Study guides › B/B › Biology
The Nervous System
Neurons carry information with electrical and chemical signals. You will learn resting and action potentials, synaptic transmission, brain regions, autonomic versus somatic control, reflex arcs, and how the eye and ear turn stimuli into signals.
Study this chapter in PrepMed (free)
What this chapter covers
- Neuron Structure & the Resting Potential. Every nerve signal starts from a charge difference across the membrane, built by ion gradients and leak channels.
- The Action Potential. The action potential is all-or-none and has named phases tied to specific channels. Expect a graph question.
- Synapses & Neurotransmitters. Synaptic transmission converts an electrical signal to a chemical one and back. Drug and toxin questions target its steps.
- Brain Regions & Their Functions. The MCAT links lesions to deficits. Know what each brain region does and what fails when it is damaged.
- Autonomic & Somatic Control, Reflexes & Senses. Sympathetic versus parasympathetic wiring, the reflex arc, and the eye and ear appear often. Learn the pathway of each.
Key points to know
- Resting potential is about −70 mV, set mainly by K⁺ leak channels
- Na⁺/K⁺ ATPase moves 3 Na⁺ out and 2 K⁺ in per ATP
- Threshold about −55 mV; peak about +35 mV; undershoot about −80 mV
- Upstroke: voltage-gated Na⁺ channels; downstroke: Na⁺ inactivation plus K⁺ efflux
- Ca²⁺ entry triggers neurotransmitter release
- Ionotropic = fast channel; metabotropic = slow G protein
- Broca = produce speech; Wernicke = understand speech
- Hippocampus = making new memories; amygdala = fear
Try a practice question
Where are action potentials normally initiated in a motor neuron?
- Dendrites
- Terminal bouton
- Axon hillock
- Node of Ranvier
Show the answer
C. The axon hillock has the highest density of voltage-gated Na⁺ channels and integrates inputs from the soma, so it reaches threshold first. Nodes of Ranvier regenerate the signal but do not start it.
Common questions
What does this chapter cover?
The Nervous System covers Neuron Structure & the Resting Potential, The Action Potential, Synapses & Neurotransmitters, Brain Regions & Their Functions, Autonomic & Somatic Control, Reflexes & Senses.
What should I know first?
Resting potential is about −70 mV, set mainly by K⁺ leak channels Na⁺/K⁺ ATPase moves 3 Na⁺ out and 2 K⁺ in per ATP Threshold about −55 mV; peak about +35 mV; undershoot about −80 mV
24 original practice questions accompany this chapter in the app. Spaced review brings missed ideas back at the right time; it helps memory but cannot promise you will not miss an idea again.