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The Adrenal Glands Part 1

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Anatomy of the adrenal glands. Hypothalamic Pituitary Adrenal Axis ... Congenital adrenal hyperplasia ... and epinephrine (adrenaline): 'Fight or ... – PowerPoint PPT presentation

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Title: The Adrenal Glands Part 1


1
The Adrenal GlandsPart 1
  • ERM Lecture
  • 4/ 2007
  • Steven Chessler M.D., Ph.D.

2
  • Anatomy of the adrenal glands
  • Hypothalamic Pituitary Adrenal Axis
  • Renin-angiotensin system
  • Steroid hormones
  • Congenital adrenal hyperplasia (CAH)
  • Adrenal disorders
  • Adrenal hyperfunction (Cushings syndrome)
  • Adrenal insufficiency (Addisons disease and
    others)
  • Pheochromocytoma (adrenal medulla)

3
The Adrenal Glands
4
Adrenal Cross Section
5
Zones of the Adrenal Cortex
6
Adrenal Zonation and Vasculature
-blood flow -steroid gradient
7
Overview Hypothalamic-Pituitary-Adrenal (HPA)
Axis
8
PROCESSING OF POMC IN THE PITUITARY ACTH (and
MSH, beta-endorphin)
9
Addisons Disease effect of MSH activity
10
The HPA Axis and the Stress Response
  • Glucocorticoids trigger the release of sugar from
    body stores to provide quick energy for fight or
    flight.
  • Injected into the brain in animals, CRH causes
    arousal and behavioral changes suggesting fear or
    emotional distress.
  • Beta-endorphin (like ACTH a part of POMC)
    partially antagonizes these responses.

11
  • My mind sent a message to my hypothalamus, and
    told it to release the hormone CRF into the short
    vessels connecting my hypothalamus and pituitary
    gland.
  • The CRF inspired my pituitary gland to dump the
    hormone ACTH into my bloodstream. My pituitary
    had been making and storing ACTH for just such an
    occasion.
  • And some of the ACTH in my bloodstream reached
    the outer shell of my adrenal gland, which had
    been making glucocorticoids for emergencies.
    My adrenal gland added the glucocorticoids to my
    bloodstream. They went all over my body,
    changing glycogen into glucose. Glucose was
    muscle food. It would help me fight like a
    wildcat or run like a deer.
  • -Kurt Vonegut, Jr., Breakfast of Champions

12
Adrenal medulla also participates in stress
response
Adrenal Gland Glomerulosa Fasciculata Reticularis
Medulla
1. Efferent sympathetic inflow 2. Cortisol-rich
blood ? epinephrine release
Kidney
BDA
13
Cortisol and epinephrine (adrenaline)
  • Fight or flight hormones
  • Secretion increased 4-5 fold with marked
    stress -emotional or physical
  • Catabolic
  • Support/ defend blood pressure
  • Supply energy, e.g. glucose fatty
    acids -usually at the expense of anabolic
    processes, e.g. protein synthesis, fuel
    storage and growth

14
Source of plasma catecholamines
  • Norepinephrine
  • Almost all from sympathetic nerve fibers
  • Epinephrine
  • Almost all from adrenal medulla (85)

BDA
15
Physiological Effects of Glucocorticoids
16
(No Transcript)
17
The Hypothamic-Pituitary-Adrenal Axis
18
  • Anatomy of the adrenal glands
  • Hypothalamic Pituitary Adrenal Axis
  • Renin-angiotensin-aldosterone system
    (Kidney-Adrenal Axis)
  • Steroid hormones
  • Congenital adrenal hyperplasia (CAH)
  • Adrenal disorders
  • Adrenal hyperfunction
  • Adrenal insufficiency
  • Pheochromocytoma (adrenal medulla)

19
Components of RAA axis
  • Renin
  • Acts to start cascade
  • Angiotensin (II)
  • Aldosterone

BDA
(slide by Brad Anawalt, M.D.)
20
Function of R-A-A axis
  • Responds to changes in blood pressure sensed at
    the kidney
  • ? body Na content and blood volume
  • K homeostasis

(slide by Brad Anawalt, M.D.)
21
Glomeruli
(Modified from Ham AW. Histology. Philadelphia
JB Lippincott, 1969. by A. Dubrow and L.
Desimone)
22
Glomeruli
Renal sympathetic nerves
U
JG cells
Efferent arteriole
Afferent arteriole
(slide by Brad Anawalt, M.D.)
23
Stimulators of Renin Release
  • ? sympathetic/adrenergic activity
  • ? renal perfusion pressure
  • ? serum K
  • ? urinary lumen Na , macula densa

(B. Anawalt, M.D.)
24
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25
Angiotensin II increases blood pressure
  • vasoconstriction
  • - (direct effect on BP)
  • aldosterone
  • - (indirect effect on BP)

BDA
26
Aldosterone
BDA
27
Renin-Angiotensin-Aldosterone Axis
?
blood volume UNa near macula densa
BDA
28
Summary function of R-A-A axis
  • Initiate cascade to defend blood pressure
  • (renin)
  • ? body Na content and blood volume
  • (aldosterone)
  • ? arterial BP
  • (aldosterone angiotensin II )
  • K homeostasis
  • (aldosterone)

(slide by Brad Anawalt, M.D.)
29
11b-Hydroxysteroid Dehydrogenase in
Aldosterone-Sensitive Tissues Modulation of
Cortisol Levels
11bHSD2
  • Cortisol binds mineralacortidoid receptor
  • Impaired 11bHSD2 apparent mineralacorticoid
    excess -example licorice
  • Synthetic glucorticoids lower mineralacorticoid
    activity

30
  • Anatomy of the adrenal glands
  • Hypothalamic Pituitary Adrenal Axis
  • Renin-angiotensin system
  • Steroid hormone biosynthesis
  • Congenital adrenal hyperplasia (CAH)
  • Adrenal disorders
  • Adrenal hyperfunction (Cushings syndrome)
  • Adrenal insufficiency (Addisons disease and
    others)
  • Pheochromocytoma (adrenal medulla)

31
(No Transcript)
32
(No Transcript)
33
CAH 21-Hydroxylase Deficiency
34
CAH 21-Hydroxylase Deficiency
  • Salt-Wasting - severe hypotension often present
    from birth due to mineralocorticoid deficiency.
  • Simple virilizing form less severe
    mineralocoritcoid deficiency.
  • Nonclassical, late childhood and adult-onset
    form - Presents as androgen excess in females.
    May resemble Polycyctic Ovarian
    Syndrome. -hirsutism, acne, menstrual
    irregularity.

35
Ambiguous Genitalia in Congenital Adrenal
Hyperplasia
36
Neonatal Screening
37
ACTH Stimulation test for 21-Hydroxylase
deficiency
38
  • Anatomy of the adrenal glands
  • Hypothalamic Pituitary Adrenal Axis
  • Renin-angiotensin system
  • Steroid hormones
  • Congenital adrenal hyperplasia (CAH)
  • NEXT SESSION
  • Adrenal disorders
  • Adrenal hyperfunction (Cushings syndrome)
  • Adrenal insufficiency (Addisons disease and
    others)
  • Pheochromocytoma (adrenal medulla)
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