Adrenal Gland Lecture 8-9

7/31/2019 Adrenal Gland Lecture 8-9

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Suprarenal Glands

Divided into two parts; each with separate

functions

Suprarenal Cortex

Suprarenal Medulla


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The Adrenal Cortex

Figure 25.9a


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C. The Adrenal Glands

Adrenal medulla

Adrenal cortexThree specific zones and each produces a specificclass of steroid hormone

Zona glomerulosa mineralocorticoids (Aldosterone)

Zona fasciculata glucocorticoids ( Cortisole)Zona reticularis - androgens


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Hormones of the Adrenal CortexHormones of the Adrenal Cortex

Slide 9.29aCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Glucocorticoids (including cortisone andcortisol)

Produced in the middle layer of the adrenalcortex

Promote normal cell metabolism

Help resist long-term stressors

Released in response to increased bloodlevels of ACTH


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Slide 9.29bCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Sex hormones

Produced in the inner layer of the adrenalcortex

Androgens (male) and some estrogen(female)


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Functions of mineralocorticoids

Aldosterone exerts the 90% of the mineralocorticoid

activity. Cortisol also have mineralocorticoid activity, but

only 1/400th that of aldosterone

Aldosterone increases renal tubular (principal cells)

reabsorption of sodium & secretion of potassium

Excess aldosterone ECF volume & arterial pressure, but

has only a small effect on plasma sodium concentration


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Excess aldosterone causes hypokalemia & muscle

weakness, & too little aldosterone causes

hyperkalemia & cardiac toxicity

Excess aldosterone increases tubular (intercalatedcells) hydrogen ion secretion, with resultant mild

alkalosis

Aldosterone stimulates sodium & potassium

transport in sweat glands, salivary glands, &

intestinal epithelial cells

Functions of mineralocorticoids


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Effect of cortisol on protein metabolism

Reduction of protein storage in all cells except

those of liver protein catabolism & protein

synthesis Cortisol increases liver & plasma proteins

Mobilizes aminoacids from non hepatic cells, thus

increase blood amino acid level.

amino acid transport to liver cells & transport

of amino acids into other cells

Functions of glucocorticoids


11/29Figure 21.15


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Slide 9.28bCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 9.10


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Renin-angiotensin-aldosterone axis Principal factor

controlling Ang II levelsis renin release.

Decreased circulatingvolume stimulates renin

release via: Decreased BP (symp

effects on JGA).

Decreased [NaCl] atmacula densa (NaClsensor)

Decreased renalperfusion pressure(renal baroreceptor)


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REGULATION OF CORTISOL

SECRETIONHYPOTHALAMUS

CRH

ANTERIOR PITUITARY

ACTH

ADRENAL CORTEX

TARGET ORGANS

CORTISOL

STRESSDIURNAL

RHYTHM+

+-

-INCREASED

BLOOD GLUCOSE

BLOOD AA

BLOOD FATTY ACIDS


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Pathway of RAAS


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Figure 6.12b


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Atrial natriuretic peptide

Decreased blood pressure

stimulates renin secretion


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Adrenal

cortexCorticosterone

Angiotensinogen

(Lungs)

(considered volume receptors)

Angiotensin I

Converting

enzymes

Angiotensin II(powerful vasoconstrictor)Angiotensin III(powerful vasoconstrictor)

Renin-Angiotensin System:

N.B. Aldosterone is the main regulator of Na+ retention.


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Renin-Angiotension-Aldosterone System


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Na+

Reabsorption

Angiotensisn II can raise

blood pressure by:

vasoconstrictoreffects.

stimulating

aldosterone secretion.

Insert fig. 17.26


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nephron

low

Blood Osmolarity

blood osmolarity

blood pressure

ADH

increasedwater

reabsorption

increasethirst

renin

increasedwater & saltreabsorption

high

pituitary

angiotensinogenangiotensin

nephronadrenal

gland

aldosterone

JuxtaGlomerularApparatus (JGA)

Ooooooh!Zymogen!


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Hormones of the Adrenal MedullaHormones of the Adrenal Medulla

Slide 9.30Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Produces two similar hormones(catecholamines)

Epinephrine

Norepinephrine

These hormones prepare the body todeal with short-term stress


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Effects of Epinephrine

Gets you ready to fight or run

Heightens your senses, tenses your muscles,

openings breathing passages, etc.

In response to stress

Take less than 30 seconds to kick in and last

several minutes


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C. Disorders of the Adrenal Gland

1. Hypoaldosteronism

loss of water/Na+

Addisons disease low aldosterone & cortisol

2. Hyperaldosteronism

3. Cushings syndrome

hypersecretion of cortisol,androgens,aldosterone

15 4 Adrenal glands


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Adrenal glands can malfunction

Cushing syndrome hypersecretion ofglucocorticoids by the adrenal cortex characterized

by weight gain in the trunk of the body but notarms and legs

15.4 Adrenal glands


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Cushings Disease

Proximal muscle

wasting & weakness

Osteoporosis

Glucose intolerance

HTN, hypokalemia

Thromboembolism

Depression, Psyc

Infection

Glaucoma

15 4 Adrenal glands


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Adrenal glands can malfunction

Addisons disease hyposecretion of

glucocorticoids by the adrenal cortex

characterized by bronzing of the skin

15.4 Adrenal glands

Adrenal Gland Lecture 8-9

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