Tiêu đề 8- CLASS - COLOUR PRINT.pdf ✅

2 30- 52 HUMAN HEALTH & DISEASE 3 53 - 78 CLASS - VIII BIOLOGY 1 CHEMICAL CO-ORDINATION AND INTEGRATION 01 - 29 HUMAN REPRODUCTION WORK SHEETS - 1-3 120 - 198 4 HUMAN SKELETAL SYSTEM 79 - 90 5 CELL : THE UNIT OF LIFE 91- 119 W.S

INTRODUCTION • The neural system and the endocrine system jointly co-ordinate and regulate the physiological functions in the body. • The neural co-ordination is fast very exact and short lived, whereas chemical co-ordination is usually slow, widespread and long lasting. • All cells of our body are not innervated by nerve fibres but the cellular function need to be continuously regulated so a special kind of coordination and integration has to be provided. This function is carried out by hormones. [29] 1 01 CHEMICAL CO-ORDINATION & INTEGRATION
Chemical Co-ordination & Integration (Endocrine) ENDOCRINE GLANDS AND HORMONES • Endocrine glands lack ducts and are hence, called ductless glands. Their secretions are called hormones. • Classical definition of hormone – A chemical produced by endocrine glands and released into the blood and transported to a distantly located target organ. • Current scientific definition of hormones – Non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts. • The new definition covers a number of new molecules in addition to the hormones secreted by the organised endocrine glands. • Invertebrates possess very simple endocrine systems with few hormones whereas a large number of chemicals act as hormones and provide coordination in the vertebrates. Types of Hormones Water soluble Lipid soluble Amine Peptides and protein Hormones Steroid Hormones eg. Epinephrine, Norepinephrine Thyroid Hormones eg. Oxytocin, Vaso pressin, MSH, PTH, TSH, FSH, LH eg. Minera corticoids, Gulco corticoids. Testosterone, Estrogen, progesterone eg. Thyroxine [229]