PSYCH101: Introduction to Psychology

2a. Discuss the role of genetics in human psychology and gene-environment interactions

• What is the gene-environment interaction?
• What's the difference between genotype and phenotype?

Although psychology is a social science defined as the study of the mind, the fields of genetics and biology are also important. We draw on these fields to understand the biological causes of behaviors and understand the significance of brain functions and development.
 
The nature-nurture debate is significant in this line of inquiry. Do our genes (nature) or our contexts and experiences (nurture) cause us to behave the way we do? Consequently, scientists differentiate between genotypes (our genetic makeup) and phenotypes (inherited physical traits and characteristics).
 
Genes do not exist in isolation – nature alone does not predict human behavior. Our genes provide the general structure (possible range for behaviors) in which we operate, but our inherited traits and our surroundings (nurture/environment) also contribute to our behaviors.
 
Our genes (nature) determine the possible range of a certain behavior (for example, artistic development), while our environment (nurture) determines its potential. For example, when a child has an innate talent for music (singing of playing an instrument) (genetic) and is raised in a home where parents provide ample opportunities and resources to foster a love for music, the child is more likely to reach their full potential of musical talent compared to a child who is not reared in such a fostering environment.
 
To review, see Human Genetics, Twin and Adoption Studies, and Risk Factors for Developing Schizophrenia.
 

2b. Explain the structure and function of neurons, neural communication, the brain, the spinal cord, the central nervous system, the peripheral nervous system, and the physiological and behavioral effects of neurotransmitters and psychoactive drugs

• What are the basic parts of a nerve cell?
• How do neurons communicate with each other?
• How do the central and peripheral nervous systems differ?
• What are neurotransmitters?
• What is the effect of psychoactive drugs on neurotransmitters?

A nerve cell, or neuron, consists of a cell body, membrane, an axon covered in a myelin sheath, dendrites, and terminal buttons. Neurons rely on chemical messengers called neurotransmitters to communicate with each other; these neurotransmitters are stored in a neuron's terminal button. When a neuron is activated, an action potential fires or activates the neuron and releases the neurotransmitter into the synaptic gap between neurons. When the receiving dendrites receive the signal, the receptors open and allow sodium ions (Na+) to move into the receiving cell. This causes the internal state of the receiving neuron to become positive. If this charge is strong enough to meet the threshold of excitation for the receiving neuron, it will become activated and start firing.
 
The central nervous system (CNS) consists of the brain and the spinal cord, while the peripheral nervous system (PNS) is made up of the nerve cells throughout one's body. Essentially, the PNS connects the CNS to the rest of the body.
 
There are a number of neurotransmitters, which each have different effects on behaviors. For example, dopamine and serotonin are associated with mood and sleep, while acetylcholine and glutamate are linked to memory. The release or inhibition of neurotransmitter release is associated with specific behaviors, so if a neuron fires and releases acetylcholine, a person will have enhanced memory and cognition. However, when neurons are inhibited from releasing this neurotransmitter, the person will experience decreased memory.
 
Psychoactive drugs can impact neurotransmitters, such as by forcing or inhibiting the release of a neurotransmitter to regulate behavior. These are called agonist and antagonist responses, respectively. For example, patients experiencing schizophrenia symptoms have been found to have an overactive dopamine presence. Medications used to treat these patients consist primarily of dopamine antagonists to regulate this imbalance.
 
To review the structures and functions of neurons, see Cells of the Nervous System, Introduction to Neurons, Action Potentials, Neuron Action Potential, Neurotransmitters and Their Functions, Neurotransmitters: Type, Structure, and Function, Parts of the Nervous System, and The Nervous System.
 

2c. Describe how researchers study and examine the brain and its functions, the behavioral effects of brain injuries, and the significance of split-brain operations

• How can radiation and magnetic fields be used to study the brain?
• What is a stroke, and how can it affect brain functioning?
• What is the role of split-brain operations, and what are some consequences?

If brain functioning is impaired by an accident (damage to the head during a car accident) or a stroke, researchers can draw upon brain imaging techniques to explore further. Strokes occur when brain cells are deprived of oxygen and thus cannot function properly anymore.
 
Brain imaging techniques among patients with brain injuries can inform the field of neuropsychology greatly as we are still learning about specific brain structures and functions.

There are two methods involving radiation that allow researchers to study and take pictures of human brains. These techniques are particularly useful since they are pain-free and not very invasive. They can provide ample evidence of brain functioning and damage following a stroke or an accident, for example. Computerized tomography (CT) is an x-ray of the brain. Magnetic resonance imaging (MRI) uses magnetic fields to image the brain.
 
Fibers connect the two hemispheres of our brain. Some patients with severe epilepsy undergo split-brain surgery to separate these fibers to disconnect the hemispheres to stop the spread of seizures. This surgery can tame epilepsy, but patients display several side effects. For example, they may be able to name an object but not be able to grasp it with their hand.
 
To review, see The Brain and Spinal Cord, Phantom Limb Pain, and The Brain.
 

2d. Describe the endocrine system and the role of hormones in regulating body functions

• What are the major glands in the endocrine system?
• How do hormones regulate body functions?

The endocrine system includes several glands that rely on chemical substances called hormones to communicate with each other and regulate behaviors such as metabolism, growth, sexual functions, sleep, reproduction, and mood.
 
The pituitary gland is the master gland of the endocrine system; it regulates growth and pain hormones, among others. The thyroid gland regulates metabolism and appetite, while the pancreas secretes hormones that regulate sugar. Adrenal glands regulate stress hormones, and gonads secrete sexual hormones.
 
Unlike neurotransmitters, hormones travel through the body in the bloodstream. Hormones are often slow to act but tend to last longer than neurotransmitters. When hormones travel throughout the bloodstream, they must attach to their intended receptor cells to relay a message. When a hormone binds to the correct cell, a biological process activates the receiving cell and corresponding gland. The major glands release hormones to regulate several functions, such as growth, appetite, sex, reproduction, and stress.
 
To review, see The Endocrine System, More on the Endocrine System, and The Brain.
 

2e. Describe the stages of sleep (REM and NREM), their importance in proper psychological function, common sleep problems and disorders, and hypnosis

• What are the stages of sleep? Differentiate between REM and NREM
• Describe common sleep problems and disorders

Sleep is a daily period of time and state of consciousness when the nervous system is relaxed and relatively inactive. Research has shown that sleep is essential to our everyday health and functioning; even a short period without sleep changes our mood, awareness, and overall psychological functioning.
 
Non-REM (or NREM) sleep has four stages. Stage One sleep is the transition from being awake to sleeping; Stage Two is deeper, more relaxing sleep; and Stages Three and Four are deep sleep. Our brain waves are progressively bigger and slower during each stage. REM sleep is characterized by rapid eye movements but no muscle response. During REM sleep, our brain waves show similar patterns to when we are awake. Common sleep disorders include insomnia (inability to fall or stay asleep), sleepwalking, sleep apnea (difficulty breathing during sleep), and narcolepsy (the tendency to fall asleep).
 
Hypnosis describes a state in which we are unaware of our surroundings or perceive our surroundings as different from what they are. It can help people cope with pain through a process we call dissociation and can entertain a crowd through participants that fulfill the social role of a hypnotized person.
 
To review sleep, see Why We Sleep, Stages of Sleep, Sleep Problems and Disorders, and More on Sleep Disorders. To review hypnosis, read Other States of Consciousness.

2f. Explain how substance use disorders are classified; differentiate among major drug categories (stimulants, depressants, antipsychotics, opioids, hallucinogens)

• What are examples of depressants, stimulants, opioids, and hallucinogenic drugs?
• What effects do these drugs have?

Sleep is an altered state of consciousness. Psychoactive drugs, such as prescription drugs or illegal substances, can also induce altered states. Drugs impact our brains and behaviors in several ways, and we categorize them by their function.
 
For example, alcohol, marijuana, and barbiturates have a sedative effect on the body and central nervous system. We call these substances depressants because they slow the body and brain functioning down. We call drugs that stimulate the brain and body increase activity stimulants. Stimulants such as cocaine and amphetamines increase dopamine activity and often increase body activity or feelings of pleasure.
 
Opioids, such as heroin and morphine, have an analgesic effect on the body and typically decrease pain sensations. Hallucinogens, such as LSD and PCP, profoundly alter the users' perceptions and sensations by causing vivid hallucinations or strange and new body sensations (like ants crawling on one's skin).
 
To review psychoactive drugs, see Substance Use and Abuse, Substance Use Disorders, Commonly Abused Drugs, and Drugs and the Brain.
 

Unit 2 Vocabulary

Be sure you understand these terms as you study for the final exam. Try to think of the reason why each term is included.

• central nervous system
• computerized tomography (CT)
• depressant
• endocrine system
• genotype
• hallucinogen
• hormone
• hypnosis
• magnetic resonance imaging (MRI)
• nature-nurture debate
• neuron
• neurotransmitter
• non-REM sleep
• opioid
• peripheral nervous system
• phenotype
• psychoactive drugs
• REM sleep
• sleep disorder
• split-brain surgery
• stimulant