4BBA1010 - Building Blocks from Cells to Tissues to Organs to Organisms

4BBA1010 - Building Blocks from Cells to Tissues to Organs to Organisms

  • Instructor: Dr. Joaquim Nunes Vieira

  • Institution: School of Cardiovascular & Metabolic Medicine & Sciences, Denmark Hill

  • Dates: 20th and 21st October 2025

  • Contact: Joaquim.nunes_vieira@kcl.ac.uk

Overview of Anatomy

  • Old Anatomy vs New Anatomy:

    • Old Anatomy: Traditional understanding without advanced technological insights.

    • New Anatomy: Enhanced by technology such as microscopy, imaging, and molecular biology.

    • Serves various medical disciplines (surgery, cardiology, urology, pathology).

    • Covers scales from molecular/cellular (microanatomy) to organ systems.

    • Forms the basis for modern medical treatment approaches (e.g., cancer therapies).

  • Definition of Anatomy:

    • A branch of natural science studying the structure of organisms and their parts, including cell, tissue, and organ organization.

Learning Outcomes

  • Understand the extension of modern anatomical systems from cellular/molecular levels to full organ systems.

  • Define tissue and organ, including examples of each tissue type.

  • Classify epithelia and relate structure to function.

  • Differentiate types of connective tissue and understand the role of extracellular material in determining connective tissue function.

  • Know the composition and characteristics of nervous tissue.

  • Identify the three types of muscle tissue.

  • Grasp the four levels of organization: cells, tissues, organs, and systems.

  • Comprehend how the interplay between these organizational levels informs modern medicine, therapies, and systems biology.

Scales of Life

  • Hierarchical Organization:

    • Atoms

    • Molecules

    • Cells (smallest living unit)

    • Tissues

    • Organs

    • Body systems

    • Organisms

    • Ecosystems

    • Biosphere

Functional Anatomy and Structural Organization

  • Cells:

    • Simplest units of living matter capable of maintaining life and reproduction.

  • Tissues:

    • Level between cells and organs.

    • Group of similar, generally identical cells performing specific functions.

  • Organs:

    • Complex units composed of various tissue types working together for a specific function (e.g., stomach consists of muscle, connective, epithelial, and nervous tissues).

  • Systems:

    • Most complex units, consisting of multiple organs performing a defined function (e.g., urinary system).

11 Systems of the Human Body

  1. Respiratory system

  2. Reproductive system

  3. Integumentary system

  4. Urinary system

  5. Skeletal system

  6. Digestive system

  7. Nervous system

  8. Lymphatic system

  9. Endocrine system

  10. Circulatory system

  11. Muscular system

Scale and Visualization

  • Measurement Units:

    • Various scales from atoms and small molecules to entire organisms.

    • Most organs and tissues can be observed under considerable magnification.

    • most common metric is meters

  • Resolution:

    • Defined as the smallest distance between two points discernible as separate objects, critically important for microscopy.

Microscopic Techniques

  • Light Microscope:

    • Commonly used for viewing cells and tissues; typical resolution limits and magnification.

    • allows you to see some level of cells tissues and organisms

  • Transmission Electron Microscope (TEM):

    • Used for high-resolution imaging of internal cell structures. (e.g. ribosomes and mitochondria)

  • Scanning Electron Microscope (SEM):

    • Provides detailed images of cell surfaces.

The Anatomy of a Cell

  • Essential components include:

    • Rough Endoplasmic Reticulum

    • Nucleus and Nuclear Envelope

    • Nucleolus and Chromatin

    • Ribosomes

    • Golgi Apparatus

    • Secretory Vesicles and Lysosomes

    • Centrioles

    • Plasma Membrane

    • Organelles such as Mitochondria

Understanding Tissues

  • Definition of a Tissue:

    • A group of similar cells that work together for specific functions; the organization between individual cells and complete organs.

    • level of organisation within a cell

    • work together to perform a specific function

  • Extracellular Matrix:

    • Material filling spaces between cells, abundant in some tissues e.g.connective tissues and minimal throughout other tissue types.

Classification of Epithelia

  • Key characteristics:

    • Sheets of interconnected cells covering/lining surfaces (e.g., skin, blood vessels).

    • barriers from the external enviornment,

  • Functions:

    • Protective (body surfaces), secretory, and absorptive (enable substance exchange e.g. GI tract).

  • Classification Criteria:

    1. Cell Shape:

    • Squamous (flattened), Cuboidal, Columnar

    1. Arrangement:

    • Simple (single layer), Pseudostratified, Stratified (multiple layers): stratified squamous, transitional

    1. Specializations:

    • Cilia (movement, driven by microtubule cell structure, motile, defence mechanism), Microvilli (heavily irrigated supporting absorption, supported my actin, increased surface area, static), Keratinised (protection, cornified outer layer of dead keratinized cells )

    1. Specialized Cells:

    • E.g., Goblet cells for mucus secretion, example of an epithelial tissue with more than one cell type.

    • epithelium classification: pseudostratified, columnar, ciliated, with goblet cells

Examples of Epithelial Cell Types

  • Simple Epithelia:

    • Simple Squamous: e.g., endothelial cells lining blood vessels. flattened

    • Simple Cuboidal: e.g., salivary gland ducts.

    • Simple Columnar: e.g., the inner surface of the small intestine.

Connective Tissue

  • Major types include: soft and hard

    • seperated by large amounts of extracellular materis - matrix

      • Soft Connective Tissue: Fibroblasts, Adipose cells

      • Hard Connective Tissue: Chondrocytes (cartilage), Osteocytes (bone)

  • Functions:

    • Structural support (structural framework to preserve body form), space filler, storage, attachment (cells to body wall (?)), physical protection, immune defense (defense against pathogens), and transportation (conduit for blood vessles and nerves & transport of material around the body(blood, lymph)), wound healing,

Properties of Connective Tissue Matrix

  • Major Components:

    • Proteoglycans: core proteins with many charged carbohydrate side chains, hydrated to form a gel.

    • Collagen: rope like, provides tensile strength without stretching.

    • Elastic Fibres: Allow stretch and resilience (elastin and fibrillin proteins).

  • matrix determines properties

Nervous Tissue

  • accumulation of nervous tissue cell bodies from the brain and spinal cord and ganglia

  • Composition:

    • Neurons: Send and receive electrical signals.

    • Glial Cells: Support and wrap around neurons to speed nerve signal, some provide support/nutrient for neurons.

  • Spinal Cord Structure:

    • White matter: Contains axons and glia; Grey matter: Contains cell bodies and glial cells.

Muscle Tissue Types

  • Skeletal Muscle:

    • Attached to skeleton for voluntary movement.

    • clustered giant gells with many nuclei, striated muscle

  • Smooth Muscle:

    • Involuntary (e.g. peristalsis), found in hollow organs and blood vessels.

    • individual cells (in a normal situation), striated

  • Cardiac Muscle:

    • Unique to the heart, striated like skeletal muscle.

    • individual cells, spindle shap orientation, NO striations

Tissues in Organs

  • An organ is a collection of multiple tissues performing specific functions.

  • Examples:

    • Stomach: Contains muscle, connective, epithelial, and nervous tissues.

    • Liver: Composed mostly of rows of epithelial cells (hepatocytes) and endothelial cells lining blood sinuses. Blood (fluid connective tissue) and small amounts of soft connective tissue (fibroblasts and fat cells, storage), smooth muscle and some nerves

    • Brain: Mainly nervous tissue (neurons and glia) with some connective and epithelial cells. endothelial cells (epithelia) lining blood vessels containing bloos (fluid connective tissue), some smooth muscle in walls of larger blood vessels, some soft connective tissue surrounding larger blood vessels

    • Esophagus: Stratified squamous epithelium lining lumen, endothelial cells liing blood velssels connective tissues, muscle, and nervous tissues present. ——-

Organ Systems

  • At least two organs working together for specific functions form a system.

  • Example: Urinary System:

    • Comprised of: kidneys, ureters, bladder, and urethra.

    • Functions to maintain composition and regulate body fluid volume, electrolyte concentrations, blood pH, regulate red blood cell production, and maintain blood pressure.

    • muscle cells, nerve cells, epithelial cells, connective cells

Functional Anatomy in Medicine

  • Importance of understanding anatomy at various levels for oncologists, surgeons, pathologists, and geneticists.

  • Example: Squamous cell carcinoma — understanding from cells to systems to develop targeted therapy in skin.

Concept of Systems Biology

  • Systems Biology is a modern biological discipline investigating interactions across different levels of organization using computational methods.

Conclusion

  • For further questions, contact Dr. Joaquim Nunes Vieira at Joaquim.nunes_vieira@kcl.ac.uk