Neurons and the Nervous System Flashcards
Cell Body
Nucleus with chromosomes
Dendrites
Receive information from other neurons
Axon
Transmits information to other neurons, muscles, and glands
Myelin
Insulating layer of fatty material
Composed of glial cells
Helps the efficient transmission of signals to other cells
Nodes of Ranvier
Gaps within the myelin sheath
Action Potential
A neural impulse that travels down an axon like a wave
Stimulates the release of neurotransmitters into the synapse
“All-or-none”—electrical impulse is the same no matter how much stimulation the neuron receives
Resting Potential
High concentration of K+ inside neuron
Lower concentration of K+ outside neuron
Higher concentration of Na+ outside neuron
K+ channels in cell membrane open in resting state
K+ moves out of neuron, leaving a -70 mv charge
The Action Potential is Initiated
The electrical charge reaches a threshold
K+ channels close
Na+ channels open
Na+ flows into the neuron
+ charge inside the neuron increases
Charge inside the neuron is +40 millivolts
The Action Potential Travels Down the Axon
Intracellular fluid is positively charged (+40 millivolts)
Adjacent Na+ channels open
The action potential travels down the axon membrane
K+ channels open
K+ moves out of the cell
Intracellular fluid becomes negative again
K+ channels close
Na+/K+ Pump Restores Ion Balance
Na+ and K+ channels close
Na+ concentration is higher inside the cell
K+ concentration is lower inside the cell
Na+/K+ pump restores resting state charge
The Refractory Period
Another action potential can’t occur during the refractory period
After the action potential reaches +40 mv, membrane channels return to original state
The neuron can now generate another action potentia
Reuptake
Neurotransmitters are absorbed back into the presynaptic neuron
Enzyme Deactivation (Disassembly)
Neurotransmitters are broken down by enzymes in the synapse
Autoreceptors
Neurotransmitters bind to autoreceptor sites on the presynaptic neuron
Agonists
Chemical that binds to receptor
Triggers responses
Enhances neurotransmitter action
Antagonists
Chemical that binds to receptor
Blocks receptor
Peripheral Nervous System
Gathers information from the body and sends CNS decisions out to the body
Connects the central nervous system to the body’s organs and muscles
Autonomic nervous system
Somatic nervous system
Central Nervous System
The body’s decisionmaker.
Sensory Neurons
Carry messages IN from the body’s tissues and sensory receptors to the CNS for processin
Motor Neurons
Carry instructions OUT from the CNS out to the body’s tissues
Interneurons
(In the brain and spinal cord) Process information between the sensory input and motor output.
The Autonomic Nervous System
Sympathetic Nervous System
Parasympathetic Nervous System
Arousal
Returning the body to its resting state
Endocrine System
Sends molecules as messages through the bloodstream
A set of glands that produce chemical messengers called hormones
EEG (Electroencephalogram)
Recording of the electrical waves sweeping across the brain’s surface
Useful in studying seizures and sleep.
