Glossary — Key Terms — Notes | NoteTube

Term	Definition	NEET Relevance
Ammonotelism	Excretion of nitrogenous waste primarily as ammonia	Identify aquatic organism examples
Ureotelism	Excretion of nitrogenous waste primarily as urea	Mammals + terrestrial amphibians + marine fish
Uricotelism	Excretion of nitrogenous waste primarily as uric acid (semi-solid)	Birds, reptiles, land snails, insects
GFR	Glomerular Filtration Rate — volume of plasma filtered per minute $\frac{125 mL}{min}$	Most tested numerical value
Nephron	Structural and functional unit of the kidney (~1 million/kidney)	All kidney physiology revolves around this
Bowman's capsule	Cup-shaped structure enclosing the glomerulus; site of filtration	First part of nephron
Glomerulus	Tuft of capillaries within Bowman's capsule; site of ultrafiltration	High-pressure filtration site
Malpighian body	Glomerulus + Bowman's capsule	Synonym: renal corpuscle
PCT	Proximal Convoluted Tubule — bulk reabsorption (65–70%) of filtrate	Glucose, amino acid reabsorption
Loop of Henle	U-shaped nephron segment; establishes medullary osmotic gradient	Counter-current mechanism
DCT	Distal Convoluted Tubule — hormonal (conditional) reabsorption	ADH, aldosterone, PTH act here
Collecting duct	Final urine concentration under ADH; urea recycling	ADH action site
ADH	Antidiuretic hormone (vasopressin) — increases water reabsorption in DCT and collecting duct	Concentrated urine production
Aldosterone	Mineralocorticoid from adrenal cortex — Na+ reabsorption, K+ secretion in DCT	RAAS effector
ANF	Atrial Natriuretic Factor — decreases Na+ reabsorption; released by atria when volume is high	Opposes aldosterone/RAAS
RAAS	Renin-Angiotensin-Aldosterone System — blood pressure regulation cascade	Triggered by low BP; key pharmacology target
Renin	Enzyme from JG cells; converts angiotensinogen to angiotensin I	RAAS initiation
Angiotensin II	Active vasoconstrictor; stimulates aldosterone secretion	Central RAAS molecule
ACE	Angiotensin Converting Enzyme — converts angiotensin I to angiotensin II (in lungs)	Drug target (ACE inhibitors)
Counter-current mechanism	Loop of Henle + vasa recta maintain medullary gradient 300–1200 mOsm/L	Key for urine concentration
Ornithine cycle	Urea cycle in liver; converts NH3 to urea	Why liver is an excretory organ
Uremia	Accumulation of urea in blood due to kidney failure	Classic disorder question
Renal calculi	Kidney stones — usually calcium oxalate crystals	Most common stone type
Glomerulonephritis	Inflammation of glomeruli → proteinuria, haematuria	Post-streptococcal or autoimmune
Haemodialysis	Artificial kidney filtration through semipermeable membrane	Treatment for renal failure
Obligatory osmosis	Water reabsorption in PCT that is compelled by solute reabsorption; no ADH needed	Distinguishes PCT from DCT water reabsorption
Facultative reabsorption	Hormone-regulated water/solute reabsorption in DCT and collecting duct	ADH-dependent
JGA	Juxtaglomerular Apparatus — renin-secreting cells + macula densa at DCT-glomerulus junction	Blood pressure sensor/effector
Vasa recta	Capillary loops parallel to loop of Henle; counter-current exchanger	Preserves medullary gradient