Biology Chapter: Tissues Overview

Epithelial Tissues

• Covers most organs and cavities in the body
• Acts as a barrier between different body systems, like the skin, mouth lining, blood vessels, lung alveoli, and kidney tubules.
• Cells are tightly packed, forming a continuous sheet with minimal spaces between them.
• Anything entering or leaving the body passes through at least one layer of epithelium
• Different epithelia have varying structures that correspond to their functions.
  • For example, cells lining blood vessels and lung alveoli have a simple flat structure for selective substance transfer.

Connective Tissues

• Provide support and structure within the body
• Cells are embedded in a matrix (intercellular materials).
• The matrix can vary in consistency depending on function, from jelly-like to fluid, dense, or rigid.

Blood

• Fluid (liquid) matrix containing plasma, red blood cells (RBCs), white blood cells (WBCs), and platelets.
• Plasma contains proteins, salts, hormones, and transports gases, digested food, hormones, and waste materials.

Compact Bone

• Connective tissue that forms the framework of the body, supporting and anchoring muscles and organs.
• Strong, non-flexible tissue formed with calcium and phosphorus compounds
• Bone cells are embedded in a hard matrix

Hyaline Cartilage

• Connective tissue with widely spaced cells.
• Matrix is composed of proteins and sugars.
• Smoothens bone surfaces at joints, found in the nose, ear, trachea, and larynx.
• More flexible than bone

Areolar Tissue

• Found between the skin and muscles, around blood vessels, and nerves within bone marrow.
• Fills spaces in organs, supports internal organs, and helps in tissue repair.

Adipose Tissue

• Stores fats (fat globules) below the skin and between internal organs.
• Acts as an insulator.

Muscular Tissue

• Made of elongated cells (muscle fibers).
• Responsible for movement in the body.

Muscle Types

• Striated Muscles:
  • Also called skeletal muscles.
  • Attached to bones.
  • Help in body movement.
  • Show alternating light and dark bands (striations) under a microscope.
  • Tissues are long, cylindrical, and unbranched.
  • Multinucleate (having many nuclei).
• Smooth Muscles:
  • Found in the walls of internal organs (e.g., the digestive tract, bronchi of the lungs, the ureters, and the eye).
  • Long spindle-shaped, uninucleate and unstriated.
  • Control involuntary movements (e.g., moving food through the digestive system).
• Cardiac Muscles:
  • Found in the heart.
  • Cylindrical, branched, and uninucleate.
  • Responsible for rhythmic contraction and relaxation throughout life.

Nervous Tissue

• All cells respond to stimuli.
• Nerve tissue cells are highly specialized for being stimulated.
• Neurons:
  • Consist of a cell body containing a nucleus and cytoplasm.
  • Have long thin hair-like parts called axons.
  • Also have many short, branched parts called dendrites.
  • Processes:
    • Carry impulses throughout the body.
    • Processes called dendrites receive messages from other nerve cells.
    • Nerve fibers are bundled together by connective tissue to form larger structures.
    • The signal travels along a nerve fiber.
    • Nerve impulse allows a functional combination of nerve and muscle tissue.
    • Nerve-muscle combination enables rapid movement when stimulated.

Plant Tissues

• Meristematic Tissues: Tissues in growing regions of the plant. These cells can divide.
• Permanent Tissues: Tissues derived from meristematic tissues. These cells do not divide and perform various functions.
  • Simple Tissues: Parenchyma, collenchyma, sclerenchyma are the three types.
  • Complex Tissues: Xylem and phloem.

Animal Tissues

• Epithelial Tissue: Depending on shape and function, divided into squamous, cuboidal, columnar, ciliated, and glandular.
• Connective Tissue: The functions include binding and support.
• Muscular Tissue: Responsible for movement.
• Nervous Tissue: Involved in receiving and transmitting stimuli to control responses.

Cilia

• Hair-like structures on the surface of some eukaryotic cells.
• Help to move/propel.

Collagen

• Epithelial cells lie on a delicate non-cellular basement membrane, which contains a special form of matrix protein called collagen.

This quiz explores the structure and functions of epithelial and connective tissues, as well as the composition of blood. Understanding these basic biological concepts is essential for comprehending how different systems in the body interact and function together. Test your knowledge on the various types of tissues and their roles in the human body.