The Endocrine System and Plant Hormones

Hormones

Play a vital role in regulating various biological processes in both plants and animals.

Endocrine System

In charge of creating and releasing hormones to maintain countless bodily functions.

Auxin

Stimulates elongation, controls time of fruit and leaf, plays a role in growth movement of plant toward or away from a stimulus, and apical dominance.

Gibberellins

Hormone that promotes cell elongation, marked elongation of stem, stimulates flowering, plays a role in germination, and inhibits the formation of adventitious roots on cutting.

Cytokinins

Hormone that promotes cell division and cell enlargement, inhibits aging, and helps induce dormancy in buds and seeds.

Abscissic Acid

Promotes formation of abscission layers at bases of leaves and fruits leading to their droppings, and inhibits germination of some seeds.

Ethylene

Hormone that promotes ripening of fleshy fruits and promotes abscission of leaves.

Florigen

Flowering hormone whose existence has been postulated but not yet proven.

Tropism

Growth response of plants to environmental stimulus.

Phototropism

Growth toward or away from light shining mainly on one side of the organism.

Gravitropism

Growth response to the earth's gravitational force.

Thigmotropism

Unequal growth response of plants resulting from physical contact with solid objects in their surrounding.

Hydrotropism

Growth response to water.

Photoperiodism

A biological response to a change in the relative length of daylight and darkness in a twenty-four-hour cycle.

Anterior Pituitary Hormones

Includes hormones such as ACTH, FSH, LH, Prolactin, and MSH.

ACTH

Adrenocorticotrophic hormone.

FSH

Follicle-stimulating hormone that stimulates the ovary (follicle).

LH

Luteinizing hormone that stimulates testes in male and Corpus Luteum in female.

Prolactin

Stimulates milk secretion by mammary glands.

Growth Hormone

Promotes cell metabolism; effects of deficiency or excess include dwarfism and gigantism.

MSH

Melanophore-Stimulating hormone that controls adjustable skin pigment cells.

Posterior Pituitary Hormones

Includes hormones produced by neurosecretory cells of hypothalamus such as Oxytocin and ADH.

Oxytocin

Causes smooth muscle responses of uterus and increased or reduced water excretion.

ADH

Vasopressin or antidiuretic hormone that promotes reabsorption of water by kidney.

Pancreas

Produces insulin which converts glucose to glycogen and glucagon which converts glycogen to glucose.

Gastrin

Stimulates gastric juice secretion.

Secretin

Stimulates pancreatic juice secretion.

Testosterone

Promotes cell respiration, blood circulation, and maintains primary and secondary sex characteristics.

Estradiol

Maintains primary and secondary sex characteristics and sex urge.

Progesterone

Promotes secretion of oviduct and uterine growth; involved in abortion during pregnancy.