Chapter 3 Flashcards
What was the original idea philosophers had about the brain? What did early scientists observe as well?
“enchanted loom;” brain is one big woven web of material (based on what brain looks like)
What did Santiago Ramón y Cajal do with regards to the brain?
new technique for staining neurons, highlighting different shapes and sizes; discovered 3 parts of neuron
What is the neuron’s cell body?
the largest component of neuron that coordinates the information-processing tasks and keeps the cell alive; contains neucleus
What are dendrites?
receive information from other neurons and relay it to cell body; comes from greek word for tree
What is the axon?
carries information to other neurons, muscles, or glands
What is the myelin sheath? What is it composed of?
an insulating layer of fatty material covering axons in many neurons; composed of glial cells
What are glial cells?
support cells found in the nervous system
Do the dendrites and axons of neurons touch each other?
no; small gap thats part of a synapse
What is a synapse?
the junction or region between the axon of one neuron and the dendrites or cell body of another
What are the three major types of neurons?
1) sensory neurons
2) motor neurons
3) interneurons
Sensory neurons receive info from _____ and convey it to ______ via ____________
receive information from the external world & convey info to brain via spinal cord
Motor neurons carry signals from ______ _____ to ____________ to produce ________; often have long _______
spinal cord; muscles; movement; axons
Interneurons connect ______ _____, _______ _____, or other _______
sensory neurons; motor neurons; interneurons
T/F Most of the nervous system is composed of interneurons
TRUE
What are the two stages of electrochemical action of neurons?
1) conduction
2) transmissions
What is conduction? Moves from the ______ to the _______
the movement of an electric signal within neurons, from the dendrites to the cell body, then throughout the axon
What is transmissions?
the movement of electrical signals from one neuron to another over the synapse
What is the neuron’s resting potential? What is it caused by?
the difference in electric charge between the inside and the outside of a neuron’s cell membrane; caused by a difference in concentration of ions
Describe briefly the process of chemical pumps and how they can create quick electrical impulses
Na+ pumped out, K+ ions are pumped inside neurons, creating potential energy; electrical stimulation opens pumps, flooding K+ out and Na+ in towards equilibrium, releasing electrical signal
What is an action potential?
An electrical signal that is conducted along a neuron’s axon to a synapse
In order for an action potential to occur, the electric shock has to reach a _______
threshold
What is a refractory period?
the time following an action potential during which a new action potential cannot be initiated
What is the name of the processes by which the electric charge travels down an axon? Describe the process
saltatory conduction; the action potential dominos/jumps across nodes of Ranvier, creating action potentials each time and thus transferring the signal
What clumps in places down the axon?
myelin sheath