REVIEW Neural and Hormonal Systems

Learning Objectives

Page 47

Test Yourself by taking a moment to answer each of these Learning Objective Questions (repeated here from within the module). Research suggests that trying to answer these questions on your own will improve your long-term memory of the concepts (McDaniel et al., 2009).

Question

3-1 Why are psychologists concerned with human biology?
ANSWER: Psychologists working from a biological perspective study the links between biology and behavior. We are biopsychosocial systems, in which biological, psychological, and social-cultural factors interact to influence behavior.

Question

3-2 What are neurons, and how do they transmit information?
ANSWER: Neurons are the basic building blocks of the nervous system, the body's speedy electrochemical information system. A neuron receives signals through its branching dendrites, and sends signals through its axons. Some axons are encased in a myelin sheath, which enables faster transmission. Glial cells provide myelin, and they support, nourish, and protect neurons; they may also play a role in learning and thinking. If the combined signals received by a neuron exceed a minimum threshold (about negative 55 millivolts), 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. Absolute or relative refractory periods are tiny (millisecond) breaks between action potentials.

Question

3-3 How do nerve cells communicate with other nerve cells?
ANSWER: 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 reabsorbs the excess neurotransmitter molecules in the synaptic gap. If incoming signals are strong enough, the receiving neuron generates its own action potential and relays the message to other cells.

Question

3-4 How do neurotransmitters influence behavior, and how do drugs and other chemicals affect neurotransmission?
ANSWER: Neurotransmitters travel designated pathways in the brain and may influence specific behaviors and emotions. Acetylcholine (ACh) affects muscle action, learning, and memory. Endorphins are natural opiates released in response to pain and exercise. Drugs and other chemicals affect brain chemistry at synapses. Agonists increase a neurotransmitter's action, and may do so in various ways. Antagonists decrease a neurotransmitter's action by blocking production or release.

Question

3-5 What are the functions of the nervous system's main divisions, and what are the three main types of neurons?
ANSWER: The central nervous system (CNS)—the brain and the spinal cord—is the nervous system's decision maker. The peripheral nervous system (PNS), which connects the CNS to the rest of the body by means of nerves, gathers information and transmits CNS decisions to the rest of the body. The two main PNS divisions are the somatic nervous system (which enables voluntary control of the skeletal muscles) and the autonomic nervous system (which controls involuntary muscles and glands by means of its sympathetic and parasympathetic divisions). Neurons cluster into working networks. There are three types of neurons: (1) Sensory (afferent) neurons carry incoming information from sensory receptors to the brain and spinal cord. (2) Motor (efferent) neurons carry information from the brain and spinal cord out to the muscles and glands. (3) Interneurons communicate within the brain and spinal cord and between sensory and motor neurons.

Question

3-6 How does the endocrine system transmit information and interact with the nervous system?
ANSWER: 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, including the adrenal 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.

Terms and Concepts to Remember

Test yourself on these terms.

Question

biological psychology (p. 36)
neuron (p. 36)
dendrites (p. 36)
axon (p. 36)
myelin (MY-uh-lin) sheath (p. 37)
glial cells (glia) (p. 37)
action potential (p. 37)
threshold (p. 38)
refractory period (p. 39)
all-or-none response (p. 39)
synapse (SIN-aps) (p. 39)
neurotransmitters (p. 40)
reuptake (p. 40)
endorphins (en-DOR-fins) (p. 41)
agonist (p. 42)
antagonist (p. 42)
nervous system (p. 42)
central nervous system (CNS) (p. 42)
peripheral nervous system (PNS) (p. 42)
nerves (p. 42)
sensory (afferent) neurons (p. 42)
motor (efferent) neurons (p. 43)
interneurons (p. 43)
somatic nervous system (p. 43)
autonomic (aw-tuh-NAHM-ik) nervous system (ANS) (p. 43)
sympathetic nervous system (p. 43)
parasympathetic nervous system (p. 44)
reflex (p. 44)
endocrine (EN-duh-krin) system (p. 45)
hormones (p. 45)
adrenal (ah-DREEN-el) glands (p. 46)
pituitary gland (p. 46)
the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.
neurons that carry incoming information from the sensory receptors to the brain and spinal cord.
chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues.
a nerve cell; the basic building block of the nervous system.
the division of the autonomic nervous system that calms the body, conserving its energy.
the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft.
a molecule that inhibits or blocks a neurotransmitter's action.
a neuron's reaction of either firing (with a full-strength response) or not firing.
chemical messengers that cross the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.
a neurotransmitter's reabsorption by the sending neuron.
a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state.
the scientific study of the links between biological (genetic, neural, hormonal) and psychological processes. (Some biological psychologists call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists.)
“morphine within”—natural, opiate-like neurotransmitters linked to pain control and to pleasure.
neurons that carry outgoing information from the brain and spinal cord to the muscles and glands.
neurons within the brain and spinal cord; communicate internally and process information between the sensory inputs and motor outputs.
the division of the autonomic nervous system that arouses the body, mobilizing its energy.
the division of the peripheral nervous system that controls the body's skeletal muscles. Also called the skeletal nervous system.
the body's “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream.
a fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmission speed as neural impulses hop from one node to the next.
a molecule that increases a neurotransmitter's action.
the body's speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems.
the level of stimulation required to trigger a neural impulse.
the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.
a neural impulse; a brief electrical charge that travels down an axon.
the brain and spinal cord.
bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sense organs.
a neuron's often bushy, branching extensions that receive messages and conduct impulses toward the cell body.
cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning, thinking, and memory.
the neuron extension that passes messages through its branches to other neurons or to muscles or glands.
a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.
the endocrine system's most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands.
a simple, automatic response to a sensory stimulus, such as the knee-jerk response.

Experience the Testing Effect

Test yourself repeatedly throughout your studies. This will not only help you figure out what you know and don’t know; the testing itself will help you learn and remember the information more effectively thanks to the testing effect.

Question 2.1

1. The neuron fiber that passes messages through its branches to other neurons or to muscles and glands is the .

Question 2.2

2. The tiny space between the axon of one neuron and the dendrite or cell body of another is called the

A.
B.
C.
D.

Question 2.3

3. Regarding a neuron's response to stimulation, the intensity of the stimulus determines

A.
B.
C.
D.

Question 2.4

4. In a sending neuron, when an action potential reaches an axon terminal, the impulse triggers the release of chemical messengers called .

Question 2.5

5. Endorphins are released in the brain in response to

A.
B.
C.
D.

Question 2.6

6. The autonomic nervous system controls internal functions, such as heart rate and glandular activity. The word autonomic means

A.
B.
C.
D.

Question 2.7

7. The sympathetic nervous system arouses us for action and the parasympathetic nervous system calms us down. Together, the two systems make up the nervous system.

Question 2.8

8. The neurons of the spinal cord are part of the nervous system.

Question 2.9

9. The most influential endocrine gland, known as the master gland, is the

A.
B.
C.
D.

Question 2.10

10. The secrete(s) epinephrine and norepinephrine, helping to arouse the body during times of stress.

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