Biology Basics for Medical Students

Introduction and Terminology

• Biology is the natural science of life and living organisms, including their structure, function, growth, evolution, distribution, and taxonomy.
• Studying biology is crucial for medical students as it forms the foundation of understanding the human body, its structure, function, and processes.
• Biology provides fundamental knowledge about cells, organs, systems, genetics, and diseases, essential for diagnosing and treating patients.
• Understanding biology is essential for medical research, informed clinical decisions, and the practice of medicine.

Branches of Biology

• Botany: Study of plants, including structure, physiology, ecology, and evolution.
• Zoology: Study of animals, covering behavior, physiology, anatomy, classification, and evolution.
• Microbiology: Study of microorganisms (bacteria, viruses, fungi, protozoa), their impact on agriculture, industry, and health.
• Genetics: Study of heredity, variation, genes, chromosomes, inheritance patterns, and genetic disorders.
• Ecology: Study of the interactions between organisms and their environment, including the connections between organisms, their habitats, and ecosystems.

Branches of Biology (Continued)

• Physiology: Study of the functions and processes of living organisms and their parts (cells, tissues, organs, and organ systems).
• Anatomy: Study of the structure of organisms (arrangement of tissues, organs, organ systems) through dissection, imaging, and comparative anatomy.
• Biochemistry: Study of chemical processes and substances in living organisms (structure and function of biomolecules like proteins, carbohydrates, lipids, and nucleic acids).
• Biotechnology: Applying biological principles and techniques to develop products and technologies for various purposes (like medicine, agriculture, industry, and environmental conservation).

Branches of Biology (Continued)

• Cytology: Study of cells in terms of structure, function, and chemistry.
• Histology: Study of microscopic anatomy of cells and tissues in plants and animals.
• Immunology: Study of the immune system and its response to pathogens and foreign substances.
• Embryology: Study of prenatal development of gametes, fertilization, embryo development, and congenital disorders that occur before birth (teratology).

Characters of Living Organisms

• Organisms are composed of cells: All organisms are comprised of cells, the basic structural and functional units, categorized as unicellular (single-cell) or multicellular (many cells).
• Growth: An increase in size and number of cells. Indicates addition of new cells and an increase in size.
• Development: Includes all changes during the organism's life cycle, from fertilized egg to fully developed being.

Characters of Living Organisms (Continued)

• Reproduction: Ability of an organism to produce its kind, and can be asexual (without fusion) or sexual (fusion of gametes).
• Movement: Most organisms exhibit one form of movement – crawling, walking, swimming, or flying; micro-organisms use specialized structures like cilia or flagella.
• Metabolism: Sum of all chemical activities within an organism's cells and tissues.

Characters of Living Organisms (Continued)

• Homeostasis: Maintaining a stable internal environment despite external changes, including body temperature, fluid balance, and chemical concentrations (like sodium, potassium, and calcium).
• Responsiveness to stimuli: Ability of an organism or system to respond to changes in its environment (temperature, light, chemicals, and others). Demonstrated through reflexes, changes in hormone/heart rate and directional movement.
• Adaptation: The capacity to survive in a particular environment.

Biological Organization

• Chemical level: Atoms (basic units), molecules (two or more atoms bonded together).
• Cellular level: Organelles (specialized structures within a cell), cells (basic units of life).
• Tissue level: Groups of similar or dissimilar cells performing specific tasks, e.g., epithelial tissue, connective tissue.
• Organ level: Structures composed of different tissues performing a specific function, e.g., heart, lungs, liver.
• Organ system level: A group of organs that work together to carry out major functions, e.g., digestive, respiratory.
• Organism level: Individual living being performing all functions needed for survival.
• Population level: Groups of the same species living in the same area.
• Community level: Populations of different species living in the same area.
• Ecosystem level: Living organisms and their surroundings (biotic and abiotic components), where they interact.
• Biosphere level: The sum of all the Earth's ecosystems.

Diversity of Life

• Classifications of life’s diversity (kingdoms) based on characteristics, features, structure, and function.
• Scientific classifications are categorized into three domains (Archaea, Bacteria, Eukarya) to reflect evolutionary relationships.

Scientific Method

• Observation, critical questions, hypothesis, prediction, experiments, results, interpretation, conclusions.