Week 2: Neuroanatomy and Neurophysiology Flashcards
(47 cards)
Interaction between central and peripheral nervous system
Determines movement and physiological changes based on mental state
Microglia
Small; function in the immune system; dispose of disease and respond to injury; regulate synapses and cell death
Astroglia/Astrocyte
Nutrition support to neurons; contract/relax blood vessels; regulate connections; can functions similar to a neuron
Regulates synapse content in tripartite synapses
Oligodendroglia
Specific to the CNS; involved in myelination to axons
Counterpart in the PNS is the Schwann Cell
Neuron structure
Dendrites receive, axon terminals send. Cell body integrates signals received from the dendrites. Excitable neurons can generate and receive electrochemical signal. Neurons vary in length and structure
Molecular properties of a neuron
Phospholipid bilayer membrane; negative charge and selective permeability. Positive potassium and negative A- inside, positive sodium and negative chloride outside (creates the resting potential difference) Channels in the membrane allow particles to cross only when opened.
Potassium (K+) movement
High concentration inside neuron, low outside. Strong chemical flow, low electrical. K+ will flow outward
Sodium (Na+) movement
High concentration outside neuron. Both chemical and electrical flow point inward. Strong urge to flow inward.
Leak Channels
Open channels that allow potassium to constantly flow out of the cell
Exchanger channel
Will exchange Na+ to replenish K+ being let out by the leak channel
Ion movement during neurotransmission
Extracellular chemicals open ligand-gated channels and allow sodium to flow in. Cell depolarizes (gets less negative). Most often excitatory neurotransmitter is glutamate
Excitatory post-synaptic potential (EPSP)
Depolarizing; potential occurs in the neuron receiving (post-synaptic)
Inhibitory post-synaptic potential (IPSP)
Hyperpolarization and less cell activity. Linked with GABA (Gamma-aminobutyric acid)
Critical point
The summation of constant EPSP and IPSP charges must reach the critical point (-55 mV) for an action potential to fire. Voltage-gated channels open at this critical threshold and allow sodium into the cell
Action Potential Propagation down the Axon
As sodium enters, potassium leaves. Once an area has conducted a signal, it cannot conduct again for a sec, driving forward movement of AP. Myelin allows for jumps in depolarization, facilitating transmission of AP.
Dangers of myelin loss
Lack of myelin can slow or stop neuron signals, causing lack of brain activity. Lack of myelin is that cause of multiple sclerosis
Refractory period
Neuron cannot fire until the ionic gradients reset. In order to fire, it would take much more excitation due to hyperpolarization after firing
Ionotropic receptor
When a receptor is also a channel. Can signal very quickly, but is a minority case
Metabatropic receptor
A receptor that is not a channel itself. Most typical kind of receptor. Must communicate with the channel, causing slower transmission
Neurotransmitters
Over 100 exist, but not many are studied in depth. Each neurotransmitter has many different functions.
Brain Cortex
Outer layer: grey matter, consists of cell bodies
Inner layer: white matter, consists of myelinated axons
Rows of cells usually point in the same direction. Gyrus = ridge, sulcus = valley
Tract (CNS)/Nerve (PNS)
Bundle of axons headed in the same direction (not physically bound, but close in proximity)
Meninges
Membrane covering the brain. 3 layers: dura, arachnoid, and pia. Cushions and protects the brain from infection
Cerebrospinal fluid
fluid located under arachnoid layer that cushions and nourishes/cleans the brain; circulates through the ventricles
