[BIO137] Tissues

Simple Squamous Epithelium

Def: A single layer of flattened, elongated cells, arranged around a larger empty space.
Location: Found in the walls of the alveoli, lining blood vessels, forming the walls of capillaries, serous membranes.
Function: Diffusion and filtration

Simple Cuboidal Epithelium

Def: A single layer of cube-like cells with large round nuclei, usually arranged in a circle.
Location: Kidney tubules
Function: Absorption and secretion

Simple Columnar Epithelium

Def: A single layer of tall, column-like cells with a single, neat row of oval-shaped nuclei, usually toward the base of the cell.
Location: Lining the small and large intestines (microvilli)
Function: Absorption and secretion

Pseudostratified Columnar Epithelium

Def: A single layer of cells of differing heights. Nuclei are in irregular rows, and cilia cover the outer apical surface.
Location: Lining the trachea and uterine tubes
Function: Secretion of mucus

Non-keratinized Stratified Squamous Epithelium

Def: Many layers of cells. Cells toward the apical surface are flattened and become more irregular toward the basal surface.
Location: Lining mouth, esophagus, and vagina
Function: Protection from abrasion and infection

Transitional Epithelium

Def: Many layers of cells with varying and irregular shapes. Causes an irregularly shaped inner region (lumen) of the urinary bladder and ureters.
Location: Ureters, urinary bladder
Function: Elasticity, stretch and recoil

Areolar Connective Tissue

Def: Loose arrangement of thick collagen and thin elastic and reticular fibers that crisscross randomly.
Location: Surrounding most organs just deep to the epithelium
Function: Wraps and cushions organs, holds fluids and defensive cells

(White) Adipose Connective Tissue (FAT)

Def: Greatly enlarged cells (adipocytes), nearly the entire volume of which is filled with a fat vacuole (white space)
Location: Under skin, around eyes and kidneys, in breasts and buttocks
Function: Energy storage, cushioning, insulation

Reticular Connective Tissue

Def: Dark-staining reticular fibers, many nuclei of lymphoblasts and other cells. (white blood cells are pink)
Location: Spleen, bone marrow, lymph nodes.
Function: Forms a scaffolding to support loose tissue cells

Dense Regular Connective Tissue

Def: Densely packed parallel fibers with fibroblasts, evidenced by their flattened, elongated nuclei, scattered throughout. (use all collagen)
Location: Ligaments and tendons.
Function: Attaches bone to bone or bone to muscle, resisting tensile forces on a single direction

Dense Irregular Connective Tissue

Def: Irregular clumps of collagen fibers separated by space, with an overall blotchy appearance.
Location: Dermis of skin.
Function: Provides resistance against tensile forces in many directions.

Elastic Connective Tissue

Def: Densely packed collagen fibers with dark wavy elastic fibers.
Location: Walls of blood vessels, but more abundant in arteries than veins
Function: Elasticity

Hyaline Cartilage

Def: Smooth, glassy appearance with distinctive lacunae, most occupied by chondrocytes. Lacunae often paired.
Location: Nose, larynx, trachea, costal cartilage, covering ends of long bones
Function: Structural support, cushions joints.

Elastic Cartilage

Def: Distinctive large, often paired lacunae. Dark elastic fibers.
Location: Earlobe and epiglottis
Function: Flexibility

Fibrocartilage

Def: Nearly parallel, wavy collagen fibers with distinctive chondrocytes in lacunae.
Location: Intervertebral disks, pubic symphysis, menisci of knee.
Function: Resist compressive forces.

Blood

Def: Numerous pinks, round erythrocytes with larger purple leukocytes scattered throughout.
Location: Within blood vessels.
Function: Transport of nutrients, gases, wastes, etc.

Bone

Def: Large dark circles with concentric circles surrounding them like tree rings.
Location: Bones.
Function: Support, protection, mineral storage, attachment sites for muscles.