Biological Psychology: The Brain at Work

Introduction to Biological Psychology

Biological psychology explores how the brain and nervous system influence thoughts, feelings, and behaviors. This field focuses on the physiological mechanisms underlying psychological processes, emphasizing the role of neurons, neurotransmitters, and brain structures.

The Nervous System

Main Divisions of the Nervous System

The nervous system is an intricate network responsible for communication throughout the body. It is divided into two main parts:

• Central Nervous System (CNS): Consists of the brain and spinal cord. It processes information and coordinates activity.

• Peripheral Nervous System (PNS): Composed of nerves that connect the CNS to the skin, muscles, and glands, facilitating communication between the CNS and the rest of the body.

The nervous system is also influenced by the Endocrine System, which regulates bodily functions through hormones.

Neurons: The Building Blocks of the Nervous System

Definition and Types of Neurons

Neurons are specialized cells that receive and transmit information throughout the nervous system. They are essential for brain communication and bodily control.

• Sensory Neurons: Transmit signals from the body to the brain.

• Motor Neurons: Send signals from the brain to muscles and glands.

• Interneurons: Facilitate communication between sensory and motor neurons.

Components of the Neuron

Each neuron has distinct structural components that enable its function:

• Cell Body (Soma): Contains the nucleus and maintains cell health.

• Dendrites: Treelike extensions that receive information from other neurons and transmit it to the cell body.

• Axon: An elongated fiber that sends electrical signals away from the cell body toward other neurons, muscles, or glands.

• Myelin Sheath: A fatty layer surrounding the axon, which insulates and speeds up signal transmission.

• Terminal Buttons: Branching structures at the end of the axon that form junctions with other cells and release neurotransmitters.

Action Potential: The electrical voltage that travels down the axon, enabling communication between neurons.

Diagram of a Neuron

The following diagram illustrates the major components of a neuron:

• Cell body (soma)

• Dendrites

• Axon

• Myelin sheath

• Terminal buttons

*Additional info: The diagram typically shows dendrites branching from the cell body, the axon extending from the soma, myelin sheath segments along the axon, and terminal buttons at the axon's end.*

Neural Communication

Electrical and Chemical Signaling

Neurons communicate using both electrical impulses and chemical messengers:

• Electrical Communication: The action potential travels along the axon.

• Chemical Communication: Neurotransmitters are released at synapses to relay signals to other neurons.

Neurotransmitters: The Body's Chemical Messengers

Neurotransmitters are chemicals that transmit signals across synapses between neurons. They can either excite or inhibit the activity of the receiving neuron.

• Excitatory Neurotransmitters: Increase the likelihood that a neuron will fire.

• Inhibitory Neurotransmitters: Decrease the likelihood that a neuron will fire.

Major Neurotransmitters and Their Functions

Drug Effects on Neurotransmitters

Drugs can influence neurotransmitter activity in several ways:

• Agonists: Mimic or enhance the action of a neurotransmitter (e.g., cocaine is a dopamine agonist).

• Antagonists: Block the action of a neurotransmitter (e.g., curare is an acetylcholine antagonist).

• Reuptake Inhibitors: Block the reabsorption of neurotransmitters, increasing their availability in the synapse (e.g., SSRIs for serotonin).

• Enzyme Inhibitors: Prevent the breakdown of neurotransmitters, prolonging their effects (e.g., MAOIs for depression).

Key Takeaways

• The nervous system consists of the CNS and PNS, which coordinate bodily functions and responses.

• Neurons are the fundamental units of the nervous system, specialized for communication.

• Neurotransmitters play crucial roles in regulating mood, movement, memory, and behavior.

• Drugs can act as agonists, antagonists, reuptake inhibitors, or enzyme inhibitors to alter neurotransmitter activity.