Week 3 - Central Nervous System Flashcards
Whats the anatomical division of the CNS
Brain and Spinal Cord
Whats the anatomical division of the PNS
Neurons outside the CNS
Whats the sensory division
Afferent fibers transmit impulses from receptors to the CNS
Whats the motor division
Efferent fibers transmit impulses from CNS to effector organs
What are the roles of axons
Carries electrical message (action potentials) away from the cell body.
Covered by Schwann cells
Whats the role of Schwann cells
Form discontinuous myelin sheath along the length of axon
Whats the role of the synapse
Contact point between axon of one neuron and dendrite of another
Whats the regular resting potential in a cell
-70 mv
What impacts the magnitude of resting membrane potential
(ON SHEET)
Permeability of plasma membrane to ions
Difference in ion concentrations across the membrane
Explain the exchange of sodium and potassium at the cell membrane
(ON SHEET)
Its maintained by the sodium potassium pump. Potassium tends to diffuse out of the cell so to overcome this the pump transports 3 sodium ions out and 2 potassium ions in. By using energy from ATP which helps aid muscle contraction
When does an action potential occur
Occurs when a stimulus of sufficient strength depolarizes the cell. This opens Na+ channels so Na+ diffuses into the cell making the inside become more positive
What is repolarization
The return to resting membrane potential. K+ leaves the cell rapidly and Na+ channels close
What is the all or none law
Once a nerve impulse is initiated, it will travel the length of a neuron
Whats the role of sodium channels
Lets sodium enter the cell to make the cell more positively charged helping increase action potential
Whats the role of Excitatory postsynaptic potentials (EPSP)
To promote neural depolarization in 2 ways
What are the 2 ways that EPSP can promote depolarization
(ON SHEET)
Temporal summation - rapid, repetitive excitation from a single excitatory presynaptic neuron.
Spatial summation - summing EPSPs from several different presynaptic neurons
Whats the effect of Inhibitory postsynaptic potentials (IPSP)
Causes hyperpolarization (more negative resting membrane potential)
Whats the effect of neurons with more negative membrane potential
The more negative the membrane potential the more able they are to resist depolarization
What are proprioceptors
Sensors that provide information about joint angle, muscle length and muscle tension which is integrated to give information about the position of the limb in space
Whats the role of muscle spindles
Respond to changes in muscle length