Neuronal Communication Weak Areas Flashcards
MS is an autoimmune disease that damages the nervous system. Suggest how the immune system causes damage to the nervous system
Antigens on the neurone activates the immune system
Antibodies are produced that are specific to neurone’s antigen
Allows phagocytes to break down the myelin sheath
Why is transmission of AP along an axon slower in the absence of saltatory conduction?
The whole axon needs to be depolarised
No nodes of Ranvier to allow the jumping of an action potential from one node to another along the axon
TTX is also known to reduce the speed of conduction in the purkyne fibres of the heart. Suggest and explain the effect this would have on the heart
Heart rate would reduce because :
The rate of transmission of the nerve impulse from the AVN to the purkyne fibres would be lower, this reduces the rate of ventricular systole
TTX can cause paralysis and death within minutes - it is a neurotoxin. TTX binds to external surface of the voltage gated sodium ion channels in the axon membrane which changes their 3” structure of the channel. This means the membrane channel can’t open.
Using this info explain how TTX affects the activity of the neurones.
No Na+ ions are able to move across the membrane
This means that the membrane can’t be depolarised
Therefore membrane potential remains at resting as no generator potential is established due to change in the potential difference that Na+ causes the membrane
This means that no action potential can be generated and therefore there is no release of a neurotransmitter across a synapse to carry the nerve impulse.
