Usmle 1 Endocrinology

• Endocrine:  Hormone travels through the blood stream

• • Exocrine: Secretion into anything but blood
•   • Pancreas 
•     • Exocrine Function 
•     • Secrete zymogens

• • Paracrine- works in the vicinity/surrounding area
•    • Somatostatin
•      • GI somatostatin only works in GI
•      • Pancreatic somatostatin only works in pancreas

• • Autocrine: secretion acts on the same cell that secreted it
•    • Wherever it is released is where it works
•    • Thymus and thymopoietin

• • Merocrine/Apocrine: Apex of the cell is secreted with the secretion
•    • Sweat glands all over body

• • Holocrine:  The whole cell is secreted with the secretion
•    • Sweat glands in groin and axilla

• Require second messengers because can’t get through cell membrane.

• • cAMP –used by SNS
• • cGMP – used by PNS

• Catabolism activated by phosphorylation's.

• Anabolism deactivated by phosphorylation

• • All have nuclear membrane receptor
•    • Except: cortisol
•       • has receptor in cytoplasm

• • Affect DNA:
•    • replication
•    • transcription
•    • translation

• Affects protein

• No second messenger needed

• Made by: renal parenchymal cells

• Signal: hypoxia (NOT anemia)

• Inhibitor: increased oxygen

• Where it goes: bone marrow

• What it does: erythropoiesis

• Second messenger: tyrosine kinase

• First….check erythropoietin

• Normal erythropoietin below

• • Gaisbock syndrome
•   • hypertension 
•   • erythrocytosis without         
•      • splenomegaly
•      • leukocytosis
•      • thrombocytosis

• Stress polycythemia

• • Spurious (not real) 
•    • Due to loss of plasma volume

• Decreased erythropoietin

• You have a cancer !!!!!!!!

• Bone marrow is acting on its own

• • POLYCYTHEMIA RUBRA VERA
•    • Hct > 60%

• • Essential thrombocythemia
•    • platelets >600k

• • Increased erythropoietin
•    • due to hypoxia

• • Acute hypoxia
•    • tachypnea and dyspnea

• • Chronic hypoxia
•    • clubbing
•    • angiogenin-new vessels

• • Restrictive LD
•    • COPD

• • RENAL CELL CARCINOMA-     
•    • adults
•    • Wilms tumor in children

• • Where it came from
•   • Zona Glomerulosa

• • Stimulus:
•   • hypovolemia
•   • hyponatremia
•   • hyperkalemia

• • Inhibition: 
•   • hypervolemia

• • Where it goes:
•   • Late DCT of Kidney

• • What it does: 
•   • stimulate synthesis of Na-K pumps

• • Second messenger: 
•    • none

• Adrenal Insufficiency (too little)

• • MCC: 
•   • 21-hydroxylase Deficiency
•     • Hypovolemia → ↓Na/↑K
•     • Female pseudohermaphrodite

•   • 11- hydroxylase Deficiency
•     • HTN → ↑Na/↓K

• • In adults:
•   • Abrupt withdrawal of steroids
•   • Autoimmune adrenalitis

• • Over production
•   • Serum Na ↑
•   • HypoKalcemia
•   • ↑ BP: more likely to depolarize

• From:
•   • Zona Reticularis

• • Stimulus:
•   • Controls male external genitalia in utero
•   • Increase in appetite
•   • Aggression and violence
•   • Increases libido and RBC count

• • Stimulated by:
•   • ACTH

• Second messenger: none

• • DHT:
•   • made in testes by 5 alpha reductase

• Leads to secondary male characteristics at puberty.

• Responsible for hair growth

• Too much leads to hair loss, especially in the middle and front of scalp

• • Male patterned baldness
•   • FENESTERIDE blocks 5 alpha reductase
•   • FLUTAMIDE blocks DHT receptors

• • Epinephrine: immediately
• • Glucagon: within 20 minutes
• • Cortisol: within 2 to 4
• • GH: after 24 hours
• • Insulin: within 30 min
• • ADH: within 30 min

• • From:
•    • Adrenal Medulla

• • Stimulus:
•    • Stress/Hypoglycemia

• • Inhibition:
•    • hyperglycemia

• • Where it goes:
•    • liver and
•    • adrenal cortex

• • What it does:
•    • gluconeogenesis;
•    • glycogenolysis

• Second messenger: c-AMP

• An excess of NE and Epi

• • Pheochromocytoma (Adult)
•   • Adrenal medulla tumor
•   • Diaphoresis
•   • MEN II

• • Neuroblastoma (Child)
•   • Hypsarrhythmia (dancing eyes)
•   • opsoclonus (dancing feet)
•   • Highest regression rate
•   • MC abdominal CA in children
•   • (+) Posterior Mediastinum

• Rule of 10’s

• •Dx:
•   • In urine
•     • VMA (Vanillylmandelic Acid)
•     • metanephrines 
•     • If elevated: VMA, Metaneph
•       • CT     
•       • MRI
•   • Phentolamine
•     • short acting α1 Blockers

• • Tx:
•   • phenoxybenzamine
•     • longer acting, not specific

• • 10% malignancy
• • 10% bilateral
• • 10% Familial
• • 10% Metastatic
• • 10% Seen in children

• within 2- 4 hours

• • Where it came from:
•   • Zona Fasciculata

• • Stimulus:
•   • stress
•   • hypoglycemia

• • Inhibitor:
•   • hyperglycemia

• • Where it goes:
•   • everywhere >PERMISSIVE

• • What it does:
•   • Proteolysis   
•     • Gluconeogenesis
•   • up regulates ALL receptors during stress

• • Second messenger:
•   • none

• • Too much:
•   • Pituitary adenoma:
•   • Cushing’s disease 
•   • to much ACTH

•   • Small cell carcinoma:
•     • Cushing’s disease

•   • Adrenal adenoma:
•     • Cushing’s syndrome

• • Disease affects one organ
• Syndrome affects many organs

• • Too little:
•   • Adrenal insufficiency (Addison's)

• • Stimulus:
•   • Growth
•   • Stress

• • Inhibited: 
•   • Hyperglycemia

• • Fxn: 
•   • Proteolysis

• • Second messenger:
•   • tyr-kinase

• Don’t have enough

• Get short stature (rare cause)

• • If somatomedin did not work anywhere in the body:
•    • Pygmies

• • Achondroplasia (AD)
•   • Dwarfism
•   • FGF receptor 3
•   • Cell signaling defect
•   • Head and Trunk are normal size but have short limbs

• • Laron Dwarf
•   • Somatomedin receptor insensitivity at extremities only
•   • Tyr-kinase not working
•   • Symmetrical everywhere

• Too much Acromegaly

• “My clothes don’t fit” 

• • Growth is not symmetrical
•   • coarse features

• • Responds to all the new glucose around
•    
• • osmolarity relationship
•    
• • pushes the sugar into cells

• Antidiuretic hormone

• normalizes the osmolarity

• helps blood vessels constrict and helps the kidneys control the amount of water and salt in the body

• • Glucagon
• • Insulin 
• • Somatostatin
• • Pancreatic Polypeptide

• • From:
•    • pancreatic alpha cells 
•    • β1 receptors

• • Stimulus:
•    • hypoglycemia and
•    • stress

• Inhibition: hyperglycemia

• • Where it goes:
•    • adrenal cortex
•    • liver
•    • adipose tissue

• • What it does:
•    • gluconeogenesis 
•       • raises sugar
•    • glycogenolysis (glycogen)
•    • lipolysis (fat)
•    • ketogenesis

• Second messenger: c-AMP

• Pancreatic tumor

• • ↑ glucose
• • ↑ lipids
• • ↑ ketones

• Related to MEN I (Wermer’s)

• • Hormone responsible for
•   • KETOACIDOSIS 
•   • type 1 diabetes

• • From:
•   • pancreatic islet cells β cells
•     • β2 receptors
•     • α2 receptors

• • Stimulus:
•    • hyperglycemia

• • Inhibition:
•    • hypoglycemia

• • Where it goes:
•    • everywhere except BRICKLE

• • What it does:
•    • increase all anabolic processes

• • Second messenger:
•    • tyrosine kinase

• Brain

• RBC

• Intestinal Wall

• Cardiac

• Kidney

• Liver

• Exercising muscle

• • INSULINOMA
•    • Seen primarily in adults
•    • Causes hypoglycemia
•    • Measure high insulin and high C-peptide

• • Dx: cat scan
• • Tx: remove surgically

• • NESSIDIOBLASTOSIS
•    • seen primarily in infants
•    • Causes hypoglycemia
•    • Measure high insulin and high C-peptide

• Tx: subtotal pancreatectomy

• • Diabetes I
•    • DKA

• • Diabetes II
•    • No DKA

• • DKA = Diabetic ketoacidosis
•   • develops when your body doesn't have enough insulin to allow blood sugar into your cells for use as energy.

• • From:
•    • pancreatic DELTA cells

• • Stimulus:
•    • insulin 
•    • glucagon

• • Inhibition:
•    • low insulin
•    • glucagon

• • Where it goes:
•    • paracrine

• • What it does:
•    • inhibits insulin and glucagon

• • Second messenger:
•    • c-AMP

• Usually a pancreatic tumor

• • MEN I
•    • Severe constipation

• Dx: cat scan

• Tx: surgery

• from ‘F’ cells

• • only know organ with no
• known function?