Chemical signalling by hormones is the function ofendo endocrine tem, one of the two basic systems for
mmunication and regulation in the animal body.
other major communication and control system is the nervous system, a network of specialised cells, that transmit signals along dedicated pathways. Signalling by
neurons regulate the release of hormones, thus nervous and endocrine systems often overlap in functions.
TYPES OF GLANDS
Gland is an organ, tissue or cell that secretes specific chemical substance for performing a particular function.
On the basis of presence or absence of ducts, glands are
classified into endocrine glands and exocrine glands.
Exocrine gland - Is a gland that pours its secretion on the surface or into a particular region by means of ducts for performing a metabolic activity, e.g, sebaceous glands,
sweat glands, salivary glands, intestinal glands.
Endocrine gland -
isan isolated gland (separates even from epithelium forming it) which secretes hormones that are poured into venous blood or lymph for reaching the target organ because the gland is not connected with the
target organ by any duct
Heterocrine gland -- (mixed gland) is a gland that hasboth bothcrine and endocrine regions the former pouring their secretionough ducts while the latter pouring their secretion directly into blood/lymph, eg., pancreas, testes, ovaries, etc.
