Endocrine System
Study Guide, Chapter 16 The Endocrine System
Endocrine System: Overview
Acts with nervous system to coordinate and integrate activity of body cells
Influences metabolic activities via hormones transported in blood
Response slower but longer lasting than nervous system
Endocrinology
Study of hormones and endocrine organs
Endocrine System:
Controls and integrates
Reproduction
Growth and development
Maintenance of electrolyte, water, and nutrient balance of blood
Regulation of cellular metabolism and energy balance
Mobilization of body defenses
Exocrine glands
Nonhormonal substances (sweat, saliva)
Have ducts to carry secretion to membrane surface
Endocrine glands
Produce hormones
Lack ducts
Endocrine glands: pituitary, thyroid, parathyroid, adrenal, and pineal glands
Hypothalamus is neuroendocrine organ
Some have exocrine and endocrine functions
Pancreas, gonads, placenta
Other tissues and organs that produce hormones
Adipose cells, thymus, and cells in walls of small intestine, stomach, kidneys, and heart
Chemical Messengers
Hormones: long-distance chemical signals; travel in blood or lymph
Autocrines: chemicals that exert effects on same cells that secrete them
Paracrines: locally acting chemicals that affect cells other than those that secrete them
Autocrines and paracrines are local chemical messengers; not considered part of endocrine system
Chemistry of Hormones
Two main classes
Amino acid-based hormones
Amino acid derivatives, peptides, and proteins
Steroids
Synthesized from cholesterol
Gonadal and adrenocortical hormones
Mechanisms of Hormone Action
Though hormones circulate systemically only cells with receptors for that hormone affected
Target cells
Tissues with receptors for specific hormone
Hormones alter target cell activity
Hormone action on target cells may be to
Alter plasma membrane permeability and/or membrane potential by opening or closing ion channels
Stimulate synthesis of
Endocrine System: Overview
Acts with nervous system to coordinate and integrate activity of body cells
Influences metabolic activities via hormones transported in blood
Response slower but longer lasting than nervous system
Endocrinology
Study of hormones and endocrine organs
Endocrine System:
Controls and integrates
Reproduction
Growth and development
Maintenance of electrolyte, water, and nutrient balance of blood
Regulation of cellular metabolism and energy balance
Mobilization of body defenses
Exocrine glands
Nonhormonal substances (sweat, saliva)
Have ducts to carry secretion to membrane surface
Endocrine glands
Produce hormones
Lack ducts
Endocrine glands: pituitary, thyroid, parathyroid, adrenal, and pineal glands
Hypothalamus is neuroendocrine organ
Some have exocrine and endocrine functions
Pancreas, gonads, placenta
Other tissues and organs that produce hormones
Adipose cells, thymus, and cells in walls of small intestine, stomach, kidneys, and heart
Chemical Messengers
Hormones: long-distance chemical signals; travel in blood or lymph
Autocrines: chemicals that exert effects on same cells that secrete them
Paracrines: locally acting chemicals that affect cells other than those that secrete them
Autocrines and paracrines are local chemical messengers; not considered part of endocrine system
Chemistry of Hormones
Two main classes
Amino acid-based hormones
Amino acid derivatives, peptides, and proteins
Steroids
Synthesized from cholesterol
Gonadal and adrenocortical hormones
Mechanisms of Hormone Action
Though hormones circulate systemically only cells with receptors for that hormone affected
Target cells
Tissues with receptors for specific hormone
Hormones alter target cell activity
Hormone action on target cells may be to
Alter plasma membrane permeability and/or membrane potential by opening or closing ion channels
Stimulate synthesis of