Control & Coordination: The Nervous System
The electrical communication network of the human body.
The nervous system controls and coordinates all voluntary and involuntary actions in the body. It consists of the Central Nervous System (CNS) — the brain and spinal cord, and the Peripheral Nervous System (PNS) — cranial and spinal nerves.
Neurons are the structural and functional units of the nervous system. Nerve impulses travel as electrical signals along axons and cross microscopic gaps called synapses using neurotransmitters.
Key Takeaways
- •Neurons consist of cell bodies (cyton), dendrites, and a long axon.
- •The brain is divided into forebrain (thinking, memory), midbrain, and hindbrain (reflexes, balance).
- •Reflex actions are sudden, involuntary responses to stimuli controlled by the spinal cord.
Core Concepts & Definitions
1Structure of a Neuron & Synapse
Information enters through the dendrites, generates an electrical impulse, travels down the axon to the nerve endings, and stimulates the release of neurotransmitters across the synapse.
•Synapse is the junction between two neurons across which signals pass by diffusing chemicals.
•[INSERT: Detailed labeled diagram of neuron structure showing axon, myelin sheath, and dendrite]
Quick Revision Notes
- •Always verify units and maintain coordinate systems.
- •Check boundary conditions and reference variables before applying formulas.
- •Ensure decimal precision is correct on output results.
Equations & Calculation Methods
Nerve Impulse Conduction Speed
Calculates the speed of nerve conduction along myelinated axons, which can reach up to 120 meters per second.
Step-by-Step Worked Examples
Estimating Nervous Transmission Time
Problem: If a motor impulse travels from the spinal cord to a foot muscle (distance of 1.2 meters) at 60 m/s, how long does the transmission take?
Step-by-step Solution:
- 1Distance (d) = 1.2 meters.
- 2Conduction speed (v) = 60 m/s.
- 3Time (t) = d / v = 1.2 / 60 = 0.02 seconds = 20 milliseconds.
Topic FAQ
The myelin sheath acts as an electrical insulator around the axon, increasing the speed of action potential transmission via saltatory conduction.
Related Topics
Lab Experiment: Testing Human Reflex and Reaction Time
Required Materials
- Meter ruler (30 cm)
- Comfortable chair
- Data table sheet
Procedure Steps
- 1Subject sits with their forearm resting on a table, hand extending over the edge.
- 2Tester holds a ruler vertically between the subject's thumb and index finger, with the 0 cm mark at the finger level.
- 3Without warning, the tester drops the ruler. The subject catches it as quickly as possible.
- 4Record the distance marker in centimeters where the ruler was caught.
- 5Repeat 10 times and calculate the average reaction time using the kinematic formula.
Practice Quiz & Interactive Assessment
Syllabus Review Mode
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Printable Worksheet: Nerve Impulse and Brain Function
Classroom Homework Questions
- Q1.Draw and label a motor neuron. Explain the direction of impulse flow.
- Q2.Describe the structures and functions of the three major regions of the human brain.
- Q3.What is a synapse? Explain how chemical transmission occurs across it.
- Q4.Draw a flowchart representing a reflex arc when touching a hot pan.
Frequently Asked Questions
The myelin sheath acts as an electrical insulator around the axon, increasing the speed of action potential transmission via saltatory conduction.