Introduction to the Human Body and Basic Health Concepts
Domain 3: Introduction to the Human Body and Basic Health Concepts. Expect questions on levels of organisation, organ system functions, normal vital signs, homeostasis, and the meaning of health and disease.
Levels of organisation
Cell → tissue → organ → system → organism. The four basic tissues are epithelial, connective, muscular and nervous. The body has eleven systems: integumentary, skeletal, muscular, circulatory, respiratory, digestive, nervous, urinary, endocrine, reproductive and lymphatic/immune. Learn one function each: the skeleton supports and protects, the respiratory system exchanges gases, the urinary system filters blood and balances fluids.
Homeostasis and vital signs
Homeostasis is the steady internal state the body maintains. Normal adult values: temperature 36.5–37.5 °C oral, pulse 60–100 per minute, respiration 12–20 per minute, blood pressure about 120/80 mmHg, SpO2 95–100%. Count pulse and respiration for a full minute when irregular; record respiration without telling the patient, because awareness changes breathing.
Health and disease
WHO (1948) defines health as a state of complete physical, mental and social well-being, not merely the absence of disease. Communicable diseases spread from person to person; non-communicable diseases such as diabetes and hypertension do not. Endemic means constantly present in an area, epidemic a sudden rise, pandemic worldwide spread. BMI = weight in kg ÷ (height in metres)²; about 18.5–24.9 is the normal adult range.
Worked example
A reading of 148/96 mmHg is recorded. Reasoning: systolic 148 exceeds 140 and diastolic 96 exceeds 90, so the reading is raised. The correct action is to let the patient rest five minutes, recheck in the same arm with the right cuff size, and report the repeat reading rather than labelling the person hypertensive on one measurement.
Traps
- Writing 96/148 - systolic always comes first.
- Counting pulse for 15 seconds and forgetting to multiply by four.
- Treating 99 °F as fever; it is within the normal oral range.