Communication within the Nervous System

Communication within the Neuron

• The resting potential of a neuron is -70 millivolts (negative 70mV), which is a result of the concentration of ions inside and outside the cell membrane.
• The resting potential is maintained by the sodium-potassium pump, which pumps three sodium ions out of the cell for every two potassium ions that enter the cell.
• Gated channels, such as sodium and potassium channels, regulate the movement of ions across the cell membrane.
• The action potential is a brief reversal of the membrane potential, where the potential changes from -70mV to +40mV.
• The action potential has three phases: depolarization, repolarization, and hyperpolarization.
• The refractory period is the time during which the cell is incapable of repeating an action potential.

Communication between Neurons

• A synapse is the contact between two neuronal cells, where information is passed from one neuron to the next through chemical signals.
• The structure of a synapse consists of three layers: the presynaptic terminal, synaptic cleft, and post-synaptic terminal.
• Synaptic transmission is the biological process by which a neuron communicates with a target cell across a synapse.
• There are two types of synapses: chemical and electrical.
• Axon terminals can form junctions with effector organs, such as muscle cells and glands.

Reflex Arc

• Reflex action is an involuntary and sudden response to stimuli, which minimizes damage to the body from potentially harmful conditions.
• The nerve pathway followed by a reflex action is called a reflex arc, which consists of a receptor, sensory neuron, relay neuron, motor neuron, and effector.
• Reflexes do not involve the conscious part of the brain and are relatively fast responses.

Beyond Reflexes

• The nervous system plays a role in behavior beyond reflexes, involving the central nervous system, peripheral nervous system, and autonomic nervous system.
• The somatic and autonomic nervous systems work collaboratively to control action.
• The brain processes information, makes decisions, and triggers voluntary behaviors, such as emotions, memory, and perception.

Structure of the Nervous System

• The central nervous system consists of the brain and spinal cord.
• The peripheral nervous system consists of the somatic nervous system and autonomic nervous system.
• The autonomic nervous system is further divided into the sympathetic nervous system and parasympathetic nervous system.
• The enteric nervous system is a subdivision of the autonomic nervous system that controls the gastrointestinal tract.