Neuronal Communication Flashcards
Make the gap between two adjacent Schwann cells along the length of a neurone (1)
Node of Ranvier
Describe how the resting potential is established and how it is maintained in a sensory neurone (4)
TIP Sodium Potassium Pump
1) Sodium-potassium pump uses ATP
2) Sodium ions are actively pumped out of cell while potassium ions are actively pumped in
3) Potassium ions can freely diffuse out of the cell
4) whereas the membrane is less permeable to sodium ions and so fewer Na+ diffuse back in
5) The Na/K pump actively moves 3 Na+ out of and 2K+ into the axon
Outline how the first neurone communicates with the second neurone across the synapse (3)
1) Acetylcholine is released from pre-synaptic membranes
2) and diffuses across the synaptic cleft / reaches the second neurone by diffusion
3) and then attaches to receptors on post-synaptic membranes
Outline the importance of junctions between neurones in the functioning of the nervous system (3)
1) Ensures movement of action potential occurs in one direction only
2) and means one neurone can transmit impulses to many neurones
3) and further allows for summation to occur
How does the synapse allow transmission in only one direction (1)
Only the pre-synaptic neurone releases acetylcholine
Outline the events following the arrival of an action potential at the synaptic knots until the acetylcholine has been released into the synapse (3)
1) Calcium channels open
2) and calcium ions diffuse into
3) neurotransmitter in vesicles
Why is the pan Indian corpuscle described as a transducer (1)
It converts mechanical energy into the firm of electrical energy
Why does the generation of an action potential follow the All or Nothing law (1)
If the depolarisation of the membrane is insufficient then an action potential is not generated
Suggest why deformation of the plasma membrane of the tip of the neurone causes the membrane to become more permeable to sodium ions (2)
1) The increase in pressure causes sodium ion channels to open
2) Furthermore, the deformation results in temporary gaps in the phospholipid bilayer
Describe how the information about strength and intensity of a stimulus is communicated to the brain (2)
1) The information about intensity is represented by the frequency of the action potentials
2) which in turn means that high frequency of action potentials show an intense stimulus
What are the 4 stages of an action potential (4)
1) Resting potential
2) Depolarisation (becomes more positive as concentration of Na+ is higher outside cell)
3) Repolarisation (occurs due to movement of K+ out of cell when K+ channels open)
4) Hyperpolarisation (occurs when too many K+ leave the cell and ensures neurone can rest briefly between action potentials)
What’s the difference between a motor and sensory neurone in terms of den drone and axons (2)
- Motor neurones have a long axon
* Sensory neurones have a long dendron
What happens at the centre of the pancinian corpsuscle when the sensory receptor is activated to produce an action potential
1) The membrane at rest is polarised
2) it then becomes deformed due to pressure which results in the opening of Na+ channels which in turn causes Na+ to flood into the cell
3) thus causing depolarisation
What is spatial summation (1)
When 2 or more pre-synaptic neurones contribute to the post-synaptic potential
What is temporal summation (1)
When 2 or more IMPULSES IN THE SAME NEURONE contribute to a post synaptic potential
