Tissue Vocab & Identification

Histology

The study of tissues

Four Principal Tissue Types

Epithelial - Cover surfaces, line spaces/passageways, form glands

Connective - Fill internal spaces, support other tissues, transport materials, store lipids

Muscle - In skeletal muscles, heart, and walls of hollow/tubular organs

Neural - In brain, spinal cord, nerves"

Epithelial Tissue

Tissue that covers body surfaces, lines body cavities and passageways, and forms glands

Epithelial Tissue Functions

Form protective barriers

Control permeability (diffusion)

Produce specialized secretions"

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Epithelial Tissue Characteristics

Composed mostly of tightly-packed cells (little extracellular material)

Attachment of cells to a basement membrane

Exhibit POLARITY

Avascular (no blood vessels)

Can regenerate

Polarity (Epithelial)

Epithelial cells have distinct apical (top) and basal (bottom) surfaces with different structures and functions

Basement Membrane

Thin layer that anchors epithelium to underlying connective tissue and acts as a barrier to regulate movement of large molecules

Apical Surface

Top surface of epithelial cells that faces the external environment or body cavity

Basal Surface

Bottom surface of epithelial cells that attaches to the basement membrane

Pseudostratified Epithelium

Epithelial tissue that appears to have multiple layers but all cells touch the basement membrane

Simple Squamous Epithelium - Locations?

found in mesothelia lining ventral cavities and endothelia lining heart and blood vessels

Simple Cuboidal Epithelium - Locations?

found in kidney tubules and ducts of glands

Simple Columnar Epithelium - Locations?

found in stomach lining, intestines, and collecting ducts of kidneys

Ciliated Simple Columnar - Locations?

lines uterine tubes and some bronchioles

Keratinized Stratified Squamous - Locations?

Forms epidermis of skin

Non-keratinized Stratified Squamous - Locations?

lines mouth, esophagus, and vagina

Pseudostratified Ciliated Columnar - Locations?

lines respiratory tract

Transitional Epithelium - Locations?

lines urinary bladder

Microvilli

Tiny projections on apical surface of epithelial cells that increase surface area

Cilia

Hair-like projections that move materials across epithelial surfaces

Gland

Collection of epithelial cells that produce a secretion

Endocrine Gland

Gland that releases secretions into internal fluids (bloodstream) with no ducts

Exocrine Gland

Gland that releases secretions via ducts onto the surface of epithelial tissue

Serous Gland

Exocrine gland that produces watery secretion (example: sweat glands)

Mucous Gland

Exocrine gland that produces thick, slimy secretion containing mucin protein

Mixed Gland

Exocrine gland that produces both serous and mucous secretions (example: salivary glands)

Goblet Cells

Unicellular exocrine glands scattered among epithelial tissues that only produce mucus

Mucin

Protein component of mucus that gives it thick, slimy properties

Connective Tissue

Tissue that fills internal spaces, supports other tissues, transports materials, and stores lipids

Matrix

Combination of ground substance and protein fibers in connective tissue

Ground Substance

Substance produced by connective tissue cells in which cells and fibers are immersed

Protein Fibers

Strands found in most connective tissues (collagen, elastic, reticular)

Collagen Fibers

Strong, flexible protein fibers that provide tensile strength

Elastic Fibers

Protein fibers that can stretch and return to original length

Reticular Fibers

Fine, branching protein fibers that form supportive networks

Connective Tissue Proper

Category of connective tissue that connects other tissues, protects organs, and stores lipids

Supporting Connective Tissue

Category of connective tissue that provides structural support (bone and cartilage)

Fluid Connective Tissue

Category of connective tissue that transports substances (blood and lymph)

Dense Connective Tissue

Connective tissue proper with mostly protein fibers and little ground substance; tough

Loose Connective Tissue

Connective tissue proper with lots of ground substance; 'squishy,' pliable, 'cushiony'

Fibroblasts

Cells that produce fibers and ground substance in connective tissue proper

Macrophages

Immune cells in connective tissue that engulf foreign particles and debris

Mast Cells

Connective tissue cells involved in inflammatory responses

Adipocytes

Fat cells found in adipose tissue

Cartilage

Supporting connective tissue with ground substance that is a firm gel

Chondrocytes

Cells found in cartilage tissue (prefix 'chondro-' means cartilage)

Perichondrium

Layer of dense connective tissue that surrounds cartilage

Hyaline Cartilage

Most common type of cartilage; found in nose, trachea, ends of long bones

Bone

Supporting connective tissue with semi-solid ground substance hardened by mineral deposits

Osteocytes

Cells found in bone tissue (prefix 'osteo-' means bone)

Compact Bone

Dense, solid bone tissue

Spongy Bone

Bone tissue with open, lattice-like structure

Blood

Fluid connective tissue with ground substance (plasma) that is mostly water with dissolved substances

Plasma

Liquid ground substance of blood containing proteins, electrolytes, and waste products

Red Blood Cells

Cells in blood that carry oxygen

White Blood Cells

Cells in blood that fight infection

Lymph

Fluid connective tissue similar to blood but without red blood cells

Membrane

Combination of epithelial and connective tissues

Serous Membrane

Membrane that lines internal body cavities not open to outside environment; secretes watery fluid

Mucous Membrane

Membrane that lines passageways open to outside environment; secretes mucus

Synovial Membrane

Membrane that lines joint spaces; secretes synovial fluid

Cutaneous Membrane

The skin

Transudate

Watery fluid secreted by serous membranes

Mucus

Thick fluid secreted by mucous membranes

Synovial Fluid

Thin fluid secreted by synovial membranes to lubricate joints

Mesothelium

Epithelial layer of serous membranes

Lacuna (plural: Lacunae)

Small space or cavity in tissue, especially in cartilage and bone where cells are located

Elastic Cartilage

Cartilage with elastic fibers

Elastic Cartilage - Image

Elastic Cartilage - Locations?

found in external ear and epiglottis

Fibrocartilage

Cartilage with lots of collagen fibers; shock absorbers

Fibrocartilage - Locations?

found in intervertebral discs and knee joint

Fibrocartilage - Image

Reticular Connective Tissue

Loose connective tissue that forms framework of delicate organs

Reticular Connective Tissue - Locations?

delicate organs (spleen, lymph nodes, bone marrow)

Reticular Connective Tissue - Image

Elastic Connective Tissue

Dense connective tissue made mostly of elastic fibers running parallel;

Elastic Connective Tissue - Locations?

found in vertebral connections, major arteries, vocal chords

Elastic Connective Tissue - Image

Dense Regular Connective Tissue

Dense connective tissue with fibers running parallel;

Can only be pulled/stretched in one direction

Dense Regular Connective Tissue - Locations?

found in tendons and ligaments

Dense Regular Connective Tissue - Image

Adipose Tissue

Loose connective tissue consisting mostly of fat cells used for cushioning and energy storage

Adipose Tissue - Image

Adipose Tissue - Locations?

found below most areola connective tissue - around organs and below skin

Areolar Connective Tissue

Loose connective tissue with multiple fiber types;

Areolar Connective Tissue - Locations?

found surrounding organs, nerves, vessels

Areolar Connective Tissue - Image

Dense Irregular Connective Tissue

Dense connective tissue with fibers in random, meshwork arrangement;

Can be pulled/stretched in multiple directions

Dense Irregular Connective Tissue - Location?

found in dermis of skin

Dense Irregular Connective Tissue - Image