Ch. 5 Endocrinology Principles

Question 1

Hydrophilic Hormones

Answer 1

• highly water soluble
• short (peptide) or long (protein)
• insulin
• catechholamines: derived from tyrosin and secreted from adrenal medulla
  ex. norepinephrine, epinephrine and dopamine
• 50% free and 50% bound to plasma
• receptor site:: surface of target cell
• mechanism: activates second messenger system to alter activity of proteins

Question 2

Lipophilic

Answer 2

• high lipid solubility
• thyroid and steroid hormones
• produced from tyrosin and secreted from thyroid gland
• derived from cholestrol and secreted from adrenal cortex and gonads
• receptors: on DNA of cell; inside target cell
• mechanism: activation of specific genes to make new proteins that produce the effect

Question 3

cAMP Mechanism

Answer 3

G-protein- alpha is activated- adenylylcyclase (enzyme)- ATP triggers cAMP- protein Kinase A- ATP becomes ADP- activates protein+P1- celllar response

Question 4

Calcium Mechanism

Answer 4

G-protein- alpha breaks down- phoso-lipase C (PLC)- PIP2 (phosphatidylinositolBiphosphate)

• Insitol triphosphate- cytosolic ca+ in ER- calmodulin protein- ATP becomes ADP- target protein+P1- cellular response
• diacyl glycerol- PCK- ATP to ADP- protein +P1- cellular response

Question 5

Mechanism of Lipophilic Hormones (steroid)

Answer 5

• diffuse through plasma and nuclear membranes and binds with a nuclear receptor specific for it
• hormone receptor complex binds with hormone response element, a segment of DNA specific for the hormone receptor complex
• DNA binding activates specific genes, producing RNA
• RNA leaves nucleus
• in cytoplasm, RNA directs synthesis
• new proteins accomplish target cell’s response to hormone