Neuron/neurotransmitter

Info from Module 9-Biological Psychology and Neurotransmission & Module 10- The Nervous and Endocrine Systems

Neuron

a nerve cell; the basic building block of the nervous system

Key parts of a neuron

-Cell body: contains the nucleus. It is the cell’s life support center

-dendrites: a neuron’s bushy, branching extensions that receive and integrate messages, conducting impulses toward the cell body

-axons: neuron extensions that pass messages through its branches to other neurons or to muscles or glands

-myelin sheath: fatty tissue layer that encases some axons to enable greater transmission speed

-terminal branches of axon

Glial cells

cells in the nervous system that support, nourish, & protect neurons

they also play a role in learning, thinking, & memory

Synapse, synaptic gap/cleft

The___is the junction b/t the axon tip of the sending neuron & the dendrite or cell body of the receiving neuron. The tiny gap at the junction is the___or___.

this is what happens in the synaptic gap

The sending neuron reabsorbs the excess neurotransmitter molecules

Action potential

a neural impulse; a brief charge that travels down an axon.

Threshold

the lvl of stimulation required to trigger a neural impulse

refractory period

a brief resting pause that occurs after a neuron has fired

substantial action potentials can’t occur again until the axon returns to its resting state

all-or-nothing response

a neuron’s reaction of either firing a full strength response or not firing

agonist molecules

increase neurotransmitters actions

some can increase production

antagonist molecules

inhibits or blocks a neurotransmitters’ action by blocking production

reuptake

a neurotransmitter’s reabsorption by the sending neuron

Sensory (afferent) neurons

neurons that carry incoming info from the body’s tissues & sensory receptors to the brain & spinal chord

Interneurons

neurons w/in the brain & spinal chord

they communicate internally & process info b/t the sensory inputs & motor outputs

Motor (efferent) neurons

neurons that carry outgoing info from the brain & spinal cord to the muscles & glands

Acetylcholine (ACh)

-neurotransmitter that enables muscle action, learning, and memory

-under supply linked to Alzheimer’s disease, a progressive disease

Dopamine

-neurotransmitter that influences movement, learning, attention, and emotion

-excess linked to schizophrenia

-under supply linked to the tremors and decreased mobility of Parkinson’s disease

Serotonin

-neurotransmitter that affects mood, hunger and appetite, sleep, arousal and also sexual desire & temperature regulation

-under supply linked to depression and also OCD & anger

-Prozac and some other antidepressant drugs help raise levels

Norepinephrine

-helps control alertness and arousal

-Stress & fear will stimulate this neurotransmitter

-prevalent in sympathetic nervous system (increases heart rate & blood pressure; often released w/ adrenaline)

-under supply can depress mood

GABA (gamma-aminobutyric acid)

-a major inhibitory neurotransmitter

-calms the brain

-natural tranquilizer

-under supply linked to seizures, tremors, insomnia/sleepless nights, & anxiety

Glutamate

-a major excitatory neurotransmitter (stimulates the brain); involved in memory

-most common neurotransmitter

-Plays a role in long-term potentiation (LTP); pattern of neural firing that strengthens synaptic connections

-oversupply can overstimulate the brain, producing migraines or seizures

Endorphins

-involved in pain control (natural opiate)

-many of our most addictive drugs deal w/ this neurotransmitter