A&P Tissues and Connective Tissue Types: Key Structures and Functions

Simple epithelium

Single layer of cells

Stratified epithelium

Several layers of cells

Squamous epithelia

Thin and flat

Cuboidal epithelia

Square shaped

Columnar epithelia

Tall, slender rectangles

Simple Squamous epithelium

Found in heart & blood vessels, kidney tubules, inner lining of cornea, alveoli of lungs

Simple Cuboidal epithelium

Found in glands, ducts, kidney tubules, thyroid gland

Simple Columnar epithelium

Found in linings of stomach, intestine, gallbladder, uterine, kidneys

Stratified Squamous epithelium

Found in surface of skin, lining of mouth, throat, esophagus, rectum, anus, vagina

Pseudostratified Ciliated Columnar Epithelium

Found in lining of nasal cavity, trachea, bronchi, portions of male reproductive tract

Transitional Epithelium

Found in urinary bladder, renal pelvis, ureters

Merocrine secretion

Produced in Golgi apparatus and released by vesicles (exocytosis)

Apocrine secretion

Produced in Golgi apparatus and released by shedding cytoplasm

Holocrine secretion

Released by cells bursting, killing gland cells; gland cells replaced by stem cells

Three basic components of connective tissues

Specialized cells, solid extracellular protein fibers, fluid extracellular ground substance

Matrix of connective tissues

Majority of tissue volume; determines specialized function

Collagen fibers

Long, straight, unbranched; strong, but flexible; most common

Elastic fibers

Branched and wavy; return to original length after stretching; contain elastin

Reticular fibers

Thinner than collagen fibers; form branching, interwoven framework in various organs; least common

Loose connective tissue

"Packing materials" of the body; more ground substance, fewer fibers; example: fat (adipose tissue)

Dense connective tissue

Tough, strong, and durable; more fibers, less ground substance; example: tendons

Fluid connective tissues

Blood and lymph; watery matrix of dissolved proteins; carry specific cell types (formed elements)

Formed elements of blood

Red blood cells, white blood cells, platelets

Supporting connective tissues

Cartilage (gel-type ground substance for shock absorption and protection) and bone (calcified for weight support)

Cartilage matrix

Proteoglycans derived from chondroitin sulfates; ground substance proteins; chondrocytes (cartilage cells) surrounded by lacunae (chambers)