Suprarenal Glands Divided into two parts; each with separate functions Suprarenal Cortex Suprarenal...
-
date post
21-Dec-2015 -
Category
Documents
-
view
223 -
download
1
Transcript of Suprarenal Glands Divided into two parts; each with separate functions Suprarenal Cortex Suprarenal...
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