Introduction to Neurophysiology

Lecturer: Dr. Moses Kazevu

Key Topics Covered:

• Introduction to Neurophysiology
• Overview of Nervous System
• Functions of the Nervous System
• Divisions of the Nervous System
• Cells of the Nervous System
• Structures of the Central and Peripheral Nervous System

Overview of Neurophysiology

• Neurophysiology: Study of the nervous system's function.
• Nervous system: Complex network enabling organismal communication with the environment (internal and external).

Divisions of the Nervous System

1. Central Nervous System (CNS): Brain and spinal cord.
   • Brain: Forebrain, midbrain, hindbrain
   • Spinal Cord: Extends from base of skull to L1 vertebra
2. Peripheral Nervous System (PNS): Outside the CNS, further divided into:
   • Sensory (afferent): Takes information towards the CNS
   • Motor (efferent): Takes information away from the CNS

Subdivisions within PNS

• Somatic Nervous System: Voluntary control
• Autonomic Nervous System: Involuntary control
  • Sympathetic Division (Thoracolumbar)
  • Parasympathetic Division (Craniosacral)

Functions of Nervous System

1. Sensory Function: Detecting changes in environment (light, sound, pressure).
2. Motor Function: Generating movements and muscle contractions (skeletal, cardiac, smooth muscle).
3. Integrative Function: Processing sensory information and forming appropriate responses.

Cells of the Nervous System

1. Neurons: Functional units of the nervous system.
2. Neuroglia (supporting cells):
   • Astrocytes
   • Ependymal cells
   • Oligodendrocytes
   • Schwann cells (PNS)
   • Microglial cells

Structures of the Nervous System

• Gray Matter: Cell bodies, appears gray due to nasal bodies
• White Matter: Axons and nerve fibers

Major Structures in Detail

Central Nervous System

• Brain: Forebrain, Midbrain, Hindbrain
  • Forebrain (Prosencephalon): Telencephalon (cerebral hemispheres, basal ganglia, hippocampus, amygdala); Diencephalon (thalamus, hypothalamus, metathalamus, subthalamus)
  • Midbrain (Mesencephalon): Brainstem
  • Hindbrain (Rhombencephalon): Metencephalon (pons, cerebellum); Myelencephalon (medulla oblongata)
• Spinal Cord: Extends from the base of the skull to L1 vertebra, consists of 31 pairs of spinal nerves
  • Ascending Pathways: Sensory pathways carrying information to the CNS
  • Descending Pathways: Motor pathways carrying information from the CNS to peripheral areas

Peripheral Nervous System

• Sensory Receptors: Visual, auditory, chemoreceptors, somatosensory
• Ganglia: Collections of cell bodies in PNS
• Nerves: Cranial (12 pairs) and spinal nerves (31 pairs)

Functional Overview

• Medulla: Controls autonomic functions (breathing, blood pressure, reflexes)
• Pons: Assists in posture, breathing regulation
• Midbrain: Controls eye movements, relays auditory and visual information
• Cerebellum: Coordinates movement, posture, head & eye movements
• Thalamus: Sensory and motor relay station
• Hypothalamus: Regulates homeostasis (body temperature, food intake, sleep cycles, endocrine functions)
• Cerebral Hemispheres: Higher functions (perception, cognition, memory, emotions);
  • Four lobes: Frontal, Parietal, Temporal, Occipital
  • Basal Ganglia: Movement regulation
  • Hippocampus & Amygdala: Memory and emotions

Important Cranial Nerves

1. Olfactory
2. Optic
3. Oculomotor
4. Trochlear
5. Trigeminal
6. Abducens
7. Facial
8. Vestibulocochlear
9. Glossopharyngeal
10. Vagus
11. Accessory
12. Hypoglossal

Mnemonic to Remember: O O O To Touch And Feel Very Good Velvet And Help

Final Notes

• Spinal cord functions in sensorimotor integration and reflexes.
• Information is relayed to and from the brain via sensory and motor pathways.
• Each component of the nervous system has specialized roles crucial for overall function.

Subscribe to the YouTube channel for more in-depth lectures on neurophysiology!