Flashcards in The Endocrine System 2 Deck (12)
How were hormones historically measured?
Bioassays e.g. frog based pregnancy tests
What is now used to measure hormones?
Immunoassay and radioimmunoassay
How does radioimmunoassay work?
Purified hormone radioactively labelled and mixed with unlabelled hormone to compete for binding to antibody
High % of bound labelled hormone indicated low amount of unlabelled hormone
What else has been developed due to the concerns with using radioactive labels?
Labels that produce a colour change e.g. enzymeimmunoassays (EIA) and enzyme-linked immunosorbent assays (ELISA)
What is the basis of current home pregnancy tests?
An EIA variant
What is the disadvantage of antibody-based methods?
They may cross react with related molecules giving misleading results
What does it mean by endocrine glands are ductless?
The products are secreted directly into blood
What are most hormones? (Proteins, steroids or amines?)
How are proteins, steroids and amines produced?
Protein hormones produced by gene transcription and translation
Steroids and amines synthesised by enzymes
What are neurohormones that control hormone production by the pituitary gland called?
Give and example
Releasing hormones or factors
Gonadotropin releasing hormone (GnRH)
Where are steroid hormones produced in male testes?
Produced by Leydig cells, lying between the seminiferous tubules (where sperm production takes place)