Kidney Structure and Function Quiz

Kidney Structure

• Each kidney contains approximately 1.2 million nephrons
• The nephron is the functional unit of the kidney
• Nephrons filter plasma, reabsorb and secrete, and regulate filtrate
• There are three types of nephrons: cortical, midcortical, and juxtamedullary.

Glomerulus

• The glomerulus is a network of capillaries within the nephron
• It filters plasma, the liquid component of blood, creating a filtrate
• The glomerular filtration rate (GFR) measures the plasma filtered per unit of time (90-120 mL/min)
• The glomerular membrane is permeable to water but not large molecules like albumin

Urine Formation

• Glomerular filtration produces a protein-free filtrate
• About 99% of the filtrate is reabsorbed into the bloodstream
• The remaining 1% is excreted as urine.
• Kidneys produce hormones, including renin, angiotensin, aldosterone, natriuretic peptides, and urodilantin

Renal Function

• Filtering waste products from the blood
• Regulating blood pressure
• Producing hormones
• Maintaining electrolyte and acid-base balance
• The nephron filters blood into a filtrate in the glomerulus
• Waste products are secreted into filtrate, and useful products are reabsorbed
• The filtrate is modified in the tubule by reabsorption and secretion

Renal Function: Hormones

• Renin-angiotensin-aldosterone system (RAAS): Regulates blood pressure
• Erythropoietin: Stimulates red blood cell production
• Vitamin D: Aids in calcium absorption

Renal Function: Acid-Base Balance

• Kidneys regulate body's acid-base balance by excreting hydrogen ions and reabsorbing bicarbonate ions.

Renal Tests

• Tests assess kidney function: Blood tests (e.g., creatinine, BUN), urinalysis, and clearance tests (e.g., creatinine clearance)

Urinary Tract

• The urinary tract consists of the kidneys, ureters, bladder, and urethra
• Urine is made in the kidneys, travels down the ureters to the bladder, and exits the body through the urethra.
• Obstructions in the urinary tract can affect its function

Upper Urinary Tract Obstruction

• Hydroureter: Accumulation of urine in the ureter
• Hydronephrosis: Enlargement of the renal pelvis and calyces
• Ureterohydronephrosis: Dilation of both the ureter and the pelvicaliceal system
• Increased pressure in the glomerulus can lead to decreased kidney function and filtration

Lower Urinary Tract Obstruction

• Neurogenic bladder: Dysfunction of the urinary bladder due to nerve issues.
• Overactive bladder
• Underactive bladder
• Can result from various conditions like urethral strictures, enlarged prostate, or pelvic organ prolapse

Urinary Tract Infection (UTI)

• Inflammation of the urinary tract caused by bacteria (e.g., Escherichia coli).
• Types include acute cystitis (inflammation of the bladder), painful bladder syndrome/interstitial cystitis, and acute/chronic pyelonephritis (inflammation of the kidney and renal pelvis).

Kidney Stones

• Formed when salts in urine become supersaturated
• Factors such as gender, geographic location, diet and fluid intake influence risk
• Classified by the minerals that make up the stone

Glomerular Disorders

• Glomerulonephritis: Inflammation of the glomerulus
• Causes include immune responses, infections, medications, and other conditions.
• Symptoms include hematuria, proteinuria, oliguria, hypertension, and edema.
• Nephrotic syndrome: Characterized by excessive protein in urine (greater than 3.5g/day)

Chronic Kidney Disease (CKD)

• Progressive loss of renal function, typically affecting multiple organ systems
• Classified into five stages based on GFR (glomerular filtration rate)
• Common causes include hypertension, diabetes, and systemic lupus erythematosus
• Impacts fluid and electrolyte balance, calcium, phosphate, and bone metabolism, and can cause anemia

Acute Kidney Injury (AKI)

• Sudden decline in kidney function with decreased GFR and urine output
• Results from ischemia, toxic injury, or sepsis.
• Common causes include prerenal (reduced blood flow), intrarenal (damage to the kidney itself), and postrenal (obstruction of urine flow) causes