Adrenal_physiology by_Abdul_Qahar(A_Q)
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Transcript of Adrenal_physiology by_Abdul_Qahar(A_Q)
Presenting By Abdul Qahar (A Q)Presenting By Abdul Qahar (A Q)
Buner CampusBuner Campus
Edited, Prepared and shared ByEdited, Prepared and shared ByAbdul QaharAbdul Qahar
I. I. IntroductionIntroductionAdrenal GlandsAdrenal Glands
• suprarenal – they sit on top of the kidneys
• each is composed of 2 distinct regions:
A. A. Adrenal MedullaAdrenal Medulla - the inner region - comprises 20% of the gland - secretes epinephrine and
norepinephrine - derived from ectoderm
B. B. Adrenal Adrenal CortexCortex
• the outer regionthe outer region• comprises 80% of the comprises 80% of the
glandgland• secretes corticosteroidssecretes corticosteroids• derived from mesodermderived from mesoderm
1) Zona Glomerulosa 1) Zona Glomerulosa (outermost region)(outermost region)
- produces mineralocorticoids (aldosterone)
2) Zona Fasiculata 2) Zona Fasiculata (middle region)(middle region)
- produces glucocorticoids (cortisol) as well as estrogens and androgens
3) Zona Reticularis 3) Zona Reticularis (innermost region)(innermost region)
- same function as zona fasiculata
DHEA – dehydroepiandrosteroneDHEA – dehydroepiandrosterone• an adrenal androgen in females• responsible for growth of pubic and axillary hair
CC. Pathologies Associated with . Pathologies Associated with Adrenal Adrenal Androgen Androgen HypersecretionHypersecretion
1.1.Adrenogenital SyndromeAdrenogenital Syndrome - hypersecretion of androgens or estrogens- hypersecretion of androgens or estrogens
a) a) in the adult femalein the adult female:: - masculinization (i.e. hirsutism)- masculinization (i.e. hirsutism)
b) b) in the female embryoin the female embryo:: - female pseudohermaphroditism- female pseudohermaphroditism
c) c) in the adult malein the adult male:: - no effect- no effect
d) d) in young boysin young boys:: - precocious pseudopuberty- precocious pseudopuberty
II. Mineralocorticoids II. Mineralocorticoids (Aldosterone)(Aldosterone)A. A. FunctionsFunctions - promotes reabsorption of Na+ and
secretion of K+ from the distal portion of the nephron
B. B. Regulation of SecretionRegulation of Secretion1. Renin Angiotensin - Angiotensin II stimulates aldosterone secretion
2. Potassium - high levels of K+ induce aldosterone
secretion 3. ACTH
- no direct role
C. C. PathologiesPathologies 1. Hypersecretion1. Hypersecretion
a. a. primary hyperaldosteronismprimary hyperaldosteronism - Conn’s syndrome- Conn’s syndrome
- usually due to a tumor on the gland- usually due to a tumor on the gland
- too much secretion of gland itself- too much secretion of gland itself
b. b. secondary hyperaldosteronismsecondary hyperaldosteronism - default in renin angiotensin system- default in renin angiotensin system
- most common in atherosclerosis of - most common in atherosclerosis of renal arteries renal arteries
2. Hyposecretion (defer to 2. Hyposecretion (defer to later)later)
III. Glucocorticoids III. Glucocorticoids (Cortisol)(Cortisol) A. Metabolic Effects - overall effect: increase plasma glucose
levels, often at the expense of proteins and fats
1. CHO Metabolism a. gluconeogenesis
cortisol helps convert skeletal muscle protein to CHO’s and eventually
glycogen
b. decrease glucose utilization(anti- insulin effect)
2. Protein 2. Protein MetabolismMetabolism - proteins are mobilized by cortisol to be converted to CHO’s in a fasting state
- lean body mass decreases
3. Fat Metabolism3. Fat Metabolism - cortisol causes lipolysis (inhances
catecholamines) - expectations: person will be thin, but
if excessive cortisol see unusual fat distribution (i.e. “buffalo hump”)
4. Increases Hunger4. Increases Hunger
B. Other EffectsB. Other Effects
1. 1. Fetal DevelopmentFetal Development
• Cortisol aids in maturation of the lungs, especially with the production of surfactant
• Maturation of g.i. enzymes
B. Other Effects AdultsB. Other Effects Adults 1. 1. StressStress
- Hans Selye: experimented by stressing animals
- results: stress is associated with increased levels of glucocorticoids
- explanation: glucocorticoids mobilize a pool of amino acids to construct needed proteins or enzymes to face the stress
B. Other Effects (cont.)
2. Anti-inflammatory - during tissue damage, phospholipase A2 activity
increases releasing arachadonic acid to aid in synthesis of prostaglandins & leukotrienes - glucocorticoids enhance production of
macrocortin which inhibits phospholipase A2 and thus the inflammatory response
3. Immune Response - glucocorticoids suppress the immune system
by decreasing the number of T lymphocytes - used frequently after organ transports
B. Other Effects (cont.)
4. Vasoconstriction - Glucocorticoids necessary for
vasocontrictioneffects of the catecholamines
5. Stimulates Erythropoietin
6. Increases Bone Reabsorbtion
7. Decreases REM Sleep
C. RegulationC. Regulation - it’s a classic negative feedback system
- low glucocorticoid levels cause the hypothalamus to secrete corticotropin releasing hormone (CRH) - CRH and low glucocorticoid levels cause
the anterior pituitary to release ACTH - ACTH stimulates glucocorticoid
production at the adrenal cortex* Stress and hypoglycemia can also trigger the
release of CRH
D. D. PathologiesPathologies
1) 1) HypersecretionHypersecretion - Cushing’s Syndrome - caused by too much exogenogeous cortisol,
too much ACTH, an adrenal tumor, or ACTH secreting tumor
–Symptoms»Proteolysis»Moon-faced and buffalo hump
) )
D. D. Pathologies CONT.Pathologies CONT.2) 2) HyposecretionHyposecretion a) a) Primary Adrenal Cortical Primary Adrenal Cortical InsufficiencyInsufficiency
- Addison’s Disease - due to autoimmuno destruction of
the gland
b) b) Secondary Adrenal Cortical Secondary Adrenal Cortical InsufficiencyInsufficiency
- due to too little ACTH
EICOSANOIDSEICOSANOIDS
ARACHIDONIC ACID
prostaglandinsprostaglandins
leukotriensleukotriens
thromboxanesthromboxanes
prostacyclinsprostacyclins
Prostaglandin Nomenclature
•3 Groups•PGA•PGE•PGF
•Double BondsDouble Bonds
•Optical IsomerOptical Isomer
Prostaglandin Functions
• Reproduction
• Respiratory
• Nervous
• Immune
• MANY OTHERS!!
Abdul Qahar BuneriAbdul Qahar Buneri [email protected]
www.slideshare.net/abdulqahar045www.slideshare.net/abdulqahar045