Module 1

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

Biology 30 Learn EveryWare © 2009 Alberta Education