Chapter 04 Tissues – Seeley’s Anatomy & Physiology (Lecture Notes)

Vocabulary flashcards covering tissues, epithelial classes, connective tissue, muscle, nervous tissue, membranes, glands, and tissue repair/inflammation concepts.

Tissue

A group of cells that interact to form a functional unit; four main tissue types exist: epithelial, connective, muscle, and nervous.

Histology

The microscopic study of tissues.

Biopsy

Removal of tissue samples for diagnostic purposes.

Autopsy

Examination of organs of a dead body to determine cause of death.

Embryonic germ layers

Early-forming layers that give rise to all tissues: endoderm (inner), mesoderm (middle), and ectoderm (outer).

Endoderm

Inner germ layer that forms the lining of the digestive tract and derivatives.

Mesoderm

Middle germ layer that forms tissues such as muscle, bone, and blood vessels.

Ectoderm

Outer germ layer that forms the skin and neuroectoderm.

Epithelial tissue

Tissue composed mainly of tightly packed cells; covers body surfaces and lines glands.

Avascular

Lacking blood vessels; nutrients diffuse from underlying connective tissue.

Basement membrane

Two-layer structure (basal lamina and reticular lamina) connecting epithelium to underlying tissue.

Basal lamina

Basement membrane layer secreted by epithelial cells; contains laminin, fibronectin, collagen, and proteoglycans; has lamina lucida and lamina densa.

Lamina lucida

A clear layer of the basal lamina adjacent to epithelial cells.

Lamina densa

Dense layer of the basal lamina providing structural support.

Apical surface

Free (top) surface of epithelial cells exposed to the external environment or lumen.

Basal surface

Bottom surface attached to underlying tissues.

Lateral surfaces

Surfaces between adjacent epithelial cells.

Regeneration

High capacity to replace damaged cells in epithelial and some tissues.

Microvilli

Nonmotile extensions that increase cell surface area for absorption or secretion.

Cilia

Motile projections that move mucus and particles along the epithelial surface.

Endothelium

Simple squamous epithelium lining blood vessels and the heart.

Mesothelium

Simple squamous epithelium lining serous membranes of body cavities.

Simple epithelium

Single cell layer; named by cell shape (squamous, cuboidal, columnar).

Squamous

Flat, scale-like epithelial cells.

Cuboidal

Cube-shaped epithelial cells.

Columnar

Tall, column-like epithelial cells.

Simple squamous epithelium

One layer of flat cells; facilitates diffusion/filtration; lines vessels, alveoli, kidneys, serous membranes.

Simple cuboidal epithelium

One layer of cube-shaped cells; secretion/absorption; lines kidney tubules, glands, choroid plexuses.

Simple columnar epithelium

One layer of tall cells; secretion/absorption; often with microvilli or cilia.

Pseudostratified columnar epithelium

Appears stratified but is a single layer; often ciliated with goblet cells; lines respiratory tract.

Stratified squamous epithelium

Multiple cell layers; surface cells flatten; keratinized or nonkeratinized; protective.

Stratified cuboidal epithelium

Two or more layers; ducts and secretory regions; protective and secretory roles.

Stratified columnar epithelium

Multiple layers with tall cells on the surface; relatively rare.

Transitional epithelium

Stratified epithelium that changes shape (cuboidal to squamous) with stretch; lines urinary system.

Desmosomes

Disk-shaped cell junctions that anchor cells together to resist stress.

Hemidesmosomes

Attach epithelial cells to the basement membrane, preventing detachment.

Tight junctions

Junctions that seal spaces between cells to prevent material passage; anchor cells together.

Adhesion belts

Protein belts below tight junctions that strengthen cell–cell adhesion.

Gap junctions

Intercellular channels that permit ions and small molecules to pass between cells; coordinate activity (e.g., in cardiac muscle).

Endocrine gland

Ductless gland; secretes hormones directly into the bloodstream.

Exocrine gland

Gland with ducts that open onto a surface; secretes onto surfaces or into cavities.

Unicellular glands

Glands consisting of a single cell, such as goblet cells, that secrete mucus.

Goblet cell

Unicellular exocrine gland that secretes mucus to protect and lubricate surfaces.

Merocrine secretion

Secretory mode of exocytosis; cells remain intact (e.g., many sweat glands, salivary glands).

Apocrine secretion

Secretory mode where a portion of the cell’s cytoplasm is released with the product (e.g., mammary glands).

Holocrine secretion

Secretory mode where entire cells disintegrate to release product (e.g., sebaceous glands).

Areolar connective tissue

Loose connective tissue that cushions and supports; contains fibroblasts, macrophages, mast cells, and adipocytes.

Adipose tissue

Loose connective tissue rich in adipocytes; stores fat; provides insulation and cushioning.

Reticular tissue

Loose connective tissue with a reticular fiber network; supports lymphoid and hematopoietic organs.

Dense regular connective tissue

Dense connective tissue with collagen fibers aligned in the same direction; forms tendons and ligaments.

Dense irregular connective tissue

Dense connective tissue with collagen fibers in multiple directions; provides strength in various directions (e.g., dermis).

Dense elastic connective tissue

Dense connective tissue rich in elastic fibers; allows stretch and recoil (e.g., ligaments in the vocal cords, arterial walls).

Hylaine cartilage

Glassy cartilage with a firm matrix; chondrocytes in lacunae; found in ribs, trachea, embryonic skeleton.

Fibrocartilage

Cartilage with thick collagen fibers; very tough; resists compression (e.g., intervertebral discs, pubic symphysis).

Elastic cartilage

Cartilage with abundant elastic fibers; highly flexible (e.g., external ear, epiglottis).

Bone (osseous tissue)

Rigid connective tissue with mineralized matrix; osteocytes in lacunae; compact and spongy forms.

Spongy bone

Cancellous bone with trabeculae and marrow-filled spaces; lighter than compact bone.

Compact bone

Dense bone with concentric lamellae around a central canal; strong outer shell.

Blood

Fluid connective tissue with plasma and formed elements (red cells, white cells, platelets); transports substances and defends the body.

Hematopoietic tissue

Bone marrow; red marrow forms blood cells; yellow marrow stores fat.