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Module 1.3a

Sending
neuron Figure 1.3-6
Agonists and antagonists
Vesicles
containing Action Curare poisoning paralyzes
neurotrans- potential its victims by blocking ACh
mitters receptors involved in muscle
movements. Morphine mimics
endorphin actions. Which is
an agonist, and which is an
Synaptic
gap antagonist? (Information from
Higgins & George, 2007.)
Neurotransmitter
molecule
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Receiving neuron
Receptor
sites
Neurotransmitters carry a message
from a sending neuron across a synapse
Copyright © Bedford, Freeman & Worth Publishers.
to receptor sites on a receiving neuron.

Agonist mimics
Receptor site on neurotransmitter, Antagonist blocks
receiving neuron Neurotransmitter opening receptor site. neurotransmitter
opens the from opening
receptor site. receptor site.
Drug

Open Open

®
AP Science Practice Check Your Understanding
Examine the Concept Apply the Concept
▶ Serotonin, dopamine, and endorphins are all chemical ▶ Can you recall a time, perhaps after a workout, when you
messengers called ____________ . felt the effects of endorphins? How would you explain those
feelings?
▶ Curare poisoning paralyzes animals by blocking ACh
receptors involved in muscle movements. Morphine mimics the
actions of endorphins. Which is an agonist, and which is an
antagonist?

Answers to the Examine the Concept questions can be found in Appendix C at the end of the book.

The Endocrine System

How does the endocrine system transmit information and interact with the
1.3-4 How does the endocrine system transmit information and interact with the endocrine [EN-duh-krin]
1.3-4

nervous system? system the body’s “slow”
nervous system?
chemical communication system;
a set of glands and fat tissue
So far, we have focused on the body’s speedy electrochemical information system. Inter- that secrete hormones into the
connected with your nervous system is a second communication system, the endocrine bloodstream.

.
system The endocrine system’s glands and fat tissue secrete another form of chemical
The Neuron and Neural Firing: Neural Communication and the Endocrine System Module 1.3a 35

03_myersAPpsychology4e_28116_ch01_002_163.indd 35 15/12/23 9:21 AM