Wk 2 - Functional Neuroanatomy Flashcards
Neurons differ from other cells in that they are… (x1)
And they serve which three functions?
Excitable - conducting electrical signals, communicating through chemical signals
Reception – of info from neighbouring neurons
Conduction – integration of info from adjacent neurons
Transmission – of signal to adjacent
Motor neurons are… (x2)
Plus description, location, function
Multipolar efferent neurons, that move toward central organ or point – messages from the brain/spinal cord to muscles/organs
Length of fibres - Short dendrite, long axons
Location - Dendrites and cell body located in spinal cord, axon outside spinal cord
Function - Conducts impulse to an effector (muscle or gland)
Sensory neurons are… (x2)
Plus description, location, function
Unipolar afferent neurons, move away from central organ/point – messages to brain/spinal cord from receptors
Length of fibres - Long dendrites, short axon
Location - Cell body and dendrite outside of spinal cord, cell body is in a dorsal root ganglion
Function - Conduct impulse to spinal cord
Interneurons are… (x2)
Plus description, location, function
Typically pictured with short/no axon, that relays message form sensory neurone to motor neuron
Make up the brain and spinal cord
Length of fibres – short dendrites and short or long axon
Location – entirely within the spinal cord or CNS
Function – interconnect sensory with appropriate motor neuron
Nine structural features of a typical neuron…
Cell body/soma Cell membrane Dendrites Axon hillock Axon Meyelin Nodes of Ranvier Buttons Synapse
Function of neuron’s cell body/soma (x1)
Metabolic centre of neuron
Neuron’s cell membrane is… (X1)
Semipermeable membran enclosing neuron
Dendrites are… (x1)
That…. (x1)
Short processes out of cell body,
Receive most of synaptic contacts
The axon hillock is… (X2)
Cone region between cell body and axon,
Previously thought to be originator of signals but now found to happen in initial segment of axon
The axon is… (x1)
Long narrow process from cell body
Myelin is… (x1)
Fatty insulation around many axons
Nodes of Ranvier are… (x1)
Gaps between sections of myelin, where signal is refreshed as it travels
Buttons are… (x2)
Ends of axon branches
That release chemicals into synapses
Synapses are… (x2)
Gaps between neurons
The chemical transfer space
Six structures (+functions) inside the soma
Endoplasmic reticulum – folded membranes that holds ribosomes that produce proteins (neurotransmitters)
Cytoplasm – clear internal fluid of cell
Golgi complex – membranes that package large protein molecules into vesicles
Tubules – carry material throughout neurons/vesicles of proteins down to synapses over a period of days
Nucleus – spherical DNA-containing structure
Mitochondria – sites of aerobic (oxygen-consuming) energy release
Two structures (+ functions) inside the synaptic buttons (tubules terminate here)
Synaptic vesicles – smaller packages of neurotransmitter packaged up by golgi apparatus in button
Neurotransmitters – molecules released from active neurons, influencing activity of other cells
Neuron cell membrane consists of… (x1)
Which contains… (x2 + functions)
Lipid bilayer
Channel proteins – like fast-acting gates, certain molecules get through when open; and
Signal proteins – allows slower transmission of signal across membrane
Four key ions involved in resting membrane potential are?
Na+, K+, Cl-, protein-
The resting membrane potential of a neuron is…. (x1 + reasons)
-70mV charge
Less charge inside cell than out, due to relative concentration of ions;
Some permeate membrane more easily than others
Four passive, plus one active factors affecting resting potential
Random motion
Differential permeability of membrane
Electrostatic pressure – similar to magnetism, like repels like
Concentration gradients – high dissipates to low
Energy-using process: Sodium-potassium pump
The ionic basis of the resting membrane potential is… (x5)
Cl- ions are in status quo – concentration pressure matches electrostatic
Na+ is pushed in by 12mV of combined electrostatic and concentration gradient
K+ have 20mV so balance is maintained by expelling it
Pump holds resting potential by pumping 2 K in for every 3 Na out
Changes in the resting potential make it more or less likely to fire
Two effects of changes in the post-synaptic potential
Which are result of… (x1)
Becoming less negative is excitatory (EPSP)
Slightly more negative in inhibitive – shuts off action or reduces likelihood of firing (IPSP)
Thousands of signals at same time – are summed either spatially or temporally, and enough excitatory trigger action potential
Saltatory conduction is… (x1)
And occurs through… (x2)
Resulting in… (x1)
‘Skipping’ conduction in myelinated axons, which is refreshed at each stage
Passive conduction occurs, instantly and decrementally, along each myelin segment
New action potential generated at each node of ranvier
Instant conduction along segments = faster than un-myelinated axons
The three phases of an action potential are…
Rising phase: membrane reaches threshold, opens ion channels = massive depolarisation
Repolarisation, then
Hyperpolarisation as potassium channels slower to close, during which you get:
Absolute refractory period, and
Relative refractory period
The absolute refractory period occurs… (x1)
During which time… (x2)
During hyperpolarisation, from 1-3ms
Potential is so negative that no amount of stimulation will cause action potential.
Makes sure info only goes in one direction
The relative refractory period occurs… (x1)
During which time… (x2)
During hyperpolarisation, from 3-4.5 ms)
Potential is still negative, but can fire if given extra stimulation. Important because rate of firing is info for gauging stimulus intensity
Schwann cells are… (x2)
Glial cells of the PNS
Similar to function of oligodendrocytes (myelin production) in CNS – can guide axonal regeneration
