Suprarenal Glands

• Divided into two parts; each with separate functions

• Suprarenal Cortex

• Suprarenal Medulla

The Adrenal Cortex

Figure 25.9a

C. The Adrenal Glands

• Adrenal medulla

• Adrenal cortex

Three specific zones and each produces a specific class of steroid hormone

Zona glomerulosa – mineralocorticoids (Aldosterone)

Zona fasciculata – glucocorticoids ( Cortisole )

Zona reticularis - androgens

Hormones of the Adrenal CortexHormones of the Adrenal Cortex

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

Glucocorticoids (including cortisone and cortisol)

Produced in the middle layer of the adrenal cortex

Promote normal cell metabolism

Help resist long-term stressors

Released in response to increased blood levels of ACTH

Hormones of the Adrenal CortexHormones of the Adrenal Cortex

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

Sex hormones

Produced in the inner layer of the adrenal cortex

Androgens (male) and some estrogen (female)

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

• Excess aldosterone causes hypokalemia & muscle

weakness, & too little aldosterone causes

hyperkalemia & cardiac toxicity

• Excess aldosterone increases tubular (intercalated

cells) hydrogen ion secretion, with resultant mild

alkalosis

• Aldosterone stimulates sodium & potassium

transport in sweat glands, salivary glands, &

intestinal epithelial cells

Functions of mineralocorticoids

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

Figure 21.15

Hormones of the Adrenal CortexHormones of the Adrenal Cortex

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

Figure 9.10

Renin-angiotensin-aldosterone axis• Principal factor

controlling Ang II levels is renin release.

• Decreased circulating volume stimulates renin release via:– Decreased BP (symp

effects on JGA).– Decreased [NaCl] at

macula densa (“NaCl sensor”)

– Decreased renal perfusion pressure (“renal” baroreceptor)

REGULATION OF CORTISOL SECRETIONHYPOTHALAMUS

CRH

ANTERIOR PITUITARY

ACTH

ADRENAL CORTEX

TARGET ORGANSCORTISOL

STRESSDIURNALRHYTHM

+ +-

-INCREASEDBLOOD GLUCOSEBLOOD AABLOOD FATTY ACIDS

Pathway of RAAS

Figure 6.12b

• Atrial natriuretic peptide

• Decreased blood pressure stimulates renin secretion

Renin

Aldosterone

Adrenalcortex

Corticosterone

Angiotensinogen

(Lungs)

renal blood flow &/or Na+

++ Juxtaglomerular apparatus of kidneys

(considered volume receptors)

Angiotensin I

Convertingenzymes

Angiotensin II(powerful

vasoconstrictor)

Angiotensin III(powerful

vasoconstrictor)

• Renin-Angiotensin System:

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

Renin-Angiotension-Aldosterone System

Na+ Reabsorption

• Angiotensisn II can raise blood pressure by:

– vasoconstrictor effects.

– stimulating aldosterone secretion.

Insert fig. 17.26

nephron

low

Blood Osmolarity

blood osmolarityblood pressure

ADH

increasedwater

reabsorption

increasethirst

renin

increasedwater & saltreabsorption

high

pituitary

angiotensinogenangiotensin

nephronadrenalgland

aldosterone

JuxtaGlomerularApparatus (JGA)

Ooooooh!Zymogen!

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 to deal with short-term stress

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

C. Disorders of the Adrenal Gland

1. Hypoaldosteronism

loss of water/Na+

Addison’s disease – low aldosterone & cortisol

2. Hyperaldosteronism

3. Cushing’s syndrome

hypersecretion of cortisol,androgens,aldosterone

Adrenal glands can malfunction

• Cushing syndrome – hypersecretion of glucocorticoids by the adrenal cortex characterized by weight gain in the trunk of the body but not arms and legs

15.4 Adrenal glands

Cushing’s Disease

• Proximal muscle wasting & weakness

• Osteoporosis• Glucose intolerance• HTN, hypokalemia• Thromboembolism• Depression, Psyc• Infection• Glaucoma

Adrenal glands can malfunction

• Addison’s disease – hyposecretion of glucocorticoids by the adrenal cortex characterized by bronzing of the skin

15.4 Adrenal glands