Neurons & Synapses Flashcards
What are the main components of a neuron?
Soma (cell body), Dendrites, Axon, myelin sheath, nodes of ranvier, presynaptic terminals, axon hillock
What are the different types of neurons?
Multipolar (more than 2 neurites) , Bipolar (2 neurties), Pseudounipolar neuron (one neurite extending from cell body)
What are the types of synapses?
Electrical Synapse & Chemical synapse
What is an electrical synapse? What does it need?
Relatively simple structure allowing the direct transfer of ionic current from one cell to another; Gap junction, connexins, and connexons
What is a chemical synapse? What does it need?
Specialized pre- and post- synaptic structures employing chemicals to transfer information between a neuron and another neuron or cell type
What are the types of Chemical synapses based on location?
Axo-dendritic, Axo-somatic, Axo-axonic
What are examples of chemical excitatory synapses? Inhibitory?
Excitatory: Glutamate & Aspartate
Inhibitory: GABA & Glycine
What are the structures involved in a chemical synapse?
Axon, mitochondrion, Synaptic vesicles, pre-synaptic membrane, synaptic cleft, post-synaptic membrane, post-synaptic receptors
What are the glial cells? What do they do?
Oligodendrocytes: form the myelin sheath in the CNS
Schwann cells: cells that form the myelin sheath in the PNS
Astrocytes: Provide structural and functional support, and nutrients
Microglia: Acts as phagocytes
Ependymal cells: epithelial cells lining the ventricles
What are the properties of the phospholipid membrane?
Bilayer with polar (hydrophylic) heads on the outside and non-polar (hydrophobic) tails on the inside
What are the levels of protein structure?
Primary, Secondary, Tertiary, Quaternary
What is diffusion? How does it work?
Dissolved ions distribute evenly because ions flow down concentration gradient when the channels are permeable to specific ions
What is the Equilibrium Potential (Eion)?
No net movement of ions when separated by a phospholipid membrane. Point at which voltage difference exactly balances ionic concentration gradient
What is the Nernst Equation used for? What does it take into consideration?
Used to calculate the exact value of the equilibrium potential for each ion. Takes into consideration: charge of the ion, temperature, ratio of the external and internal ion concentrations
What is the Resting Membrane Potential of K+?
-80mV; concentrated more on inside than out
What is the Resting Membrane Potential of Na+?
62 mV; more concentrated on outside than inside
What is the Resting Membrane Potential of Ca2+?
123mV; more on outside than inside
What is the Resting Membrane Potential of Cl-?
-65mV; more on outside than inside
What is the resting membrane potential?(#)
-65mV
What does the Goldman Equation take into consideration?
Permeability of membrane to different ions
What are the forces that maintain the resting membrane potential?
Passive forces - use no energy (Diffusion and Electrical forces)
Active forces - uses energy ATP (Na+/K+ pump)
What is hyperpolarization?
Increases polarization of nerve cells: inside more negative; concept of IPSP
What is depolarization?
Decreases polarization of nerve cells: inside less negative; concept of EPSP
How are synaptic potentials produced?
Neurotransmitters bind to NT recepotr on post-synaptic membrane. Binding opens ion channels in the post-synaptic membrane and produces IPSP and EPSP
What is the concept of spatial summation?
- 2 simultaneous EPSP or IPSP on different neurons sum to produce a greater potential
- a simultaneous EPSP and IPSP lesson each other
What is the concept of temporal summation?
-2 EPSP or 2 IPSP elicited in rapid succession sum to produce a larger potential
Where are excitatory synapses found? Inhibitory synapse?
Excitatory synapse located at distal dendrite. Inhibitory synapse located more proximally at cell bodies
