In-Depth Notes on Neuroscience and Physiology

Synapse and Neurotransmitters

  • Synapse: A contact point between two nerve cells involving a gap across which impulses pass by diffusion of a neurotransmitter.
    • Responsible for signal transmission between neurons.
  • Neurotransmitters: Chemical messengers transmitting signals between nerve cells (neurons) and other body cells.
    • Vital for balancing neural signals to maintain brain function.
    • Regulate autonomic responses (breathing, heart rate) and psychological functions (learning, mood).
    • Essential for memory retention in memory-relevant brain areas.
  • Types of Neurotransmitters:
    • Glutamate (GLU): Most excitatory neurotransmitter in the cortex.
    • GABA (Gamma-aminobutyric acid): Inhibitory neurotransmitter; controls neuronal excitability, promotes calmness, and regulates anxiety.
    • Serotonin: Influences mood and anxiety levels.
    • Norepinephrine: Associated with stress responses and regulates heart rate and blood pressure.
    • Dopamine: Related to reward and motivation.

The Central Nervous System (CNS)

  • Components: Brain and spinal cord.
    • Brain controls body functions like awareness, movement, thinking, speech, and senses.
    • Spinal cord carries messages to and from the brain.
  • Protection: The brain is protected by the skull and three meninges:
    • Dura mater: Tough outer layer.
    • Arachnoid mater: Web-like, contains cerebrospinal fluid.
    • Pia mater: Thin layer close to the brain.

Mechanisms of Behavior

  • Three mechanisms:
    1. Receiving Mechanism: Sense organs (receptors).
    2. Connecting Mechanism: Nervous system (connectors).
    3. Reacting Mechanism: Muscles and glands (reactors).

Physiology

  • The study of normal functions in living organisms and their parts.
  • In psychology, it investigates the biological bases of behavior and psychological states, focusing on neural signals and hormonal functions.

The Sense Organs

  • Five Senses:
    • Sight: Eyes detect light; utilize electromagnetic waves.
    • Hearing: Ears detect sound waves and vibrations, assisting with balance.
    • Smell: Nose detects odors; utilizes gaseous particles.
    • Taste: Tongue detects flavors via soluble substances.
    • Touch: Skin perceives pressure, temperature, pain through tactile receptors.

The Peripheral Nervous System (PNS)

  • Main Parts:
    • Somatic Nervous System: Controls voluntary movements, relays sensory info.
    • Autonomic Nervous System: Regulates involuntary functions (breathing, digestion).
  • Connects CNS to the rest of the body to send and carry out commands.

Major Divisions of the Brain

  • Mesencephalon (Midbrain): Regulates movement, processes auditory/visual information.
  • Prosencephalon (Forebrain): Processes sensory info, reasoning, autonomic and motor functions.
  • Rhombencephalon (Hindbrain): Regulates autonomic functions, coordinates movement, and maintains balance.

Neurons

  • Definition: Basic structural and functional unit of the nervous system, specialized for signal transmission.
  • Types of Neurons:
    1. Sensory Neuron: Detects environmental stimuli and transmits info to the brain.
    2. Interneuron: Connects sensory and motor neurons for complex processing.
    3. Motor Neuron: Transmits signals from the brain to muscles, causing movement.
  • Parts of a Neuron:
    • Cell Body: Maintains neuron's structure, contains genetic info, provides energy.
    • Dendrites: Receive/process signals from other neurons.
    • Axon: Transmits signals, often insulated by myelin for faster conduction.

Brain Hemispheres

  • Left Hemisphere: Controls the right side of the body, involved in language, reasoning, and analytical tasks.
  • Right Hemisphere: Controls the left side of the body, involved in creativity, artistic functions, and spatial orientation.
  • Corpus Callosum: Connects both hemispheres; allows communication between them.

Spinal Nerves

  • Structure: 31 pairs of spinal nerves connecting the spinal cord to various body regions.
    • Each nerve pair serves a specific area (e.g., cervical nerves innervate the neck).
  • Function: Mixed nerves that relay sensory and motor information from the body to the spinal cord/directly interact with it.

Autonomic Nervous System

  • Divisions:
    • Sympathetic Division: Prepares body for stress ("fight-or-flight"); increases heart rate, dilates airways.
    • Parasympathetic Division: Supports rest and digestion; slows heart rate, stimulates digestion.

Cranial Nerves

  • 12 pairs of cranial nerves responsible for various functions such as smell (Olfactory), vision (Optic), eye movement (Oculomotor), and facial sensations (Trigeminal).

Functions of the Spinal Cord

  • Acts as a communication highway between the brain and body.
  • Manages reflex movements without brain intervention, indicating its significance in bodily responses.