Introduction
Today, we’re diving into the fascinating world of neurobiology. As you progress in your studies, you’ll encounter numerous terms that might seem similar but have distinct meanings. In this lesson, we’ll unravel the top 10 commonly confused words in neurobiology, ensuring you never mix them up again.
1. Axon vs. Dendrite
The first pair of words that often cause confusion are ‘axon’ and ‘dendrite.’ While both are integral parts of a neuron, they serve different functions. Axons transmit signals away from the cell body, acting as the neuron’s output. On the other hand, dendrites receive signals from other neurons, serving as the input. So, remember, axons send, and dendrites receive.
2. Synapse vs. Gap Junction
Next up, we have ‘synapse’ and ‘gap junction.’ These terms refer to the points of contact between neurons. A synapse is a specialized junction where signals are transmitted chemically, using neurotransmitters. In contrast, a gap junction is a direct connection, allowing electrical signals to pass between neurons. So, synapses involve chemicals, while gap junctions involve direct electrical connections.
3. Action Potential vs. Resting Potential
Moving on, let’s clarify the difference between ‘action potential’ and ‘resting potential.’ Neurons have an electrical charge, which can change. The resting potential refers to the neuron’s baseline charge when it’s not actively transmitting signals. In contrast, an action potential is a brief, rapid change in charge that occurs when a neuron is stimulated. So, resting potential is the baseline, while action potential is the temporary change.
4. Myelin Sheath vs. Node of Ranvier
Our next pair, ‘myelin sheath’ and ‘node of Ranvier,’ are related to the structure of axons. The myelin sheath is a fatty, insulating layer that wraps around some axons, speeding up signal transmission. The node of Ranvier, on the other hand, is the small gap between myelin sheaths. It’s a crucial site for signal regeneration. So, myelin sheaths insulate, while nodes of Ranvier aid in signal regeneration.
5. Excitatory vs. Inhibitory
When it comes to neurotransmitters, two terms often cause confusion: ‘excitatory’ and ‘inhibitory.’ Excitatory neurotransmitters increase the likelihood of an action potential in the receiving neuron, while inhibitory neurotransmitters decrease that likelihood. So, excitatory neurotransmitters promote activity, while inhibitory neurotransmitters dampen it.
6. Gray Matter vs. White Matter
In neuroanatomy, we often refer to ‘gray matter’ and ‘white matter.’ Gray matter consists of cell bodies, dendrites, and unmyelinated axons. It’s involved in information processing. In contrast, white matter contains myelinated axons, forming the communication pathways. So, gray matter processes, while white matter transmits.
7. Central Nervous System vs. Peripheral Nervous System
The ‘central nervous system’ (CNS) and ‘peripheral nervous system’ (PNS) are two fundamental divisions of the nervous system. The CNS includes the brain and spinal cord, while the PNS comprises the nerves outside of the CNS. So, the CNS is the central command, while the PNS connects it to the rest of the body.
8. Sensory Neurons vs. Motor Neurons
Neurons can be classified based on their function. ‘Sensory neurons’ transmit sensory information from the body to the CNS, allowing us to perceive the world. ‘Motor neurons,’ on the other hand, carry signals from the CNS to muscles and glands, enabling movement and response. So, sensory neurons bring information in, while motor neurons send signals out.
9. Plasticity vs. Stability
The brain is incredibly adaptable, and two terms often used to describe this adaptability are ‘plasticity’ and ‘stability.’ Plasticity refers to the brain’s ability to change and reorganize, often in response to experiences or injuries. Stability, on the other hand, refers to the brain’s ability to maintain essential functions and structures. So, plasticity enables change, while stability ensures core functions.
10. Neurotransmitter vs. Hormone
Our final pair, ‘neurotransmitter’ and ‘hormone,’ are both chemical messengers but differ in their mode of transport. Neurotransmitters are released by neurons and act locally, transmitting signals across synapses. Hormones, on the other hand, are secreted by glands into the bloodstream, affecting distant target cells. So, neurotransmitters act locally, while hormones have a more widespread effect.