Study guide
4.4 The Nervous System
ATI TEAS 7 Nursing Admission
Track your progress as you read
Finished sections get a check mark.
1 Introduction to the ATI TEAS 7
1.1 About the ATI TEAS 7 Exam 1.2 Content Area Breakdown 1.3 Scoring and Program Requirements 1.4 Building Your TEAS Study Plan
2 Reading
2.1 Identifying the Main Idea 2.2 Making Inferences and Drawing Conclusions 2.3 Summarizing and Paraphrasing 2.4 Understanding Text Structure 2.5 Author's Purpose, Tone, and Point of View 2.6 Evaluating Arguments, Evidence, and Credibility 2.7 Integrating Information and Interpreting Graphics 2.8 TEAS Reading Strategies, Pacing, and Practice
3 Mathematics
3.1 Whole Numbers and Basic Operations 3.2 Fractions 3.3 Decimals and Percentages 3.4 Ratios and Proportions 3.5 Algebra and Equations 3.6 Measurement and Unit Conversions 3.7 Statistics and Data Interpretation 3.8 Geometry Basics
4 Science
4.1 The Cardiovascular System 4.2 The Respiratory System 4.3 The Digestive System 4.4 The Nervous System 4.5 The Musculoskeletal System 4.6 The Urinary and Reproductive Systems 4.7 Cell Biology and Genetics 4.8 Chemistry Basics 4.9 Scientific Reasoning and the Scientific Method
5 English & Language Usage
5.1 Grammar and the Parts of Speech 5.2 Sentence Structure 5.3 Punctuation 5.4 Spelling and Word Usage 5.5 Vocabulary in Context and Word Parts 5.6 Paragraph Organization and the Writing Process 5.7 Formal vs. Informal Language, Audience, and Tone 5.8 TEAS English Section Strategies and Pacing
4.4 The Nervous System
Key Takeaways Explain This Topic AI
The central nervous system (CNS) is the brain and spinal cord; the peripheral nervous system (PNS) is all nerves outside it
A neuron has dendrites (receive), a cell body, and an axon (transmit); the myelin sheath speeds transmission
A neuron's resting membrane potential is about −70 mV; reaching the threshold of about −55 mV triggers an all-or-none action potential
The sympathetic division drives “fight or flight”; the parasympathetic division drives “rest and digest”
The four cerebral lobes are frontal (reasoning), parietal (sensory), temporal (hearing/memory), and occipital (vision)
Last updated: October 2026
The nervous system is the body's rapid communication and control network. It senses the environment, processes information, and triggers responses — all in milliseconds. On the TEAS you will be asked to split the system into its anatomical divisions, label the parts of a neuron, explain how a nerve impulse travels, locate functions to brain regions, and distinguish the two branches of the autonomic system. The unifying idea is that neurons communicate using a combination of electrical signals (along the axon) and chemical signals (across the gap between neurons).
Two Main Divisions: CNS and PNS
Every part of the nervous system belongs to one of two divisions.
- Division Components Role
- Central nervous system (CNS) Brain and spinal cord Integration, processing, decision-making
- Peripheral nervous system (PNS) All nerves and ganglia outside the CNS Carries information to and from the CNS
The PNS is further split into a somatic division (voluntary control of skeletal muscle) and an autonomic division (involuntary control of organs and glands).
The Neuron: The Functional Unit
A neuron is a specialized cell built to carry signals. Each part has one job, so expect questions that match a part to its function.
- Part Function
- Dendrites Branch-like extensions that receive incoming signals
- Cell body (soma) Contains the nucleus; the metabolic center
- Axon Long fiber that transmits the signal away from the cell body
- Myelin sheath Fatty insulation that speeds signal transmission
- Synaptic terminals Release neurotransmitters to the next cell
The simplest way to remember the flow is “dendrites receive, axons transmit.” Signals always travel one direction within a neuron: dendrite → cell body → axon → synaptic terminal.
The Action Potential
A nerve signal is an action potential , a brief electrical event that sweeps down the axon. Understanding it requires a few standard numbers.
Resting potential: At rest, the inside of the neuron is about −70 mV relative to the outside (more sodium outside, more potassium inside).
Reaching threshold: A stimulus must push the membrane to about −55 mV , the threshold, to fire.
Depolarization: Sodium (Na⁺) channels open and sodium rushes in , making the inside positive.
Repolarization: Potassium (K⁺) rushes out , returning the inside to negative.
Synaptic transmission: At the axon's end, the signal triggers release of neurotransmitters across the synapse to the next neuron.
A crucial test concept is that the action potential is all-or-none : once threshold is reached, a full-strength impulse fires; a stronger stimulus does not produce a bigger impulse, only more frequent ones. Below threshold, nothing fires.
Major Neurotransmitters
Neurotransmitters are the chemical messengers released at the synapse. A few appear repeatedly on the exam:
- Acetylcholine — muscle activation and memory
- Dopamine — reward, movement, and mood
- Serotonin — mood, sleep, and appetite
- GABA — the main inhibitory (calming) transmitter
- Glutamate — the main excitatory transmitter, involved in learning
- Brain Regions and the Four Lobes
The brain has three broad regions plus four cortical lobes you must locate.
- Region Main Functions
- Cerebrum Thinking, memory, voluntary movement, the senses
- Cerebellum Balance, coordination, fine motor control
- Brainstem Vital automatic functions: breathing, heart rate
The cerebrum's surface is divided into four lobes :
- Lobe Location Function
- Frontal Front Reasoning, planning, speech, voluntary movement
- Parietal Top-back Touch and other sensory processing
- Temporal Sides Hearing, memory, language comprehension
- Occipital Back Vision
A reliable mnemonic for the back lobe: the occipital lobe is at the back of your head, the opposite end from your eyes, yet it is where vision is processed.
The Reflex Arc
A reflex is an automatic, protective response that bypasses the brain to save time. The pathway is the reflex arc :
Stimulus (e.g., a hot stove) → 2. Receptor detects it → 3. Sensory neuron carries the signal to the spinal cord → 4. Integration center (spinal cord) → 5. Motor neuron carries the command out → 6. Effector (a muscle) → 7. Response (you pull your hand away).
Because the signal is processed in the spinal cord, you withdraw your hand before you consciously feel the pain.
The Autonomic Nervous System
The autonomic division controls involuntary functions through two opposing branches that the TEAS contrasts directly.
- Branch State Effects
- Sympathetic “Fight or flight” ↑ heart rate, ↑ breathing, dilates pupils, slows digestion
- Parasympathetic “Rest and digest” ↓ heart rate, ↑ digestion, constricts pupils
Think of the sympathetic system as the accelerator that prepares you for danger and the parasympathetic system as the brake that conserves energy and runs routine maintenance like digestion.
Worked Example: You step on a sharp object and instantly lift your foot, only feeling pain a moment later. Trace the pathway. The sharp object is the stimulus ; pain receptors in the skin detect it; a sensory neuron carries the signal to the spinal cord (the integration center); an interneuron routes it to a motor neuron , which signals the leg muscle (the effector ) to contract and lift the foot. The reflex is completed in the spinal cord, so you react before the pain signal even reaches your conscious brain.