Hormones secreted where
Into extracellular fluid; circulates in blood, hemolymph
Role of hormones
Communicates regulatory responses through interaction with a specific receptor
- Reproduction
- Development
- Energy metabolism
- Growth
- Behavior
Endocrine system
Chemical signaling by hormones
Levels of cellular regulation
Intracellular, local environment, systematic regulation
Intracellular regulation
Within the individual cells themselves (positive or negative regulation)
- Covalent modification
- Phosphorylation
Local environment regulation
Cells response to the immediate environment, including presence of other cells
- Local factors secreted by other cells
- Extracellular matrix
Systematic regulation
Provides integration of activities of cells distant from each other
- Endocrine system
- Nervous system
- Overlap between endocrine and nervous system
Endocrine signaling
Hormone enters the blood
Paracrine signaling
Hormone works on a neighboring cell
Autocrine signaling
Hormone works on itself
Neuroendocrine signaling
Neurons release hormone that then acts on a receptor on a cell
Hormones
Types of hormones
Steroids (lipids)- derivatives of cholesterol, derivatives of arachidonic acids (lipids), proteins/peptides, catecholamines, glycoproteins
Which hormones act via membrane receptor
Which hormones act via nuclear receptor
Hormone classification
-Amines
- Peptides
- Steroids
- Prostaglandins
Amines
Peptides
Steroid hormones
Prostaglandins
Derived from arachidonic acid
Examples of steroid hormones
Plasma membrane receptors
RTK signaling (EGF-EGFR)
-hormone binds to receptor and induces receptor dimerization with other nearby RTK
- Cytoplasmic kinase domains are activated
- Receptor becomes autophorsphorylated on tyrosine residues
- Results in creation of binding sites for an addutional factor which activates the subsequent signaling pathway (2nd messenger system)
JAK/STAT signaling (Growth hormone)