Introduction Flashcards
What is autocrine signalling?
Chemicals affect the same cell that secreted them. Receptor expressed on the cell that secreted the chemical.
What is paracrine signalling?
Chemicals are secreted onto neighbouring target cells
What is endocrine signalling?
Chemicals diffuse into the blood stream (hormones) to reach target cells.
Compare the speed of endocrine and neural communciation
Endocrine: slower and duration of effect is longer (hours to days or longer)
Nervous system effects: minutes to hours
What are neurohormones
Neurons secrete neurotransmitters which diffuse into the blood stream and bind to target cell
Difference between endocrine and exocrine glands
Endocrine glands are ductless (secrete hormones into bloodstream)
Exocrine glands: substances travel from duct to the surface (do not release hormones)
What are the three main types of hormones
Peptide, steroid, amine
Explain brief synthesis of peptide hormone
Synthesised in the ER as preprohormone, cleaved as prohormone in golgi apparatus
- released via exocytosis via secretory vesicles
What are peptide hormones? Are they hydrophobic/philic, lipophobic/philic?
Amino acids of varying length. Are hydrophilic and lipophobic
What is the half life of peptide hormone
Short half life, only a few minutes
When are steroid hormones synthesised?
De novo, as needed
Where are steroid hormones synthesised?
Smooth ER of adrenals, placenta, gonads
What are steroid hormones derived from
Lipids (cholesterol mainly)
What extends the half-life of steroid hormones
Bound to carrier proteins in plasma, prevents metabolism of steroid hormones
Where the receptors in a peptide hormone, compared to steroid hormone?
Peptide: cell surface
Steroid hormone: cell membrane, nucleus, cytoplasm
