Cell Junctions and Tissue Overview

These flashcards cover key concepts related to cell junctions and the various types of tissues in the human body, aiding in the understanding of histology and the structure-function relationship of different tissue types.

Tight Junctions

Web-like strands of transmembrane proteins that fuse cells together and seal off passageways between adjacent cells.

Adherens Junctions

Transmembrane glycoproteins called cadherins insert into plaque to join cells, resembling a belt, and help resist separation during contractive activities.

Desmosomes

Cell junctions that use cadherin proteins to connect adjacent cells, providing strength and stability under tension.

Hemidesmosomes

Cell structures that anchor cells to the basement membrane using integrin proteins; they do not connect adjacent cells.

Gap Junctions

Specialized intercellular connections that allow direct communication between neighboring cells through tiny fluid-filled tunnels called connexons.

Histology

The scientific study of tissues, including their structure, composition, and function.

Neurons

Specialized nerve cells that conduct nerve impulses.

Neuroglia

Support cells in the nervous system that perform various functions, including maintaining homeostasis.

Epithelial Tissue

A type of tissue that covers body surfaces, lines cavities and organs, and forms glands.

Connective Tissue

A diverse group of tissues that support, bind together, and protect other tissues and organs of the body.

Extracellular Matrix

The material located between cells in connective tissue, composed of protein fibers and ground substance that determines the tissue's qualities.

Mucous Membranes

Membranes that line body cavities open to the exterior and contain epithelial cells that secrete mucus.

Serous Membranes

Moist membranes found in closed body cavities that secrete serous fluid to reduce friction.

Endocrine Glands

Glands that secrete hormones directly into the bloodstream without ducts.

Exocrine Glands

Glands that secrete products into ducts that lead to external surfaces or cavities.

Merocrine Secretion

A mode of secretion in which products are released via exocytosis without loss of cellular material.

Apocrine Secretion

Secretion involving the pinching off of a portion of the cell that accumulates at the apex, often resulting in some loss of cytoplasm.

Holocrine Secretion

A type of secretion where entire cells break apart to release their product, and the lost cells are replaced by division.

Macrophages

Phagocytic cells derived from monocytes, found in connective tissue, crucial for immune defense.

Mesothelium

A simple squamous epithelium that forms the serous membranes lining body cavities and covering organs.

Fibroblasts

The most common and active cells in connective tissue proper, responsible for synthesizing components of the extracellular matrix.

Basement Membrane

A thin, acellular layer underlying epithelial tissue, providing structural support and regulating substance passage.

Muscle Tissue

Tissue specialized for contraction, responsible for movement, composed of elongated cells called muscle fibers.

Ground Substance

The unstructured material that fills the space between cells and contains the connective tissue fibers, composed of water, adhesion proteins, and polysaccharides.

Collagen Fibers

Strong, flexible protein fibers made of collagen, providing high tensile strength to connective tissues and resisting pulling forces.

Elastic Fibers

Thin, branching protein fibers made of elastin, allowing tissues to stretch and recoil to their original shape.

Mast Cells

Immune cells found in connective tissue proper, that release histamine and other substances during inflammatory and allergic reactions.

Adipose Tissue

A type of loose connective tissue composed primarily of adipocytes, specialized for storing fat/energy, insulating the body, and protecting organs.

Cartilage

A vascular supporting connective tissue with a flexible matrix, made of chondrocytes, found in joints, the nose, ears, and trachea.

Simple Squamous Epithelium

A single layer of flattened, scale-like cells, specialized for diffusion and filtration, found in areas like the air sacs of the lungs and lining of blood vessels.

Stratified Squamous Epithelium

Multiple layers of cells with the most superficial layers being squamous, providing protection in areas subject to abrasion, such as the skin and lining of the mouth.

Simple Cuboidal Epithelium

A single layer of cube-shaped cells, specialized for secretion and absorption, found in kidney tubules and gland ducts.

Simple Columnar Epithelium

A single layer of tall, column-shaped cells, often ciliated or containing microvilli for absorption and secretion, found in the gastrointestinal tract.

Pseudostratified Columnar Epithelium

Appears stratified but is a single layer of columnar cells of varying heights with nuclei at different levels, often ciliated and associated with mucus secretion, found in the respiratory tract.

Stratified Cuboidal Epithelium

Two or more layers of cube-shaped cells, primarily protective, found in ducts of sweat glands and salivary glands.

Stratified Columnar Epithelium

Multiple layers of cells with superficial cells being columnar, protective and secretory, found in parts of the urethra and large ducts.

Transitional Epithelium

A stratified epithelium with cells that can change shape (from cuboidal to squamous) based on the distension of the organ, found in the urinary bladder.

Areolar Connective Tissue

A type of loose connective tissue with loosely arranged collagen and elastic fibers, widely distributed as packaging material, underlies epithelia.

Adipocyte

A cell specialized for the storage of fat, found in adipose tissue.

Dense Regular Connective Tissue

A dense connective tissue with collagen fibers arranged in parallel bundles, providing great tensile strength in one direction, found in tendons and ligaments.

Dense Irregular Connective Tissue

A dense connective tissue with collagen fibers arranged irregularly, providing tensile strength in multiple directions, found in the dermis of the skin and joint capsules.

Reticular Fibers

Fine, branching collagen fibers that form a delicate supporting network (stroma) in soft organs like the spleen and lymph nodes.

Hyaline Cartilage

The most common type of cartilage; flexible and resilient, providing support and cushioning, found in synovial joints, trachea, and nose.

Endothelium

A simple squamous epithelium that lines the internal surface of blood vessels, lymphatic vessels, and the heart.

Chondrocytes

Mature cartilage cells that reside in lacunae (small cavities) within the extracellular matrix of cartilage.

Osteocytes

Mature bone cells, derived from osteoblasts, that maintain the bone matrix and are housed in lacunae within the calcified bone tissue.

Elastic Cartilage

Cartilage characterized by a high proportion of elastic fibers, providing great flexibility while maintaining shape, found in the external ear and epiglottis.

Fibrocartilage

The strongest type of cartilage, rich in thick collagen fibers, offering tensile strength and shock absorption, found in intervertebral discs, menisci, and the pubic symphysis.

Bone Tissue

A hard, calcified connective tissue that forms the structural framework of the body, providing support and protection.

Blood

A fluid connective tissue composed of plasma and formed elements (red blood cells, white blood cells, and platelets), responsible for transport of substances throughout the body.

Synovial Membranes

Connective tissue membranes that line the cavities of freely movable (synovial) joints, secreting synovial fluid to lubricate articular cartilage.

Nervous Tissue

Tissue primarily composed of neurons and neuroglia, specialized to generate, transmit, and interpret electrical impulses throughout the body.

Cutaneous Membrane

The skin; an organ system composed of an epidermis (epithelial tissue) and a dermis (connective tissue), protecting the body's exterior surface.

Goblet Cells

Unicellular exocrine glands shaped like a goblet, found in the epithelia of the respiratory and intestinal tracts, that secrete mucin to form mucus.