Kidney location

Retroperitoneal

Hilus function

Entry/exit for blood vessels, nerves, ureters

Kidney lobes

Up to 18 lobes each containing nephrons

Glomeruli location

Located in cortex, not medulla

Nephrons per glomerulus

Each nephron contains one glomerulus

Protein-free filtrate location

Bowman space

Mesangial cell functions

Phagocytic, contractile, regulate blood flow, hyperplasia in disease

Mesangial cell limitations

Do not cover entire endothelium; do not drain Bowman capsule

Glomerular filtrate

Similar to plasma minus proteins

Hypovolemic shock renal effects

Decreased BP → decreased renal perfusion → decreased GFR

Hypovolemic shock urine output

Less than 30 mL/hr

SNS effect on kidneys

Afferent arteriole vasoconstriction

Urosepsis renal effect

SNS activation → afferent vasoconstriction → decreased GFR → oliguria

Severe blood loss vasoconstrictors

Angiotensin II, ADH, endothelins

Proximal tubule function

Site of most reabsorption and secretion (~2/3)

Proximal tubule secretion

Penicillin, aspirin, morphine

Water transport

Reabsorbed passively

Active transport substances

Sodium, phosphate, calcium

Ascending loop of Henle

Impermeable to water; reabsorbs solutes; produces dilute filtrate (~100 mOsm)

ADH function

Increases water permeability in collecting ducts; concentrates urine

Desmopressin uses

Enuresis and diabetes insipidus

Posterior pituitary damage

No ADH → dilute urine, low urine osmolality, high thirst, high urine output, weight loss

Kidney acid-base role

Eliminate H⁺ and generate new bicarbonate

Compensation limits

Lungs and buffers help but cannot replace renal H⁺ elimination

Thiazide diuretics

Cause K⁺ loss; increase Ca²⁺ reabsorption

Loop diuretics

Most potent; rapid diuresis; cause K⁺ loss

Aldosterone antagonists

Potassium-sparing; block Na⁺ reabsorption

ACE inhibitors

Decrease aldosterone; risk of hyperkalemia

Osmotic diuretics

Cause Na⁺ loss; excess use may cause hyperkalemia

AKI risk factors

Diabetes mellitus, hypertension, contrast dye

Renal dysfunction labs

Increased creatinine, BUN, cystatin-C; glucose in urine

Normal urine findings

No protein; specific gravity 1.038–1.040

24-hour urine test

Quantifies substances like protein; not for bacteria or glucose

Left-out urine sample

Discard and recollect due to lysed RBCs and bacterial overgrowth

Congenital renal disorders

Renal hypoplasia, cystic dysplasia, horseshoe kidney

Not congenital

Renal cell carcinoma, hydronephrosis

Autosomal dominant PKD

Cysts, flank pain, hematuria, recurrent UTIs; kidneys enlarged

Urinary obstruction risk factors

Pregnancy, BPH, renal calculi, neurogenic bladder

BPH consequences

Hydroureter, pain, distal ureter distention

Renal calculi etiology

Diet, metabolism, hormones, endocrine factors; genetics not primary

Ureteral colic pain

Excruciating intermittent flank pain radiating to groin

Ureteral colic associated signs

Nausea, hematuria, restlessness