EXCRETION AND OSMOREGULATION

 

EXCRETION AND OSMOREGULATION

V.S. Of Kidney

Metabolism : The Sum total of all biochemical reaction is called 'metabolism'. It involves catabolism (breaking down) and anabolism (building up) processes.

Metabolic waste products: Metabolism produces a variety of by-products, some of which need to be eliminated, such byproducts are called metabolic 'waste products'.

Excretion : Elimination of nitrogenous metabolic waste products from the body is called excretion.

Urochrome : A yellow colour pigment found in the urine is called urochrome.

Deamination: Body of an organism is unable to store excess amino acids, hence excess amino acids are essentially broken down by a process called deamination and removed.

Ammonotelism : Elimination of nitrogenous wastes in the form of ammonia is called ammonotelism and the animals are called an ammonotelic animal.

Ammonotelic organisms: Organisms excreting their nitrogenous waste in the form of  ammonia is called ammonotelic organisms. 1 gm ammonia requires about 300 – 500 ml of water for its elimination.

Ureotelism : Elimination of nitrogenous wastes in the form of urea (H₂N-CO-NH₂) is called as ureotelism.

Ureotelic organisms: Organisms excreting their nitrogenous waste in the form of  urea is called Ureotelic organisms. 1 gm urea requires about 50 ml of water for its elimination.

Ornithine Cycle: The cycle that occurs in the liver which converts ammonia into urea is called ornithine/urea cycle (Krebs and Hanseleit, 1932) in which  3 ATP molecules are used to produce one molecule of urea.

Uricotelism: Elimination of nitrogenous wastes in the form of uric acid is called as uricotelism. Uric acid is the least toxic. Ammonia is converted into uric acid by the process called inosinic acid pathway.

Uricotelic organisms: Organisms excreting their nitrogenous waste in the form of  uric acid is called Uricotelic organisms. 1 gm uric acid requires about 10 ml of water for its elimination.

Guanotelism: Animals like spiders, scorpions and penguins excrete guanine this mode of excretion is called guanotelism.

Gouty Arthritis: It is a type of arthritis caused due to accumulation of uric acid in joints.

Creatinine : It is a waste product produced by muscles from the breakdown of a compound called creatine.

Homeostasis : The maintenance of constant internal environment of the body is called homeostasis.

Osmoregulation : The maintenance of constant osmotic pressure in the fluids of an organism by the control of water and salt concentrations.

Osmoconformers: Osmoconformers are marine organisms that maintain their internal environment isotonic to their external environment.

Osmoregulators: Osmoreulators are organisms that control their internal environment independent of their external environment.

Salt Glands: Many marine organisms have special glands called salt glands near nostrils, these are capable of secreting salts by active transport and help to manage osmotic balance. E.g. sea turtles and marine iguanas.

Stenohaline organisms: Most organisms can tolerate only a narrow range of salt concentration. Such organisms are called stenohaline organisms. (steno: narrow).

Euryhaline organisms: Organisms capable of tolerating wide changes in salinity are called euryhaline organisms ex. barnacles, clams etc.

Protonephridia / Flame cells: These are the network of dead-end tubes called protonephridia or flame cells, they are found mostly in animals that lack true body cavity.

        e.g. Platyhelminthes. Protonephridia are also found in rotifers, some annelids and Amphioxus.

Metanephridia: These are unbranched coiled tubes that connect to the body cavity through the funnel-like structures called nephrostomes, body fluid enters the nephridium through nephrostome and gets discharged through nephridiopore. eg. Earthworms.

Malpighian body: Bowman’s capsule along with glomerulus is called malpighian body.

Glomerulus : The network of capillaries into the bowman’s capsule is called the glomerulus.

Podocyte : A special type of squamous cells having a foot like pedicels that are wrapped around capillaries of the glomerulus are called podocyte.

Loop of Henle: ‘U’ shaped tube consisting of descending and ascending limb.

Collecting tubule: A short, straight part of DCT is called collecting tubule.

Juxta glomerular apparatus: The macula densa and the JG  cells together form juxta glomerular apparatus.

Ultrafiltration : The filtration of blood under high pressure in glomerulus is called ultrafiltration.

Nephrons : Mammalian kidneys are a collection of functional units called nephrons, which are well designed to extract metabolic waste.

Nephrology : Nephrology is a branch of biology that deals with structure, functions and disorders of the urinary system.

Urinary pole: In Bowman’s capsule, Parietal wall is thin consisting of simple squamous Epithelium which continues into the neck and the lumen of the neck is called a urinary pole.

Cortical nephrons: These nephrons are with the shorter loop of Henle which extend very little in the medulla. Most of the nephrons are cortical nephrons.

Juxtamedullary nephrons: Few nephrons have a longer loop of Henle that runs deep into the medulla. These are called Juxtamedullary nephrons.

JG Cells: Some smooth muscle cells of the wall of afferent arteriole are modified in such a way that their sarcoplasm is granular, These cells are called ‘juxtaglomerular (JG) cells.

Glomerular Hydrostatic Pressure /  GHP: The flow of blood flows with greater pressure through glomerulus is called glomerular hydrostatic pressure (GHP), it is about 55 mm Hg.

Effective Filtration Pressure / EFP: Glomerular hydrostatic pressure is opposed by the osmotic pressure of blood (normally, about 30 mm Hg) and capsular pressure (normally, about 15 mm Hg). Hence net / effective filtration pressure i.e. EFP is 10 mm Hg.

Augmentation / Tubular secretion: Secretion of H⁺ ions in DCT and for pH regulation of blood is called as tubular secretion or augmentation.

Peritubular capillary : The tiny blood vessels, supplied by the efferent arteriole, that travel alongside nephrons allowing reabsorption and secretion between blood and the inner lumen of the nephron.

Tubular secretion: The movement of substances from the blood into the tubular fluid is called tubular secretion.

Osmolarity: Total number of solute particles present in per litre of a solution is called osmolarity.

Osmoreceptors: The special receptors present in the Hypothalamus of the midbrain which can detect the change in osmolarity of blood is called osmoreceptors.

Diabetes insipidus: In absence of ADH, diuresis (dilution of urine) takes place and the person tends to excrete a large amount of dilute urine. This condition is called diabetes insipidus.

Albuminuria: Excessive albumin in urine (albuminuria) indicates injury to the endothelial capsular membrane is called albuminuria.

Kidney stones / renal calculi: The stone formed in any portion of urinary tract-from kidney tubules to the external opening are called kidney stones or renal calculi.

Calcium stones: These kidney stones are usually are calcium oxalate stones or calcium phosphate ones.

Struvite stones: These are formed in response to bacterial infection caused by urea splitting bacteria. These grow quickly and become quite large.

Uric acid stones: In people who don't drink enough water or consume high protein diet can suffer from this type of stones.

Cystine stones: It is a genetic disorder that causes the kidney to excrete too much of certain amino acid.

Uremia: Blood normally contains 0.01 to 0.03% urea; but if it rises above 0.05%, it is called uremia, it is harmful and may lead to kidney failure.

Nephritis: It is the inflammation of kidneys characterized by proteinuria.

Acute Renal failure /ARF: It is a sudden worsening of the renal function that most commonly happens after severe bleeding is called acute renal failure, there is a decrease in urine output.

Oliguria : It means scanty (insufficient quantity) urine  i.e. less than 400 ml/day or less than 0.5 ml/kg/h in children.

Chronic Renal failure/CRF :  It is a progressive and generally irreversible decline in glomerular filtration rate (GFR), it may be caused due to chronic glomerulonephritis.

Haemodialysis : The artificial means of filtration of blood is called haemodialysis.

Peritoneal dialysis: It is a type of dialysis which uses the peritoneum in a person's abdomen as the membrane through which fluid and dissolved substances are exchanged with the blood is called peritoneal dialysis.

Kidney Transplantation: It is the organ transplant of a healthy kidney into a patient with end-stage of renal disease.