PHYSIOLOGY
Hall, J. E. (2016). Guyton and Hall Textbook of Medical Physiology (13th ed.). Elsevier.
Adrenocortical Hormones
INTRODUCTION CORTICOSTEROIDS: MINERALOCORTICOIDS,
• The two adrenal glands are small organs, each about 4 GLUCOCORTICOIDS, AND ANDROGENS
grams, located above the kidneys. Each gland has two • The adrenal cortex produces two main types of
main parts: hormones:
o Adrenal Medulla (20% of the gland): This part is (1) Mineralocorticoids – affect the electrolyte (the
connected to the body's sympathetic nervous “minerals”) of the extracellular fluids, especially
system, which is responsible for the "fight or flight" sodium and potassium.
response. The medulla releases two hormones, (2) Glucocorticoids – exhibit important effects that
epinephrine (adrenaline) and norepinephrine increase blood glucose concentration
(noradrenaline), when the body is under stress or - Both have additional effects on both protein
excitement. These hormones produce effects and fat metabolism, as well as carbohydrate
similar to the activation of the sympathetic nervous metabolism
system, such as increased heart rate and • The cortex also produces small amounts of sex
alertness. hormones, mainly androgenic hormones, which have
o Adrenal Cortex: This part produces a different set similar effects to testosterone. Normally, they have
of hormones called corticosteroids, which are little impact, but in certain disorders, excessive
made from cholesterol. These hormones have amounts can cause masculinizing effects.
similar chemical structures but slightly different • Over 30 steroid hormones come from the adrenal
properties, allowing them to perform a variety of cortex, but the two most important are:
important functions in the body, such as regulating o Aldosterone – the principal mineralocorticoid,
metabolism, immune response, and stress. which controls sodium and potassium balance.
• The adrenal glands play key roles in stress response and o Cortisol – the principal glucocorticoid, which
body regulation, with the medulla handling quick helps regulate metabolism and stress response.
reactions and the cortex managing longer-term
processes. SYNTHESIS AND SECRETION OF ADRENOCORTICAL
HORMONES
THE ADRENAL CORTEX HAS THREE DISTINCT LATERS
• The adrenal cortex is made up of three distinct layers,
each responsible for producing specific hormones:
(1) Zona Glomerulosa (Outer Layer, ~15% of the
cortex)
o Located just beneath the capsule.
o Produces aldosterone, a key
mineralocorticoid that regulates sodium and
potassium balance.
o Contains the enzyme aldosterone synthase,
necessary for aldosterone production.
o Secretion is mainly controlled by angiotensin
II and potassium levels in extracellular fluid.
(2) Zona Fasciculata (Middle and Widest Layer, ~75%
of the cortex)
o Produces glucocorticoids like cortisol and
corticosterone, which help regulate
metabolism and stress response.
o Also produces small amounts of adrenal
androgens and estrogens.
Prepared by: Yam Flynge Ferrer
Email:
, o Secretion is controlled by the hypothalamic- o Angiotensin II, which stimulates aldosterone
pituitary axis via adrenocorticotropic production.
hormone (ACTH).
(3) Zona Reticularis (Inner Layer) SYNTHETIC PATHWAYS FOR ADRENAL STEROIDS
o Produces adrenal androgens, including • The adrenal cortex produces aldosterone, cortisol,
dehydroepiandrosterone (DHEA) and and androgens through complex enzyme-driven
androstenedione, as well as small amounts reactions in the mitochondria and endoplasmic
of estrogens and glucocorticoids. reticulum.
o Secretion is regulated by ACTH, though other • Each hormone is produced in a specific pathway, and
factors like cortical androgen-stimulating enzyme defects can lead to abnormal hormone levels,
hormone may also play a role. such as excess masculinizing hormones.
• Regulation of Aldosterone and Cortisol • Chemical Structures of Aldosterone and Cortisol
o Aldosterone secretion (zona glomerulosa) is o Cortisol has a keto-oxygen at carbon 3 and
controlled by angiotensin II and potassium and hydroxyl groups at carbons 11 and 21.
affects only the zona glomerulosa. o Aldosterone has an additional oxygen atom at
o Cortisol and adrenal androgen secretion (zona carbon 18, distinguishing it from cortisol.
fasciculata and zona reticularis) are regulated by
• Important Corticosteroids: The adrenal cortex
ACTH, with little effect on the zona glomerulosa.
secretes both natural and synthetic corticosteroids
with different potencies:
ADRENOCORTICAL HORMONES: SYNTHESIS, Mineralocorticoids (Regulate Sodium & Potassium Balance)
TRANSPORT, AND METABOLISM
Very potent; accounts for
Aldosterone about 90 percent of all
ADRENOCORTICAL HORMONES ARE STEROIDS mineralocorticoid activity
DERIVED FROM CHOLESTEROL 1/30 as potent as aldosterone,
• All steroid hormones produced by the adrenal cortex Deoxycorticosterone but very small quantities are
come from cholesterol. secreted
• The adrenal cortex can make small amounts of Slight mineralocorticoid
Corticosterone
activity
cholesterol, but about 80% comes from low-density
Synthetic; slightly more potent
lipoproteins (LDLs) in the blood. 9α-Fluorocortisol
than aldosterone
• LDLs, which are rich in cholesterol, attach to specific
Very slight mineralocorticoid
receptors on adrenal cell membranes and enter the Cortisol activity, but a large quantity is
cells through endocytosis. secreted
• Inside the cells, cholesterol is released and used for Slight mineralocorticoid
Cortisone
steroid hormone synthesis. activity
Regulation of Cholesterol Transport Glucocorticoids (Regulate Metabolism & Stress Response)
• ACTH (Adrenocorticotropic Hormone) increases: Very potent; accounts for about
• The number of LDL receptors on adrenal cells. Cortisol 95 percent of all glucocorticoid
• The activity of enzymes that release cholesterol from activity
LDL. Provides about 4 percent of total
Corticosterone glucocorticoid activity, but is
• Once inside the cell, cholesterol is transported to much less potent than cortisol
mitochondria, where the enzyme cholesterol Cortisone Almost as potent as cortisol
desmolase converts it into pregnenolone—the first Synthetic; four times as potent as
step in adrenal steroid synthesis. Prednisone
cortisol
• This step is regulated by: Synthetic; five times as potent as
Methylprednisone
o ACTH, which stimulates cortisol production. cortisol
Synthetic; 30 times as potent as
Dexamethasone
cortisol
Prepared by: Yam Flynge Ferrer
Email:
Hall, J. E. (2016). Guyton and Hall Textbook of Medical Physiology (13th ed.). Elsevier.
Adrenocortical Hormones
INTRODUCTION CORTICOSTEROIDS: MINERALOCORTICOIDS,
• The two adrenal glands are small organs, each about 4 GLUCOCORTICOIDS, AND ANDROGENS
grams, located above the kidneys. Each gland has two • The adrenal cortex produces two main types of
main parts: hormones:
o Adrenal Medulla (20% of the gland): This part is (1) Mineralocorticoids – affect the electrolyte (the
connected to the body's sympathetic nervous “minerals”) of the extracellular fluids, especially
system, which is responsible for the "fight or flight" sodium and potassium.
response. The medulla releases two hormones, (2) Glucocorticoids – exhibit important effects that
epinephrine (adrenaline) and norepinephrine increase blood glucose concentration
(noradrenaline), when the body is under stress or - Both have additional effects on both protein
excitement. These hormones produce effects and fat metabolism, as well as carbohydrate
similar to the activation of the sympathetic nervous metabolism
system, such as increased heart rate and • The cortex also produces small amounts of sex
alertness. hormones, mainly androgenic hormones, which have
o Adrenal Cortex: This part produces a different set similar effects to testosterone. Normally, they have
of hormones called corticosteroids, which are little impact, but in certain disorders, excessive
made from cholesterol. These hormones have amounts can cause masculinizing effects.
similar chemical structures but slightly different • Over 30 steroid hormones come from the adrenal
properties, allowing them to perform a variety of cortex, but the two most important are:
important functions in the body, such as regulating o Aldosterone – the principal mineralocorticoid,
metabolism, immune response, and stress. which controls sodium and potassium balance.
• The adrenal glands play key roles in stress response and o Cortisol – the principal glucocorticoid, which
body regulation, with the medulla handling quick helps regulate metabolism and stress response.
reactions and the cortex managing longer-term
processes. SYNTHESIS AND SECRETION OF ADRENOCORTICAL
HORMONES
THE ADRENAL CORTEX HAS THREE DISTINCT LATERS
• The adrenal cortex is made up of three distinct layers,
each responsible for producing specific hormones:
(1) Zona Glomerulosa (Outer Layer, ~15% of the
cortex)
o Located just beneath the capsule.
o Produces aldosterone, a key
mineralocorticoid that regulates sodium and
potassium balance.
o Contains the enzyme aldosterone synthase,
necessary for aldosterone production.
o Secretion is mainly controlled by angiotensin
II and potassium levels in extracellular fluid.
(2) Zona Fasciculata (Middle and Widest Layer, ~75%
of the cortex)
o Produces glucocorticoids like cortisol and
corticosterone, which help regulate
metabolism and stress response.
o Also produces small amounts of adrenal
androgens and estrogens.
Prepared by: Yam Flynge Ferrer
Email:
, o Secretion is controlled by the hypothalamic- o Angiotensin II, which stimulates aldosterone
pituitary axis via adrenocorticotropic production.
hormone (ACTH).
(3) Zona Reticularis (Inner Layer) SYNTHETIC PATHWAYS FOR ADRENAL STEROIDS
o Produces adrenal androgens, including • The adrenal cortex produces aldosterone, cortisol,
dehydroepiandrosterone (DHEA) and and androgens through complex enzyme-driven
androstenedione, as well as small amounts reactions in the mitochondria and endoplasmic
of estrogens and glucocorticoids. reticulum.
o Secretion is regulated by ACTH, though other • Each hormone is produced in a specific pathway, and
factors like cortical androgen-stimulating enzyme defects can lead to abnormal hormone levels,
hormone may also play a role. such as excess masculinizing hormones.
• Regulation of Aldosterone and Cortisol • Chemical Structures of Aldosterone and Cortisol
o Aldosterone secretion (zona glomerulosa) is o Cortisol has a keto-oxygen at carbon 3 and
controlled by angiotensin II and potassium and hydroxyl groups at carbons 11 and 21.
affects only the zona glomerulosa. o Aldosterone has an additional oxygen atom at
o Cortisol and adrenal androgen secretion (zona carbon 18, distinguishing it from cortisol.
fasciculata and zona reticularis) are regulated by
• Important Corticosteroids: The adrenal cortex
ACTH, with little effect on the zona glomerulosa.
secretes both natural and synthetic corticosteroids
with different potencies:
ADRENOCORTICAL HORMONES: SYNTHESIS, Mineralocorticoids (Regulate Sodium & Potassium Balance)
TRANSPORT, AND METABOLISM
Very potent; accounts for
Aldosterone about 90 percent of all
ADRENOCORTICAL HORMONES ARE STEROIDS mineralocorticoid activity
DERIVED FROM CHOLESTEROL 1/30 as potent as aldosterone,
• All steroid hormones produced by the adrenal cortex Deoxycorticosterone but very small quantities are
come from cholesterol. secreted
• The adrenal cortex can make small amounts of Slight mineralocorticoid
Corticosterone
activity
cholesterol, but about 80% comes from low-density
Synthetic; slightly more potent
lipoproteins (LDLs) in the blood. 9α-Fluorocortisol
than aldosterone
• LDLs, which are rich in cholesterol, attach to specific
Very slight mineralocorticoid
receptors on adrenal cell membranes and enter the Cortisol activity, but a large quantity is
cells through endocytosis. secreted
• Inside the cells, cholesterol is released and used for Slight mineralocorticoid
Cortisone
steroid hormone synthesis. activity
Regulation of Cholesterol Transport Glucocorticoids (Regulate Metabolism & Stress Response)
• ACTH (Adrenocorticotropic Hormone) increases: Very potent; accounts for about
• The number of LDL receptors on adrenal cells. Cortisol 95 percent of all glucocorticoid
• The activity of enzymes that release cholesterol from activity
LDL. Provides about 4 percent of total
Corticosterone glucocorticoid activity, but is
• Once inside the cell, cholesterol is transported to much less potent than cortisol
mitochondria, where the enzyme cholesterol Cortisone Almost as potent as cortisol
desmolase converts it into pregnenolone—the first Synthetic; four times as potent as
step in adrenal steroid synthesis. Prednisone
cortisol
• This step is regulated by: Synthetic; five times as potent as
Methylprednisone
o ACTH, which stimulates cortisol production. cortisol
Synthetic; 30 times as potent as
Dexamethasone
cortisol
Prepared by: Yam Flynge Ferrer
Email:
