Cell Properties Flashcards
(19 cards)
What is the function of the neuron and what are its components?
Function:
- Integrate and relay information
- Generate electrical signaling
Components:
- Soma/Cell body
- Dendrites
- Axon/Axon Hillock
- Pre and Postsynaptic neurons
How are electrical potentials created ?
Varying ion concentrations of each side of the cell membrane
Selective plasma membrane for ions
Ions transported via ACTIVE TRANSPORTERS and ION CHANNELS
-> Function in opposition to each other
What are the different types of Ion Channels?
- Mechanosensitive Channels
- Open in response to sensory stimuli (stretch, touch, pressure, temperature, chemicals) - Ligand-Gated Ion Channels
- Open in response to the binding of a neurotransmitter (ligand) on the postsynaptic cell membrane (needs something to attach to open) - Voltage-Gated Ion Channels
- Open in response to changes in cell membrane electrical potential
- Important for the propagation of Action Potentials
What is Resting Membrane Potential?
Electrical difference between the inside and outside of a cell
About -70mV for a neuron (-40 to -90mV)
What are the Altered Resting Membrane Potentials?
- Receptor Potentials
- Transient (brief) change due to activation of sensory neurons by external stimuli - Synaptic Potentials
- Transient change due to the transmission of information from one neuron to another - Action Potentials
- Transient change in electrical signal that travels the length of the axon
What is the difference between Local and Action Potential?
Local (think dendrite)
- Passive propagation
- Decrease in amplitude with Increased time (small amplitude)
- Progression to an Action Potential…
-> Temporal (many happening)
-> Spatial summation (more widespread)
- Travel short distances
- Depolarizing or hyperpolarizing
- Receptor or synaptic potential
Action Potential (think axon)
- Active propagation (and passive)
- AP maintained throughout the length of the axon
- “All or none” principle- once it starts, its gonna happen
- Large Amplitudes
- Travel Long distances
- Depolarizing
What is Refractory Period and what are the two types?
- Time in which a nerve is less responsive to further stimulation
- Absolute Period: membrane unresponsive to stimuli (not possible to respond to another stimulus)
- Relative Period: Returning toward resting membrane potential
Results in continued progression of the AP
What are seizures?
Abnormal electrical activity within the brain that results in uncontrolled, excessive electrical discharges
Epilepsy: neurological disorder which causes recurring, unprovoked seizures
Classification of Seizures
- Focal or generalized: onset or beginning of a seizure
- Aware or impaired: level of awareness during a seizure
- Motor vs. non-motor symptoms during a seizure
What do non neuronal cells do?
Support the signaling function of neurons; DO NOT participate directly with synaptic transmission
What do astrocytes do?
- Found w/in CNS (brain and spinal cord)
- Functions to maintain appropriate chemical environment for electrical signaling (keeps environment clean during information transmission)
-> contributes to blood brain barrier: podocytes of the astrocytes make blood brain barrier selective
What is the Blood Brain Barrier?
- Diffusion barrier between the cerebral vasculature and the substance of the brain
- Provides protection and maintains homeostasis
- SELECTIVE PERMEABILITY
What are Oligodendrocytes and Schwann Cells?
Oligodendrocytes (CNS)-> Can NOT regenerate Schwann Cells (PNS) -> CAN regenerate
- Form myelin sheaths around axon (these cells are the myelin sheath) (high in fat/lipid)
- Increases speed of transmission of electrical signals
What is the difference between GBS and MS?
BOTH ARE AUTOIMMUNE DEMYELINATION DISORDERS
Guillain-Barre Syndrome
- Attacks Schwann cells
- Acute inflammation and demyelination of peripheral nerves
- Typically preceded by a mild infection
Multiple Sclerosis
- Attacks Oligodendrocytes
- Demyelination of CNS results in white matter plaques (like roadblocks on a highway)
- Cause unknown
What do microglia (phagocytes) cells do?
- Scavenger cells
- Secrete signaling molecules that modulate inflammation
- Stimulated during recovery and disease ( can become over-activated )
What is Alzheimer’s Disease?
Neurodegenerative disorder
- Most common form of dementia
-> Characterized by impairments in memory, thinking, and behavior
- Proposed to be the result of an accumulation of Extracellular amyloid plaques and intracellular neurofibrillary tangles
-> Resultant neuroinflammation
Blood Brain Barrier malfunction causes a release of factors that are harmful to neurons
- Leaky BBB allows for amyloid beta to accumulate
- Microglia stimulated in response to increase in amyloid beta
- Dysfunction leads to chronic inflammation
What are Neural Stem Cells?
Immature/undifferentiated cells
- Located in hippocampus and lining of the lateral ventricles in mammalian brains
- Capacity to differentiate into neurons, astrocytes, or Oligodendrocytes
Types
- Human embryonic
- Tissue specific
- Induced pluripotent
What are Human Embryonic Stem Cells (hESC)
Pluripotent: ability to generate all cell types that make up the body
-Obtained from the blastocyst in early embryonic development
What are Tissue-Specific Stem Cells (adult stem cells)
Multipotent
- Differentiate into the specific tissue or organ in which they reside
- Difficult to isolate and grow
What are Induced Pluripotent Stem Cells?
Adult cells PROGRAMMED to become pluripotent cells
- disease specific stem cells (research)
- patient specific stem cells (minimize rejection)
Blood forming stem cells (multi potent): ONLY FDA approved stem cell based therapy
