Why A&P matters in nursing
Understanding anatomy and physiology helps you explain symptoms, recognise deterioration early, understand drug actions, make sense of blood results, and provide informed, holistic care.
Cardiovascular System
The Heart
- 4 chambers: 2 atria (top), 2 ventricles (bottom)
- Right side → deoxygenated blood to lungs
- Left side → oxygenated blood to body
- 4 valves prevent backflow
Blood Vessels
- Arteries — away from heart (thick walls)
- Veins — towards heart (have valves)
- Capillaries — gas exchange (1 cell thick)
SA Node → AV Node → Bundle of His → Bundle Branches → Purkinje Fibres
SA Node = pacemaker (60–100 bpm). If it fails, AV node takes over (40–60 bpm).
Blood Pressure
- Normal: <140/90 mmHg
- Hypertension: ≥140/90
- Hypotension: <90/60
Heart Rate
- Normal: 60–100 bpm (adult)
- Tachycardia: >100 bpm
- Bradycardia: <60 bpm
Respiratory System
Upper Airways
- Nose & nasal cavity (warms, filters, humidifies)
- Pharynx (throat)
- Larynx (voice box)
Lower Airways
- Trachea (windpipe)
- Bronchi → Bronchioles
- Alveoli (gas exchange)
Gas exchange at alveoli
Oxygen diffuses from alveoli → blood. Carbon dioxide diffuses from blood → alveoli to be exhaled. ~300 million alveoli provide a huge surface area. Surfactant prevents alveoli from collapsing.
O2 Sats
- Normal: 94–98% (room air)
- COPD target: 88–92%
- <94% — consider oxygen therapy
Respiratory Rate
- Normal adult: 12–20 breaths/min
- Tachypnoea: >20/min
- Bradypnoea: <12/min
Renal & Urinary System
Filtration (glomerulus) → Reabsorption → Secretion → Excretion
Key Kidney Functions
- Filter waste products from blood
- Regulate fluid balance
- Control blood pressure (renin)
- Produce erythropoietin (red blood cells)
- Activate vitamin D
- Regulate electrolytes (Na+, K+, Ca2+)
Urine Output & Kidney Function
- Normal: >0.5 ml/kg/hr
- Oliguria: <400 ml/24hr
- Anuria: <100 ml/24hr
- ↑ Creatinine = kidney damage
- eGFR <60 = chronic kidney disease
- ↑ Urea = dehydration/failure
Nervous System
Central Nervous System
- Brain (cerebrum, cerebellum, brainstem)
- Spinal cord
- Protected by meninges and CSF
Peripheral Nervous System
- Cranial nerves (12 pairs)
- Spinal nerves (31 pairs)
- Autonomic: Sympathetic & Parasympathetic
Sympathetic — "Fight or Flight"
- ↑ Heart rate & BP
- Dilates pupils
- ↑ Blood to muscles
- ↓ Digestion
Parasympathetic — "Rest & Digest"
- ↓ Heart rate & BP
- Constricts pupils
- ↑ Digestion
- ↑ Secretions
GCS — Glasgow Coma Scale
Eye (1–4) + Verbal (1–5) + Motor (1–6) = 3–15. Normal: 15. Severe injury: ≤8. GCS <8 — protect the airway.
Homeostasis — Normal Ranges
| Parameter | Normal Range |
|---|
| Body Temperature | 36.5–37.5°C |
| Blood Glucose (fasting) | 4–7 mmol/L |
| Blood pH | 7.35–7.45 |
| Serum Sodium | 135–145 mmol/L |
| Serum Potassium | 3.5–5.0 mmol/L |
| Serum Calcium | 2.2–2.6 mmol/L |
| Urine Output | >0.5 ml/kg/hr |
Red flags — when A&P knowledge saves lives
Hypoxia + confusion — urgent assessmentChest pain + sweating + pallor — possible MISudden severe headache — possible SAHNo urine + rising creatinine — AKIHot red swollen limb + SOB — DVT/PEAltered consciousness + fever — meningitis