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Cells in the nervous system that communicate with on another to perform information-processing tasks
Cell body or soma
The part of a neuron that coordinates information-processing tasks and keeps cells alive
The part of a neuron that receives information from other neurons and relays it to the cell body
The part of a neuron that carries information to other neurons muscles or glands
A neuron is made up of three parts
- A cell body that houses the chromosomes with the organism's DNA and maintains the health of the cell
- Dendrites that receive info from other neurons
- Axon that transmits info to other neurons, muscles and glands
Which components of the neuron allow them to communicate?
An axon insulated with myelin can more efficiently transmit signals.
How do the three types of neurons work together to transmit info?
Sensory neurons receive the info, motor neurons carry signals from the spinal cord to the muscles and interneurons deliver the info from the sensory neurons to the motor neurons
An insulating layer of fatty material
Support cells found in the nervous system
The junction or region between the axon of one neuron and the dendrites or cell body of another
Neurons that receive info from the external world and convey this info to the brain via the spinal cord
Neurons that carry signals from the spinal cord to the muscles to produce movement
Neurons that connect sensory neurons motor neurons or other interneurons
Types of neurons
- Neurons have a cell body, an axon and at least one dendrite,
- Size and shape of neurons vary
- Purkinje cell has an elaborate tree like assemblage of dendrites.
- Pyramidal cells have a triangular cell body and a single, pong dendrite with many smaller dendrites
- Bipolar cells have only one dendrite and a single axon
The difference in electric charge between the inside and outside of a neuron's cell membrane
Neurons are the
Building blocks of the nervous system. They process outside info, communicate it with each other, and send messages to the body's muscles and organs
Neurons are composed of three major parts
- The cell body: Contains the nucleus which houses the organism's genetic material
- Dendrites: receive sensory signals from other neurons and transmit this info to the cell body
- Axon: Carries signals from the body to other neurons or to muscles and organs in the body
Neurons don't actually
Touch. They are separated by a small gap which is part of the synapse across which signals are transmitted from one neuron to another
Glial cells provide
Support for neurons, usually in the form of myelin sheath, which coats the axon to facilitate the transmission of ion. In demyelinating diseases the myelin sheath deteriorates
Neurons are differentiated according to
- The functions they perform.
- Three major types fo neurons: sensory (ex. Bipolar cells), motor and interneurons (ex. Purkinje cells)
What difference between the inside and outside of the neuron's cell membrane creates the resting potential?
Resting potential is potential energy created by the flow of K+ when the channels in the cell membrane allow K+ to flow
Like the flow of electricity when you turn on a light the action potential is all or none. Either
The switch is turned on or the room remains dark. Similarly either the electrical stimulation in the neuron reaches the threshold to fire an action potential, or it remains at the resting potential
An electric signal that is conducted along a neuron's axon to a synapse
The time following an action potential during which a new action potential cannot be initiated
Knoblike structures that branch out from an axon
Chemicals that transmit information across the synapse to a receiving neuron's dendrites
Parts of the cell membrane hat receive the neurotransmitter and initiate or prevent a new electric signal
Why is an action potential an all or nothing event?
Electric stimulation below the threshold fails to produce an action potential, whereas electric stimulation at or above the threshold always produces at he action potnetial
How does a neuron communicate with another neuron?
Axons ending in terminal buttons filled with tiny vessels that contain neurotransmitters that transmit info across the synapse to a receiving neuron's dendrites. These dendrites contain receptors
A neurotransmitter involved in a number of functions, including voluntary motor control
A neurotransmitter that regulates motor behavior, motivation, pleasure and emotional arousal
The major excitatory neurotransmitter in the brain
GABA (gamma-aminobutyric acid)
The primary inhibitory neurotransmitter in the brain
A neurotransmitter that is particularly in evolved in states of vigilance, or heightened awareness of dangers in the environment
A neurotransmitter that is involved in the regulation of sleep and wakefulness, eating and aggressive behavior
Chemicals that act within the pain pathways and emotion centers of the brain
Drugs that increase the action of a neurotransmitter
Drugs that block the function of a neurotransmitter
Myelin and Nodes of Ranvier
Myelin is formed by a type of glial cell, and it wraps around a neuron's axon to speed the movement of the action potential along the length of the axon. Breaks in the myelin sheath are called the nodes of Fancier. The electric impulse jumps from node to node, thereby speeding the conduction of info down the axon
- 1. The action potential travels down the axon and
- 2. Stimulates the release of neurotransmitters from vesicles
- 3. The neurotransmitters are released into the synapse, where they float to bind with receptor sites on a dendrite of a postsynaptic neuron, initiating a new action potential. The neurotransmitters are cleared out of synapse by
- 4. Reuptake into the sending neuron
- 5. Being broken down by enzymes in the synapse or
- 6. binding to auto receptors on the sending neurons
How do neurotransmitters create the feeling of runner's high?
Subjective highs result form the release of endorphins-chemical messengers acting in emotion and pain centers that elevate mood and dull the experience of pain.
How does L-dopa alleviate symptoms of Parkinson's disease?
- Dopamine is created in neurons by modification of a common molecule called L-dopa.
- Ingesting L-dopa will elevate the amount of L-dopa in the brain and spur the surviving neurons to produce more dopamine
- L-dopa acts as an agonist for dopamine.
The actions of agonist and antagonist drugs
Agonist and antagonist drugs can enhance or interfere with synaptic transmission at every point in the process; in the production of neurotransmitters, in the release of neurotransmitters, at the auto-receptors, in reuptake, in the postsynaptic receptors and in the synapse itself
The conduction of an electric signal within a neuron happens when
The resting potential is reversed by an electric impulse called an action potential
The neuron's resting potential is due to differences inthe
Potassium (K+) concentrations inside and outside of the cell membrane, resulting in open channels that allow K+ to flow outside the membrane white closed channels don't allow sodium ions (Na+) and other ions to flow into the neuron
Communication between neurons takes place through synaptic transmission, where
An action potential triggers release of neurotransmitters from the terminal buttons of the sending neuron's axon, which travel across the synapse to bind with receptors in the receiving neuron's dendrite
Neurotransmitters bin to dendrites on
Specific receptor sites
Neurotransmitters leave the synapse through
Reuptake, through enzyme deactivation, and by binding to autoreceptors
Some of the major neurotransmitters are acetylcholine (ACh)
Dopamine, glutamate, GABA, norepinephrine, serotonin and endorphins
Drugs can affect behavior by
- Acting as agonists, that is by facilitating or increasing the actions of neurotransmitters or as
- Antagonists, but blocking the action of neurotransmitters. Recreational drug use can have an effect on brain function