WRITTEN NOTES Flashcards
Cell signalling:
Autocrine?
Paracrine?
Endocrine?
auto - cell signals itself
para - signals immediately adjacent cells
endo - signalling molecule enters circulation & transported by blood to target distant cells.
which hormone types are hydrophilic and which are hydrophobic?
hydrophilic - amines, peptides & proteins.
hydrophobic - steroid hormones
what is the primary determinant of plasma concentration in the control of hormone levels?
rate of secretion (negative feedback maintains plasma concentration at set level
how do rate of elimination and secretion contribute to hormone concentration?
plasma concentration of hormone = rate of secretion - rate of excretion
which hormone types have the longest and shortest half-life?
amines (adrenaline): ~seconds
proteins & peptides: ~mins
steroids & thyroid hormones: ~hours-days (due to extensive protein binding that suppresses elimination.
what are the 3 types of hormone receptors?
G-protein coupled (GPCR) - cell surface
Receptor kinases - cell surface
Nuclear receptors - intracellular
Describe GPCRs.
activated by amines & some proteins/peptides; major signalling pathways include complying to G2, Gi or Gq.
Ligand is hydrophilic
Describe receptor kinases.
activated by proteins/peptides - hydrophilic ligand
Describe nuclear receptors.
Class 1 - activated by steroid hormones (when ligand is absent most are located in the cytoplasm bound to inhibitory heat shock proteins - move into nucleus when activated).
