Central Nervous System & Neurotransmitters Quiz

Central Nervous System & Neurotransmitters

• The nervous system controls bodily functions and reactions to surroundings.
• The nervous system has components such as the brain, spinal cord, spinal nerves, and specialized sense organs.

Nervous System Outline

• Define the nervous system
• List components of nerve cells, describing their function
• Describe synapse and its components
• List different neurotransmitters and their functions

Introduction

• Living organisms react to environmental changes (stimuli).
• A response to a stimulus is called a response.
• Responsiveness is also known as sensitivity or irritability.

Sense Organs

• Sense organs detect stimuli and are also called receptors.
• They transmit electrical signals (nerve impulses) to the central nervous system.
• Sense organs help the body adjust to environmental changes.
• They allow body parts to coordinate.
• Sense organs include smell, sight, touch, taste, and hearing.

Nerve Impulses

• Nerve impulses are electrical messages transmitted through the peripheral nervous system to the central nervous system.
• Sensory nerves carry signals from the receptors to the spinal cord.
• The spinal cord carries signals to motor nerves for movement.

Neurotransmitters

• The human body has around 1 trillion nerve cells.
• Around 100 chemicals (neurotransmitters) transmit messages between nerves.

Nervous System Components

• The central nervous system consists of the brain and the spinal cord.
• The peripheral nervous system encompasses nerves and sensory structures located outside the brain and spinal cord.
• The peripheral nervous system is further subdivided into the somatic and autonomic nervous systems.
  • The somatic system controls voluntary muscle actions.
  • The autonomic system controls involuntary processes (e.g. smooth muscle, glands) and is further divided into sympathetic and parasympathetic systems.
    • Sympathetic ("fight or flight")
    • Parasympathetic ("rest and digest")

Nervous System Cells (Neurons)

• Neuron structure fits its function: many entry points for signals; one path out; transmits signals
• The neuron has: dendrites, cell body, axon; myelin sheath; synaptic terminal; synapse

Parts of a Neuron

• Nucleus: controls the entire neuron.
• Dendrites: receive signals from other cells.
• Cell body: organizes and maintains the cell's function.
• Cell membrane: protects the cell.
• Axon Hillock: generates the impulse in the neuron.
• Axon: transfers signals to other cells and organs.
• Myelin sheath: increases signal speed.
• Axon terminal: forms junctions with other cells.
• Node of Ranvier: allows diffusion of ions.
• Schwann cell: produces the myelin sheath.

Synapse

• A synapse is a junction between two neurons (or a neuron to an effector like muscle or gland).
• Nerve impulses are transmitted across the synaptic gap via chemicals called neurotransmitters.

Neurotransmitter Discovery

• Until the early 20th century, it was thought that communication in the brain was entirely electrical.
• Otto Loewi discovered acetylcholine (ACh), the first known neurotransmitter.

Neurotransmitters (Function)

• They transmit a message across the synapse to a target cell.
• Released from synaptic vesicles into the synaptic cleft.
• They bind to receptors on the target cell.
• The exact number of neurotransmitters is unknown, but over 200 are identified.

Neurotransmitter Effects

• Neurotransmitters can be excitatory, inhibitory, or modulatory.
• Excitatory neurotransmitters (e.g., glutamate) increase neuronal activity.
• Inhibitory neurotransmitters (e.g., glycine, GABA) decrease neuronal activity.
• Modulatory neurotransmitters (e.g., neuropeptides) influence the sensitivity of neurons.

Key Neurotransmitters & Their Functions

• A number of key neurotransmitters play specific roles, including those shown on the table.

Neurotransmitter Classification

• Neurotransmitters are classified into categories like Amino Acids, Monoamines, Catecholamines, Indolamines, Soluble Gases, and Neuropeptides.

Neurotransmitter Identification Criteria

• Four main criteria to identify neurotransmitters:
  1. Chemical must be synthesized or present in a neuron.
  2. Chemical must be released upon neuron activation, triggering a response in targets.
  3. The same response should occur when the chemical is experimentally placed on the target.
  4. A mechanism to remove the chemical from the activation site must exist.

Examples of Neurotransmitters & Functions

• Adrenaline (fight or flight)
• Noradrenaline (concentration, attention, blood vessel contraction)
• Dopamine (pleasure motivation, movement)
• Serotonin (well-being, mood, sleep cycle regulation)
• GABA (calming, motor control)

Acetylcholine Functions and Deficiency

• Acetylcholine (ACh) is crucial for movement, heart rate, and memory.
• It works through muscarinic and nicotinic receptors.
• Deficiency in ACh can affect memory, cognition, and muscle function.

Foods Rich in Choline

• Foods with high choline content support ACh production.

Improving Acetylcholine Levels

• Lifestyle changes can influence ACh levels. (e.g. stress management, blood sugar levels, strategic caffeine use).

Impacts of Decreased or Increased Neurotransmitter Production

• Neurotransmitter imbalances can lead to various disorders (e.g., Parkinson's Disease, schizophrenia).
  • Parkinson's: low dopamine leading to motor control issues
  • Schizophrenia: possible unusually high dopamine.

Test your knowledge on the central nervous system and neurotransmitters. This quiz covers the definitions, components, and functions of nerve cells and neurotransmitters, along with the role of sense organs in responding to stimuli. Challenge yourself with questions related to nerve impulses and their significance in bodily functions.