Renal System and Nephron (Chapter 1-6)

Vocabulary flashcards covering key renal system terms, nephron anatomy, and the RAAS and water/hemodynamics concepts discussed in Chapter 1-6.

Nephron

The functional unit of the kidney where filtration, reabsorption, and excretion occur.

Glomerulus

A tuft of capillaries where plasma is filtered; surrounded by Bowman's capsule.

Bowman's capsule

Encases the glomerulus and collects the filtrate produced by glomerular filtration.

Cortex

The outer region of the kidney that contains glomeruli and proximal tubules.

Medulla

The inner region of the kidney containing the loop of Henle and collecting ducts; site of the osmotic gradient.

Proximal Convoluted Tubule

Main site of reabsorption of water, Na+, Cl-, glucose, amino acids, and bicarbonate.

Loop of Henle

U-shaped portion of the nephron with descending (water-permeable) and ascending (Na+/Cl--reabsorbing) limbs; creates the medullary osmotic gradient.

Descending limb

Part of the loop of Henle permeable to water but not to Na+ or Cl-.

Ascending limb

Part of the loop of Henle that reabsorbs Na+ and Cl-; water movement is limited.

Distal Convoluted Tubule

Site of fine-tuning urine composition; selective reabsorption of ions; regulated by aldosterone and ADH.

Collecting duct

Receives filtrate from multiple nephrons; final adjustments of water and ion reabsorption; influenced by ADH and aldosterone.

Renal pelvis

Region where urine collects before entering the ureter.

Ureter

Tube that transports urine from the kidney to the bladder.

Afferent arteriole

Blood vessel that delivers blood to the glomerulus.

Efferent arteriole

Blood vessel that exits the glomerulus and leads to peritubular capillaries.

Filtrate

Fluid that passes from blood through the glomerulus into Bowman's capsule.

Juxtaglomerular apparatus

Specialized cells near the afferent arteriole that regulate renin release.

Renin

Enzyme released by the juxtaglomerular apparatus in response to low blood volume; initiates RAAS.

Angiotensin I

Formed from renin acting on angiotensinogen; converted to Angiotensin II in the lungs.

Angiotensin II

Potent vasoconstrictor that stimulates aldosterone release and promotes sodium reabsorption, increasing blood pressure.

Aldosterone

Hormone from the adrenal cortex that increases sodium reabsorption in the distal tubules and collecting ducts.

Antidiuretic Hormone (ADH)

Hormone from the hypothalamus that increases water reabsorption, concentrating urine; does not directly alter sodium.

RAAS (Renin-Angiotensin-Aldosterone System)

Hormonal cascade that regulates sodium reabsorption, blood volume, and blood pressure.

Osmotic gradient

Medullary gradient that drives water reabsorption in the loop of Henle and concentrates urine.

Sodium reabsorption

Movement of sodium from filtrate back into the blood; enhanced by RAAS in distal parts of the nephron.

Homeostasis (water, electrolytes, acid-base)

Kidney function to maintain stable body fluid composition and pH.

Renal artery

Blood vessel delivering oxygenated blood to the kidney.

Renal vein

Blood vessel returning filtered blood from the kidney to circulation.