Structure Of The Nervous System

Structure Of The Nervous System

• Central Nervous System (CNS): Comprises the brain and spinal cord.

  • Brain: Controls thoughts, emotions, memory, and sensory processing.
  • Spinal Cord: Connects the brain to the rest of the body, transmitting signals.

• Peripheral Nervous System (PNS): Connects the CNS to limbs and organs.

  • Somatic Nervous System: Controls voluntary movements and reflexes.
  • Autonomic Nervous System: Regulates involuntary functions (e.g., heart rate, digestion).
    • Subdivided into Sympathetic (fight or flight) and Parasympathetic (rest and digest).

Reflex Actions

• Definition: Rapid, involuntary responses to stimuli.

• Components of a Reflex Arc:

  1. Receptor: Detects the stimulus.
  2. Sensory Neuron: Transmits impulse to the spinal cord.
  3. Interneuron: Processes information (sometimes absent in simple reflexes).
  4. Motor Neuron: Carries response signal to the effector.
  5. Effector: Muscle or gland that produces the response.

• Types of Reflexes:

  • Monosynaptic: Involves one synapse (e.g., knee-jerk reflex).
  • Polysynaptic: Involves multiple synapses (e.g., withdrawal reflex).

Function Of Neurons

• Definition: Basic functional units of the nervous system, responsible for transmitting impulses.

• Types of Neurons:

  1. Sensory Neurons: Carry signals from sensory receptors to the CNS.
  2. Motor Neurons: Transmit signals from the CNS to muscles and glands.
  3. Interneurons: Connect neurons within the CNS, processing signals.

• Structure:

  • Dendrites: Receive incoming signals.
  • Cell Body: Contains the nucleus and organelles.
  • Axon: Transmits signals away from the cell body.
  • Myelin Sheath: Insulates the axon, speeding up signal transmission.

• Action Potential: Electrical signal triggered by depolarization of the neuron's membrane.

Neurotransmitters And Signaling

• Definition: Chemical messengers that transmit signals across synapses.

• Types of Neurotransmitters:

  • Excitatory: Promote the generation of action potentials (e.g., glutamate).
  • Inhibitory: Decrease the likelihood of action potentials (e.g., GABA).

• Process of Signaling:

  1. Release: Neurotransmitters are released from the presynaptic neuron.
  2. Binding: They bind to receptors on the postsynaptic neuron.
  3. Response: Binding can lead to depolarization (excitatory) or hyperpolarization (inhibitory).

• Reuptake and Degradation: Neurotransmitters are cleared from the synaptic cleft by:

  • Reuptake into the presynaptic neuron.
  • Enzymatic degradation.

Structure Of The Nervous System

• Central Nervous System (CNS) includes the brain and spinal cord, integral for processing and transmitting information.
• The brain is vital for controlling thoughts, emotions, memory, and sensory perceptions.
• The spinal cord serves as the communication highway between the brain and the rest of the body.
• Peripheral Nervous System (PNS) connects the CNS to limbs and organs, facilitating bodily functions.
• The Somatic Nervous System manages voluntary movements and reflex actions.
• The Autonomic Nervous System monitors involuntary processes like heart rate and digestion; it has two main divisions:
  • Sympathetic Division activates the body's fight or flight response.
  • Parasympathetic Division supports rest and digestion.

Reflex Actions

• Reflex actions are rapid, involuntary responses triggered by stimuli, contributing to immediate protective mechanisms.
• A reflex arc consists of essential components:
  • Receptors detect stimuli (e.g., temperature, pressure).
  • Sensory neurons relay impulses to the spinal cord for processing.
  • Interneurons process the information (sometimes absent in simple reflexes).
  • Motor neurons convey response commands from the CNS to effectors.
  • Effectors are either muscles or glands that enact the response.
• Types of reflexes include:
  • Monosynaptic reflexes involve a single synapse (e.g., knee-jerk response).
  • Polysynaptic reflexes involve multiple synapses (e.g., withdrawal reflex when touching something hot).

Function Of Neurons

• Neurons are the fundamental units of the nervous system, essential for impulse transmission.
• Three main types of neurons serve different functions:
  • Sensory neurons transmit signals from sensory receptors to the CNS.
  • Motor neurons send signals from the CNS to muscles and glands, effecting movement.
  • Interneurons connect different neurons within the CNS, playing a crucial role in signal processing.
• Neuron structure comprises:
  • Dendrites that receive signals from other neurons.
  • Cell body housing the nucleus and organelles, essential for cellular function.
  • Axon, the elongated projection that sends impulses away from the cell body.
  • Myelin Sheath, which insulates the axon and enhances signal transmission speed.
• An action potential is an electrical signal initiated by depolarization of the neuron's membrane.

Neurotransmitters And Signaling

• Neurotransmitters act as chemical messengers that enable communication between neurons at synapses.
• Types of neurotransmitters:
  • Excitatory neurotransmitters, like glutamate, encourage action potential generation.
  • Inhibitory neurotransmitters, such as GABA, reduce the chance of action potentials occurring.
• The signaling process involves:
  • Neurotransmitter release from the presynaptic neuron into the synaptic cleft.
  • Binding to specific receptors on the postsynaptic neuron.
  • Responses can involve depolarization (excitatory) or hyperpolarization (inhibitory).
• Clear signaling is maintained through:
  • Reuptake of neurotransmitters into the presynaptic neuron for reuse.
  • Enzymatic degradation of neurotransmitters to terminate their action.

Explore the intricate details of the nervous system, including the central and peripheral components. This quiz covers essential aspects such as the functions of the brain, spinal cord, and the reflex arc. Test your understanding of voluntary and involuntary responses.