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
What do axons normally end in? Describe them. What are they filled with?
terminal buttons, knoblike structures that branch out from the axon; filled with vesicles
What do vesicles contain? Describe them
neurotransmitters, chemicals that transmit information across the synapse to a receiving neuron’s dendrites
The dendrites of a receiving neuron contain _____, which are?
receptors; parts of the cell membrane that receive neurotransmitters and either initiate or prevent a new electric signal
What three ways are neurotransmitters cleared out of the synapse?
1) reuptake into the sending neuron
2) broken down by enzymes in the synapse (enzyme deactivation)
3) binding to autoreceptors in sending neuron; they signal cell to stop releasing neurotransmitters when theres excess
The action potential travels down the length of the ____ to the ______ ______, where it stimulate the release of ______ from ______ into the ______
axon; terminal buttons; neurotransmitters; vesicles; synapse
Define acetylcholine
a neurotransmitter involved in a number of functions, including voluntary motor control
Define Dopamine
a neurotransmitter that regulates motor behavior, motivation, pleasure, and emotional arousal
Define Glutamate
major excitatory neurotransmitter in the brain; enhances transmission of info between neurons
Define GABA
opposite of glutamate; primary inhibitor neurotransmitter in brain; tends to stop firing of neurons
Define norepinephrine
involved in states of vigilance, or a heightened awareness of dangers in the environment
Define Serotonin
involved in the regulation of sleep and wakefulness, eating, and aggressive behavior
Define endorphins
chemicals that act within the pain pathways and emotion centers of the brain