Neuroscience Overview Quiz

Organisation of the Nervous System & Neurotransmission

• The nervous system is a complex system responsible for coordinating and integrating multiple physiological functions.
• It works alongside the endocrine system (hormonal communication).
• It enables rapid responses to internal and external stimuli, including adaptive responses such as reflexes and complex cognitive processes.

Functions of the Nervous System

• Coordinates and integrates physiological systems.
• Acts in parallel with the endocrine system.
• Enables rapid responses to external stimuli (e.g., light, heat, blood pressure, osmotic pressure).
• Responses can be simple (e.g., reflexes) or complex (e.g., learning, memory, behavioral changes).

Why Study Neuroscience?

• To understand diseases: neurological disorders, neurodegenerative, demyelinating, mood disorders and viral/bacterial infections.
• To understand vital functions: control of vital physiological functions like appetite, blood pressure, sleep.

Study of Neuroscience

• Significant funding for neuroscience research (millions by drug companies).
• Large community of neuroscientists.
• Annual meetings attract a large number of participants (35,000+).
• Numerous scientific journals dedicated to neuroscience (over 40).

Outline of Lectures

• Lecture 1: Nervous system structure and organisation, cell types, and synaptic neurotransmission.
• Lecture 2: Modulation of synaptic function, focusing on the autonomic nervous system.
• Lecture 3: Anatomical and physiological subdivisions of the brain, and its major neurotransmitters.

Organization of the Nervous System

• Two major divisions: Central Nervous System (CNS) and Peripheral Nervous System (PNS).
• CNS includes the brain and spinal cord.
• PNS includes the sensory system, autonomic nervous system, and somatic nervous system.
• These divisions are interconnected.

Cell Types in the CNS

• Capillary (-Endothelial cells& Pericytes)
• Astrocytes
• Oligodendrocytes
• Neuron
• Myelinated axons
• Myelin (cut)
• Microglia
• Ependymal cells
• Unmyelinated axon

Anatomy of a Neuron

• Cell Body (Soma): Contains the nucleus, rough endoplasmic reticulum (RER), and mitochondria.
• Dendrites: Numerous branching extensions that receive input from other neurons.
• Axon: A single, long extension that transmits signals to other neurons.
• Axon Hillock: Area where the axon joins the cell body.
• Myelin Sheath: Insulating layer (may be present).
• Node of Ranvier: Gaps in myelin sheath.
• Axon Terminals: Branching end of the axon where neurotransmitters are released.

Neuronal Subtypes

• Afferent (Sensory): Transmit information to the CNS; have sensory receptors at their peripheral end; one type of neuron.
• Efferent (Motor): Transmit information from the CNS to effector organs (muscle, glands, or other neurons); a different type of neuron.
• Interneurons: Transmit information between neurons; found exclusively inside the CNS. (Majority).

The Central Nervous System (CNS)

• Brain and Spinal Cord: Contains input regions for sensory nerves, output regions for motor nerves, and numerous interneurons.
• Grey Matter: Contains cell bodies, dendrites, synapses, and interneurons.
• White Matter: Contains axons with myelin sheaths, and ascending/descending fiber tracts.

Glial Cells

• Many glial cells in the CNS than neurons.
• Functions include: metabolic support, buffer extracellular ions (Na+, K+), removing neurotransmitters, scavenging function, blood-brain barrier control, neuronal development guidance.

The Peripheral Nervous System (PNS)

• Parts of PNS: Sensory, Autonomic, and Somatic.
• Autonomic further divided into Sympathetic and Parasympathetic.
• Further divided into Enteric Nervous System.

The Enteric Nervous System

• Meshwork of neurons that innervate gut muscles and mucosa.
• Facilitates peristalsis and interactions with gut bacteria.

Cranial Nerves

• 12 pairs of cranial nerves with mixed sensory and motor functions.
• Nerves named using an anatomical/alphabetical mnemonic.

Spinal Nerves

• 31 pairs of spinal nerves distributed by regions (Cervical, Thoracic, Lumbar, Sacral).

The Autonomic Nervous System

• Controls automatic functions of the body, e.g., heart, glands, smooth muscles.
• Composed of sympathetic and parasympathetic divisions that usually have opposing effects.
• Sympathetic: fight-or-flight response.
• Parasympathetic: rest-and-digest response.

Neurotransmitters in the PNS

• Various neurotransmitters are used in the PNS for communication between neurons and with other organs.
• Acetylcholine (ACh) is a crucial neurotransmitter.
• Norepinephrine/Noradrenaline (NE) and epinephrine/adrenaline (Epi) are involved in the sympathetic nervous system.

Synapse and Synaptic Transmission

• Describes specialized junctions where neurons communicate.
• Has a terminal button, synaptic cleft, and receiving neuron.
• Neurotransmitters facilitate the communication process across the synapse.
• Signals transferred from one neuron (pre-synaptic neuron) to another (post-synaptic neuron).

Synaptic Organization

• Details of structure/components of a typical synapse.
• Neurons can have both one-to-one (1:1) and one-to-many (1:many) connections.

3-Dimensional Structure of Synaptic Bouton in the CNS

• Synaptic boutons consist of a complex 3-dimensional arrangement of proteins.

Dendritic Arborization

• Complex branching structures of dendrites critical for neural function.
• Important for receiving signals from multiple neurons through many synaptic inputs.
• Important for neural circuitry and computations.
• A large number of synapses exist in the CNS.

Neurons In Vitro

• Ability of cultured neurons to make synapses in vitro.

The Neuromuscular Junction (NMJ)

• Specialized type of synapse between a motor neuron and a muscle fiber.
• Has a motor end-plate.
• Characterized by specific points of contact and unique structure compared to other synapses.
• Has specific neurotransmitters involved; for example acetylcholine (ACh).

Synaptic transmission at the NMJ

• Excitation signal transmission through neurotransmitters and receptor activation in muscle fibers.

The Myotatic Reflex

• Reflex actions (e.g., knee-jerk) showing sensory and motor neurons acting together forming divergent/convergent pathways

EPSPs (Excitatory Postsynaptic Potentials)

• EPSPs depolarize the post-synaptic membrane.
• Commonly caused by increased Na+ or Ca2+ permeability.

IPSPs (Inhibitory Postsynaptic Potentials)

• Hyperpolarize the post-synaptic membrane.
• Usually due to increased Cl- or K+ permeability.

Synaptic Integration

• EPSPs and IPSPs interact and determine final post-synaptic response.
• Includes the summation of the EPSPs and IPSP effects to ultimately determine response.

Neurotransmitters - Definition

• Neurons release chemicals called neurotransmitters for communication.
• For a substance to qualify as a neurotransmitter, it must meet these four criteria: synthesis in neuron, present in presynaptic terminal, released in effect (amount) amounts, applied exogenously it mimics original effect.

Common Neurotransmitters

• Lists several common neurotransmitters.

Reading Material

• Lists recommended texts for further reading and resources (including websites).

Test your knowledge on the key concepts of neuroscience, including the functions of the sympathetic and parasympathetic nervous systems, the subdivisions of the nervous system, and synaptic mechanisms. This quiz covers major topics essential for understanding how the nervous system operates and its significance in human biology.