Tissue Level of Organization

Vocabulary practice flashcards covering types of tissues, cellular junctions, epithelial and connective structures, muscle and nervous system components, and tissue repair based directly on the lecture notes.

Tissue

A group of cells that function together and carry out specialized activities.

Four main tissue types

Epithelial, connective, muscle, and nervous tissue.

Cell junctions

Connections between cells that hold the cells together as a unit.

Tight junctions

Weblike strands of transmembrane proteins that fuse together the outer surfaces of adjacent plasma membranes to seal off passageways between adjacent cells.

Adhering junctions

A dense layer of proteins on the inside of the plasma membrane that attaches both to membrane proteins and to microfilaments of the cytoskeleton.

Desmosomes

Structures that contain plaque and transmembrane glycoproteins extending into the intercellular space between adjacent cell membranes to attach cells to one another.

Hemidesmosomes

Structures that attach epithelial cells to the basement membrane.

Gap junctions

Junctions where membrane proteins called connexins form tiny fluid-filled tunnels called connexons that connect neighboring cells.

Epithelial tissue

A body tissue that covers surfaces inside and out, composed of many densely packed cells arranged in sheets attached to a basement membrane, with little to no extracellular matrix and no nerve supply.

Connective tissue

A body tissue that provides support for the body and connects all of its parts, consisting of few scattered cells and large amounts of extracellular matrix (ECM).

Simple squamous epithelium

A single layer of flattened cells used for filtration (kidneys) and diffusion (lungs); lines the cardiovascular and lymphatic systems and forms the epithelial layer of serous membranes.

Simple cuboidal epithelium

A single layer of cube-shaped cells specialized for secretion and absorption; located in kidney tubules, ducts and secretory portions of small glands, and the ovary surface.

Ciliated simple columnar epithelium

A single layer of ciliated column-like cells that lines bronchioles, uterine tubes, paranasal sinuses, the central canal of the spinal cord, and ventricles of the brain.

Nonciliated simple columnar epithelium

A single layer of non-ciliated column-like cells specialized for secretion and absorption; lines the GI tract and glands, with mucus lubricating digestive, respiratory, reproductive, and urinary tracts.

Nonciliated pseudostratified columnar epithelium

A single layer of columnar cells where all cells touch the basement membrane but nuclei are at different heights, creating a multi-layered appearance; functions in absorption and secretion in the epididymis and many glands.

Ciliated pseudostratified columnar epithelium

A single layer of tall cells with cilia and mucus-secreting goblet cells that move mucus and trapped particles; appears multi-layered and lines most of the respiratory tract.

Stratified squamous epithelium

A tissue made of multiple cell layers with flat cells on the surface that protect underlying tissues from friction and damage; lines the skin, mouth, esophagus, and vagina.

Stratified cuboidal epithelium

Multiple layers of cube-shaped cells that provide protection and assist with secretion; commonly found in gland ducts.

Stratified columnar epithelium

Multiple layers of cells with tall, column-shaped cells on the surface providing protection and helping with secretion; found in large gland ducts and parts of the reproductive system.

Urothelium

A specialized, stretchable epithelium made of multiple layers lining the urinary tract that allows organs like the bladder to expand and contract while preventing urine leakage.

Glandular epithelium

Epithelium composed of cells specialized to produce and secrete substances into ducts or body fluids.

Unicellular gland

A single-celled secreting gland, such as a goblet cell.

Multicellular gland

A gland consisting of many cells, such as sweat, oil, and salivary glands.

Reticular fibers

Fibers made of collagen and glycoproteins that support blood vessels.

Fibroblasts

Large, flat cells that move through connective tissue and secrete fibers and ground substance.

Collagen fibers

Connective tissue fibers that provide flexibility and strength.

Mast cells

Cells in connective tissue that release chemicals such as histamine to promote inflammation.

Plasmocytes (Plasma cells)

Cells developed from B lymphocytes that secrete antibodies.

Ground substance

The material between cells in connective tissue made of water and organic material.

Neutrophils

The most abundant type of phagocytic white blood cell that destroys foreign invaders and self-destructs within a few days.

Eosinophils

White blood cells that migrate to sites of parasite infections and allergic responses.

Adipocytes

Fat cells.

Elastic fibers

Flexible and stretchy fibers that add elasticity to tissue.

Macrophages

Cells developed from monocytes that destroy bacteria and cell debris via phagocytosis.

Loose connective tissue

Tissue containing widely spaced cells and an abundance of viscous ground substance; includes reticular and adipose tissue.

Cartilage

A supportive connective tissue providing strength, flexibility, and cushioning at joints, the nose, ears, and airways.

Dense connective tissue

Connective tissue characterized by fewer cells and more densely packed fibers.

Erythrocytes

Red blood cells (RBCs) that transport oxygen to tissue cells.

Leukocytes

White blood cells (WBCs) that fight infection.

Platelets

Blood components responsible for blood clotting.

Matrix

The material surrounding and supporting cells in connective tissue, composed of ground substance and protein fibers.

Bone tissue

Tissue categorized as spongy (cancellous) or compact bone.

Embryonic tissue

Tissue types including mesenchyme (loose irregular appearance) and mucous (gel-like substance supported by fibroblasts).

Hyaline cartilage

The most common type of cartilage; found on the ends of long bones, ribs, and the nose.

Fibrous cartilage

A very tough form of cartilage found in intervertebral disks of the spine and junctions where tendons attach to bone.

Elastic cartilage

Flexible cartilage found in the external ear and epiglottis.

Mature connective tissue (bone)

Includes dense, strong compact bone on outer layers and porous spongy bone inside that helps absorb stress.

Liquid connective tissue

Connective tissue consisting of blood and lymph.

Epithelial membranes

Membranes categorized as cutaneous, mucous, or serous.

Synovial membrane

The lining of a joint that secretes synovial fluid into the joint space.

Mucous membranes

The lining of body cavities and passages that communicate directly or indirectly with the outside environment.

Serous membranes

Membranes that line body cavities lacking openings to the outside.

Muscular tissue

Tissue divided into three types: skeletal, cardiac, and smooth.

Skeletal muscle

Voluntary muscle tissue attached to bones containing long, cylindrical, striated fibers that move the skeleton.

Cardiac muscle

Involuntary muscle tissue found only in the heart, made of branched, striated fibers with desmosomes and gap junctions.

Smooth muscle

Involuntary muscle found in internal organs, featuring nonstriated fibers that are thickest in the middle and connected by gap junctions.

Nervous tissue

A body tissue that carries electrical messages back and forth between the brain and every other part of the body.

Neurons

Nerve cells that serve as the basic building blocks of the nervous system.

Neuroglia

Cells that support and protect neurons.

Dendrites

Bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body.

Axons

Neuron extensions that transmit electrical information to cells such as muscles, glands, and other neurons.

Excitable cells

Cells, such as neurons and muscle cells, that respond to stimuli by changing electrical activity to send signals.

Tissue repair

The process that replaces worn out, damaged, or dead cells; capacity is high in epithelial, moderate in connective, and limited in muscle and nervous tissues.

Fibrosis

The replacement of damaged cells with scar tissue.

Disorders of epithelial tissue

Tissue-specific disorders affecting specific organs, such as stomach ulcers and cancers.

Disorders of connective tissue

Tissue disorders that are predominantly autoimmune in nature, such as lupus.