tissues lecture

Tissue Types and Extracellular Matrix

• Types of Tissues: The discussion includes different categories of tissues and examples of each. Understanding their components is essential.

• Living Component: At least one type of cell is required in all tissue types, and often more.

• Extracellular Matrix (ECM): This is the environment outside the cell, composed of non-living components like water, proteins, ions, and various cell types such as fibrocytes, chondrocytes, osteocytes, or red blood cells.

  • Fibrocytes: Specific cells that create fibers, essential for the structure of the ECM.

  • Ground Substance: Made up of three main components:

    • Water

    • Adhesion proteins

    • Other organic molecules.

Collagen and Water Content in Connective Tissue

• Tendon vs. Blood: Tendons are expected to have a higher collagen content compared to blood; bone is also richer in collagen due to its support role.

• Fat vs. Bone: Fat contains more water than bone due to its soft, malleable structure.

  • Key Points: Understand the main protein fiber types, their water content (high, medium, or low), and associated cell types.

  • Adhesion Proteins: Responsible for trapping cells in the matrix to prevent them from being swept away by liquid movement.

Muscle Tissue

• Skeletal Muscle: Recognized for its structured, geometric organization with long, parallel cylinders. Each cell contracts simultaneously to pump blood effectively.

• Intercalated Discs: These structures connect individual muscle cells, allowing synchronized contractions.

• Epithelial Tissue: Always faces an open surface, e.g., the lining of the intestines. Must remain a top layer on any organ, showcasing its protective and absorptive functions.

• Smooth Muscle: Responsible for involuntary movements, such as in blood vessels and digestive organs.

Immune Response and Inflammation

• Antibiotic Misuse: Frequent usage, especially without bacterial infections, can induce microbial resistance, complicating treatments for infections.

• Inflammatory Response Process:

  1. Initial Damage: Vessels rupture due to injury - signals release SOS chemicals.

  2. Recruitment of White Blood Cells: Inflammatory chemicals are released, drawing cells for clotting and protection.

  3. Positive Feedback Mechanism: Activated white blood cells recruit more cells, promoting rapid response.

  4. Stages of Inflammation:

     • Heat, Redness, Pain, Swelling: Visible signs of inflammation indicating the body’s response to injury.

     • Organization: Involves recruiting necessary components to repair damage (e.g., collagen). Mitosis occurs to regenerate tissue.

     • Deep Cuts: If injury is extensive, scarring can occur because deeper tissue layers do not regenerate at the same rate as epithelial cells.