Study Guide for HK 2810 - Study Answer Collection

Study Guide for HK 2810 - Study Answer Collection Concepts of CNS - answer - - changes in conductance & current (ion) flow - fundamental unit is Action Potential - all neurons are not created equal - graded potentials - spontaneous depolarizers - directionality - synapse How do we create "different" neurons? (more/less sensitive neurons) - answer - - use membrane potential How do we create more sensitive neurons? - answer - - make resting membrane potential close to threshold (-65mV) so that only a small number of EPSPs are needed to fire an AP - eg. -66mV - only 1 EPSP is needed for AP to occur How do we create less sensitive neurons? - answer - - make resting membrane potential far from threshold (-65mV) so that a large number of EPSPs are needed to fire an AP - eg. -100mV - need a summation of 16 EPSPs for AP to occur Graded potentials - answer - - strength of the stimulus is proportional to the change in membrane potential Spontaneous depolarizers - answer - - have unstable membrane potential - can generate their own AP How do spontaneous depolarizers generate their own AP? - answer - - cells have "leaky" Na channels in their membrane, so that threshold is continuously being hit after every AP (after an AP, when membrane is repolarizing, Na channels are already opening, leading to another AP) What are examples of spontaneous depolarizers? - answer - - heart beat - breathing How is directionality of CNS ensured? - answer - - cell asymmetry What type of synapse is seen in CNS? - answer - - chemical (ionotropic and/or metabotropic) What are the 2 main cell types of the CNS? - answer - - neurons - glial cells What is the role of glial cells in the CNS? - answer - - support structure for brain - oligodendrocytes (lays down myelin) - controls neural environment - phagocytic - plays critical role in blood brain barrier What is the role of oligodendrocytes? - answer - - lays down myelin - influences speed of conductance (eg. need fast conduction - myelinate cells; need slow conduction - no myelination) How do glial cells maintain neural environment? - answer - - helps maintain ion gradients How do glial cells play a role in the blood brain barrier? - answer - - glial cells form an extra layer around blood vessels (capillaries) to protect substances from entering the brain from the blood - limits the flux of substances that would normally not be in the brain from entering the brain (specifically from entering the cerebral spinal fluid) How does segregation work? - answer - - labelled lines - topographical maps - coding How does integration work? - answer - - convergence - divergence - feedback - feed forward - lateral inhibition - principle of summation Labelled lines - answer - - specific nerve carrying specific info to a specific part of the brain - segregation of info Topographical maps - answer - - parts of the brain map different parts of the body Examples of topographical maps - answer - - primary sensory cortex - primary motor cortex - cerebellum - primary visual cortex Coding - answer - - based on conduction velocity - segregates info Convergence - answer - - info coming from multiple neurons and synapsing with a single neuron - summation of EPSPs & IPSPs Divergence - answer - - info from a single neuron synapsing with multiple neurons - info is divided up Feedback - answer - - neuron sends info to another neuron, & that neuron sends info back to initial neuron - can increase the brain's sensitivity to that signal (positive feedback) - can "turn off" a signal (negative feedback) Feed forward - answer - - neuron sends info to another neuron, skipping neurons in between Vision - flow of information: - answer - 1) Retina 2) Optic nerve 3) LGN of thalamus 4) Superior colliculus 5) Primary visual cortex Example of labelled lines & functional segregation in vision - answer - - right side of right eye & right side of left eye send info to right LGN - left side of left eye & left side of right eye se