Lecture 9 Flashcards
Peptide Hormones mode of action
- Can not penetrate target cells
- Bind to surface receptors and activate intracellular processes through second messengers
Steroid Hormones
- Penetrate plasma membrane and bind to internal receptors (usually in the nucleus)
- Influence expression of genes of the target cell
-It takes several hours to days to show effect due to lag for protein synthesis
2 Main Types of Receptors
- Intracellular receptors
- Plasma membrane receptors
Intracellular receptors
- Bind lipid soluble hormones
- Cytosolic and nuclear
- Directly alter gene transcription (cause genomic effects)
Plasma membrane receptors
- G protein-coupled receptors
- Receptor-enzyme receptors
- Receptor-Channel
Integrin Receptor
G Protein -Coupled Receptors (GPCR)
- Membrane-spamming proteins
- Cytoplasmic tail linked to a G protein
When GPCRs are activated, they…
- Open ion channels in the membrane
- Alter enzyme activity on the cytoplasmic side of the membrane
G protein: Gs
Target: Adenylyl cyclase
Activity: Stimulatory
G protein: Gq
Target: Phospholipase C
Activity: Simulatory
G protein: Gi
Target: Adenylyl cyclase
Activity: Inhibitory
Liver- Fight or Flight Responses mediated by GPCR
Glucose release (epinephrine)
Fat- Fight or Flight Responses mediated by GPCR
Fatty acid release (epinephrine)
Heart- Fight or Flight Responses mediated by GPCR
Muscle contraction (epinephrine)
Skeletal muscle blood vessels- Fight or Flight Responses mediated by GPCR
Less vasoconstriction (norepinephrine)
Intestine, skin and kidney-Fight or Flight Responses mediated by GPCR
Vasoconstriction (norepinephrine)