Biological Bases of Mental Life and Behavior Study Notes

Chapter 6: Biological Bases of Mental Life and Behaviour

Learning Outcomes

  • After studying this chapter, you should be able to:

    • 6.1 describe the basic units of the nervous system.

    • 6.2 describe the major structures and functions of the endocrine system.

    • 6.3 explain the major subdivisions of the peripheral nervous system.

    • 6.4 describe the major structures and functions of the central nervous system.

    • 6.5 describe the relative roles of genetics and environment in psychological functioning.

Concept Map: Biological Bases of Mental Life and Behaviour

  • Neurons: Basic units of the nervous system.

    • The nervous system consists of:

    • Central Nervous System (CNS)

    • Peripheral Nervous System (PNS)

  • Types of Neurons:

    • Sensory neurons carry sensory information from sensory receptors to the CNS.

    • Motor neurons transmit commands from the brain to glands and muscles of the body.

    • Interneurons connect other neurons with one another.

  • Neuron Structure: Generally has a cell body, dendrites (branch-like extensions of the cell body), and an axon that carries information to other neurons.

  • Resting Potential: When a neuron is at rest, it is polarized with a negative charge inside the cell membrane and a positive charge outside.

    • Graded Potentials: Voltage changes that occur along the cell membrane as the neuron is excited by other neurons.

    • Action Potential: The 'firing' of the neuron or a nerve impulse.

    • Neurotransmitters: Chemicals that transmit information from one neuron to another via synapse interactions.

The Endocrine System

  • A collection of glands that control various bodily functions through the secretion of hormones.

    • Sends messages through the bloodstream, affecting multiple cell types simultaneously.

  • Major Glands Include:

    • Pituitary Gland: Often referred to as the 'master gland'.

    • Thyroid: Influences growth and metabolism.

    • Adrenals: Release adrenaline and other hormones during emergencies.

    • Pancreas: Regulates blood sugar levels.

    • Gonads: Ovaries and testes, influencing sexual development and behavior.

The Peripheral Nervous System (PNS)

  • Consists of neurons carrying messages to and from the CNS.

  • Major Subdivisions:

    • Somatic Nervous System: Transmits sensory information to the CNS and directs motor commands to skeletal muscles.

    • Autonomic Nervous System: Controls basic life processes, subdivided into:

    • Sympathetic Nervous System: Prepares the body for fight or flight.

    • Parasympathetic Nervous System: Calms the body down and maintains energy after the emergency has passed.

The Central Nervous System (CNS)

  • Comprises the brain and spinal cord, reflecting its evolutionary development.

  • Spinal Cord Functions:

    • Relays sensory information to the brain and transmits motor commands back to muscles and organs.

    • Controls reflex actions that occur automatically.

Structure of the Brain

  • Hindbrain: Contains the Medulla Oblongata, Cerebellum, and parts of the Reticular Formation.

    • Medulla: Controls vital life processes like heartbeat and respiration.

    • Cerebellum: Coordinates movement, balance, and learning related to motor control.

  • Midbrain: Comprises Tectum and Tegmentum, involved with sensory functions and coordination of movement patterns.

  • Forebrain: Involved in the regulation of complex behaviors, emotions, and cognitive functions. Includes:

    • Hypothalamus: Regulates hunger, thirst, and emotional responses.

    • Thalamus: Acts as a sensory relay station, processing and transmitting sensory information to appropriate brain regions.

    • Cerebrum: Responsible for higher brain functions including sensory perception and voluntary muscle activity, consisting of the cerebral cortex (the outer layer) and various subcortical structures (like the limbic system and basal ganglia).

Major Parts of the Cerebrum

  • Cerebral Cortex: Two hemispheres divided into four lobes:

    • Occipital Lobes: Visual processing area of the brain.

    • Parietal Lobes: Process touch and spatial awareness.

    • Frontal Lobes: Involved in movement, abstract thinking, planning, and social skills.

    • Temporal Lobes: Important for language and auditory processing.

Neuroplasticity

  • Describes the brain's ability to change and develop in response to experience. Includes:

    • Neurogenesis: The process of new neuron production or repair in the CNS.

  • Cognitive neuropsychology explores how brain structure relates to psychological processes, drawing from studies of individuals with brain damage to understand normal cognitive functioning.

Genetics and Environment in Psychological Functioning

  • Discusses the roles of genetic variability (genotypes) versus observable characteristics (phenotypes).

  • Heritability: Refers to the extent to which individual differences in a trait can be attributed to genetic variation.

  • Degree of Relatedness among relatives helps scientists estimate the genetic influence on psychological traits.

    • Identical twins share 100% of genes; fraternal twins share about 50%.

    • Research indicates that genetics can account for significant variability in psychological traits such as intelligence and personality (with heritability estimates typically around .5 or higher).

    • Environmental factors also play a crucial role, with gene-environment interactions shaping psychological outcomes.

Final Thoughts

  • Advances in neuroscience and genetic studies have deepened our understanding of psychology, challenging previously held beliefs and emphasizing the integration of biological and psychological approaches in understanding human behavior.

Key Terms

  • (Key terms from the chapter include neurotransmitters, neuroplasticity, heritability, etc.).