Final Final Flashcards
(47 cards)
Depolarization Phase
When the electrical potential difference or voltage across the membrane is driven closer to 0 volts.
E.g. When a positive ion rushes into a negative cell
Causes further spread of an electrical impulse, increase the activity of a neuron
Excitatory event
Passive channels are open but joined by opening of voltage-gated Na+(sodium).
A small number of voltage-gated K+ being to open
Hyperpolarization
When the voltage membrane moves farther away from 0 volts
Leads to a decrease in the responsiveness and activity of an neuron
Reducing information transfer across a network
Inhibitory event
Closing of the K+ channels - too much K+ is released so slightly hyperpolarizes the membrane
Repolarization
Voltage-gated Na+ are inactivated
Voltage-gated K+ are fully open
Exit of K+ out of the cell returns the cell membrane to a negative membrane potential
Resting membrane potential
Inside of the axon is -60 to -70 mV
Maintained by the passive flow of K+ and Na+, active operation of the Na+/K+ pump, and one more thing….
Synapse
Communication point between a presynaptic cell and a postsynaptic cell
3 general locations on the postsynaptic cell: dendrites, somas, an axons
Axodendritic synapse, axosomatic synapse, axoaxonic synapse
Electrical synapse allow for extremely rappid and synchronized activity
Gap junction
Found in an electrical synapse
Pre- and post-synaptic cells are VERY close
Found in the cochlea
Chemical synapse
Underlies the performance of ALL forms of observable and/or voluntary behavior
Has a synaptic cleft
Communicating chemical is the neurotransmitter
Synaptic vesicle stores and releases the chemical neurotransmitter
What do chemical synapses generate?
Excitatory postsynaptic potentials are depolarizing - positive ion influx
Inhibitory postsynaptic potentials are hyperpolarizing - influx of negative ions or efflux of positive ions
Classical neurotransmitters: Amines
Acetylcholine (excitatory)
Dopamine (modulatory)
Norepinephrine (fight or flight/neuromodulatory)
Epinephrine (adrenaline/heightened activity of sympathetic nervous system)
Serotonin (regulates attention, mood, emotional states, sleep, and various cognitive functions)
Classical neurotransmitters: Amino Acids
Glutamate - most widely used throughout the brain, brainstem, and spinal cord - excitatory
GABA - principal inhibitory of CNS
Glycine - inhibitory in retina, s.c., brainstem
Nonclassical neurotransmitters
Endorphins
Substance P
Corticotropin releasing factor
Brain-derived neurotropic factor
Nitric oxide
Upper motor neuron damage
Paresis and paralysis
Increased muscle tone (hypertonia)
Pronounced resistance to external movement (spasticity)
Presence of reflex responses (Babinskin response)
Major difference between corticobulbar and corticospinal
CBT innervates cranial nerves bilaterally rather than contralaterally
One side of the brain provides signals to both Ipsilateral- and contralateral motor nuclei simultaneously - redundant set of commands
Allows you to retain theh ability to perform critical survival behaviors
Innervation of face
Contralateral for lower
Bilateral for upper
Spinal cord function
Chief input and output site for sensory and motor signals between the body (below the neck) and the nervous system
Transmission of ascending and descending information via segregated fiber tracts that interconnect to the periphery with the cerebral cortex, brainstem, and gray matter within the s.c. Itself
Where does the spinal cord begin
Continuous with brainstem beginning at the foramen magnum, which is the large hole in the bottom of the skull
Cervical region of spinal cord innervates
Neck, shoulder, arms
Thoracic segment of the spinal cord innervates
Upper trunk
Lumbar and sacral spinal nerves innervate
Lower trunk, legs, and feet
Location of lateral ventricles
Ventral to the corpus callosum
What separates the right and left lateral ventricles
Septum pellucidum
Cranial nerves on medulla
VIII, IX, X, XI, XII
3 important tracts in medulla
- Medial lemniscus (sensory) - from cuneate and gracile nuclei
- Anterolateral (ALS) - sensory info related to noxious and thermal sensations from the body below the neck
- Corticospinal (motor) - skilled and precision forms
Solitary nucleus - medulla
Key sensory nucleus mediating the sensation of taste from the tongue and tactile inputs from the laryngeal region
