Nervous System Exam 1B Material

Neurotransmitters

chemical substance produced by neurons

Synaptic delay

time from arrival of signal to beginning of action potential

Monoamines

distributed in brain; regulate emotional behavior and biological clock; synthesized from amino acids by removing carboxylic acid

Monoamine examples

epinephrine, norepinephrine, dopamine, histamine, serotonin

Amino Acid Neurotransmitters

glycine, glutamate (STRONGEST EXCITATORY), aspartate, GABA (STRONGEST INHIBITORY)

Neuropeptides

endorphins, substance P, gut-brain peptides (cholecystokinin - CKK)

Neuromodulator

chemical messenger released by neuron to affect strength of transmission

Acetylcholine

class of its own; stimulate skeletal muscles; neuromuscular junctions; excitatory or inhibitory (nicotinic & muscarinic receptors)

Endorphins

neuropeptide; natural opiates (pain-killing neurotransmitter)

Substance P

neuropeptide; mediate pain signals

Purines

nitrogen containing chemicals; ATP & adenosine

Cholinergic neurons

neurons that secrete acetylcholine

Nicotinic receptors

door opens & allows bidirectional mvmnt of Na and K; Na enters in higher #s (excitatory)

Muscarinic receptors

indirect action (more complex changes in next cell); G-protein subunit dissociates; 2nd messenger cascade

Alzheimer’s

degeneration of cholinergic neurons in CNS; treatment: drugs inhibit ACh

Anticholinergic toxicity

block binding of ACh at muscarinic receptors; often caused by overdose, laced drugs, etc.

Catecholamines

norepinephrine, epinephrine, and dopamine

Second messengers

small molecules & ions that relay signals received by cell-surface receptors to effector proteins

Primary ANS organs

thoracic & abdominal cavity viscera; body wall structures; cutaneous BVs; sweat glands; piloerector muscle

Hypothalamus

CNS regulation; direct control via relays through reticular formation

Brain stem

role in CNS regulation; direct control over autonomic functions

Cortical controls 

cerebral cortex; conscious control of ANS

Norepinephrine

Primary NT of sympathetic nervous system

Sympathetic nervous system

prepares body for physical activity & response (fight or flight)

Dual innervation

2 divisions (sympathetic and parasympathetic) innervate same target organs

Mass activation

facilitation of many structures simultaneously; important for coord. of rapid change across structures in stress response; sympathetic

Acetylcholine

Primary NT of parasympathetic nervous system

Parasympathetic nervous system

calms body functions reducing energy expenditure & assisting in bodily maintenance (rest & digest); direct stimulation

Muscarinic receptors

receptor in all cardiac & smooth muscle & gland cells; excitatory or inhibitory

Nicotinic receptors

receptor on all ANS postganglionic receptors, in adrenal medulla, at neuromuscular junctions of skeletal muscles

Adrenergic fibers

nerve fibers that, when stimulated, release catecholamine neurotransmitters—primarily norepinephrine; alpha (excitatory) and beta (inhibitory)

Enzyme amplification

single molecule of norepinephrine can produce vast amounts of product molecules in cell