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Generally, what shape are the adrenal glands?
Flattened pyramids
How many adrenal glands in one body?
Two
Where are the adrenal glands located?
On top of the kidneys
What surrounds/covers each adrenal gland?
Connective tissue -- called the capsule
What are the two main parts of each adrenal gland? Where are they, relative to each other?
The adrenal cortex and the adrenal medulla; medulla is deep to cortex (and cortex is deep to capsule)
The adrenal cortex is glandular tissue derived from ____ ____
embryonic mesoderm
The adrenal medulla arises from the same cells that give rise to ___ ___ ___
postganglionic sympathetic neurons
What are the 3 layers of the adrenal cortex, from superficial to deep?
zona glomerulosa, zona fasciculata, zona reticularis
All hormones of the adrenal cortex are derived from ___
cholesterol
What are mineralocorticoids?
a class of steroid hormones secreted by adrenal cortex; characterised by their similarity to aldosterone; influence salt and water balances in body
What is the major mineralocorticoid? Where is it secreted?
Aldosterone; adrenal cortex
Aldosterone is what type of hormone?
mineralocorticoid
Where do mineralocorticoids act?
at the distal tubule and collecting duct (in the kidney)
Name the responses to mineralocorticoids
increase Na+ absorption in blood; increase water absorption; increase blood volume and BP; increase K+ excretion; increase H+ excretion, thereby decreasing its level in the blood, thereby increasing blood pH
What effect does a mineralocorticoid have on blood pH?
it decreases blood pH by increasing H+ excretion (thereby lowering H+ conc. in blood)
What controls/regulates aldosterone secretion?
the renin-angiotensin-aldosterone cycle (RAA)
The RAA cycle controls what?
aldosterone secretion
What activates the RAA cycle/pathway?
dehydration, Na+ deficiency, or hemorrhage
Dehydration or Na+ deficiency can activate what pathway?
renin-angiotensin-aldosterone cycle
What specific molecule activates the RAA system? Where is this molecule released from?
renin, released by kidneys
Describe renin.
proteolytic enzyme; released into circulation by kidneys; activates RAA cycle; stimulates formation of angeotensin I by proteolytic cleavage of angiotensinogen
What is a proteolytic enzyme?
any enzyme that breaks down proteins (by hydrolysis of the peptide bonds connecting the amino acids)
Renin is a ___ ___
proteolytic enzyme
The ___ release ___ into the ___ to begin the ___ cycle.
kidneys; renin; circulation; RAA
Renin acts on what molecule?
angiotensinogen
What is the specific action of renin?
It cleaves angiotensinogen to form angiotensin I
Angiotensin I is formed from what molecule?
angiotensinogen
Angiotensinogin is cleaved by ___ to form ___
renin; angiotensin I
Angiotensin I is converted to ___ by ___
angiotensin II; angiotensin converting enzyme (ACE)
What is ACE?
angiotensin converting enzyme; it converts angiotensin I to angiotensin II
Angiotensin II activates the release of ___ from the adrenal cortex
aldosterone; adrenal cortex
What causes the adrenal cortex to release aldosterone?
Angiotensin II
Aldosterone is released from where? How is it released?
from the adrenal cortex; its release is stimulated by angiotensin II, which is formed from angiotensin I by ACE
Angiotensin II activates the release of ___ from the pituitary
ADH or vasopressin
Angiotensin II has two functions in the RAA cycle. What are they?
stimulates release of aldosterone from the adrenal cortex and the release of vasopressin from the pituitary
Where does angiotensin II act?
on the adrenal cortex (to release aldosterone) and on the pituitary (to release vasopressin)
Outline the RAA system.
the kidneys secrete renin into the circulation.
renin cleaves angiotensinogen into angiotensin I.
ACE (angiotensin converting hormone) converts angiotensin I to angiotensin II.
angiotensin II stimulates the release of aldosterone and vasopressin.
What triggers the release of renin?
low blood volume
Where is renin released from?
juxtaglomerular cells in the kidney
What is the effect of aldosterone when it is released by the RAA cycle?
it enhances retention (or reabsorption) of salt in the distal convoluted tubule -- this attracts water to the blood by osmosis, which increases blood volume and pressure
What is the effect of vasopressin when it is released by the RAA cycle?
it promotes the reabsorption of water and vasoconstriction
What are the final physiological results of the RAA cycle?
vasoconstriction; increased reabsorption of water; increased blood volume and pressure; increased retention of salt
Summarize aldosterone's mechanism of action.
aldosterone binds to a mineralocorticoid receptor in the cytoplasm; the receptor translocates to the nucleus; this activates gene expression; aldosterone-induced expression of proteins change the way ions in the tubule are transported
Aldosterone works by what type of action mechanism?
lipid-soluble
Where are the receptors for aldosterone?
in the cytoplasm (of cells in the kidney's distal tubule and collecting duct)
What are glucocorticoids?
hormones that act at multiple tissues to produce glucose and energy for the body
What are the three major groups of hormones of the adrenal cortex?
mineralocorticoids, glucocorticoids, and gonadocorticoids
Glucocorticoids are named for their effects on ___ ___
glucose metabolism
What is the most prominent glucocorticoid?
cortisol (hydrocortisone)
Cortisol is released in response to ___
stress
What are the target tissues of cortisol?
liver, skeletal muscle, and adipose tissue
In the liver, cortisol acts on what kind of molecules?
carbohydrates
What does cortisol do in the liver?
stimulates gluconeogenesis (increases blood glucose) and increases glycogen synthesis
Gluconeogenesis ___ blood glucose by doing what?
increases; increasing the rate of conversion of amino acids into glucose
Cortisol has ___ action on ___ in the skeletal muscle.
catabolic; proteins
What type of molecule does cortisol work on in skeletal muscle?
proteins
What does cortisol do in skeletal muscle?
inhibits glucose uptake; stimulates amino acid catabolism into glucose
What does cortisol do in adipose tissue?
stimulates lipolysis; inhibits lipogenesis in the liver
Summarize cortisol-stimulated lipolysis in adipose tissue.
triglycerides --> glycerol + free fatty acids
Lipolyis in adipose tissue increases the amount of ___ in the circulation.
free fatty acids
What does cortisol do in the adipose tissue of the liver?
it inhibits lipgenesis so that no new triglycerides are synthesized
Overall, cortisol ___ the amount of triglycerides present in adipose tissue.
decreases (by stimulating their breakdown and inhibiting their genesis)
What are the overall physiological effects of cortisol?
immunosuppression; increased blood pressure; increased sensitivity to epinephrine and NE; increased gastric acid secretion; increased H2O in urine
Summarize the mechanism of glucocorticoid action?
Most cells are target cells. The glucocorticoid binds to its receptor using the lipid-soluble method; enters nucleus to induce transcription; stimulates protein synthesis; synthesizes enzymes involved in glucose metabolism
Aldosterone is the most prominent ___, cortisol is the most prominent ___, and testosterone is the most prominent. All are hormones of the ___ ___.
mineralocorticoid; glucocorticoid; gonadocorticoid; adrenal cortex
Which cells can be target cells for glucocorticoids?
most cells
What are gonadocorticoids and where are they synthesized?
sex hormones; the zona reticularis
Gonadocorticoids include ___ and ___.
androgens and estrogens
Androgens are the ___ sex hormones; a prominent example is ___
male; testosterone
The most prominent mineralocorticoid is ___; glucocorticoid is___; and gonadocorticoid is ___. They are all hormones of the ___ ___.
aldosterone; cortisol; testosterone; adrenal cortex
Androgens may be converted to ___ after ___
estrogens, menopause
Where are hormones synthesized in the adrenal medulla?
chromaffin cells
Chromaffin cells are innervated by ___ ___ ___.
cholinergic preganglionic neurons
The two main hormones of the adrenal medulla are ___ and ___
epinephrine and norepinephrine
Epinephrine accounts for __% of the total hormones produced by the ___ ___.
80%; adrenal medulla
Norepinephrine accounts for __% of the total hormones produced by the ___ ___.
20%; adrenal medulla
Another name for epinephrine is ___.
adrenaline
Another name for norepinephrine is ___.
noradrenaline
Epinephrine and NE are involved in "___ ___ ___", which is a response to ___.
"fight or flight"; stress
Fight or flight is a response to ___, and it triggers the hormones ___ and ___.
stress; norepinephrine and epinephrine
Norepinephrine and epinephrine are ___ hormones.
catecholamine
Catecholamines (i.e. __ and __) regulate ___ ___ __ and ___ ___.
epinephrine and NE; arterial blood pressure and fuel metabolism
Catecholamines stimulate ____s, adrenergic receptors.
GPCRs
Name the three main adrenal gland disorders.
Cushing's syndrome, Addison's disease, pheochromocytoma
Cushing's syndrome is a common name for ___.
hypercorticism
Hypercorticism is another name for ___ ___.
Cushing's syndrome
The main problem of Cushing's is the ___ of ___.
hypersecretion of cortisol
Cushing's is (rare/common). It is most common in people aged ___
rare; 20-50 years
The most common cause of Cushing's is a ___ ___, which leads to ___ ___ ___. Another less common cause is an ___ ___.
pituitary tumor; increased ACTH secretion; adrenal tumor
a pituitary tumor (as in Cushing's) leads to ___ ___ ___, which thereby leads to increased ___ levels.
increased ACTH secretion; cortisol
Increased ACTH secretion leads to ___ levels of ___.
increased levels of cortisol
ACTH stimulates the release of ___ by the ___ ___.
glucocorticoids (such as cortisol); adrenal cortex
Name external (visible) symptoms of Cushing's.
upper body obesity; rounded face; increased fat around face, back, and abdomen; decreased fat in extremeties; buffalo hump; increased infections; purple streaks on skin; acne
Name internal (not visible) symptoms of Cushing's.
hypertension; hyperglycemia; increased infections; hirsutism (increased androgen secretion)
What is the main problem of Addison's Disease?
dysfunction of adrenal cortex so that it cannot produce enough cortisol (and/or aldosterone)
With Addison's Disease, the ___ ___ cannot produce enough ___ and sometimes ___.
adrenal cortex; cortisol; aldosterone
What is the PRIMARY cause of Addison's?
destruction of the adrenal gland (by autoimmune, infection (such as TB), AIDS, or cancer)
What are some reasons why the adrenal gland may be destroyed, leading to Addison's?
autoimmune destruction, infection (such as TB), AIDS, cancer
What is the SECONDARY cause of Addison's?
adrenal insufficiency because of lack of ACTH from the pituitary gland
If the pituitary gland does not produce enough ___, the adrenal cortex will not produce enough ___ leading to ___ ___.
ACTH; cortisol; Addison's Disease
What is the main visible symptom of Addison's disease?
hyperpigmentation -- overall darkening of skin or patching of darker pigment
___ is seen in over ___% of all Addison's cases.
hyperpigmentation; 90%
What is hyperpigmentation? What is it a main symptom of?
Darkening of skin (overall or in patches); Addison's Disease
What causes hyperpigmentation?
there is no negative feedback to regulate ACTH secretion; too much ACTH is secreted; ACTH stimulates melatonin production so too much melatonin is present in the skin
Describe the secondary type of Addison's Disease.
the hypothalamus or anterior pituitary is impaired, leading to decreased ACTH levels, leading to decreased cortisol production
Hyperpigmentation is ___ observed in Secondary Addison's
not
Why is hyperpigmentation observed in primary Addison's but not secondary Addison's?
In primary, there are high ACTH levels; the ACTH isn't able to stimulate cortisol production, but it still stimulates melatonin production, leading to dark skin. In secondary, there is not enough ACTH.
ACTH levels are too ___ in Primary Addison's and too ___ in Secondary Addison's.
high; low
The problem (such as tumor) in Primary Addison's is located ___; for Secondary Addison's, it is located ___.
adrenal gland; pituitary gland
What is the treatment for Cushing's?
remove tumor; use drugs to inhibit formation of the hormones
What is the treatment for Addison's?
use replacement corticosteroids to control symptoms; people often receive both glucocorticoids and mineralocorticoids
What is the treatment for pheochromocytoma?
remove the tumor; use drugs to stabilize BP and heart rate
What is pheochromocytoma?
a rare tumor of the adrenal medulla; causes too much release of NE and epinephrine