Case 4: Running on Empty Flashcards
What can hyperpigmentation be caused by? (3)
pregnancy, UV exposure, Addison’s Disease
What is p53? What does it do and what can it trigger?
Guardian of the Genome
senses DNA and cell health
can suspend proliferation for repair
DNA damage = p53 triggers apoptosis
In response to UV damage, what does p53 do? What does this substance cleave in to?
activation of gene which encodes POMC which cleaves into melanin stimulating hormone (MSH)
What does MSH stimulate?
stimulates melancortin 1 receptors
What do melancortin 1 receptors trigger?
production of 2nd messenger (cAMP)
What does cAMP do?
increases transcription of gene for melanin, therefore melanin pigment is produced
Once produced, where is melanin transferred from and to, why and how?
from melanocytes to keratinocytes
protect nuclei from DNA damage
via melanosomes
What are the layers of the medulla, cortex (3) and capsule?
adrenal medulla zona reticularis zona fasciculata zona glomerulosa capsule
What hormones are secreted from the medulla?
catecholamines (eg. adrenaline and noradrenaline)
What hormones are secreted from the zona reticularis?
sex hormones (eg. DHEA)
What hormones are secreted from the zona fasciculate?
glucocorticoids (eg. cortisol)
What hormones are secreted from the zona glomerulosa?
mineralcorticoids (eg. aldosterone)
Peptides: cell receptor site, signaling, soluble, half life, derived?
surface 2nd messenger water mins amino acids
Steroids: cell receptor site, signaling, soluble, half life, derived?
intra activates genes lipid days cholesterol
Thyroid hormones: cell receptor site, signaling, soluble, half life, derived?
intra activates genes lipid days iodinated tyrosine
Catecholamines: cell receptor site, signaling, soluble, half life, derived?
surface 2nd messengers water mins tyrosine
What are the three categories of adrenal steroids?
glucocorticoids
mineralcorticoids
sex steroids
What is cortisol? What does it do?
glucocorticoid
anti-insulin
decreases glucose uptake
permissive for the actions of catecholamines
vasoconstriction (decrease synthesis of NO)
increases bone reabsorption
What is cortisol useful for treating?
allergies
autoimmune
transplants
What are cortisol levels regulated by?
stress diurnal rhythm (high in morning due to anti-insulin properties)
What does ADH do?
conserves water
vasoconstriction
increase calcium influx
What triggers aldosterone release?
low BP and volume
What does aldosterone trigger?
increases renin secretion (which then increases angiotensin II which is RAAS system)
increased reabsorption of salt and water
Where are sex hormones secreted from? What are they regulated by?
zona reticularis
regulated by ACTH
What is a primary endocrine dysfunction?
problem with gland
What is a secondary endocrine dysfunction?
problem with under or over secretion of gland from higher pathway
What is a primary adrenocortical deficiency due to?
Addison’s disease
undersecretion
What is a secondary adrenocortical deficiency due to?
hypothalamic-pituitary disease
suppression of HPA axis due to chronically elevated steroid levels
What tests can be used to diagnose Addison’s disease? (4)
Cortisol level test (low)
Auto-antibodies test (adrenal antibodies)
Fasting glucose test (low)
ACTH stimulating test (minimal change after 30 mins)
What is an aldosterone deficiency due to?
zona glomerulosa not stimulated
What is an Addison’s crisis triggered by and what is treatment?
stress
injection of hydrocortisone
IV fluids
