Lecture C5 + C6 + C7 Flashcards
Neurons have three main parts : ______
-cell body (soma): has nucleus and most of the organelles
-dendrites: many process that receive stimuli at synapses
-axon: single long process that generate and conduct nerve impulses to other cells
Most cell bodies are in contact with many nerve endings conveying _____ stimuli from other neurons.
-excitatory or inhibitory
Due to concentrated rough ER and polysomes, cell bodies of neurons are _____ and are distinguished as ______
-basophilic (purple colour)
-Nissl substance/Nissl bodies
basophilic dye is ____ & stains ____
-purple/basic (cationic)
-anionic stuff
dendrites are the main _____ on neurons
-signal reception and processing sites
In the CNS most synapses on dendrites occur on ______, which are dynamic ______ along the small dendritic branches. Changes in them are important for _____
-dendritic spines
-membrane protrusions
-neural plasticity
neurons are classified based on _____
morphology
Multipolar neurons descr
one axon and two or more dendrites. They are the most common.
Bipolar neurons descr. + example
-one dendrite and one axon
-the sensory neurons of the retina, the olfactory epithelium, and the inner ear
Unipolar/pseudounipolar neurons descr. + example
-a single process that bifurcates close to the soma, with the longer
branch extending to a peripheral ending and the other toward the CNS (1 axon)
-These include all other sensory neurons
Anaxonic neurons descr. + function
-many dendrites but no axon
-do not produce action potentials but regulate electrical changes of adjacent neurons
Sensory neurons are _____, receiving stimuli from receptors throughout the body. Most sensory neurons are _____
-afferent
-pseudounipolar
Motor neurons are _____, sending impulses to effector organs such as muscle fibers and glands.
-efferent
Interneurons are the ones in between _______. They connect ______
-motor and sensory neurons
-spinal motor and sensory neurons.
In ALS, there is degeneration of ______
motor neurons
Neurons in your brain are classified based on ______ (2)
neurotransmitter and effect on target neurons
A neuron can be classified based on the neurotransmitter that it uses to send its messages (ex. ________ (3))
-glutamatergic neurons, GABAergic neurons, cholinergic neurons
Sometimes neurons are classified based on its effect on target neurons: excitatory neurons are mostly ______ and inhibitory
neurons are ______
-CNS glutamatergic neurons
-adult brain GABAergic neurons
CNS glutamatergic neurons are excitatory by ______
releasing glutamate which stimulates Na+ entry into post-synaptic neuron leading to depolarization
Adult brain GABAergic neurons are inhibitory by ______
releasing GABA which stimulates Cl- entry into post-synaptic neuron leading to hyperpolarization
The plasma membrane of the axon is often called the _____ and its contents are known as _____. Axons originate from the _____
-axolemma
-axoplasm
-axon hillock
Beyond the axon hillock is the _____, where ______ that generate the action potential are located.
-axon initial segment
-concentrated ion channels
Membrane potential: Cells at rest normally have excess _____ on the outside and _____ on the inside of the cell. The resulting electrical potential is called the _____
-positive charge (Na+ ions)
-negative charge (K+ ions)
-resting membrane potential (-70mV)
Action potential steps
1) synaptic input from dendrites -> local changes in membrane potential of varying magnitude (stimulus opens Na+ channels, depolarizing membrane)
2) If threshold is reached (-50mV), it triggers action potential
3) most of Na+ channels are open but K+ is closed, Na+ influx makes inside more positive than outside (happens in AIS first
4) Na+ channel close, K+ channels open and K+ flux in (cell becomes more negative) - happens in AIS first
5) K+ remain open -> hyperpolarization; K+ channel close -> membrane returns to resting state - happens in AIS first
6) depolarization spreads to regions adjacent to AIS until they depolarize too and action potential propagates (in nodes of ranvier if myelinated)
Nerve cells communicate with each other and other cells through two types of synapses: ______
-electrical synapse: one neuron (presynaptic) is connected to second neuron (postsynaptic) via gap junctions -> ions move through gap junctions (connexon made from connexin proteins) -> no delay in transmission
-chemical synapse: presynaptic and postsynaptic neurons are not
connected by gap junctions but separated by synaptic cleft; signal is sent from pre to postsynaptic neuron by chemical messanger/neurotransmitter
Bacteriorhodopsin is a ______ in the plasma membrane of archaea. It uses energy from ______ to drive active transport of protons and create an ________
-small integral membrane protein
-photons
-electrochemical proton gradient that powers an ATP synthase
Channelrhodopsins are ______
rhodopsins that have molecule retinal and under light, depolarize (moves K+ out and Na+ in)
Optogenetics is a method that uses light to ______
- modulate molecular events in a targeted manner in living cells or organisms