Chapter 2 Biology and Behavior

Chapter 2 Overview The Neurons and Neurotransmitters The Human Nervous System Discovering the Brain’s Mysteries A Closer Look at the Brain Age and Gender Differences in the Brain The Endocrine System Genes and Behavioral Genetics

What are the functions of the various parts of the neuron? Cell body Carries out life-sustaining functions Dendrites Receive signals from other neurons Axon Sends signals to other neurons, muscles, and glands Synapse Junction between neurons

What are neurotransmitters? Neurotransmitters are chemical substances that transmit messages between neurons Released into synapse by axon terminals of sending neuron Bind to receptor sites on dendrites of receiving neuron Taken back into axon terminal by the process of reuptake

What are the functions of some major neurotransmitters? Acetylcholine Affects movement, learning, memory, REM Sleep Dopamine Affects movement, attention, learning, reinforcement, pleasure Norepinephrine Affects eating, alertness, wakefulness Epinephrine Affects metabolism of glucose, energy release during exercise

What are the functions of some major neurotransmitters? Serotonin Affects mood, sleep, appetite, impulsivity, aggression Glutamate Active in areas of the brain involved in learning, thought, and emotion GABA Facilitates neural inhibition in the central nervous system Endorphins Provide relief from pain and produce feelings of pleasure and well-being

The Human Nervous System Central nervous system The brain and spinal cord Peripheral nervous system The nerves connecting the central nervous system to the rest of the body

Which brain structures are found in the hindbrain? Medulla Controls heartbeat, blood pressure, breathing, coughing, swallowing Reticular formation Plays a crucial role in arousal and attention Screens sensory messages entering the brain

Which brain structures are found in the hindbrain? Pons Plays a role in body movement Influences sleep and dreaming Cerebellum Helps the body execute smooth, skilled movements Regulates muscle tone and posture

What important structure is located in the midbrain? The midbrain links the physiological functions of the hindbrain to the cognitive functions of the forebrain Substantia nigra Controls unconscious motor movements

Which brain structures and functions are found in the forebrain? Thalamus A relay station for information flowing into or out of the brain Hypothalamus Regulates hunger, thirst, sexual behavior, body temperature, and a wide variety of emotional behaviors

Which brain structures and functions are found in the forebrain? Amygdala Structure in the limbic system that plays an important role in emotion Hippocampus Structure in the limbic system that plays a central role in storing new memories, responses to new or unexpected stimuli, and navigational ability

The Peripheral Nervous System The peripheral nervous system has two subdivisions The somatic nervous system consists of all sensory nerves and motor nerves The autonomic nervous system transmits messages between the central nervous system and the glands, the cardiac muscle, and the smooth muscles

Two parts of the autonomic nervous system Sympathetic nervous system Mobilizes the body’s resources during stress and emergencies Parasympathetic nervous system Brings the heightened bodily responses back to normal following an emergency

What is the difference between the sympathetic and parasympathetic nervous systems?

Discovering the Brain’s Mysteries Modern researchers do not have to wait to perform autopsies or wait for injuries to occur to learn about the brain Today, researchers unlock the mysteries of the brain using a variety of techniques

What does the EEG reveal about the brain? Electroencephalogram (EEG) A record of brain-wave activity made by a machine called an electroencephalograph Electrical activity in the brain is detected by electrodes placed on the scalp

How are imaging techniques helpful in the study of brain structure and function? CT scan Computerized axial tomography Uses X-rays to produce cross-sectional images of the brain MRI Magnetic resonance imaging Produces high-resolution images of the structures of the brain

How are imaging techniques helpful in the study of brain structure and function? PET scan Positron-emission tomography Reveals activity in various parts of the brain based on blood flow, oxygen use, and glucose consumption Functional MRI (fMRI) Provides images of both brain structure and function Can identify locations of brain activity more precisely and rapidly than PET scan

A Closer Look at the Brain The cerebrum The largest structure in the human brain Its functions include language, planning, and logic

What are the components of the cerebrum? Cerebral hemispheres The left and right halves of the cerebrum Corpus callosum Connects the two hemispheres Cerebral cortex Thin outer covering of cerebrum Responsible for higher mental processes of language, memory, and thinking

What are the specialized functions of the left and right hemispheres? The left hemisphere Controls the right side of the body Handles most language functions Is specialized for mathematics and logic

What are the specialized functions of the left and right hemispheres? The right hemisphere Controls the left side of the body Processes music Interprets emotional messages conveyed by tone of voice and gestures Is specialized for visual-spatial relations

Which psychological functions are associated with the frontal lobes? Motor cortex Area that controls voluntary body movement Broca’s area Area in the frontal lobe, usually in the left hemisphere, that controls the production of speech Association areas Areas involved in thinking, planning for the future, impulse control

What important structure is found in the parietal lobes? Somatosensory cortex Strip of tissue at the front of the parietal lobes where touch, pressure, temperature, and pain register in the cortex

Why are the occipital lobes critical to vision? The occipital lobes are involved in the reception and interpretation of visual information Primary visual cortex Area at the rear of the occipital lobes where vision registers in the cortex

What are the major areas within the temporal lobes, and what are their functions? Primary auditory cortex Area in each temporal lobe where hearing registers in the cortex Wernicke’s area Language area in the left temporal lobe involved in comprehending spoken language and formulating coherent speech and written language

Age and Gender Differences in the Brain The brain grows from conception until well into adulthood Throughout development, the brains of males and females differ to some degree

How do the brains of men differ from those of women? Women’s brains have equal proportions of gray and white matter in the left and right hemispheres; men’s brains have a lower proportion of white matter in the left hemisphere than in the right This may explain men’s superior ability in spatial tasks Women have more gray matter in the area of the brain that controls emotions This may explain women’s superior ability to perceive emotions Navigational information is processed in different parts of the brain in men and women Women use right parietal cortex and right frontal cortex Men use left hippocampus Men and women use different areas to process location of sound More research is needed to understand the meaning of these gender differences in the brain

The Endocrine System A system of ductless glands that manufacture hormones and secrete them into the bloodstream

What functions are associated with the various glands of the endocrine system? Pituitary gland The “master gland” Located in the brain Releases hormones that activate other endocrine glands Pineal gland Located deep in the brain Secretes the hormone melatonin which controls sleep/wakefulness cycle Thyroid gland Located below the voice box Produces thyroxine, which regulates rate at which food is metabolized

What functions are associated with the various glands of the endocrine system? Parathyroid glands Attached to the thyroid Produce parathyroid hormone which helps the body absorb minerals from the diet Thymus gland Produces hormones that are essential to immune system functioning Adrenal glands Release hormones that prepare the body for emergencies and stressful situations Gonads The ovaries in females and testes in males Produce sex hormones

Genes and Behavioral Genetics segments of DNA located on chromosomes that transmit all heredity traits Chromosomes rod shaped structures in the nuclei of cells that contain all genes and carry genetic information to make a human being Behavioral Genetics a field of research that uses twin and adoption studies to investigate the relative effects of heredity and environment on behavior

What patterns of inheritance are evident in the transmission of genetic traits? Dominant-recessive pattern a set of inheritance rules in which one dominant gene causes a trait to be expressed, but two recessive genes are required for expression of a recessive trait Multifactorial inheritance A pattern of inheritance in which a trait is influenced by both genes and environment Sex-linked inheritance Involves genes on the X and Y chromosomes Example: red-green color blindness

Ishihara Test

What kinds of studies are done by behavioral geneticists? Twin studies Examine identical (monozygotic) and fraternal (dizygotic) twins If identical twins are more alike on a trait, the trait is assumed to be more influenced by heredity If identical and fraternal twin pairs do not differ on a trait, the trait is assumed to be more influenced by environment Adoption studies Compare adopted children’s abilities and traits to those of adoptive parents and biological parents