Chapter 3 Flashcards
Neuron
- nerve cell specialized for communication
Draw a labelled diagram of a neuron
.
Dendrite
- projection that picks up impulses from other neurons
- portion of neuron that receives signals
Axon
- nerve fibre projecting from the cell body that carries nerve impulses
- portion of the neuron that sends signals
Synaptic vesicles
- spherical sac containing neurotransmitters
- travel the length of the axon to the axon terminal
- it bursts to release neurotransmitters when it reaches the end of the axon terminal
Node
- gap in the myelin sheath of an axon which helps the conduction of nerve impulses
Myelin sheath
- fatty coat that insulates the axons of some nerve cells, speeding transmission of impulses
- glial cells wrapped around axons that act as insulators of the neuron’s signal
Cell body
- materials needed by the neuron are made here
- aka soma
Neurotransmitters
- chemical messenger specialized for communication from neuron to neuron
Synapse
- terminal point of axon branch which releases neurotransmitters
- space between two connecting neurons through which messages are transmitted chemically
- consists of a synaptic cleft
Synaptic cleft
- a gap into which neurotransmitters are released from the axon terminal
- gap is surrounded by small patches of membrane on each side (one of the sending axon and one on the receiving dendrite)
Glial cell
- cell in nervous system that plays a role in the formation of myelin and the blood-brain barrier, responds to injury, removes debris, and enhances learning and memory
Astrocytes
- type of glial cell that communicate closely with neurons, control blood flow in the brain, and play a vital role in the development of the embryo
- abundant in the blood-brain barrier (protective shield that insulates the brain from infection by bacteria and other intruders)
Oligodendrocyte
- make up the myelin sheath
Resting potential
- electrical charge difference (-60mV to -70mV) across the neuronal membrane, when the neuron is not being stimulated or inhibited (inside more negative than outside)
Threshold
- membrane potential necessary to trigger an action potential
- differs between neurons, but in many it is -55mV
Action potential
- electrical impulse that travels down the axon, triggering the release of neurotransmitters
Absolute refractory period
- time during which another action potential is impossible; limits maximal firing rates
Graded potentials
- postsynaptic potentials that can be excitatory or inhibitory depending on whether positively or negatively charged particles flow across the neuronal membrane and in which direction they flow
EPSP
- excitatory postsynaptic potential
- graded potential in a dendrite that is caused by excitatory synaptic transmission
IPSP
- inhibitory postsynaptic potential
- graded potential in a dendrite that is caused by inhibitory synaptic transmission
Receptor site
- location that uniquely recognizes a neurotransmitter
Reuptake
- means of recycling neurotransmitters
- a process by which the synaptic vesicle reabsorbs the neurotransmitter
List the steps for an action potential to occur
- Resting state
- Depolarization
- Rising phase of the action potential
- Falling phase of the action potential
- Undershoot
Step 1: Resting State
-60mV to -70mV
nothing is happening
potassium ions concentrated inside
Step 2: Depolarization
More positive charged ions enter Sodium channels open Sodium ions come into the cell Cell is less polar (ie. less charged) Once potential reaches -50mV, it hits the threshold and cell will “fire”
Step 3: Rising Phase
Reaches ~ +50mV
Potassium channels are closed, but sodium is rushing in causing this increase in charge potential
Step 4: Falling Phase
Sodium channel closes and potassium channels opens
The potassium ions move out because of charge concentration gradient AND because of concentration gradient
The potential is therefore dropping (positive potassium ions are leaving)
Step 5: Undershoot
Refractory period, membrane is hyperpolarized
More polarized (more negative) than resting potential
Much more difficult for cell to fire again
Short pause where the cell is too negative to get back to threshold; can’t fire
List 8 major neurotransmitters
- Glutamate
- GABA
- Acetylcholine
- Norepinephrine
- Dopamine
- Serotonin
- Endorphins
- Anandamide
Glutamate
Main excitatory neurotransmitter in the central nervous system; participates in relay of sensory information and learning
GABA
Main inhibitory neurotransmitter in the central nervous system
Acetylcholine
Muscle contraction
Cortical arousal
Norepinephrine
Brain arousal and other functions like mood, hunger, and sleep
Dopamine
Motor function and reward
Serotonin
Mood and temperature regulation, aggression, and sleep cycles