Nervous System Pt 2 Flashcards
Basic structure of neurons (5)
Soma
Dendrite
Axon
Terminal button
Synapse
What does slide 1 diagram 1 show?
Soma (cell body)
Dendrites
Myelin sheath
Axon (inside myelin sheath)
Direction of message
Terminal buttons
What does slide 1 diagram 2 show?
Dendrites
Cell body
Nucleus
Axon hillock
Presynaptic cell
Axon
Myelin sheath
Signal direction
Synaptic terminals
Synapse
Postsynaptic cell
Internal structures
(Clockwise)
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Dendrite
Dendritic spines
Lysosome
Microtubules
Mitochondria
Myelin sheath
Membrane
Golgi apparatus
Cytoplasm
Nucleus
Axoplasmic transport
Active process by which substances are propelled along microtubules
Protein transport (5)
Proteins formed in the ER enter the Golgi bodies, where they are wrapped in a membrane and given a shipping address
Each protein package is attached to a motor molecule and moves along the micro tubule to its destination
A protein may be incorporated into the membrane…
…remain within the cell to act as an enzyme
…or be excreted from the cell by exocytosis
Neural insulation
Diagram 1
Node of ranvier
Myelinated axons
Soma of oligodendrocyte
Mitochondrion in axoplasm
Node of ranvier
Microtubule
Neural insulation
Diagram 2
(a) Axons, myelin sheath, oligodendrocyte
(b) Schwann cell
Electrical activity:
Membrane potential
Balance of two forces
Intracellular fluid (2)
Organic anions (A-)
Potassium ions (K+)
Extracellular fluid (2)
Chloride ions (Cl-)
Sodium ions (Na+)
Electrical activity diagram
Interior of cell negative (-)
Cell exterior: positive (+)
Diffusion
Movement of molecules from area of high to low concentration
Electrostatic pressure
Attraction of oppositely charged ions and repulsion of similarly charged
Sodium potassium pump
Mechanism in membrane, extrudes Na+ out, K+ in
Membrane potential
Electrical charge across a cell membrane
The difference in electrical potential inside and outside the cell
Resting potential
Membrane potential of a neuron when it is not being altered by excitatory or inhibitory Postsynaptic potentials, normally about -70 mV
Depolarization
Reduction (toward zero) of the membrane potential
Action potentials
(2)
Rapid reversal of membrane potential
Occur when the cell is depolarized to the threshold of excitation
Largely dependent upon the movement of Na+ and K+ ions through special pores in the membrane called ion channels
Action potential diagram (6)
Membrane potential (mV) on Y axis
Low Y axis: -70 High: +30
Na+ channels open, Na+ begins to enter cell
K+ channels open, K+ begins to leave the cell
Na+ channels become refractory, no more Na+ enters cell
(Stimulus, Spike Threshold)
K+ channels close, Na+ channels reset
Extra K+ outside diffuses away
Passive conduction
Conduction of electrical current, in a decremental fashion, down an axon
Saltatory conduction
Conduction of action potentials by myelinated axons. The action potential appears to jump from one node of ranvier to the next
Neuron conduction velocity
Speed of conduction (2)
Depends on diameter of axon
Myelination
All or none principle
When a neuron fires, it fires at maximum strength
Transmission of action potentials (3)
Signal conducted along the axon
Terminal buttons release NT
Transmission to another neuron across the synapse
Graded potentials (2)
(EEG source)
Excitatory Postsynaptic potentials (EPSP)
Inhibitory Postsynaptic potentials (IPSP)
Where are they summated?
How is AP triggered?
At the axon hillock
If membrane reaches threshold, AP is triggered
Neurotransmitters
Excite or inhibit the postsynaptic neuron
NT
Acetylcholine
Basal forebrain and pontine tegmentum
Memory (Alzheimer’s disease)
Arousal and attention
Dopamine
Substantia nigra
Motivated behavior (reward pathway)
Motor control
Serotonin
Dorsal raphe nucleus in brainstem
Depression
