K103 Exam 2 notes

Day 1: Tissues

  • Cells

    • Specialized to work together for a particular function.

    • Have different shapes and sizes that impact their function.

  • Organs

    • Closely associated tissues that carry out specific functions.

    • Composed of multiple tissues.

  • Systems

    • Closely associated organs that perform specific functions.

    • Different organs work together in systems.

Epithelial Tissue

  • Characteristics of Epithelial Cells

    • Very tightly packed and sit on a basement membrane which holds the bottom layer together.

    • Serve as a barrier for substances entering and exiting the body.

    • Function includes protection, absorption, secretion, and sensation depending on the type of epithelial cell.

    • Joined together by:

      • Tight junctions: Regulate what crosses between cells.

      • Gap junctions: Allow passage between cells with less regulation.

      • Desmosomes: Connect cells via a plate.

    • Epithelial cells are avascular (no blood supply) but are innervated (have nerve endings).

    • Capable of regeneration.

Epithelial Glands

  • Exocrine Glands

    • Have ducts that connect to the body surface or cavity.

  • Endocrine Glands

    • No ducts; release substances (hormones) directly into the surrounding tissue or blood.

Epithelial Membranes

  • Mucous Membrane

    • Thick, sticky membrane lining digestive, reproductive, and respiratory tracts.

  • Serous Membrane

    • Thin and watery, lubricates to allow movement, contains ions.

Types of Epithelial Tissue

  • Simple Squamous Epithelium

    • Single layer of thin, flat cells; functions in rapid diffusion, absorption, filtration, and secretion.

    • Found in: glomerulus, lung alveoli, and blood vessels.

  • Simple Cuboidal Epithelium

    • Single layer of box-like cells; functions in secretion and absorption.

    • Found in: kidney tubules and ducts.

  • Simple Columnar Epithelium

    • Tall column-shaped cells; involved in absorption and secretion.

    • Two types:

      • Non-ciliated: stomach and intestine.

      • Ciliated: bronchioles, uterine tubes.

  • Stratified Squamous Epithelium

    • Multiple layers of squamous cells; serves to protect against abrasion.

    • Two varieties:

      • Keratinized: dry surfaces like skin.

      • Nonkeratinized: moist surfaces like mouth and esophagus.

  • Stratified Cuboidal Epithelium

    • Multiple layers of cuboidal cells; functions mainly in secretion.

    • Found in sweat and other glands.

  • Pseudostratified Epithelium

    • Appears layered (but not); functions include secretion, absorption, and protection.

    • Types:

      • Nonciliated: male epididymis and urethra.

      • Ciliated: trachea, bronchi.

  • Transitional Epithelium

    • Specialized to allow stretching.

    • Found in the bladder and excretory system; cells change shape from cuboidal to squamous as the bladder fills.

Connective Tissues

  • Functions

    • Hold structures together, connect solid or liquid things.

    • Originated from the mesoderm.

  • Characteristics

    • Composed of few cells with abundant extracellular matrix.

    • Blood is considered a liquid connective tissue.

    • Comprises fibers in ECM and forms bone.

Connective Tissue Fibers

  • Collagen Fibers

    • Thick, resistant fibers providing strength.

    • Commonly found in tendons and ligaments.

  • Elastic Fibers

    • Composed of elastin; allow for elasticity and strength.

    • Present in structures like lungs and arteries.

  • Reticular Fibers

    • Thin, branched collagenous fibers forming a supporting meshwork for various tissues.

Loose Connective Tissue

  • Areolar Tissue

    • Contains elastic and collagen fibers; provides flexibility and structural support.

    • Acts as a reservoir for body fluids.

  • Adipose Tissue

    • Contains large fat vacuoles; functions include cushioning, supporting, insulating, and energy storage.

  • Reticular Connective Tissue

    • Composed mostly of reticular fibers; serves as support in organs like liver and spleen.

Dense Connective Tissue

  • Dense Regular Connective Tissue

    • Tightly packed fibers parallel to each other; provides strong support.

    • Found in tendons and ligaments.

  • Elastic Connective Tissue

    • Mainly elastic fibers; supports structures that require flexibility.

Cartilage Types

  • Hyaline Cartilage

    • Primarily collagen; provides support and reduces friction in joints.

    • Found in the end of long bones and rib cages.

  • Elastic Cartilage

    • Contains more elastin; provides flexibility and support.

    • Found in the epiglottis and parts of the larynx.

  • Fibrocartilage

    • Contains thicker collagen fibers; provides strength and shock absorption.

    • Found in intervertebral discs and knee joints.