urinary critical?

Pathway of blood through kidneys

Renal artery → segmental arteries → interlobar arteries → arcuate arteries → cortical radiate arteries → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries/vasa recta → cortical radiate veins → arcuate veins → interlobar veins → renal vein

Two parts of the nephron

Renal corpuscle and renal tubule

Renal corpuscle

Site of filtration; includes glomerulus + Bowman’s capsule

Renal tubule

Site of reabsorption and secretion (PCT, loop of Henle, DCT, collecting duct)

Mucosa of ureters and bladder

Transitional epithelium that stretches and protects against urine

Function of transitional epithelium

Allows expansion and prevents damage from toxic urine

Podocytes

Specialized cells with filtration slits that allow small molecules through but block proteins and blood cells

Filtration membrane

Glomerular endothelium + basement membrane + podocytes

Three processes of urine formation

Glomerular filtration, tubular reabsorption, tubular secretion

Glomerular filtration

Movement of water and solutes from blood into Bowman’s capsule

Tubular reabsorption

Movement of substances from tubule back into blood

Tubular secretion

Movement of substances from blood into tubule

Juxtaglomerular apparatus (JGA) cells

Macula densa and granular (juxtaglomerular) cells

Macula densa

Senses NaCl concentration in filtrate

Granular cells

Release renin in response to low blood pressure

Glomerular hydrostatic pressure (GHP)

Pressure that pushes fluid out of glomerulus into capsule

Capsular hydrostatic pressure (CHP)

Pressure that pushes fluid back into glomerulus

Glomerular osmotic pressure (OP)

Pressure that pulls fluid into glomerulus due to proteins

Net filtration pressure (NFP)

Outward pressures minus inward pressures

Effect of increased CHP

Decreases NFP and decreases filtration (↓ GFR)

RAAS trigger

Low blood pressure, low Na+, or low blood volume

Renin

Enzyme released by granular cells that starts RAAS

Angiotensin II

Causes vasoconstriction and stimulates aldosterone and ADH release

Aldosterone

Increases Na+ and water reabsorption in kidneys

Function of RAAS

Increases blood pressure and blood volume

Countercurrent multiplier

Mechanism in loop of Henle that creates a concentration gradient

Descending limb of loop of Henle

Permeable to water; water leaves

Ascending limb of loop of Henle

Impermeable to water; pumps out NaCl

Result of countercurrent system

Concentrated urine

ACE inhibitors

Block conversion of angiotensin I to angiotensin II

Effect of ACE inhibitors

Lower blood pressure due to less vasoconstriction and less water reabsorption

Reason for dizziness with ACE inhibitors

Low blood pressure reduces blood flow to brain

Antidiuretic hormone (ADH)

Hormone that increases water reabsorption in kidneys

Effect of alcohol on ADH

Inhibits ADH release

Result of alcohol consumption

Less water reabsorption, more urine output, dehydration

Symptom after alcohol

Dry mouth due to fluid loss