SIGNALLING IN THE BODY Flashcards
How do adjacent cells cells signal to each other?
Through gap junctions
What is interactive signalling?
Signalling within itself
What is autocrine signalling?
Hormone acting on the same cell but leaves the cell first
What is juxtacrine signalling?
Cells that have physical contact can signa, to each other
What is paracrine signalling?
Secreted hormones that reach target cell by simple diffusion- happens between close cells
What is endocrine signalling?
When a cell/gland secretes hormones into the extracellular fluid which can then be carried to distant cells/tissues/organs
How are neuronal and hormonal signals different?
Neurone can communicate short distances whilst hormones are sent long distances
Neuronal messages induce rapid responses whilst hormones induce slower responses
Neuronal messages are reversible whilst hormonal messages are irreversible
What are neuralgia?
The support cells of the nervous system- they provide nutrients, destroy and digest dead neurone, regulate the content or the extracellular space and hold neurones in place, they can also insulate neurones and modulate neurotransmission
What is a nerve?
A bundle of axons in the PNS
What are tracts?
Bundles of nerve fibres in the CNS
Describe the structure of a nerve?
Axons are surrounded by myelin . Many axons bundle together and are surrounded by the endoneurium.
A bundle of nerve fibres are then surrounded by a perineurium to form a fasciculus. Many fasciculus come together to form a nerve which is surrounded by an epineurium
Outline the steps of synaptic transmission?
Action potential arrives at the axon terminal
Voltage gated Ca2+ channels open and Ca2+ enters the cell
This signals vesicles to move to the membrane
Docked vesicles release neurotransmitters by exocytosis
Neurotransmitters diffuse across the synaptic cleft and bind to receptors
