The endocrine system is composed of several endocrine glands. A ductless gland is called endocrine gland. Endocrine gland secretes its product directly into the bloodstream. Hormones are produced in the endocrine glands. Hormone is mainly composed of protein. Hormones assist the nervous system in control and coordination. Nerves do not reach to every nook and corner of the body and hence hormones are needed to affect control and coordination in those parts. Moreover, unlike nervous control; hormonal control is somewhat slower.
|Endocrine gland||Location||Hormones Produced||Functions|
|Pituitary gland (Also known as the master gland)||At the base of brain||Growth hormone (GH), thyroid stimulating hormone (TSH), Follicle stimulating hormone (FSH)||GH stimulates growth, TSH stimulates functioning of thyroid gland, FSH stimulates the follicles during ovulation.|
|Thyroid Gland||Neck||Thyroxine||Controls general metabolism and growth in the body.|
|Adrenal gland||Above kidneys||Adrenalin||Prepares the body for emergency situations and hence is also called ‘Fight and flight’ hormone.|
|Pancreas||Near stomach||Insulin||Controls blood sugar level|
|Testis (male)||In scrotum||Testosterone||Sperm production, development of secondary sexual characters during puberty.|
|Ovary (female)||Near uterus||Oestrogen||Egg production, development of secondary sexual characters during puberty.|
Unlike animals, plants do not have a nervous system. Plants use chemical means for control and coordination. Many plant hormones are responsible for various kinds of movements in plants.
Movements in plants can be divided into two main types, viz. tropic movement and nastic movement.
The movements which are in a particular direction in relation to the stimulus are called tropic movements. Tropic movements happen as a result of growth of a plant part in a particular direction. There are four types of tropic movements, viz. geotropic, phototropic, hydrotropic and thigmotropic.
The movements which do not depend on the direction from the stimulus acts are called nastic movement. For example; when someone touches the leaves of mimosa, the leaves droop. The drooping is independent of the direction from which the leaves are touched. Such movements usually happen because of changing water balance in the cells. When leaves of mimosa are touched, the cells in the leaves lose water and become flaccid; resulting in drooping of leaves.
Some Plant Hormones: Auxin, gibberellins and cytokinin promote growth in plant parts. Abscissic acid inhibits growth in a particular plant part.
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