NC Cells and Membrane Potentials Flashcards
What is the telencephalon?
the most highly developed and anterior part of the forebrain, consisting chiefly of the cerebral hemispheres.
What are the characteristics of Neurones?
Polymorphus
Non-dividing
Excitable - can change resting potential
What is the Soma? And what is it also known as?
Perikaryan - Cell body
Includes the nucleus and ribosomes as well as neurofilaments for structure and support
What types of neurones are there? (morphology)
Unipolar,
Pseudo-unipolar
Bipolar
Multipolar
Pyramidal cell, Purkinje cell, Golgi cell
What are the most abundant cells in the brain? ( 4 roles )
Astrocytes, used to for cell repair, synapse formation, neuronal muturation and plasticity
What are the differences between Oligodendrocytes and Schwann cells?
Oligodendrocytes produce myelin in the CNS and Schwann in the PNS
Oligodendrocytes can myelinate a number of axons Schwann can only do a single axon segment
What are Microglia?
Act like macrophages as a part of CNS immune function
What are Ependyma?
Epithelial line vesicles full of fluid which regulate production and movement of cerebrospinal fluid.
What is the definition of Flux?
Number of molecules that cross unit area per unit time
How is electrochemical equilibrium reached?
The concentration gradient exactly balances electrical gradient.
- Calcium ions have highest concentration gradient
What is the Equilibrium potential? (E)
The potential at which electrochemical equilibrium has been reached. It is the potential that prevents diffusion of the ion down its concentration gradient.
When membrane is uniquely selected for a particular ion in question what equation can be used to find the equilibrium potential?
Nernst Equation
E = RT/zF In X2/X1
How to calculate the Equilibrium potential through Nernst equation?
Use:
E = -61/ z * log ( X inside / X outside )
How to use the GHK equation and why do we use it?
Biological membrane permeability can change. This equation takes it into consideration.
E(mV) = -61 log Pk[K]i +PNa[Na]i + PCl[Cl]o / Pk[K]o +PNa[Na]o + PCl[Cl]i
What does overshoot mean?
Membrane potential becomes positive.
What can initiate or prevent action potentials?
graded potentials. Change in membrane potential is graded in response to strength of stimulation.
Graded potentials decrease down length of axon. If it reaches threshold Na+ channels will open
What are the five stages of the action potential?
Resting membrane potential Depolarising stimulus Upstroke ( sodium influx = towards sodium equilibrium) Repolarisation After-hyperpolarisation
What is the difference in sodium gates at the start and end of repolarisation?
Activation gate is open but inactivation gate is closed.
At the end, both become closed = absolute refractory period
What is the relative refractory period?
Can trigger AP as some Na+ gates have opened if stimulus is very strong. Occurs after hyper-polarisation
What does the rate of degrading along an axon depend on? ( 3 )
Axon insulation, diameter and resistance.
In which diseases can conduction velocity be affected?
Reduced myelination can occur in multiple sclerosis and diphtheria ( other reasons can be cold, anoxia, compression and drugs)
Where are purkinje cell found?
GABA neurones found in cerebellum
What are Golgi cells found?
GABA neurones found in cerebellum
What is resting configuration?
Sodium ions enter vestibule and upon phosphorylation they are transported through protein
What is Active configuration?
Sodium removed from cell, potassium ions enter vestibule
What is an axodendritic synapse?
connection between presynaptic terminal and neuronal dendrite
What is an axosomatic synpase?
Connection between presynapatic terminal and neuronal soma
What is an Axoaxonic synapse?
Connection between presynaptic terminal and neuronal axon
What time of communication occurs between nerve and effector cell?
Paracrine - NT release
What is a miniature EPP?
Small change in end-plate potential when a quantal amount o ACh is released
What is Myasthenia gravis ? MG
Autoimmune
Antibodies against ACh receptor
Cause fatigable weakness - more pronounced with repetitive use
What is Lambert-Eaton Myastenic syndrome?
LEMS
Autoimmune
Antibodies directed against VGCC
