Hormone transport and kinetics

Question 1

What is the function of hormone transport proteins?

Answer 1

Hormone reservoir
hormone buffer
reduce hormone loss via kidneys

Question 2

Describe fast vs slow hormonal action

Answer 2

Fast e.g., epinephrine:
- rapid release from adrenal medulla
- immediate action on tissues
- fast return to normal
- water-soluble hormone
- enzymatically degraded in cell

Slow e.g., throxine (T4)
- circulates bound or free
- bound = resistant to degradation
- either converted into T3 => enters cells and alters gene expression
- or converted into water-soluble compounds by liver and excreted in kidney

Question 3

What factors affect hormone response?

Answer 3

Variation by tissue - different tissue respond to different hormones
Variation by time - initial response may differ to delayed response
Variation by dose - hormone levels outside physiological range may cause different responses
Status of target tissue - overstimuation => hypertrophy, understimulation => atrophy

Question 4

What methods are used to measure hormone levels?

Answer 4

Radioimmunoassay (RIA) - highly sensitive
Enzyme-linked immunosorbent assay (ELISA)