NUR1112 · Fundamental Skills and Knowledge for Nursing and Midwifery Practice 1
The Nervous System & Taking a Health History
Week 4 introduces the nervous system alongside the practice skills of taking a health history and performing a physical examination. The bioscience thread covers neuron structure, the central-versus-peripheral organisation, and the action potential. The practice thread covers structured history-taking and the four physical-examination techniques (inspection, palpation, percussion, auscultation), which recur in every focused assessment.
What this chapter covers
- 01Neuron structure and the organisation of the nervous system: CNS (brain + spinal cord) vs PNS (nerves + ganglia)
- 02PNS functional divisions: sensory; motor (somatic + autonomic); autonomic → sympathetic + parasympathetic
- 03The action potential: Na⁺ influx → depolarisation; Na⁺ inactivation; K⁺ efflux → repolarisation
- 04All-or-none principle and threshold; effect of blocking voltage-gated Na⁺ channels
- 05EPSP vs IPSP; temporal and spatial summation at the axon hillock
- 06Taking a structured health history (subjective data) and performing a physical examination
- 07The four physical-examination techniques: inspection, palpation, percussion, auscultation
Sequencing the neuronal action potential
- +1First: increased Na⁺ permeability. Voltage-gated Na⁺ channels open, Na⁺ flows in, and the membrane depolarises and reverses polarity (the rising phase).
- +1Second: decreased Na⁺ permeability. The Na⁺ channels inactivate, so Na⁺ influx stops and the rising phase ends.
- +1Third: increased K⁺ permeability. K⁺ channels open and K⁺ flows out, repolarising the membrane back toward rest.
- +1All-or-none and threshold: the neuron fires a full-sized action potential only if depolarisation reaches threshold; a sub-threshold stimulus produces no action potential. Blocking voltage-gated Na⁺ channels prevents depolarisation, so no action potential can occur.
Key terms
- Central nervous system (CNS)
- The brain and spinal cord — the integrative centre that processes information and coordinates responses.
- Peripheral nervous system (PNS)
- The nerves and ganglia outside the CNS; functionally divided into sensory and motor, with the motor division further split into somatic and autonomic.
- Action potential
- A rapid, all-or-none reversal of membrane potential propagated along a neuron: Na⁺ influx (depolarisation), Na⁺ inactivation, then K⁺ efflux (repolarisation).
- Threshold
- The membrane potential that must be reached for an action potential to fire; sub-threshold stimuli produce no action potential (the all-or-none principle).
- EPSP / IPSP
- Excitatory postsynaptic potential (depolarising, brings the neuron toward threshold) and inhibitory postsynaptic potential (hyperpolarising, moves it away); summation at the axon hillock decides firing.
- Physical-examination techniques
- The four systematic methods used in assessment: inspection (look), palpation (feel), percussion (tap to elicit sounds), and auscultation (listen, e.g. for air entry into the lungs).
The Nervous System & Taking a Health History FAQ
What is the correct order of ionic events in an action potential?
Increased Na⁺ permeability first (Na⁺ flows in and the membrane depolarises), then decreased Na⁺ permeability as the channels inactivate, then increased K⁺ permeability (K⁺ flows out and the membrane repolarises). Getting this Na⁺-in / Na⁺-off / K⁺-out sequence right — and pairing each with its voltage change — is the examinable core.
What are the four physical-examination techniques?
Inspection, palpation, percussion and auscultation. In NUR1112 these recur in every focused assessment: for example, auscultation is used to assess air entry into the lungs and percussion can help elicit heart sounds. Knowing which technique gives which information is a common exam and skills-demonstration point.
How do CNS and PNS divisions fit together?
The CNS is the brain and spinal cord; the PNS is the nerves and ganglia. The PNS motor output splits into somatic (voluntary, to skeletal muscle) and autonomic, and the autonomic further into sympathetic and parasympathetic. Holding this branching map in your head makes the later autonomic-nervous-system week much easier.
Can Sia help me learn the action potential and history-taking?
Yes — Sia can walk the action potential one phase at a time, quiz you on threshold and all-or-none, or give you a structured framework to practise history-taking. It explains the method and checks your reasoning; it does not complete graded work for you, and academic-integrity rules apply.
Exam move
Learn the action potential as a fixed three-step sequence (Na⁺ in → Na⁺ off → K⁺ out) tied to depolarisation and repolarisation, and be ready to state all-or-none, threshold, and the effect of Na⁺-channel blockade. Pair that bioscience with the practice skill of the week: memorise the four examination techniques and what each detects, and practise a structured health history. Both threads recur — the exam tests the physiology, the skills demonstration tests the technique. Ask Sia to quiz you on the action-potential phases and to run a mock history-taking framework.
Working through The Nervous System & Taking a Health History in NUR1112? Sia is AskSia’s AI Nursing tutor — ask any NUR1112 The Nervous System & Taking a Health History question and get a clear, step-by-step explanation grounded in how NUR1112 is taught and assessed. Read this chapter free, then take your hardest questions to Sia.
