Psychological Science, 2 ed.

Chapter 3: Genetic and Biological Foundations

Chapter Review

• Reduce Text Size (css supported browser only)
• Enlarge Text (css supported browser only)
• Email this Page to a Friend
• Print this Page

Summarizing the Principles of Genetic and Biological Foundations

What Is the Genetic Basis of Psychological Science?
1. Heredity involves passing along genes through reproduction: The Human Genome Project has mapped the approximately 30,000 genes that make up the 23 chromosomal pairs in humans. Variations of genes (alleles) are either dominant or recessive. The genome represents the genotype and the observable characteristics are the phenotype. Many characteristics are polygenetic.

2. Genotypic variation is created by sexual reproduction: Because one half of each chromosome comes from each parent and is randomly joined, there is enormous variation in the genome of the resulting zygote. Mutations also give rise to variations.

3. Genes affect behavior: Behavioral geneticists are able to examine the similarity and variation in shared characteristics in a population, based on genetic and environmental similarity; this assessment is termed heritability.

4. Social and environmental contexts influence genetic expression: Though genes guide the development of characteristics, their final expression is a complex interaction between genetic makup and environmental context.

5. Gene expression can be modified: Genetic manipulation has been achieved in other mammals (e.g., mice) but has proven difficult in humans. However, studies focusing on RNA offer new hope.

How Does the Nervous System Operate?
6. Neurons are specialized for communication: Neurons are the basic building blocks of the nervous system that receive and send chemical messages. The structure of all neurons is the same but vary by function and location in the nervous system.

7. Action potentials cause neuronal communication: Changes in the electrical charge of neurons results in an action potential (neural firing). This is the means of communication within networks of neurons.

8. Changes in electrical potential lead to action: Neural firings either continue the message to other neurons or halt it. Neurons fire due to a change in the electrical balance of positive and negative sodium and potassium ions inside and outside the neuron.

9. Action potentials spread along the axon: The dendrites receive a signal that spreads the changes in the exchange of positive and negative ions to reach a threshold, which generates an action potential. The firing of a neuron is all or none—a neuron does not partially fire. This electrical signal travels along the axon. The myelin insulation on the axon speeds transmission.

10. Neurotransmitters bind to receptors across the synapse: Neurons do not touch; they release chemicals (neurotransmitters), which bind with receptors of other neurons thus changing the charge in that neuron. The effect of neurotransmitters is halted by a variety of actions.

How Do Neurotransmitters Influence Emotion, Thought, and Behavior?
11. Acetylcholine affects motor control and mental processes: Acetylcholine acts on neurons directing muscle movement.

12. Monoamines are involved in affect, arousal, and motivation: Epinephrine and norepinephrine are involved in arousal and alertness. Serotonin is involved in impulse control, emotion, and dreaming. Dopamine affects motor control and motivation.

13. Amino acids are general inhibitory and excitatory transmitters in the brain: The amino acid GABA is the transmitter for inhibiting neuronal transmission. Glutamate does the opposite; it is involved in neuronal transmission and aids learning and memory.

14. Peptides modulate neurotransmission: Peptides change the effect of other transmitters. Cholecystokinin (CCK), endorphins, and substance P affect satiation and pain.

How Are Neural Messages Integrated into Communication Systems?
15. The central nervous system consists of the brain and spinal cord: The central nervous system is made up of the structures and functions of the brain and spinal cord.

16. The peripheral nervous system includes the somatic and autonomic systems: The structures and functions that regulate the body's internal environment is the autonomic system, which has the complementary division of the alarm response (sympathetic) and the return-to-normal- state response (parasympathetic). The somatic system relays sensory information.

17. The endocrine system communicates through hormones: Endocrine glands and organs produce and release chemical substances, which travel to tissues in the body through the bloodstream and influence a variety of processes, including sexual behavior.

18. Actions of the nervous system and endocrine system are coordinated: The endocrine system is controlled by the central nervous system. Most of the central control of the endocrine system occurs through the action of the hypothalamus and the pituitary gland, which controls the release of hormones from the rest of the endocrine glands.