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Chapter 9 The Endocrine System
Nursing ()
, lOMoARcPSD|25973474
Chapter 9 The Endocrine System
When insulin molecules, carried passively along in the blood, leave the blood and bind
tightly to protein receptors of nearby cells, the response is dramatic: Bloodborne
glucose molecules begin to disappear into the cells, and cellular activity accelerates.
Such is the power of the second great controlling system of the body, the endocrine
system. Along with the nervous system, it coordinates and directs the activity of the
body's cells. However, the speed of control in these two great regulating systems is
very different. The nervous system is "built for speed." It uses nerve impulses to prod
the muscles and glands into immediate action so that rapid
adjustments can be made in response to changes occurring both inside and outside the body. On the
other hand, the more slowly acting endocrine system uses chemical messengers called hormones, which
are released into the blood to be transported leisurely throughout the body.
Although hormones have widespread and varied effects, the major processes controlled by hormones
are reproduction; growth and development; mobilizing body defenses against stressors; maintaining
electrolyte, water, and nutrient balance of the blood; and regulating cellular metabolism and energy
balance. As you can see, the endocrine system regulates processes that go on for relatively long periods
and, in some cases, continuously.
The Endocrine System and Hormone Function: An Overview
Define hormone and target organ.
o Hormone – chemical messengers that are released into the blood to be transported
leisurely throughout the body – the “arouse” or bring about their effects on the body’s
cells primarily by altering cellular activity either by increasing or decreasing the rate of a
normal metabolic process rather than stimulating a new one
Amino acid – based molecules – proteins, peptides and amines
Steroids – made from cholesterol including sex hormones made by gonads and the
hormones produced by the adrenal cortex
Prostaglandins – made from highly active lipids found in the cell’s plasma
membrane
o Target organ – target cells – although hormones circulate to all the organs of the body,
a given hormone affects only certain tissue cells or organs – in order for a target cell to
respond to a hormone, specific protein receptors must be present on its plasma
membrane or in its interior, to which that hormone can attach – only when binding occurs
can the hormone influence the workings of the cell
Describe how hormones bring about their effects in the body.
o The precise changes that follow hormone binding depends on the specific hormone and
the target cell type, but one or more of the following occurs
Changes in plasma membrane permeability or electrical state
Synthesis of proteins or certain regulatory molecules (such as enzymes) in the
cell Activation or inactivation of enzymes
Stimulation of mitosis
o Two mechanisms by which hormones trigger changes in cells
Steroidal hormones – lipid soluble molecules
Diffuse through the plasma membranes of their target
cells Enter the nucleus
Bind specific receptor proteins there
Chapter 9 The Endocrine System
Nursing ()
, lOMoARcPSD|25973474
Chapter 9 The Endocrine System
When insulin molecules, carried passively along in the blood, leave the blood and bind
tightly to protein receptors of nearby cells, the response is dramatic: Bloodborne
glucose molecules begin to disappear into the cells, and cellular activity accelerates.
Such is the power of the second great controlling system of the body, the endocrine
system. Along with the nervous system, it coordinates and directs the activity of the
body's cells. However, the speed of control in these two great regulating systems is
very different. The nervous system is "built for speed." It uses nerve impulses to prod
the muscles and glands into immediate action so that rapid
adjustments can be made in response to changes occurring both inside and outside the body. On the
other hand, the more slowly acting endocrine system uses chemical messengers called hormones, which
are released into the blood to be transported leisurely throughout the body.
Although hormones have widespread and varied effects, the major processes controlled by hormones
are reproduction; growth and development; mobilizing body defenses against stressors; maintaining
electrolyte, water, and nutrient balance of the blood; and regulating cellular metabolism and energy
balance. As you can see, the endocrine system regulates processes that go on for relatively long periods
and, in some cases, continuously.
The Endocrine System and Hormone Function: An Overview
Define hormone and target organ.
o Hormone – chemical messengers that are released into the blood to be transported
leisurely throughout the body – the “arouse” or bring about their effects on the body’s
cells primarily by altering cellular activity either by increasing or decreasing the rate of a
normal metabolic process rather than stimulating a new one
Amino acid – based molecules – proteins, peptides and amines
Steroids – made from cholesterol including sex hormones made by gonads and the
hormones produced by the adrenal cortex
Prostaglandins – made from highly active lipids found in the cell’s plasma
membrane
o Target organ – target cells – although hormones circulate to all the organs of the body,
a given hormone affects only certain tissue cells or organs – in order for a target cell to
respond to a hormone, specific protein receptors must be present on its plasma
membrane or in its interior, to which that hormone can attach – only when binding occurs
can the hormone influence the workings of the cell
Describe how hormones bring about their effects in the body.
o The precise changes that follow hormone binding depends on the specific hormone and
the target cell type, but one or more of the following occurs
Changes in plasma membrane permeability or electrical state
Synthesis of proteins or certain regulatory molecules (such as enzymes) in the
cell Activation or inactivation of enzymes
Stimulation of mitosis
o Two mechanisms by which hormones trigger changes in cells
Steroidal hormones – lipid soluble molecules
Diffuse through the plasma membranes of their target
cells Enter the nucleus
Bind specific receptor proteins there
