SILVERTHORN
CHAPTER 23 – ENDOCRINE CONTROL OF GROWTH
AND METABOLISM
REVIEW OF ENDOCRINE PRINCIPLES
Basic principles and patterns of endocrinology:
1. The hypothalamic-pituitary control system
2. Feedback patterns – the negative feedback signal for simple endocrine pathways is the
systemic response to the hormone.
3. Hormone receptor – on the cell surface or inside the cell
4. Cellular response – hormone target cells respond by altering existing proteins or by
making new proteins
5. Modulation of target cell response – the amount of active hormone available to the cell
and the number and activity of target cell receptors determine the magnitude of target cell
response. Cells can up-regulate or down-regulate their receptors to alter their response
6. Endocrine pathologies – result from (a) excess hormone secretion, (b) inadequate
hormone secretion and (c) abnormal target cell response.
ADRENAL GLUCOCORTICOIDS
The adrenal glands sit on top of the kidneys. The adrenal cortex secretes steroid hormones and
the adrenal medulla secretes catecholamines.
Adrenal cortex
The cortex secretes three major types of steroid hormones: aldosterone, glucocorticoids and sex
hormones. The cortex is divided into three layers/ zones.
– The outer zona glumerulosa secretes aldosterone
– The middle zona fasciculate secretes mostly
glucocorticoids, which can increase glucose
concentrations. Cortisol is the main glucocorticoid.
– The inner zona reticularis secretes androgens (sex
hormones in men)
The synthesis of all steroid hormones begin with
cholesterol, which is modified my multiple enzymes to
end up as aldosterone, glucocorticoids or sex steroids
(androgens, estrogens and progesterone). The
distribution of enzymes that catalyse the different
reactions is different; enzyme that makes aldosterone is
only found in one of the three adrenal cortex zones.
Cortisol secretion is controlled by ACTH
Silverthorn – chapter 23: Endocrine control of growth and metabolism Page 1 of 8
CHAPTER 23 – ENDOCRINE CONTROL OF GROWTH
AND METABOLISM
REVIEW OF ENDOCRINE PRINCIPLES
Basic principles and patterns of endocrinology:
1. The hypothalamic-pituitary control system
2. Feedback patterns – the negative feedback signal for simple endocrine pathways is the
systemic response to the hormone.
3. Hormone receptor – on the cell surface or inside the cell
4. Cellular response – hormone target cells respond by altering existing proteins or by
making new proteins
5. Modulation of target cell response – the amount of active hormone available to the cell
and the number and activity of target cell receptors determine the magnitude of target cell
response. Cells can up-regulate or down-regulate their receptors to alter their response
6. Endocrine pathologies – result from (a) excess hormone secretion, (b) inadequate
hormone secretion and (c) abnormal target cell response.
ADRENAL GLUCOCORTICOIDS
The adrenal glands sit on top of the kidneys. The adrenal cortex secretes steroid hormones and
the adrenal medulla secretes catecholamines.
Adrenal cortex
The cortex secretes three major types of steroid hormones: aldosterone, glucocorticoids and sex
hormones. The cortex is divided into three layers/ zones.
– The outer zona glumerulosa secretes aldosterone
– The middle zona fasciculate secretes mostly
glucocorticoids, which can increase glucose
concentrations. Cortisol is the main glucocorticoid.
– The inner zona reticularis secretes androgens (sex
hormones in men)
The synthesis of all steroid hormones begin with
cholesterol, which is modified my multiple enzymes to
end up as aldosterone, glucocorticoids or sex steroids
(androgens, estrogens and progesterone). The
distribution of enzymes that catalyse the different
reactions is different; enzyme that makes aldosterone is
only found in one of the three adrenal cortex zones.
Cortisol secretion is controlled by ACTH
Silverthorn – chapter 23: Endocrine control of growth and metabolism Page 1 of 8
