Urinary System and Histology: Epithelial, Connective, and Muscle Tissues

Comprehensive vocabulary flashcards covering the gross anatomy and functional nephron structures of the urinary system alongside the identification, morphology, and histology of epithelial, connective, and muscle tissues.

Renal capsule

The outer fibrous sheath covering the external surface of the kidney.

Renal cortex

The superficial outer region of the kidney tissue, excluding the medullary pyramids.

Renal medulla

The inner functional layer of the kidney containing the renal (medullary) pyramids.

Medullary pyramid

A triangular or conical mass of tissue located within the renal medulla of the kidney.

Renal pelvis

The central collecting funnel located in the center of the kidney that channels urine into the ureter.

Renal calyx

A cuplike extension of the renal pelvis that is in direct contact with the medullary pyramids and renal medulla.

Interlobular vessels

Smaller vascular branches that penetrate into the renal cortex as vessels enter the kidney, technically distinct from the primary renal artery and vein.

Glomerulus

The capillary network and surrounding epithelium of the renal corpuscle that filters small solutes out of the blood.

Bowman's capsule

The double-walled cup of epithelial tissue surrounding the glomerular capillaries that collects filtered fluid.

Proximal convoluted tubule

The nephron tubule segment that reabsorbs ions, water, and nutrients, eliminates toxins, and regulates filtrate pH.

Descending loop of Henle

The initial segment of the loop of Henle that dips downward into the medulla and contains aquaporins allowing water to exit into the interstitial fluid.

Ascending loop of Henle

The hairpin-shaped tubule segment looping back upward that actively reabsorbs $Na^+$ and $Cl^-$ into the interstitial fluid.

Distal convoluted tubule

The convoluted segment of the renal tubule following the loop of Henle that selectively secretes and absorbs various ions to regulate blood pH and electrolyte balance.

Collecting duct

The final tubule pathway in the nephron system that reabsorbs solutes and water from the filtrate before draining into the renal calyces.

Peritubular capillaries

A low-pressure capillary network arising from the efferent arteriole that wraps around the renal tubules for solute reabsorption and secretion.

Apical surface

The upper, unattached surface of an epithelial tissue that faces the body exterior, an internal organ cavity, or a lumen.

Basal surface

The bottom surface of epithelial cells attached directly to the underlying basement membrane and connective tissue.

Simple epithelium

An epithelial classification describing a single layer of cells extending from the basal membrane to the apical surface.

Stratified epithelium

An epithelial tissue composed of two or more cell layers stacked from the basal surface to the apical surface.

Pseudostratified epithelium

A specialized simple columnar epithelium where nuclei appear at varying levels, giving a messy, non-uniform appearance of stratification.

Squamous cells

Flattened, scale-like epithelial cells featuring flattened or oval nuclei when viewed in cross section.

Cuboidal cells

Box-shaped or circular epithelial cells with round, centrally located nuclei, commonly configured in rings to form tubules.

Columnar cells

Elongated, rectangular epithelial cells with significant cytoplasmic space around the nucleus that frequently bear cilia or microvilli and may contain goblet cells.

Transitional epithelium

A stratified epithelium characterized by rounded, dome-shaped apical cells that can stretch and alter their shape, found only in stratified arrangements.

Collagen fibers

Thick connective tissue fibers that stain pink, provide high tensile strength, and are arranged uniformly or non-uniformly depending on tissue type.

Elastic fibers

Connective tissue fibers that stain dark pink, purple, or black, appearing spring-like in elastic tissue or fine and dark in elastic cartilage.

Reticular fibers

Delicate connective tissue fibers that stain dark purple to black, forming disorganized networks resembling spider webs or branching trees.

Areolar tissue

A loose connective tissue with a disorganized, mesh-like network containing collagen, elastic, and reticular fibers, found surrounding organs, nerves, and blood vessels.

Adipose tissue

A loose connective tissue consisting of adipocytes packed with lipid droplets resembling bubbles, with cell nuclei compressed against the plasma membrane.

Reticular tissue

A loose connective tissue uniquely containing only reticular fibers to form a supportive stroma within the spleen, liver, kidneys, and lymph nodes.

Dense regular connective tissue

A dense connective tissue comprising parallel, uniform bundles of collagen fibers with flattened fibroblast nuclei positioned in between, located in tendons and ligaments.

Dense irregular connective tissue

A dense connective tissue composed of irregularly arranged, non-uniform collagen fibers capable of withstanding tension from multiple directions, found in the dermis.

Elastic tissue

A dense connective tissue containing prominent, spring-like elastic fibers aligned uniformly with collagen, located in arteries, veins, the lungs, and the pericardium.

Chondrocytes

Mature cartilage cells that reside individually within hollow white spaces or capsules known as lacunae.

Hyaline cartilage

A type of cartilage with disorganized chondrocytes in lacunae dispersed within a glassy, homogeneous matrix where collagen fibers blend invisibly, found on articular surfaces, nose, and trachea.

Elastic cartilage

Cartilage filled with small, dark-staining, hair-like elastic fibers packed into the matrix surrounding chondrocytes in lacunae, found in the pinna of the ear.

Fibrocartilage

A tough cartilage consisting of parallel, uniform collagen fiber bundles interspersed with rows of chondrocytes in lacunae, found in the intervertebral discs.

Skeletal muscle

Voluntary muscle tissue characterized by prominent cross-striations perpendicular to the fibers and multiple peripheral nuclei displaced along the margins.

Smooth muscle

Involuntary, non-striated muscle tissue displaying uniform spindle-shaped fibers and elongated, centrally situated oblong nuclei, found in the gastrointestinal tract.

Cardiac muscle

Involuntary striated muscle tissue containing branching fibers, central nuclei, and dark specialized junctions called intercalated discs, found exclusively in the heart.