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LECTURE NOTES BIOLOGY STEPS A TCY Program _______________________________________________________________________________________

STEPS____________________________________________________________G e t f r e e c h a p t e r w i s e t e s t s f o r C l a s s X

t hon

w w w . t c y o n l i n e . c o m

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HORMONESHormones are chemical substances secreted in very small amounts by endocrine glands. They

coordinate the activities of living organisms & also their growth.

CHARACTERISTICS OF HORMONES

(1) Secreted in small amounts by endocrine glands

(2) Poured directly into blood

(3) Transported into body thru circulatory system.

(4) Chemical messengers

(5) Act on specific tissues/ organs (Target organs)

(6) Coordinate the activities of the body & their growth.

Gland

A gland is a structure which secretes a specific substance. A gland is made up of a group of cellsor tissues.

2 types of glands exist in body.

Endocrine g Exocrine g

secretes its secretions directly into blood. secretes its product into a duct.

Ductless Secrete secretions, digestive enzymes.

Secrete hormones Glands C ducts

Mixed/ Dual glands

Serve both functions Pancreas

Ovary

Testes

THE ENDOCRINE SYSTEM/ HORMONAL SYSTEM

Consists of a no. of glands

Name of gland Hormones Secreted Functions

(1) Hypothalamus

(+nt in brain)

(1) Releasing Hormones

(2) Inhibiting hormones

Regulates the secretions of

hormones from Pituitary(1) Growth Hormone Growth of body

Bones

Muscles regulate secretion of

(2) Pituitary (Hypophysis)

Master gland

(2) Trophic Hormone hormones from other endocrine

glands

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LECTURE NOTES BIOLOGY STEPS A TCY Program _______________________________________________________________________________________

STEPS____________________________________________________________G e t f r e e c h a p t e r w i s e t e s t s f o r C l a s s X

t hon

w w w . t c y o n l i n e . c o m

2

(3) Prolactin regulate function of mammary

gland

(4) Vasopressin regulate water and electrolyte

balance

(5) Oxytocin regulate release of milk during

lactation

(1) Tyroxine

(contains iodine)

Control of rate of metabolism(3) Thyroid

(2) Calcitonin Works opposite to Parathormone

(4) Parathyroid Parathormone Regulate Ca & P levels in blood

(1) Insulin Lower blood glucose level(5) Pancreas

(2) Glucogen Upper blood glucose level

(6) Adrenal (1) Adrenalin

(2) Corticoids

Regulate heart rate, breathing rate,

BP, carbo metabolism, numeral

balance

(7) Testes (males) (1) Testosterone Controls development of male sex

organs & male features

(1) Oestrogen Development of female sex organs,

female features such as fenuine

voice, soft skin, mammary glands

Controls uterus changes in

menstrual cycle

(8) Ovaries

(2) Progesterone

Maintains pregnancy

Endocrine glands produce hormones

Hormone act as a messenger bt. Nervous system & organs of body thus help in control &

coordination of the activities along nervous system.