Neurophysiology Lecture

Introduction

• Lecture by Dr. Smith on the topic of Neurophysiology.
• Focus on understanding the nervous system's functioning and its impact on behavior and bodily functions.

Nervous System Overview

Central Nervous System (CNS)

• Comprises the brain and spinal cord.
• Processes information and coordinates activity.
• Brain: Center for processing sensory info, governing thoughts, emotions, and actions.
• Spinal Cord: Transmits signals between the brain and the rest of the body.

Peripheral Nervous System (PNS)

• Consists of nerves and ganglia outside the brain and spinal cord.
• Divided into somatic (voluntary control of body movements) and autonomic nervous systems (controls bodily functions not consciously directed, like heartbeat and digestion).

Neurons

• Basic unit of the nervous system (nerve cells).
• Types include sensory neurons, motor neurons, and interneurons.
• Structure: Cell body, dendrites (receive signals), axon (transmits signals), myelin sheath (insulates axon and speeds up signal transmission).

Brain Function and Structure

Major Regions of the Brain

1. Cerebrum
   • Largest part of the brain, controls higher functions like thought, action, and sensory processing.
   • Divided into left and right hemispheres, each with four lobes (frontal, parietal, occipital, temporal).
2. Cerebellum
   • Located under the cerebrum, controls balance and coordination.
3. Brainstem
   • Connects brain to spinal cord, regulates vital functions (heart rate, breathing).
4. Limbic System
   • Involved in emotion, memory, and arousal.
   • Key structures: hippocampus (memory), amygdala (emotion).

Neural Communication

Synaptic Transmission

• Process by which neurotransmitters are released by a neuron, cross the synaptic gap, and bind to receptors on another neuron.
• Steps: Action potential arrives at axon terminal -> Ca2+ ions enter -> neurotransmitter vesicles fuse with membrane and release neurotransmitters -> neurotransmitters bind to receptors -> signal is propagated.

Neurotransmitters

• Chemical messengers that transmit signals across a chemical synapse.
• Examples: Dopamine, serotonin, acetylcholine, GABA, glutamate.

Action Potential

• Electrical impulse that travels down the axon, triggering the release of neurotransmitters.
• Steps: Resting potential, depolarization (Na+ channels open), repolarization (K+ channels open), refractory period.

Autonomic Nervous System (ANS)

Sympathetic Nervous System

• Activates 'fight or flight' response during perceived threat.
• Increases heart rate, dilates pupils, inhibits digestion.

Parasympathetic Nervous System

• Activates 'rest and digest' response when the body is relaxed.
• Decreases heart rate, constricts pupils, stimulates digestion.

Disorders of the Nervous System

Neurological Disorders

• Alzheimer's Disease: Affects memory and cognitive function, progressive neurodegeneration.
• Parkinson's Disease: Affects motor functions, characterized by tremors and stiffness.
• Multiple Sclerosis (MS): Autoimmune disorder that damages the myelin sheath of neurons, leading to communication issues between the brain and body.

Mental Health Disorders

• Depression: Associated with neurotransmitter imbalances, particularly serotonin.
• Anxiety Disorders: Linked to excessive activity in certain brain regions and neurotransmitter imbalances.

Conclusion

• Understanding neurophysiology is crucial for diagnosing, treating, and managing neurological and mental health disorders.
• Ongoing research is vital for advancing our knowledge and developing new treatments.

Reminder: Revise the major functions of brain regions and the process of synaptic transmission.