Module 1
1. Module 1
1.60. Page 9
Module 1—The Nervous System
Lesson Summary
In this lesson, you have explored the following focusing questions:
- How does the anatomy and function of the synaptic gap and neuromuscular junction facilitate the transmission of nerve impulses between neurons and between neurons and effectors?
- How do chemicals taken into the body and disorders, such as Parkinson’s disease, compromise synaptic transmission?
The parts of the nervous system—neurons, neural pathways, receptors, effectors, and synapses—all fit together like the pieces of a puzzle. If one piece fails to fit, the system doesn’t work right. Disorders, such as Parkinson’s disease, and chemical substances, such as drugs, can interrupt the function of the system.
Lesson Glossary
Consult the glossary in the textbook for other definitions that you may need to complete your work.
acetylcholine: one of the most common neurotransmitters of both the somatic nervous system and the parasympathetic nervous system
Acetylcholine functions by binding to receptors on the postsynaptic membrane and either depolarizing or hyperpolarizing the membrane.
cholinesterase: an enzyme necessary to decompose acetylcholine in the synaptic cleft so that the products (choline and ethanoic acid) can be reabsorbed by the presynaptic membrane; also called acetylcholinesterase
dopamine: generally an excitatory neurotransmitter in the CNS
excitatory neurotransmitter: a neurotransmitter that promotes nerve impulse transmission in the postsynaptic membrane by opening sodium channels
GABA (gamma aminobutyric acid): an inhibitory neurotransmitter in the CNS
glutamate: an excitatory neurotransmitter in the CNS
inhibitory neurotransmitter: a neurotransmitter that hinders nerve impulse transmission in the postsynaptic neuron by hyperpolarizing it
neuromuscular junction: a tiny gap located between an axon terminal and a muscle cell
neurotransmitter: a chemical messenger released from the synaptic knob of a neuron at a synapse that diffuses across the synaptic cleft, binds to specially shaped protein receptors on the postsynaptic membrane, and stimulates the postsynaptic neuron
norepinephrine: a neurotransmitter released by sympathetic neurons of the autonomic system to produce an excitatory effect on target muscles; also called noradrenalin
postsynaptic membrane:the surface membrane on the dendrites of a receiving neuron across the synaptic cleft; contains receptor sites for neurotransmitters
Note the role of “shape” in controlling biological processes.
postsynaptic neuron: the receiving neuron
presynaptic membrane: the surface membrane surrounding the synaptic knob and facing the synaptic cleft
presynaptic neuron: the sending neuron
serotonin: an inhibitory neurotransmitter in the CNS
synapse (also synaptic cleft and synaptic gap): the location or junction in a neural pathway where one neuron communicates with another neuron; a tiny gap between the synaptic terminal of an axon and the signal receiving dendrite or cell body of another neuron or an effector, such as a muscle
synaptic cleft: a tiny space separating the synaptic knob of a transmitting neuron from a receiving neuron or effector cell
synaptic knob: the tiny enlarged ending on an axon terminal
synaptic vesicle: a tiny membranous sac that, in this case, contains neurotransmitters