Overview of the Nervous System

Function: Coordinates body activities by transmitting signals between different parts of the body.
Divisions:
- Central Nervous System (CNS): Brain and spinal cord.
- Peripheral Nervous System (PNS): All neural tissue outside the CNS.

Neurons:
- Functional units that transmit impulses.
- Components: Dendrites (receive signals), Soma (cell body), Axon (transmits signals).
- Types:
  - Sensory neurons: Carry signals from sensory receptors to CNS.
  - Motor neurons: Transmit signals from CNS to muscles/glands.
  - Interneurons: Connect neurons within CNS.
Glial Cells (Neuroglia):
- Support and protect neurons.
- Types:
  - Astrocytes: Maintain blood-brain barrier, regulate blood flow.
  - Oligodendrocytes: Myelinate CNS axons.
  - Schwann cells: Myelinate PNS axons.
  - Microglia: Immune defense in CNS.

Resting Membrane Potential:
- Typical value: -70 mV.
- Maintained by sodium-potassium pump and ion channels.
Action Potential:
- Rapid change in membrane potential.
- Phases:
  1. Depolarization: Sodium influx.
  2. Repolarization: Potassium efflux.
  3. Hyperpolarization: Increased potassium permeability.
- Threshold potential: Approx. -55 mV; triggers action potential.
Synaptic Transmission:
- Process by which neurons communicate.
- Neurotransmitters released from presynaptic neuron bind to receptors on postsynaptic neuron.
- Types of neurotransmitters:
  - Excitatory: Increase likelihood of action potential (e.g., glutamate).
  - Inhibitory: Decrease likelihood of action potential (e.g., GABA).

Sensory Function: Detects stimuli and transmits sensory information to the CNS.
Integrative Function: Processes and interprets sensory input; generates responses.
Motor Function: Produces responses by activating muscles or glands.

Components:
1. Receptor: Detects stimulus.
2. Sensory neuron: Conducts impulse to CNS.
3. Integration center: Processes information (often involves interneurons).
4. Motor neuron: Carries impulse to effector.
5. Effector: Muscle or gland that responds.

Function: Regulates involuntary bodily functions.
Divisions:
- Sympathetic: Prepares body for 'fight or flight' response.
- Parasympathetic: Promotes 'rest and digest' functions.

The ability of the nervous system to change and adapt.
Involves strengthening or weakening synapses and the formation of new neural connections.

The physiology of the nervous system is essential for the coordination and regulation of body functions.
Understanding the structure and function of neurons, synaptic transmission, and the overall organization of the nervous system is crucial for studying neurobiology and related fields.

Coordinates body activities via signal transmission between various body parts.
Divided into:
- Central Nervous System (CNS): Comprised of the brain and spinal cord.
- Peripheral Nervous System (PNS): Encompasses all neural tissue outside the CNS.

Neurons:
- Serve as the functional units for impulse transmission.
- Components include:
  - Dendrites: Receive incoming signals.
  - Soma: Contains the cell body.
  - Axon: Conducts signals away from the neuron.
- Types of neurons:
  - Sensory Neurons: Transmit signals from sensory receptors to the CNS.
  - Motor Neurons: Relay signals from the CNS to muscles and glands.
  - Interneurons: Facilitate communication between neurons within the CNS.
Glial Cells (Neuroglia):
- Provide support and protection for neurons.
- Types of glial cells:
  - Astrocytes: Maintain the blood-brain barrier and regulate blood flow.
  - Oligodendrocytes: Form the myelin sheath around CNS axons.
  - Schwann Cells: Create myelin sheath around PNS axons.
  - Microglia: Act as immune defense in the CNS.

Resting Membrane Potential:
- Approximately -70 mV, maintained by sodium-potassium pumps and ion channels.
Action Potential:
- A rapid change in membrane potential characterized by several phases:
  - Depolarization: Influx of sodium ions.
  - Repolarization: Efflux of potassium ions.
  - Hyperpolarization: Increased permeability to potassium.
- Threshold potential: Around -55 mV, necessary to trigger an action potential.
Synaptic Transmission:
- The process for neuronal communication involving neurotransmitter release from the presynaptic neuron to receptors on the postsynaptic neuron.
- Types of neurotransmitters:
  - Excitatory Neurotransmitters: Increase the likelihood of an action potential (e.g., glutamate).
  - Inhibitory Neurotransmitters: Decrease the likelihood of an action potential (e.g., GABA).

Sensory Function: Involves detection of stimuli and transmission of sensory information to the CNS.
Integrative Function: Processes sensory input and generates responses.
Motor Function: Activates muscles or glands to produce responses.

Function: Regulates involuntary bodily functions without conscious control.
Consists of:
- Sympathetic Division: Initiates 'fight or flight' responses.
- Parasympathetic Division: Facilitates 'rest and digest' activities.

Represents the nervous system's capacity for change and adaptation.
Involves adjustments in synaptic strength and the formation of new neural connections.

Understanding the physiology of the nervous system is vital for coordinating and regulating bodily functions.
Insights into neuron structure, synaptic transmission, and overall nervous system organization are essential for studies in neurobiology and related disciplines.