Neuron Structure – MCAT Biology | MedSchoolCoach

Neuron Structure

MCAT Biology - Chapter 7 - Section 1.4 - Organ Systems - Neuron Structure
Play Video about MCAT Biology - Organ Systems - Nervous System - Neuron Structure

Sample MCAT Question - Neuron Structure

The site of signal propagation between a neuron and another cell is called:

a) a synapse.

b) a dendrite.

c) an axon.

d) a soma.

A is correct. A synapse. The synapse is the junction between two neurons, or a neuron and its effector targets, such as a gland or organ. At chemical synapses, the presynaptic neuron will release chemicals, called neurotransmitters, across the synaptic cleft, which are received by target receptors on the postsynaptic neuron. This will create a response in the postsynaptic neuron, that may or may not result in the generation of an action potential. At electrical synapses, electrical charge will diffuse directly from the presynaptic neuron into the postsynaptic neuron through gap junctions. Thus, the synapse, whether chemical or electrical, is the site of signal propagation between cells.

Get 1-on-1 MCAT Tutoring From a Specialist

With MCAT tutoring from MedSchoolCoach, we are committed to help you prepare, excel, and optimize your ideal score on the MCAT exam.

 

For each student we work with, we learn about their learning style, content knowledge, and goals. We match them with the most suitable tutor and conduct online sessions that make them feel as if they are in the classroom. Each session is recorded, plus with access to whiteboard notes. We focus on high-yield topics if you’re pressed for time. If you have more time or high-score goals, we meticulously cover the entire MCAT syllabus.

Neuron Structure

The neuron is made up of several essential components that are important to know for the MCAT exam. (These structures are illustrated in Figure 1.)
Neuron Structure (Dendrites Soma, Axon, Myelin Sheath, Synapse) - MCAT Biology
Figure 1. Neuron Structure (Dendrites Soma, Axon, Myelin Sheath, Synapse)

Dendrites & Soma

First, there is the cell body or the soma, which is the location of the cell nucleus as well as several other organelles. Emanating from the soma are dendrites, which are branched extensions of the soma that receive signals from other neurons. These signals are integrated in the soma and determine whether the cell will send its own signal by firing an action potential.

Axons, Myelin Sheaths, & Nodes of Ranvier

Next, there are the axons, which are long, slender projections of nerve fibers that send signals away from the soma. Most axons are very small in diameter, but they can reach great lengths. For instance, the motor neurons that control leg movement have axons that are up to one meter long.

 

Axons are covered by myelin sheaths. These sheaths insulate the axon and increase the efficiency of signal transduction. Without myelin sheaths, the signals neurons send along their axons, or action potentials, would not be as fast. The gaps between myelin sheaths are known as the Nodes of Ranvier. These are essential for the efficient and speedy transmission of the signal down the axon. When an action potential is transmitted, it does not travel the whole length of the axon, but appears to “jump” from node to node, thus ensuring faster signal transduction.

Synapses: Junctions Between Neurons

Lastly, the synapse is the junction between two neurons or, more accurately stated, the junction between the neuron and another cell. (Instead of synapsing onto another neuron, a neuron may synapse onto a muscle cell, gland, or organ.) The synapse is the site of signal propagation between two cells. 

 

The neuron that transmits the signal is known as the presynaptic neuron, and the neuron which receives the signal is known as the postsynaptic neuron. In order for the signal to be propagated, the presynaptic neuron will release neurotransmitters that bind to receptors on the postsynaptic cell. Upon binding the neurotransmitters, the postsynaptic cell will undergo a reaction that may or may not result in the firing of an action potential. In order to transmit signals across long distances — from the central nervous system to muscle fibers in the leg, say — several neurons with multiple synapses are usually required.

Explore More MCAT Masterclass Chapters

Take a closer look at our entire MCAT Masterclass or explore our Biochemistry lessons below.

Interview - Job interview

One-on-One Tutoring

Are you ready to take your MCAT performance to a whole new level? Work with our 99th-percentile MCAT tutors to boost your score by 12 points or more!

See if MCAT Tutoring can help me

Talk to our enrollment team about MCAT Tutoring

Medical College Admission Test - MCAT Physics

MCAT Go Audio Course

Engaging audio learning to take your MCAT learning on the go, any time, any where. You'll be on the way to a higher MCAT score no matter where you are. Listen to over 200+ lessons.

Stock photography - Image

MCAT Practice Exams

Practice makes perfect! Our mock exams coupled with thorough explanations and in-depth analytics help students understand exactly where they stand.

MCAT Prep App Mobile

MCAT Prep App

Access hundreds of MCAT videos to help you study and raise your exam score. Augment your learning with expert-created flashcards and a question banks.

Happy April Fool’s Day from MedSchoolCoach!


While mastering sleep-learning is still a dream, MCAT Go helps you study for the MCAT while you are awake. Listen to MCAT Go for free (a $99 value) by entering your email below to receive an exclusive discount code. This ain’t no joke.