Anatomy & Physiology – NHPC Exam Guide Part 2: Human Development and Ageing Author: SB Thapa

 Table of Contents

1. 1. Chapter 1 – Introduction to Human Growth and Development

2. 2. Chapter 2 – Prenatal Development

3. 3. Chapter 3 – Postnatal Development

4. 4. Chapter 4 – Adulthood and Maintenance of Health

5. 5. Chapter 5 – Ageing and Senescence

6. 6. Chapter 6 – Common Age-Related Disorders

7. 7. Chapter 7 – Death and Dying

Chapter 1 – Introduction to Human Growth and Development

Growth refers to the quantitative increase in body size, mass, or organ dimensions, while development involves qualitative changes, including functional and behavioral maturity. Together, they represent the dynamic processes through which a single-celled zygote becomes a mature human capable of reproduction and adaptation.

The stages of human life include prenatal, neonatal, childhood, adolescence, adulthood, and old age. Each stage is influenced by genetic, hormonal, nutritional, and environmental factors. For instance, thyroid and growth hormones regulate physical growth, while environmental stress and nutrition determine overall development potential.

[Diagram Placeholder: Human Life Span Curve]

Exam Tip: Questions often test the difference between growth and development, and examples of each.

Clinical Insight: Growth retardation may result from endocrine disorders such as hypothyroidism or malnutrition.

Chapter 2 – Prenatal Development

Prenatal development spans approximately 38–40 weeks and is divided into three trimesters. The embryonic period (first 8 weeks) involves organ formation, while the fetal period focuses on growth and maturation. Fertilization occurs in the fallopian tube when a sperm unites with an ovum to form a zygote, which undergoes cleavage to become a blastocyst before implantation in the uterine wall.

By the end of the first trimester, most organs are formed. The second trimester is marked by rapid growth, and the third trimester prepares the fetus for extra-uterine life. Teratogens such as alcohol, nicotine, certain drugs, and radiation can cause congenital malformations during this sensitive period.

[Diagram Placeholder: Timeline of Prenatal Development]

Exam Tip: The first trimester is the most critical period for organogenesis and is highly sensitive to teratogens.

Clinical Insight: Folic acid supplementation before conception reduces the risk of neural tube defects.

Chapter 3 – Postnatal Development

Postnatal development begins at birth and continues until full maturity. It includes physical growth, psychological development, and social adaptation. Infancy is characterized by rapid brain and skeletal growth. In childhood, motor and language skills develop, while adolescence brings hormonal changes and the onset of puberty.

Puberty is triggered by the activation of the hypothalamic–pituitary–gonadal axis, resulting in increased secretion of gonadotropins and sex hormones. Secondary sexual characteristics such as breast development in females and facial hair in males appear during this stage.

[Diagram Placeholder: Growth Hormone Regulation Pathway]

Exam Tip: Understand the role of growth hormone and sex steroids in puberty and bone growth.

Clinical Insight: Delayed puberty may be caused by pituitary dysfunction or chronic malnutrition.

Chapter 4 – Adulthood and Maintenance of Health

Adulthood represents the period of maximum physiological efficiency, usually from 20 to 40 years of age. All organ systems function at peak capacity, though subtle decline begins toward middle age. Maintaining health during adulthood requires balanced nutrition, regular exercise, mental well-being, and stress management.

Lifestyle factors play a major role in long-term health. Regular physical activity maintains cardiovascular and musculoskeletal health, while chronic stress or poor diet contributes to hypertension, obesity, and diabetes.

Clinical Insight: Early adoption of a healthy lifestyle significantly reduces the risk of age-related diseases.

Exam Tip: NHPC exams may ask about physiological peaks and preventive health strategies.

Chapter 5 – Ageing and Senescence

Ageing, or senescence, is a natural, progressive decline in physiological function. It involves structural and biochemical changes that affect cells, tissues, and organs. Genetic, environmental, and lifestyle factors determine the rate and expression of ageing in individuals.

Several theories explain ageing: 1. Genetic theory – cells have a limited number of divisions (Hayflick limit). 2. Free radical theory – accumulation of oxidative damage leads to cellular dysfunction. 3. Telomere shortening – progressive loss of DNA at chromosome ends triggers senescence. 4. Hormonal theory – decline in endocrine activity accelerates tissue ageing.

Systemic changes include decreased cardiac output, reduced lung elasticity, slower reflexes, and bone demineralization. Muscle mass decreases (sarcopenia), and sensory perception dulls. Despite these declines, cognitive and emotional health can be maintained through active engagement and exercise.

[Diagram Placeholder: Cellular Ageing and Oxidative Stress]

Exam Tip: Know which systems decline earliest with ageing (e.g., reproductive and musculoskeletal).

Clinical Insight: Regular exercise and antioxidant-rich diets delay many ageing effects.

Chapter 6 – Common Age-Related Disorders

Common disorders in old age include osteoporosis, osteoarthritis, hypertension, type 2 diabetes, and Alzheimer’s disease. These conditions arise due to cumulative cellular damage, hormonal changes, and decreased repair mechanisms.

Osteoporosis results from bone mass loss due to decreased estrogen in postmenopausal women. Osteoarthritis involves joint cartilage degeneration, leading to pain and stiffness. Alzheimer’s disease is characterized by progressive neuronal loss and memory impairment.

Preventive strategies include regular physical activity, balanced diet, blood pressure control, and cognitive engagement. Rehabilitation and community support improve quality of life in the elderly.

Clinical Insight: Early screening and physiotherapy improve functional independence in older adults.

Exam Tip: NHPC questions often test mechanisms and prevention of age-related conditions.

Chapter 7 – Death and Dying

Death represents the irreversible cessation of all biological functions that sustain life. Clinical death refers to the stoppage of heartbeat and respiration, whereas biological death occurs when irreversible brain damage has taken place.

The process of dying often follows stages described by Kübler-Ross: denial, anger, bargaining, depression, and acceptance. Understanding these stages helps healthcare professionals provide empathetic end-of-life care.

Ethical issues include decisions on life support, organ donation, and euthanasia. Cultural and spiritual beliefs influence how individuals and families approach death and bereavement.

Exam Tip: Differentiate between clinical and biological death.

Clinical Insight: Palliative care focuses on comfort, dignity, and symptom relief in terminal illness.

Please give your opinions for any improvement or what could be done.