Lab 9 Nervous System Flashcards
What is Chronaxie?
It’s the minimal duration that’s necessary to elicit an AP, if the stimulus strength is twice the Rheobase.
What factor determines if we have a monophasic or biphasic CAP?
The distance btw the electrodes
Define local response
The decreasing magnitude of potential change due to physical process
What is resting membrane potential?
The difference btw intra and extracellular space potential
What’s the name of the fibers leading impulses from organ to spinal cord?
Neuron fibers type Ia and type II
Explain exteroceptive reflex
Receptors outside of the effector organ
E.g in the skin and the effector is the muscle, pick up a signal and through an arch, reaches the muscle
Explain the all- or none-law concerning the AP?
Must have a certain polarization to get a reaction, either or not.
Explain depolarization
Positive charges decreases inside the cell
Define threshold
When depolarization reaches a certain level
Main component of reflex arch?
Receptor Afferent nerve Synapse Efferent nerve Target organ
How to check a normal reaction of Achilles reflex?
Hit just above the insertion of Achilles’ tendon on a free hanging leg
In which phase do you have absolute refractory period?
In the period before repolarization where the CAP will disappear.
What is proprioceptive(reflexes)?
Receptors in the organ
Spinal reflexes where the receptors are in the organ(muscle)
This reflex doesn’t fatigue!!
4 stages of an AP?
Depolarization
Overshoot
Repolarization
Post-hyperpolarization
What’s frequency coding?
Stronger stimulus, more frequent AP
Describe CAP
“Compound Action Potentials”
A summation of different fibers that make up a nerve
Receptors in an intrafusal muscle
Nuclear chain receptors and bag receptors
Describe the normal reaction of an ankle jerk reflex
Stretching the ankle, plantar flexion
Where do you tap to get the knee jerk reflex?
Patellar ligament
Which channel opens during repolarization?
Potassium channels
What is a rheobase?
Minimal stimulus intensity that generates an AP after long time application
Give the most characteristic features of non-myelinated impulse transmission
AP propagates step by step, a channel activates immediately the adjacent one.
The conduction velocity is slow.
The most characteristics of impulse transmission of myelinated fibers
AP develops only in the Nodes of Ranvier (Where Na+ channels occur).
AP propagates by leaping from one node to the other
What’s saltatory conduction?
When the AP of myelinated fibers is leaping from one node to the other
What does the conduction velocity of the AP of myelinated fibers depend on?
The diameter of the fiber
The distance btw the Nodes of Ranvier
