Urinary System Anatomy Flashcards

Kidney Membranes

• Renal capsule: A fibrous layer that protects against infection.
• Adipose capsule: Fatty tissue providing cushioning and anchorage.
• Renal fascia: A dense outer layer securing the kidney in place.

Anatomy of the Kidney

• Cortex: The outer, light-colored, granular region.
• Medulla: Contains cone-shaped medullary pyramids, essential for urine formation.
• Renal pelvis: Funnel-shaped tube that collects urine from major calyces.
• Calyces:
  • Major calyces collect urine from minor calyces.
  • Minor calyces interface with renal papillae to gather urine.
• Renal corpuscle: Comprising glomerulus and Bowman's capsule, responsible for initial blood filtration.
• Renal hilum: Entry point for vessels, nerves, and ureters.

Blood Flow Through the Kidney

• Blood circulates from aorta to:
  • Renal artery → Segmental artery → Interlobar artery → Arcuate artery → Cortical radiate artery → Afferent arteriole → Glomerulus → Efferent arteriole → Peritubular capillaries/vasa recta → Cortical radiate vein → Arcuate vein → Interlobar vein → Renal vein → Inferior vena cava.

Nephron Structure

• Nephron: The fundamental structural and functional unit of the kidney, consisting of the glomerulus and renal tubules.

Filtration, Reabsorption, and Secretion

• Filtration: Removes waste while retaining essential substances.
• Reabsorption: Transfers ions from filtrate back to the bloodstream.
• Secretion: Eliminates unwanted substances and helps maintain blood pH.

Glomerular Blood Pressure

• Glomerulus has higher filtration membrane permeability and blood pressure compared to other capillaries.
• Plasma proteins are retained in blood, contributing to oncotic pressure.

Filtration Mechanism

• Hydrostatic pressure: The primary force driving filtration.
• Filtration membrane: Composed of fenestrated capillaries, podocytes, and a basement membrane facilitating the selective passage of substances.

Glomerular Filtration Rate (GFR)

• Normal GFR ranges between 120-125 ml/min.
• Changes in GFR affect the reabsorption of substances; excessively high or low GFR obstructs optimal renal function.

Types of Nephrons

• Cortical nephrons: Constitute 85% of nephrons, primarily in the cortex with short loops of Henle.
• Juxtamedullary nephrons: Positioned at the cortex-medulla junction, crucial for producing concentrated urine.

Renal Hormones

• Hormones like ADH and aldosterone regulate kidney functions, affecting water and sodium balance.

Ureter, Bladder, and Urethra Functions

• Ureters transport urine; bladder stores urine; urethra expels urine from the body.

Urine Characteristics

• Fresh urine is pale yellow; changes in color or odor can indicate conditions.
• Typical pH is slightly acidic, with specific gravity indicating solute concentration.

Water Gain and Loss

• Main sources of water gain: Ingestion, food, and metabolism.
• Loss occurs through urine, perspiration, respiration, and gastrointestinal system.

Body Fluid Compartments

• Intracellular fluid (ICF): Majority of body water found within cells.
• Extracellular fluid (ECF): Includes plasma and interstitial fluid, containing less water than ICF.

Hydrogen Ion Regulation

• Managed through buffering systems (bicarbonate, phosphate, protein) and organ mechanisms (lungs and kidneys).

Acidosis and Alkalosis

• Most common acid-base imbalance is respiratory acidosis.
• Infants with colic can experience respiratory alkalosis due to hyperventilation.

Functions of the Kidneys

• A WET BED: Refers to Acid-base balance, Water removal, Erythropoiesis, Toxin removal, Blood pressure control, Electrolyte balance, and Vitamin D activation.

Urine Formation Pathway

• Follows path: Glomerulus → Glomerular capsule → PCT → Nephron Loop → DCT → Collecting Duct → Papilla → Minor calyx → Major calyx → Renal pelvis → Ureters → Bladder → Urethra.