Organization & Structure
What is the basic functional unit of the nervous system?
The neuron
What is the resting membrane potential of a typical neuron?
–70 mV
Which neurotransmitter is released at cholinergic synapses?
Acetylcholine (ACh)
Which part of the brain is responsible for conscious thought, memory, and voluntary movement?
The cerebrum
Which cranial nerve is responsible for the sense of smell?
Olfactory
What are the four main functions of the nervous system?
Sensory input, integration, motor output, and homeostasis/regulation
The sodium–potassium pump moves how many sodium and potassium ions?
3 Na⁺ out and 2 K⁺ in
What is the “all-or-none” principle of action potentials?
Once threshold is reached, the neuron fires at full strength or not at all
Which part of the brain coordinates balance and smooth movement?
The cerebellum
This sensory nerve has two branches: one for hearing and one for balance and equilibrium.
Vestibulocochlear
Which glial cell produces myelin in the CNS?
Oligodendrocyte
A stimulus that makes the inside of a neuron less negative is called what?
Depolarization
What type of summation occurs when multiple synapses stimulate a neuron at different locations?
Spatial summation
The brainstem is made up of what three structures?
The midbrain, pons, and medulla oblongata
This motor nerve controls most of the eye movements, including lifting the eyelid and constricting the pupil.
Oculomotor
Which glial cell maintains the blood–brain barrier?
Astrocyte
What is the threshold stimulus?
The minimum depolarization needed to trigger an action potential
How does myelination affect the speed of an action potential?
It increases conduction speed through saltatory propagation
The pons and medulla oblongata help control what vital body functions?
Breathing, heart rate, and blood pressure
Which cranial nerve controls heart rate, digestion, and respiratory functions, and is also known as the “wandering nerve”?
Vagus
Trace the flow of information through the nervous system — from a sensory receptor detecting a stimulus to the effector responding.
Sensory receptor → Afferent (sensory) neuron → CNS (integration) → Efferent (motor) neuron → Effector (muscle or gland)
Compare graded potentials and action potentials in terms of strength, propagation, and function.
Graded potentials vary in strength, occur locally, fade with distance, and can be depolarizing or hyperpolarizing.
Action potentials are all-or-none, self-propagating, travel long distances, and are always depolarizing.
List the major steps in generating an action potential in the correct order.
1️⃣ Depolarization to threshold →2️⃣ Activation of Na⁺ channels (Na⁺ influx) → 3️⃣ Inactivation of Na⁺ channels, activation of K⁺ channels (K⁺ efflux) → 4️⃣ Repolarization → 5️⃣ Return to resting potential
Trace the flow of cerebrospinal fluid (CSF) — from its formation to where it’s returned to circulation.
Choroid plexus → Ventricles → Central canal and subarachnoid space → Arachnoid granulations → Superior sagittal sinus → Venous circulation
A patient has difficulty chewing, loss of taste on the front of the tongue, and drooping on one side of the face. Which two cranial nerves are most likely affected?
Trigeminal and Facial