The Endocrine System - PPT - MBBS PDF Download

 Page 1


The Endocrine 
System 
Page 2


The Endocrine 
System 
2 
Overview of the Endocrine System 
? System of ductless glands that secrete 
hormones 
? Hormones are “messenger molecules” 
? Circulate in the blood 
? Act on distant target cells 
? Target cells respond to the hormones for which they 
have receptors 
? The effects are dependent on the programmed 
response of the target cells 
? Hormones are just molecular triggers 
? Basic categories of hormones 
? Amino acid based: modified amino acids (or amines), 
peptides (short chains of amino acids), and proteins 
(long chains of amino acids) 
? Steroids: lipid molecules derived from cholesterol 
Page 3


The Endocrine 
System 
2 
Overview of the Endocrine System 
? System of ductless glands that secrete 
hormones 
? Hormones are “messenger molecules” 
? Circulate in the blood 
? Act on distant target cells 
? Target cells respond to the hormones for which they 
have receptors 
? The effects are dependent on the programmed 
response of the target cells 
? Hormones are just molecular triggers 
? Basic categories of hormones 
? Amino acid based: modified amino acids (or amines), 
peptides (short chains of amino acids), and proteins 
(long chains of amino acids) 
? Steroids: lipid molecules derived from cholesterol 
3 
Endocrine Organs 
? Purely endocrine organs 
? Pituitary gland 
? Pineal gland 
? Thyroid gland 
? Parathyroid glands 
? Adrenal: 2 glands 
? Cortex 
? Medulla  
? Endocrine cells in other 
organs 
? Pancreas 
? Thymus 
? Gonads 
? Hypothalamus 
Page 4


The Endocrine 
System 
2 
Overview of the Endocrine System 
? System of ductless glands that secrete 
hormones 
? Hormones are “messenger molecules” 
? Circulate in the blood 
? Act on distant target cells 
? Target cells respond to the hormones for which they 
have receptors 
? The effects are dependent on the programmed 
response of the target cells 
? Hormones are just molecular triggers 
? Basic categories of hormones 
? Amino acid based: modified amino acids (or amines), 
peptides (short chains of amino acids), and proteins 
(long chains of amino acids) 
? Steroids: lipid molecules derived from cholesterol 
3 
Endocrine Organs 
? Purely endocrine organs 
? Pituitary gland 
? Pineal gland 
? Thyroid gland 
? Parathyroid glands 
? Adrenal: 2 glands 
? Cortex 
? Medulla  
? Endocrine cells in other 
organs 
? Pancreas 
? Thymus 
? Gonads 
? Hypothalamus 
4 
Mechanisms 
of hormone 
release 
(a) Humoral: in response to changing 
levels of ions or nutrients in the blood 
(b) Neural: stimulation by nerves 
(c) Hormonal: stimulation received from 
other hormones 
Page 5


The Endocrine 
System 
2 
Overview of the Endocrine System 
? System of ductless glands that secrete 
hormones 
? Hormones are “messenger molecules” 
? Circulate in the blood 
? Act on distant target cells 
? Target cells respond to the hormones for which they 
have receptors 
? The effects are dependent on the programmed 
response of the target cells 
? Hormones are just molecular triggers 
? Basic categories of hormones 
? Amino acid based: modified amino acids (or amines), 
peptides (short chains of amino acids), and proteins 
(long chains of amino acids) 
? Steroids: lipid molecules derived from cholesterol 
3 
Endocrine Organs 
? Purely endocrine organs 
? Pituitary gland 
? Pineal gland 
? Thyroid gland 
? Parathyroid glands 
? Adrenal: 2 glands 
? Cortex 
? Medulla  
? Endocrine cells in other 
organs 
? Pancreas 
? Thymus 
? Gonads 
? Hypothalamus 
4 
Mechanisms 
of hormone 
release 
(a) Humoral: in response to changing 
levels of ions or nutrients in the blood 
(b) Neural: stimulation by nerves 
(c) Hormonal: stimulation received from 
other hormones 
5 
Pituitary__________ 
(hypophysis) 
Hypothalamus___________ 
Hypothalamus__ 
Anterior pituitary__ 
(adenohypophysis) 
 
_____________Posterior pituitary 
                         (neurohypophysis) 
Learn the 3 endocrine organs on this slide: 
 Hypothalamus 
 Pituitary (hyophysis) 
 Pineal