Histology INTRO

Vocabulary flashcards covering the key terms, definitions, and concepts from the lecture notes on tissue types, membranes, glands, connective tissue, cartilage, bone, blood, lymph, and wound healing.

Nervous tissue

Specialized for rapid communication and control of body activities.

Epithelial tissue

Forms linings and coverings throughout the body (surface, cavities, glands); includes epidermis and mucous/serous membranes.

Muscle tissue

Specialized for contraction to produce movement; includes skeletal, cardiac, and smooth types.

Connective tissue

Supports, binds, and protects other tissues; most diverse tissue type; includes bone, cartilage, fat, and blood.

Skeletal muscle

Attached to long bones it has long cylindrical fibers and multiple nuclei per fiber, striated appearance due to alternating light and dark bands (sarcomeres). Has a voluntary control.

Cardiac muscle

Found in the heart. Has branched fibers connected by intercalated discs striated like skeletal muscle typically one nucleus per fiber, involuntary control, intercalated discs contain desmosomes and gap junctions.

Smooth muscle

Found in walls of hollow organs like the G.I. tract and blood vessels. Has spindle shaped cells with a single nucleus and no striations. Involuntary control.

Tendon

Dense fibrous connective tissue that attaches muscle to bone.

Bone (osseous tissue)

Rigid connective tissue with mineralized matrix; supports, protects, and houses osteocytes in lacunae.

Cartilage

Firm but flexible connective tissue with chondrocytes in lacunae within a gel-like matrix rich in proteoglycans.

Ground substance

Noncellular, gel-like extracellular matrix surrounding cells and fibers; determines tissue consistency.

Fibroblast

Cell that synthesizes extracellular fibers and matrix.

Fibrocyte

Mature fibroblast that maintains fibers.

Adipocyte

Fat cell that stores triglycerides for energy and cushioning.

Erythrocyte

Red blood cell; transports oxygen and carbon dioxide.

Leukocyte

White blood cell; defends against infection and debris.

Thrombocyte

Platelet; essential for blood clotting (hemostasis).

Areolar connective tissue

Loose connective tissue with a gel-like ground substance; supports epithelia and provides space for vessels.

Adipose tissue

Connective tissue dominated by adipocytes; stores fat, cushions, and insulates.

Mesenchymal cell

Multipotent stem cell that can differentiate into fibroblasts, adipocytes, and other connective tissue cells.

Endothelium

Simple squamous epithelium lining blood vessels.

Simple squamous epithelium

One cell layer of flat cells; thin for diffusion; lines vessels (endothelium) and alveoli.

Simple cuboidal epithelium

One cell layer of cube-shaped cells; common in glands and kidney tubules.

Simple columnar epithelium

One layer of tall cells; lines digestive tract; often with microvilli and goblet cells for secretion/absorption.

Nonciliated simple columnar epithelium

Simple columnar epithelium without cilia; specialized for secretion and absorption (often with microvilli).

Ciliated simple columnar epithelium

Simple columnar epithelium with cilia on the apical surface; moves mucus or oocytes (e.g., in uterine tubes).

Pseudostratified ciliated columnar epithelium

Appears multi-layered but is a single layer; has varying nucleus positions and cilia; lines respiratory tract.

Stratified squamous epithelium

Many cell layers; apical cells flat; protects underlying tissue; keratinized in skin, nonkeratinized in mouth/esophagus.

Keratin

Protein produced in epidermal cells; accumulates to form a tough, protective outer layer.

Keratinized stratified squamous epithelium

Stratified squamous epithelium with surface dead cells filled with keratin (epidermis).

Nonkeratinized stratified squamous epithelium

Stratified squamous epithelium without keratin; lines moist mucous membranes (mouth, esophagus, vagina).

Stratified cuboidal epithelium

Two or more layers of cube-shaped cells; lines ducts (e.g., salivary gland ducts) and supports secretion.

Stratified columnar epithelium

Two or more layers with tall apical cells; uncommon; lines some ducts and glands; involved in secretion.

Transitional epithelium

Stratified epithelium with cells that change shape (squamous/cuboidal) with stretch; lines urinary tract (e.g., ureter).

Goblet cell

Unicellular mucus-secreting gland; secretes mucin to form mucus.

Mucin

Protein that gives mucus its thick, slippery consistency.

Endocrine gland

Glands that secrete hormones into the bloodstream.

Exocrine gland

Glands that secrete onto surfaces or ducts (e.g., sweat, salivary glands).

Merocrine secretion

Secretory vesicles release product by exocytosis; cell remains intact.

Apocrine secretion

Secretory product released with apical portion of cell pinched off.

Holocrine secretion

Secretory product formed when whole cell disintegrates (cell death) to release secretion.

Pancreatic islets (Islets of Langerhans)

Endocrine tissue of the pancreas that secretes insulin and glucagon to regulate blood glucose.

Acinar cells

Exocrine cells of the pancreas that secrete digestive enzymes into the pancreatic duct.

Pancreatic duct

Duct that carries pancreatic juice to the duodenum.

Serous membrane

Membrane that lines ventral body cavities; has parietal and visceral layers with serous fluid in between.

Mucous membrane

Lined with mucous-secreting epithelium; lines digestive, respiratory, urinary, and reproductive tracts.

Synovial membrane

Connective tissue membrane lining joint cavities; produces synovial fluid for lubrication.

Epidermis

Outer layer of the skin; stratified squamous epithelium with keratin.

Dermis

Middle, thicker layer of skin beneath the epidermis; contains connective tissue, hair follicles, glands; contains two layers.

Papillary layer

Superficial dermal layer of areolar connective tissue; supports epidermis.

Reticular layer

Deep dermal layer of dense irregular connective tissue; provides strength and elasticity.

Cutaneous membrane

Skin; composed of epidermis and dermis and associated structures.

Hyaline cartilage

Most common cartilage; glassy matrix; found at ends of bones, nose, tracheal rings, and rib stcartilages.

Fibrocartilage

Cartilage with high collagen content; strong and compressible; intervertebral discs and pubic symphysis.

Elastic cartilage

Cartilage with many elastic fibers; flexible and returns to shape (external ear, epiglottis, Eustachian tube).

Chondrocyte

Cartilage cell residing in a lacuna.

Lacuna

Small space inside cartilage or bone that houses a cell (chondrocyte or osteocyte).

Proteoglycan

Matrix component rich in glycosaminoglycans (e.g., chondroitin sulfate) that gives cartilage its gel-like consistency.

Hydroxyapatite

Mineral form of calcium phosphate that hardens bone matrix.

Osteocyte

Mature bone cell housed in a lacuna.

Blood plasma

Liquid extracellular matrix of blood; contains water, nutrients, hormones, and plasma proteins.

Lymph

Fluid derived from extracellular fluid; leukocytes present, erythrocytes absent; circulates in lymphatic system.

Dense regular connective tissue

Collagen fibers parallel, predominant cells are fibroblasts or fibrocytes. it forms tendons and ligaments, resists on directional stress.

Dense irregular connective tissue

Collagen fibers run in multiple directions; resists multidirectional stress. Found in reticular layer of dermis and joint capsules.

Elastic connective tissue

Abundant elastic fibers; Allow stretch and recoil. (Elastic arteries like the aorta; certain ligaments).

Blood

Liquid connective tissue with plasma as the matrix

Hemostasis

First step of wound healing; Blood clotting to stop bleeding and cover wound surface.

Inflammation

Second step of wound healing; immune activation, leukocytes infiltrate to defend against infection and remove damaged tissue. Cardinal signs; redness, swelling, heat, and pain

Proliferation

Third step of wound healing; Cell division and tissue growth; fibroblasts laid down collagen; formation of granulation tissue; I just pulled together by wound contraction; angiogenesis (new blood vessels) occur.

Remodeling

Fourth step of wound healing; Collagen fibers reorganized to increase strength; epithelial tissue grows from edges to cover surface; regeneration versus fibrosis determines outcome.

Regeneration

Replacement by the same cell type restoring original structure

Fibrosis

Connective tissue fills wound; can impede full restoration of original function.

Capillaries

Capillaries are tiny vessels lined by simple squamous endothelium, allowing rapid diffusion of nutrients and gases