Psychology Unit One: Nervous System Overview

Unit One: Area of Study 2 Outcome 2

• How are mental processes and behaviour influenced by the brain?
• The roles of the hindbrain, midbrain, and forebrain (including the cerebral cortex) are crucial in behaviour and mental processes.

Overview of the Nervous System

• The nervous system comprises neurons.
• A neuron is a single nerve cell.
• Neurons form neural pathways, linking up to transmit information throughout the body.
• Neurons are the building blocks of the nervous system.
• All neurons have specialised functions. Some receive and transmit information between other neurons, while others send information to cells and muscles within the brain.

Structure of a Neuron

• Dendrites: Numerous branches that receive information from other neurons. Dendritic spines amplify these interactions.
• Soma (cell body): Coordinates the neuron's metabolic activities.
• Axon: Transmits signals (nerve impulses/action potentials) to other neurons or cells.
• Myelin sheath: Fatty insulation around the axon for faster transmission.

Axon Terminals, Synapses, and Neurotransmitters

• Information travels in one direction along a neuron.
• Axon terminals store neurotransmitters.
• Neurotransmitters transmit information across the synapse (gap between neurons).
• Neurotransmitters are chemical messengers.

Types of Neurons

• Sensory neurons: Receive and transmit sensory information from the internal and external environment to the CNS.
• Motor neurons: Transmit messages from the CNS to muscles, organs, and glands to stimulate activity.
• Interneurons: Create connections between sensory and motor neurons. Relay messages within the CNS.

The Nervous System

• The nervous system consists of the CNS (brain and spinal cord) and the PNS (everything else).
• The CNS receives, processes, and coordinates responses to information.
• The CNS receives information via the PNS about what's happening both inside and outside the body.

The Central Nervous System (CNS)

• The brain and spinal cord comprise the CNS.
• The CNS has protection: the skull (brain) and vertebral column (spinal cord).
• The CNS receives information from the PNS, processes it, and activates appropriate responses.
• The spinal cord transmits sensory and motor information between the brain and periphery.

The Peripheral Nervous System (PNS)

• The PNS contains nerves outside the CNS.
• The PNS is just as important as the CNS; it relays information from sensory organs, muscles, and glands to the CNS.
• The PNS is divided into the somatic and autonomic nervous systems.

The Autonomic Nervous System (ANS)

• The ANS controls involuntary actions (e.g., digestion, heartbeat, breathing).
• The ANS has two subdivisions:
• Sympathetic nervous system (fight-or-flight response).
• Parasympathetic nervous system (rest-and-digest response).

Regions of the Brain

• The brain is divided into four major regions:
• Hindbrain: Cerebellum, medulla oblongata, and pons.
• Midbrain: Substantia nigra, reticular formation.
• Forebrain: Thalamus, hypothalamus, limbic system, cerebrum.
• Cerebral cortex: Outer layer of the cerebrum.

The Cerebral Cortex

• A thin layer of neurons.
• Accounts for half the brain's weight.
• Divided into two hemispheres.
• Contains specific areas (e.g., visual cortex, auditory cortex) for processing sensory information.
• Involved in receiving, processing complex sensory information (e.g., symbolic thinking, language, emotion).
• Has three areas: sensory, motor, and association areas.

Cerebral Hemispheres

• Divided into left and right hemispheres.
• Connected by the corpus callosum.
• Each hemisphere controls the opposite side of the body.
• Specialisation of each hemisphere, although both are involved across many functions.

Cortical Lobes of the Cerebral Cortex

• Frontal lobe
• Temporal lobe
• Parietal lobe
• Occipital lobe

Specific areas within each lobe

• Primary motor cortex
• Broca's area
• Primary auditory cortex
• Wernicke's area
• Primary somatosensory cortex
• Primary visual cortex