Question

1. what is a glial cell? 2. what is the basic functional unit of the nervous system. 3. what is a reflex arc? 4. what three neurons work together in the reflex arc? 5. briefly describe what happens when you touch a hot surface with your hand. 6. what is an action potential? 7. what must happen for an action potential to occur? 8. what does permeability mean? 9. complete the table below. term: depolarization, all or nothing principle description

Explanation:

1. A glial cell is a non - neuron cell that provides support and protection for neurons in the nervous system, such as by insulating axons, supplying nutrients to neurons, and maintaining the extracellular environment.
2. The basic functional unit of the nervous system is the neuron, which is specialized for transmitting electrical and chemical signals.
3. A reflex arc is a neural pathway that controls a reflex. It typically consists of a sensory receptor, a sensory neuron, an inter - neuron (in some cases), a motor neuron, and an effector (such as a muscle or gland).
4. In a reflex arc with three neurons (sensory, inter - neuron, motor), the sensory neuron detects the stimulus (e.g., touching a hot surface), sends the signal to the inter - neuron in the spinal cord, and the inter - neuron then relays the signal to the motor neuron which causes the effector (e.g., a muscle) to respond (withdraw the hand).
5. When you touch a hot surface with your hand, sensory receptors in the skin detect the heat. The sensory neuron sends an electrical signal (action potential) to the spinal cord. In the spinal cord, an inter - neuron processes the signal and sends it to a motor neuron. The motor neuron then stimulates the muscles in the hand to contract and pull the hand away.
6. An action potential is a brief electrical charge that travels down an axon. It is generated when the membrane potential of a neuron reaches a certain threshold, causing a rapid influx of sodium ions and efflux of potassium ions.
7. For an action potential to occur, the membrane potential of the neuron must reach the threshold potential. This is usually due to the opening of voltage - gated ion channels in response to a stimulus, allowing sodium ions to enter the cell and depolarize the membrane.
8. Permeability refers to the ability of a membrane to allow substances (such as ions) to pass through it. In neurons, the permeability of the cell membrane to sodium and potassium ions changes during an action potential, which is crucial for the generation and propagation of the electrical signal.
9. (No table content provided to complete).

Answer:

1. Glial cells support and protect neurons.
2. The neuron is the basic functional unit of the nervous system.
3. A reflex arc is a neural pathway for reflexes, often with sensory, motor, and sometimes inter - neurons and an effector.
4. Sensory neuron detects stimulus, inter - neuron relays in spinal cord, motor neuron causes effector response.
5. Sensory receptors detect heat, signal travels via sensory neuron to spinal cord, inter - neuron and motor neuron cause muscle contraction to withdraw hand.
6. An action potential is a brief electrical charge down an axon.
7. The membrane potential must reach the threshold potential for an action potential.
8. Permeability is the ability of a membrane to allow substances through.
9. (No answer as table is incomplete).