mammary gland etc.
Mixed or heterocrine gland: This gland consists both exocrine and endocrine
glands. E.g. Pancreas, testes and ovaries.
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Pituitary gland: It is the master gland which is attached to the base of the brain. It
produces many hormones like Growth Hormones, Luteinizing Hormone (LH),
Thyroid Stimulating Hormone (TSH), Follicle stimulating Hormone (FSH), Oxytocin,
Anti Diuretic Hormone (LTH) etc.
Write the differences between endocrine and exocrine gland.
Endocrine glands:
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A type of ductless glands
Secrete into the blood
Contain blood vessels
Secrete hormones
Target of the gland is located away from the gland
Mainly control long term activities of the target organs.
Exocrine gland:
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May or may not have duct
Pour their secretions directly at the site of action
Do not contain blood vessels
Secrete enzymes
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Write the properties of hormones.
• Hormones are secreted from the cluster of living cells.
• It travels through the blood to reach target organs.
• Hormones serve as chemical messengers and bring about chemical
coordination of varies parts in the body.
• They do not catalyze any reactions, they function by stimulating or
inhibiting the target organs.
• Do not remain permanently in blood, soon after their function is over, they
become destroyed, inactivated or excreted.
• Like vitamins they act in very low concentration and amount.
Write the differences between nervous system and hormonal system.
Name different glands, hormones and their functions.
Gland
Hormones
Functions
Pituitary
Follicle Stimulating
Hormone (FSH)
Stimulates egg development and
estrogen secretion in female and sperm
production.
Luteinizing Hormone
(LH)
Stimulates egg release (Ovulation) in
female and testosterone production in
males.
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Gland
Hormone
Functions
Pituitary
Anti-diuretic hormone
(ADH)
Controls the water content of the
blood.
Thyroid Stimulating
hormone (TSH)
Stimulates the secretion of thyroxine
from the thyroid glands.
Control intake of iodine by the
thyroid tissue.
Human Growth
Hormone
Controls the growth of tissue, bone,
muscle and internal organs.
Also influences metabolic processes.
Pancreas
Testes
Ovaries
Insulin
Lowers blood glucose
Glucagon
Raises blood glucose
Testosterone
Controls development of female
secondary sexual characteristics.
Estrogen
Progesterone
Adrenals
Adrenaline
Controls development of female
secondary sexual characteristics.
Regulates menstrual cycle
Prepares body for physical activity.
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Describe the effect of adrenaline.
There is a pair of adrenal glands located on just above each kidney. It produces
adrenaline hormones. It above each kidney. It produces adrenaline hormone. It is
known as flight fright and fight hormones.
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