Signalling between Cells 1 Flashcards
Why do cells need to communicate?
Process Information - sensory stimuli
Self Preservation
- spinal reflexes
- Sympathetic nervous system
Voluntary Movement
Homeostasis
- Thermoregulation
- Glucose Homeostasis
What happens during Hypoglycaemia?
Glucagon - secreted by alpha cells in the IoL
Stimulates gluconeogenesis and glycogenolysis in the liver
What happens during Hyperglycaemia?
Insulin - secreted by beta cells in the IoL
- it has paracrine effects
- inhibits glucagon secretion by nearby alpha cells
- has endocrine effects on liver cells.
Examples of Paracrine Signalling?
Nitric Oxide produced by endothelial cells in blood vessels
Osteoblast activating factors produced by adjacent osteoblasts
Describe signalling between membrane attached proteins?
- blood borne virus detected in the blood stream by an APC
- APC digests the pathogen and expressed MHC class II on the surface.
- T-lymphocytes engages with the MHC molecule through TCR interaction
Describe Autocrine Signalling?
- Activated T lymphocyte initiates cascade of reactions
- Activated T lymphocyte IL-2 receptor on surface
- Activated T lymphocyte secrete IL-2
- IL2 binds to receptor on its own surface having an effect on its cell
Describe signalling at the Neuromuscular Junction?
- VGSC opens –> membrane depolarisation
- VGKC opens –> membrane repolarisation
- VGCC -> Calcium influx -> vesicle exocytosis
- Acetylcholine binds to sarcolemmal nicotinic receptors
- ACh is metabolised by cholinesterase and recycled
- Ca2+ is a second messenger
Identify Receptor Types?
Ionotropic Receptor - ligand binding opens an ion permeable pore
G-protein coupled receptor - ligand binding activates intracelllar G-protein
Enzyme-linked receptor - ligand binding leads to receptor clustering which activates internal enzymes.
Intracellular Receptor - a membrane permeable ligand binds to a receptor inside the cell.
