(nerve cell) basic building block of the nervous system
Life support center of the neuron. No role in neural signaling
the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body
the extension of a neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands
Axon Terminal Branches
branching ends of axon that connect to dendrites of other cells
A layer of fatty (glial) cells encasing the axon fibers of many neurons. Acts as an insulator or conductor and enables greater transmission speed of impulses
The charge maintained when there are no action potentials. Excess negative charge inside compared to outside.
level of stimulation required to trigger an Action Potential. Each neuron receives many excitatory and inhibitory signals. When the excitatory signals minus the inhibitory signals exceed a minimum intensity (threshold) the neuron fires an action potential.
All or nothing response. A neuron either fires or it does not. Movement of an electrical impulse down the axon. A strong stimulus can trigger more neurons to fire, and to fire more often, but it does not affect the action potentials strength or speed. Intensity of an action potential remains the same throughout the length of the axon.
Ions involved in Action Potential
The principal ions involved are sodium and potassium. Sodium ions enter the cell, and potassium ions leave, restoring equilibrium.
Small storage sacs located there at the end of the terminal branches of the axon containing neurotransmitter molecules. Stimulation causes vesicle to open, releasing the neurotransmitter into the synapse
junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron
neurons that communicate within the CNS and intervene between sensory inputs and motor outputs
Motor / Efferent Neurons
carry outgoing information from the CNS to muscles and glands
Sensory / Afferent Neurons
carry incoming information from the sense receptors to the central nervous system
Excite their target neurons. They make them do something else. (Send a message, release a chemical, etc.)
Inhibit their target neurons. They prevent something from happening. (Stop a message,stop release a chemical, etc.)
Evoke neuromodulation. Convey information to a region of neurons either enhancing or dampening their activities. In contrast, neurotransmitters only convey information between two neurons.
neural "cables" containing many neurons part of the peripheral nervous system connect the central nervous system with muscles, glands, and sense organs
the body's speedy, electrochemical communication system consists of all the nerve cells of the peripheral and central nervous systems
Central Nervous System (CNS)
the brain and spinal cord
Peripheral Nervous System (PNS)
sensory and motor neurons that connect the CNS to the rest of the body
Somatic Nervous System
the part of the PNS that controls the body's skeletal muscles
Autonomic Nervous System (ANS)
the part of the PNS that controls the glands and the muscles of the internal organs (such as the heart)
Sympathetic Nervous System
division of the ANS that arouses the body, mobilizing its energy in stressful situations
Parasympathetic Nervous System
division of the ANS that calms the body, conserving its energy
chemicals that are used to relay, amplify and modulate signals between a neuron and another cell. chemical messengers that when released by the sending neuron travel across the synapse and bind to receptor sites on the receiving neuron influencing whether the receiving neuron will generate a neural impulse (action potential)
Neurotransmitters in the synapse are reabsorbed into the sending neurons through the process of reuptake. This process "applies the brakes" on neurotransmitter action.
Fits receptor well and mimics (acts like) the NT Ex. nicotine for ACh.
Fits receptor poorly, occupying the site without activating the receptor (blocks the NT) Ex. beta blockers (block epinephrine and norepinephrine)
block reuptake sites on transmitting neuron (Prozac, Paxil, Zoloft - block reuptake of serotonin. Opiates - block reuptake of endorphins. Cocaine - block reuptake of dopamine. Anti-Convulsants - block reuptake of Gaba)
Affects mood, hunger (and satiety), sleep and arousal. Undersupply linked to depression. Found in the CNS
Helps control alertness and arousa. Oversupply - "Fight or flight" response. Undersupply - can depress mood. Both a NT and a stress hormone. Found in CNS and ANS.
enables muscle action, learning and memory. undersupply - Alzheimer's Disease (Deterioration of memory, reasoning and language skills). Nicotine works on ACh receptors can artificially stimulate skeletal muscles leads to slight trembling movement Found in both CNS and PNS; only NT used in the somatic nervous system
involved in working memory, possibly involved eating and sleep patterns, motivation, pleasure and pain relief. Marijuana is an agonist. Found in CNS.
Gamma-Aminobutyric Acid (GABA)
Main inhibitory neurotransmitter. Undersupply - linked to seizures, tremors, and insomnia (Benzodiazepines (ex: Valium) and alcohol block GABA receptors) Found in the CNS
Major excitatory neurotransmitter. involved in memory. Oversupply - associated with epileptic seizures and migraine headaches (why some people avoid MSG in food). Found in CNS and PNS
"morphine within". natural, opiate-like neurotransmitters linked to pain control and to pleasure released in response to pain. opiates block endorphin receptors. involved in healing effects of acupuncture, runner's high. Opioid neuropeptides - inhibit release of GABA and stimulate release of Dopamine Found in the CNS.
Involved in movement, attention, learning, pleasure and emotion. Excess dopamine - linked to schizophrenia. Loss of dopamine - tremors and decreased mobility of Parkinson's disease. Found in CNS and PNS. Also a neurohormone.
substances other than NTs released by a neuron at a synapse and conveying information to a region of neurons, either enhancing or dampening their activities. In contrast, neurotransmitters only convey information between two neurons.
Neurotransmitters vs. Hormones: Distance traveled
Neurotransmitters - travel across a synapse. Hormones - travel longer distances between release and target sites
Neurotransmitters vs. Hormones: Speed of communication
Neurotransmitters - take rapid, specific action. Hormones - slower communication
chemical messengers produced in one tissue that affect others can be released by: organs (stomach, intestines, kidneys, brain) and glands (the endocrine system)
The Endocrine System
the body's "slow" chemical communication system - a set of glands that synthesize and secrete hormones into the bloodstream
subcortical structure of the brain that releases hormones or releasing factors that cause pituitary gland to release hormones
"Master endocrine gland", regulates growth, produces hormones that control hormone production in other glands
pair of glands just above the kidneys that secrete hormones that help arousal in stress (epinephrine (adrenaline) and norepinephrine)