Endocrinology intro Flashcards
What are the types of cell to cell communication
Autocrine: Cell secretes chemical messenger that binds to receptor on same cell
Paracrine: Cell produces signal to introduce change in nearby cells
Endocrine: Cell to cell, where cell secretes hormone into circulatory system to act upon distant target organs
Neural signalling: info from one cell to another through neurones
What structure can hormones have
Protein, small peptide, steroid, amines
Example of steroid hormones
Cholesterol derivatives:
Oestrogen
Aldosterone
Cortisol
What is cholesterols role
Important precursor
Example of protein and small peptide hormones
Protein: Insulin
Peptide: ADH
Example of amine based hormones
Epinephrine
Thyroxin
what does a hormones chemical structure affect? (3 effects)
1) Transportation in plasma
2) If it enters the cell or not
3) degradation and half life (how long it acts in the body)
Does testosterone enter the cell?
Yes, due to diffusion through the plasma bilayer, binding to nuclear receptors
How do epinephrine and peptide hormones get transported?
Hydrophilic, travel free in solution in plasma
Steroid and thyroid transportation?
VERY HYDROPHOBIC
carried in blood bound to a variety of plasma proteins including albumin
Plasma hormone binding proteins (3 proteins)
Albumin
Thyroxin binding globulin
Sex hormone binding protein
Do hormones and their respective proteins covalently bind?
NO.
Weak binding, to allow for equilibrium shifts.
What are the two receptor types?
Receptors on cell membrane for hydrophilic hormones
Inside the cell receptors for hydrophobic.
For cell membrane receptors, what is the mechanism?
Activation of a secondary messenger within a cell to promote release
e.g cAMP, Ca2+, cGMP
For receptors inside the cell, what is the mechanism?
Change in gene expression (stimulation or inhibition)
G protein coupled receptors
Go through membrane 7 times like a wiggle worm.
Fish bone structure
connected to GDP
activates cAMP
cAMP effects in the body
Heart- increase heart rate and contractility
Liver- Increase glycogenesis, and gluconeogenesis
Lung- relaxation of the bronchial smooth muscles
Tyrosine Kinase Receptors
Dimerization of hormone, creating a cross bridge.
Phosphorylation of tyrosine kinase, activates relay proteins through phosphorylation
two tyrosine receptors come together
INSULIN mechanism
Inside cell receptor mechanism
Receptor Dimer, binds to DNA, change in gene expression
Protein and peptide synthesis
Modification in ER to make active hormone
DNA—> RNA —-> POMC (proopiomelanocortin)
which is then fragmented and produces 3 hormones:
MSH,
ACTH
Endorphin
Steroid hormone synthesis
Cholesterol carbons modified.
No genes for cortisol, enzymatic reactions to create cortisol
Cholesterol—-> Pregnenolone—–> progesterone—–> Androgens+ estrogens
Progesterone—–> glucocorticoids—-> Mineralocorticoids
