Physiology as an Integrated Science: Control Systems and Homeostasis

Physiology as an Integrated Science

Introduction to Physiology

Physiology is the study of how living organisms function, focusing on the mechanisms that maintain life. It integrates knowledge from molecular biology, cell biology, and anatomy to explain how organ systems work together to sustain homeostasis.

• Definition: Physiology examines the processes and functions of living systems.

• Integration: Links molecular, cellular, tissue, organ, and organismal levels.

• Application: Understanding physiology is essential for medicine, health sciences, and research.

Module Concepts – Part 1

Key Themes in Physiology

This module introduces foundational concepts in physiology, emphasizing the importance of control systems and homeostasis in maintaining health, especially in the context of an ageing population and chronic disease.

• Ageing Population & Chronic Disease: The demographic shift towards older populations increases the prevalence of chronic diseases, impacting healthcare systems and physiological research.

• Function vs Process:

  • Function (Teleological Approach): Explains why a process occurs (e.g., why the heart pumps blood).

  • Process (Mechanistic Approach): Describes how a process occurs (e.g., the steps of muscle contraction).

• Homeostasis: The regulation of the body's internal environment to maintain stable conditions necessary for survival.

• Control Systems: Feedback and feedforward loops that regulate physiological variables.

• Biomolecules: Proteins, lipids, carbohydrates, and nucleic acids are the building blocks of physiology.

• Ligand-Protein Interactions: Proteins interact with specific molecules (ligands) to perform functions such as signaling and transport.

Additional info: Students are expected to build on prior knowledge from cell biology, organelles, membranes, selective permeability, DNA, biomolecules, transcription/translation, homeostasis, endocrinology, and cell-cell communication.

Levels of Organisation and Related Fields of Study

Hierarchical Structure of Biological Systems

Biological systems are organized into hierarchical levels, each studied by different scientific disciplines.

• Chemistry: Molecules

• Molecular Biology: Cells

• Cell Biology: Tissues

• Physiology: Organs, organ systems, organisms

• Ecology: Populations, ecosystems

Example: The study of muscle contraction involves chemistry (ATP), molecular biology (actin/myosin), cell biology (muscle cells), and physiology (muscle function in movement).

A Crowded and Ageing World

Demographic Changes and Health Implications

Global population trends show an increase in the proportion of older adults, raising questions about healthspan versus lifespan.

• Population Age Structure: The percentage of people aged 65+ is rising, while the proportion of children (

  • Healthspan vs Lifespan: Are people living longer, healthier lives, or spending more years in poor health?

  • Patterns of Disease and Death: Chronic diseases become more prevalent with age, affecting quality of life and healthcare resources.

Example: The graph shows a projected increase in the elderly population, emphasizing the need for physiological research into ageing and chronic disease management.