Rucete ✏ Campbell Biology In a Nutshell
Unit 7 ANIMAL FORM AND FUNCTION — Concept 48.1 Neuron Structure and Organization Reflect Function in Information Transfer
Neurons are the fundamental units of the nervous system. Their unique structure enables them to receive, process, and transmit information efficiently. The organization of these cells is closely tied to their specific functions in sensory input, integration, and motor output.
1. Information Processing Stages
- Sensory input: detects stimuli via sensory neurons
- Integration: interneurons interpret and process input
- Motor output: motor neurons activate muscles or glands
- Example: a cone snail detects prey, processes the signal, and fires a harpoon-like tooth
2. Neuron Structure
- Cell body contains nucleus and organelles
- Dendrites: branched extensions that receive signals
- Axon: long projection that transmits signals
- Axon hillock: where signals originate
- Synaptic terminals connect to other cells at synapses
- Neurotransmitters carry signals to postsynaptic cells
3. Types of Neurons
- Sensory neurons: carry stimulus data to the CNS
- Interneurons: interpret information in the CNS
- Motor neurons: send signals to muscles or glands
4. Neuron Shape and Signal Transmission
- Neurons vary in shape but share core signal mechanisms
- Signal function depends on connection, not structure
- Axons and dendrites may branch to enhance signal transmission and input integration
5. Synapses and Signal Transmission
- Synapses are communication junctions
- Presynaptic terminals release neurotransmitters to postsynaptic cells
- Cone snail venom disrupts electrical signaling and synaptic function
6. Central and Peripheral Nervous Systems
- CNS: brain and spinal cord; processes information
- PNS: connects CNS to the rest of the body
- Both systems depend on glial cells for support and protection
- Glia outnumber neurons in many brain regions
In a Nutshell
Neurons are specialized for rapid communication through electrical and chemical signals. Their structure reflects their function—receiving input via dendrites, processing it in the cell body, and transmitting it through axons to synapses. The nervous system’s organization into sensory, integration, and motor pathways allows animals to sense, think, and act effectively.