AP Psych Midterm Review Unit 3A
How do neurotransmitters influence behavior, and how do drugs and other chemicals affect neurotransmission?
Each neurotransmitter travels a designated path in the brain and has a particular effect on behavior and emotions. Ace tylcholine affects muscle action, learning, and memory. Endorphins are natural opiates released in response to pain and exercise. (See Table 3A.1 on p. 57 to review the key neurotransmitters.) Drugs and other chemicals affect communication at the synapse. Agonists bind to and activate receptors, thus mimicking particular neurotransmitters. Antagonists block receptors, thus blocking a neurotransmitter's natural effect.
What are neurons, and how do they transmit information?
Neurons are the elementary components of the nervous system, the body's speedy electrochemical information system. Sensory neurons carry incoming information from sense receptors to the brain and spinal cord, and motor neurons carry information from the brain and spinal cord out to the muscles and glands. Interneurons communicate within the brain and spinal cord and between sensory and motor neurons. A neuron sends signals through its axons, and receives signals through its branching dendrites. If the combined signals are strong enough, the neuron fires, transmitting an electrical impulse (the action potential) down its axon by means of a chemistry-to-electricity process. The neuron's reaction is an all-or-none process.
What are the functions of the nervous system's main divisions?
One major division of the nervous system is the central nervous system (CNS), the brain and spinal cord. The other is the peripheral nervous system (PNS), which connects the CNS to the rest of the body by means of nerves. The peripheral nervous system has two main divisions. The somatic nervous system enables voluntary control of the skeletal muscles. The autonomic nervous system, through its sympathetic and parasympathetic divisions, controls involuntary muscles and glands. Neurons cluster into working networks.
How does the endocrine system—the body's slower information system—transmit its messages?
The endocrine system is a set of glands that secrete hormones into the bloodstream, where they travel through the body and affect other tissues, including the brain. The endocrine system's master gland, the pituitary, influences hormone release by other glands. In an intricate feedback system, the brain's hypothalamus influences the pituitary gland, which influences other glands, which release hormones, which in turn influence the brain.
How do nerve cells communicate with other nerve cells?
When action potentials reach the end of an axon (the axon terminals), they stimulate the release of neurotransmitters. These chemical messengers carry a message from the sending neuron across a synapse to receptor sites on a receiving neuron. The sending neuron, in a process called reuptake, then normally absorbs the excess neurotransmitter molecules in the synaptic gap. The receiving neuron, if the signals from that neuron and others are strong enough, generates its own action potential and relays the message to other cells.
