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Assignment 1-15
Assignment 1-15 Answers


Excretory products and their elimination


19. Extract(1-15) Animals accumulate ammonia, urea, uric acid, carbon dioxide, water and ions like Na+, K+, Cl-, phosphate, sulphate, etc., either by metabolic activities or by other means like excess ingestion. These substances have to be removed totally or partially. Here we learn the mechanisms of elimination of these substances with special emphasis on common nitrogenous wastes. Ammonia, urea and uric acid are the major forms of nitrogenous wastes excreted by the animals. Ammonia is the most toxic form and requires large amount of water for its elimination, whereas uric acid, being the least toxic, can be removed with a minimum loss of water.

The process of excreting ammonia is Ammonotelism. Many bony fishes, aquatic amphibians and aquatic insects are ammonotelic in nature. Ammonia, as it is readily soluble, is generally excreted by diffusion across body surfaces or through gill surfaces (in fish) as ammonium ions. Kidneys do not play any significant role in its removal. Terrestrial adaptation necessitated the production of lesser toxic nitrogenous wastes like urea and uric acid for conservation of water.

Mammals, many terrestrial amphibians and marine fishes mainly excrete urea and are called ureotelic animals. Ammonia produced by metabolism is converted into urea in the liver of these animals and released into the blood which is filtered and excreted out by the kidneys.
Some amount of urea may be retained in the kidney matrix of some of these animals to maintain a desired osmolarity. Reptiles, birds, land snails and insects excrete nitrogenous wastes as uric acid in the form of pellet or paste with a minimum loss of water and are called uricotelic animals.

A survey of animal kingdom presents a variety of excretory structures. In most of the invertebrates, these structures are simple tubular forms whereas vertebrates have complex tubular organs called kidneys. Some of these structures are mentioned here. Protonephridia or flame cells are the excretory structures in Platyhelminthes (Flatworms, e.g., Planaria), rotifers, some annelids and the cephalochordate – Amphioxus. Protonephridia are primarily concerned with ionic and fluid volume regulation, i.e., osmoregulation.

Nephridia are the tubular excretory structures of earthworms and other annelids. Nephridia help to remove nitrogenous wastes and maintain a fluid and ionic balance. Malpighian tubules are the excretory structures of most of the insects including cockroaches.

Malpighian tubules help in the removal of nitrogenous wastes and osmoregulation. Antennal glands or green glands perform the excretory function in crustaceans like prawns.

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Where is the antennal gland located? Antennal or maxillary glands are located in the head, and empty at the base of the second antenna or first maxilla. These organs have a bulbous structure, the labyrinth, which receives filtrate from arterial blood under pressure

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Crawfish and prawns are both crustaceans, but prawns have branching gills and live in salt water, and crawfish have featherlike gills and live in fresh water.

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coxal gland, in certain arthropods, one of a pair of excretory organs consisting of an end sac where initial urine is collected, a tubule where secretion and reabsorption may take place, and an excretory pore at the base (coxa) of one of the legs. Variations among the species include highly convoluted tubule sections, doubling back of straight tubule sections, and expansion of the terminal end into a bladder. In many higher crustaceans the excretory glands are located in the head. They are called antennal glands or maxillary glands, depending on whether they open at the base of the antennae or at the maxillae. If the tubule adjacent to the excretory pore is green, the gland is called a green gland.

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Identify the glands that perform the excretory function in prawns. Solution In prawns, the excretory organs are known as antennary glands or green glands. These glands are opaque while pea-sized structures enclosed in the coxa of each 2nd antenna. They mainly excrete ammonia.

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What is coxa in cockroach? The coxa is the upper part of the leg. The coxa region helps in the attachment of the leg to the thorax region of the body. Then comes the trochanter which acts as the knee of the cockroach. It helps the cockroach to bend its leg.

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1. Which are three major forms of nitrogenous wastes excreted by the animals?
2. Which is most toxic form of nitrogenous wastes and requires large amount of water for its elimination.
3. What is Ammonotelism?
4. Give three examples of ammonotelic animals.
5. Which animals are called ureotelic animals?
6. In which organ of the body Ammonia produced by metabolism is converted into urea? 7. Name a few uricotelic animals.
8. a. Name the animals in which protonephridia or flame cells are the excretory structures. b. What is osmoregulation?
9. What are nephridia? Mention their main function and group of animals in which they are present?
10. Which are excretory structures of most of the insects including cockroaches.
11. In which animals antennal glands or green glands are present? What is their function?
12. Draw a well labeled diagram of protonephridia.
13. Draw a well labeled diagram of nephridia.
14. Draw a well labeled diagram of alimentary canal of cockroach showing malpighian tubules.
15. Draw a well labeled diagram of antennal glands.

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1. Which are three major forms of nitrogenous wastes excreted by the animals?
1. Ammonia, urea and uric acid are the major forms of nitrogenous wastes excreted by the animals. 2. Which is most toxic form of nitrogenous wastes and requires large amount of water for its elimination
2. Ammonia is the most toxic form and requires large amount of water for its elimination 3. What is Ammonotelism?
3. The process of excreting ammonia is Ammonotelism. 4. Give three examples of ammonotelic animals.
4. Many bony fishes, aquatic amphibians and aquatic insects are ammonotelic in nature.
5. Which animals are called ureotelic animals?
5. Mammals, many terrestrial amphibians and marine fishes mainly excrete urea and are called ureotelic animals.
6. In which organ of the body Ammonia produced by metabolism is converted into urea?
6. Ammonia produced by metabolism is converted into urea in the liver of these animals and released into the blood which is filtered and excreted out by the kidneys. Some amount of urea may be retained in the kidney matrix of some of these animals to maintain a desired osmolarity.
7. Name a few uricotelic animals.
7. Reptiles, birds, land snails and insects excrete nitrogenous wastes as uric acid in the form of pellet or paste with a minimum loss of water and are called uricotelic animals.
8. a. Name the animals in which protonephridia or flame cells are the excretory structures.
b. What is osmoregulation?
8. Protonephridia or flame cells are the excretory structures in Platyhelminthes (Flatworms, e.g., Planaria), rotifers, some annelids and the cephalochordate – Amphioxus. Protonephridia are primarily concerned with ionic and fluid volume regulation, i.e., osmoregulation .
9. What are nephridia? Mention their main function and group of animals in which they are present?
9. Nephridia are the tubular excretory structures of earthworms and other annelids. Nephridia help to remove nitrogenous wastes and maintain a fluid and ionic balance.
10. Which are excretory structures of most of the insects including cockroaches. 10. Malpighian tubules are the excretory structures of most of the insects including cockroaches.
11. In which animals antennal glands or green glands are present? What is their function?
11. Antennal glands or green glands perform the excretory function in crustaceans like prawns.
13. Draw a well labeled diagram of nephridia.
14. Draw a well labeled diagram of alimentary canal of cockroach showing malpighian tubules.
15. Draw a well labeled diagram of antennal glands.

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19. Extract(16-30) Human excretory system
In humans, the excretory system consists of a pair of kidneys, one pair of ureters, a urinary bladder and a urethra (Figure).
Kidneys are reddish brown, bean shaped structures situated between the levels of last thoracic and third lumbar vertebra close to the dorsal inner wall of the abdominal cavity.

Each kidney of an adult human measures 10-12 cm in length, 5-7 cm in width, 2-3 cm in thickness with an average weight of 120- 170 g.
Towards the centre of the inner concave surface of the kidney is a notch called hilum through which ureter, blood vessels and nerves enter. Inner to the hilum is a broad funnel shaped space called the renal pelvis with projections called calyces.
The outer layer of kidney is a tough capsule. Inside the kidney, there are two zones, an outer cortex and an inner medulla.

The medulla is divided into a few conical masses (medullary pyramids) projecting into the calyces (sing.: calyx). The cortex extends in between the medullary pyramids as renal columns called Columns of Bertini (Figure).

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Where is the renal fascia?
Gerota's fascia (anterior renal fascia) is thin connective tissue (collagen) that surrounds your kidneys and adrenal glands. This tissue joins with posterior renal fascia to separate your kidneys from your other organs.
Does the renal fascia protect the kidney?
Each kidney is held in place by connective tissue, called renal fascia, and is surrounded by a thick layer of adipose tissue, called perirenal fat, which helps to protect it. A tough, fibrous, connective tissue renal capsule closely envelopes each kidney and provides support for the soft tissue that is inside.
What are the 3 layers of the kidney called?
Each kidney consists of an outer renal cortex, an inner renal medulla, and a renal pelvis.

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Each kidney has nearly one million complex tubular structures called nephrons (Figure), which are the functional units.
Each nephron has two parts – the glomerulus and the renal tubule. Glomerulus is a tuft of capillaries formed by the afferent arteriole – a fine branch of renal artery. Blood from the glomerulus is carried away by an efferent arteriole.
The renal tubule begins with a double walled cup-like structure called Bowman’s capsule, which encloses the glomerulus.
Glomerulus alongwith Bowman’s capsule, is called the malpighian body or renal corpuscle (Figure).
The tubule continues further to form a highly coiled network – proximal convoluted tubule (PCT). A hairpin shaped Henle’s loop is the next part of the tubule which has a descending and an ascending limb. The ascending limb continues as another highly coiled tubular region called distal convoluted tubule (DCT).
The DCTs of many nephrons open into a straight tube called collecting duct, many of which converge and open into the renal pelvis through medullary pyramids in the calyces. The Malpighian corpuscle, PCT and DCT of the nephron are situated in the cortical region of the kidney whereas the loop of Henle dips into the medulla.
In majority of nephrons, the loop of Henle is too short and extends only very little into the medulla. Such nephrons are called cortical nephrons.
In some of the nephrons, the loop of Henle is very long and runs deep into the medulla. These nephrons are called juxta medullary nephrons.
The efferent arteriole emerging from the glomerulus forms a fine capillary network around the renal tubule called the peritubular capillaries. A minute vessel of this network runs parallel to the Henle’s loop forming a ‘U’ shaped vasa recta. Vasa recta is absent or highly reduced in cortical nephrons.

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19. Extract(31-45) urine formation Urine formation involves three main processes namely, glomerular filtration, reabsorption and secretion, that takes place in different parts of the nephron.
The first step in urine formation is the filtration of blood, which is carried out by the glomerulus and is called glomerular filtration.
On an average, 1100-1200 ml of blood is filtered by the kidneys per minute which constitute roughly 1/5th of the blood pumped out by each ventricle of the heart in a minute.
The glomerular capillary blood pressure causes filtration of blood through 3 layers, i.e., the endothelium of glomerular blood vessels, the epithelium of Bowman’s capsule and a basement membrane between these two layers.
The epithelial cells of Bowman’s capsule called podocytes are arranged in an intricate manner so as to leave some minute spaces called filtration slits or slit pores. Blood is filtered so finely through these membranes, that almost all the constituents of the plasma except the proteins pass onto the lumen of the Bowman’s capsule. Therefore, it is considered as a process of ultra filtration.
The amount of the filtrate formed by the kidneys per minute is called glomerular filtration rate (GFR).
GFR in a healthy individual is approximately 125 ml/minute, i.e., 180 litres per day !

The kidneys have built-in mechanisms for the regulation of glomerular filtration rate. One such efficient mechanism is carried out by juxta glomerular apparatus (JGA).
JGA is a special sensitive region formed by cellular modifications in the distal convoluted tubule and the afferent arteriole at the location of their contact.
A fall in GFR can activate the JG cells to release renin which can stimulate the glomerular blood flow and thereby the GFR back to normal.

A comparison of the volume of the filtrate formed per day (180 litres per day) with that of the urine released (1.5 litres), suggest that nearly 99 per cent of the filtrate has to be reabsorbed by the renal tubules. This process is called reabsorption.
The tubular epithelial cells in different segments of nephron perform this either by active or passive mechanisms. For example, substances like glucose, amino acids, Na+, etc., in the filtrate are reabsorbed actively whereas the nitrogenous wastes are absorbed by passive transport. Reabsorption of water also occurs passively in the initial segments of the nephron (Figure).
During urine formation, the tubular cells secrete substances like H+, K+and ammonia into the filtrate. Tubular secretion is also an important step in urine formation as it helps in the maintenance of ionic and acid base balance of body fluids.


19. Extract(46-60) Function of the tubules Proximal Convoluted Tubule (PCT):

PCT is lined by simple cuboidal brush border epithelium which increases the surface area for reabsorption. Nearly all of the essential nutrients, and 70-80 per cent of electrolytes and water are reabsorbed by this segment.
PCT also helps to maintain the pH and ionic balance of the body fluids by selective secretion of hydrogen ions, ammonia and potassium ions into the filtrate and by absorption of HCO3 -from it.

Henle’s Loop: Reabsorption in this segment is minimum. However, this region plays a significant role in the maintenance of high osmolarity of medullary interstitial fluid. The descending limb of loop of Henle is permeable to water but almost impermeable to electrolytes.
This concentrates the filtrate as it moves down. The ascending limb is impermeable to water but allows transport of electrolytes actively or passively.
Therefore, as the concentrated filtrate pass upward, it gets diluted due to the passage of electrolytes to the medullary fluid.

Distal Convoluted Tubule (DCT):
Conditional reabsorption of Na+ and water takes place in this segment. DCT is also capable of reabsorption of HCO3 -and selective secretion of hydrogen and potassium ions and NH3 to maintain the pH and sodium-potassium balance in blood.

Collecting Duct : This long duct extends from the cortex of the kidney to the inner parts of the medulla. Large amounts of water could be reabsorbed from this region to produce a concentrated urine.
This segment allows passage of small amounts of urea into the medullary interstitium to keep up the osmolarity. It also plays a role in the maintenance of pH and ionic balance of blood by the selective secretion of H+ and K+ ions(Figure).

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No urine should flow back into the ureter when the bladder is squeezing. Each ureter has a one-way valve where it enters the bladder that prevents urine from flowing back up the ureter. But in some people, urine flows back up to the kidney. This is called vesicoureteral reflux.

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What prevents backflow of urine into the kidneys? Once in the bladder, the ureteral valve, a mechanism that is not well understood, prevents backflow of urine to the kidney that can cause severe damage and induce end-stage renal disease.

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Mechanism of concentration of the filtrate
Mammals have the ability to produce a concentrated urine. The Henle’s loop and vasa recta play a significant role in this. The flow of filtrate in the two limbs of Henle’s loop is in opposite directions and thus forms a counter current. The flow of blood through the two limbs of vasa recta is also in a counter current pattern.
The proximity between the Henle’s loop and vasa recta, as well as the counter current in them help in maintaining an increasing osmolarity towards the inner medullary interstitium, i.e., from 300 mOsmolL–1 in the cortex to about 1200 mOsmolL–1 in the inner medulla.
This gradient is mainly caused by NaCl and urea.
NaCl is transported by the ascending limb of Henle’s loop which is exchanged with the descending limb of vasa recta. NaCl is returned to the interstitium by the ascending portion of vasa recta.
Similarly, small amounts of urea enter the thin segment of the ascending limb of Henle’s loop which is transported back to the interstitium by the collecting tubule.

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interstitium- The interstitium is a contiguous fluid-filled space existing between a structural barrier, such as a cell membrane or the skin, and internal structures, such as organs, including muscles and the circulatory system.
What's the biggest organ on your body?
The skin is the body's largest organ.
Is interstitium larger than skin?
But, according to a 2018 article , the interstitium may now be the largest organ. Their findings, which classify the interstitium as an organ, suggest that it might be bigger than the skin.
Interstitium lies below the skin’s surface and between muscles, lining the digestive tract, lungs and urinary systems, and surrounding arteries and veins. The team suspects that the interconnected, fluid-filled compartments act as shock absorbers that prevent vital tissue damage in organs, muscles and vessels.
The researchers think that the interstitium acts as a sort of shock absorber. It compresses and distends (like the lungs and even the intestines), but this change in size, they think, might be working to keep tissues in the body from tearing as other organs and muscles in the body move about.
The renal interstitium is defined as the intertubular, extraglomerular, extravascular space of the kidney. It is bounded on all sides by tubular and vascular basement membranes and is filled with cells, extracellular matrix, and interstitial fluid.

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The above described transport of substances facilitated by the special arrangement of Henle’s loop and vasa recta is called the counter current mechanism (Figure.). This mechanism helps to maintain a concentration gradient Figure .
Diagrammatic representation of a nephron and vasa recta showing counter current in the medullary interstitium. Presence of such interstitial gradient helps in an easy passage of water from the collecting tubule thereby concentrating the filtrate (urine). Human kidneys can produce urine nearly four times concentrated than the initial filtrate formed.

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19. Extract(61-70 )
Regulation of kidney function
The functioning of the kidneys is efficiently monitored and regulated by hormonal feedback mechanisms involving the hypothalamus, JGA and to a certain extent, the heart.
Osmoreceptors in the body are activated by changes in blood volume, body fluid volume and ionic concentration. An excessive loss of fluid from the body can activate these receptors which stimulate the hypothalamus to release antidiuretic hormone (ADH) or vasopressin from the neurohypophysis. ADH facilitates water reabsorption from latter parts of the tubule, thereby preventing diuresis.
An increase in body fluid volume can switch off the osmoreceptors and suppress the ADH release to complete the feedback. ADH can also affect the kidney function by its constrictory effects on blood vessels. This causes an increase in blood pressure. An increase in blood pressure can increase the glomerular blood flow and thereby the GFR.
The JGA plays a complex regulatory role. A fall in glomerular blood flow/glomerular blood pressure/GFR can activate the JG cells to release renin which converts angiotensinogen in blood to angiotensin I and further to angiotensin II.
Angiotensin II, being a powerful vasoconstrictor, increases the glomerular blood pressure and thereby GFR. Angiotensin II also activates the adrenal cortex to release Aldosterone.
Aldosterone causes reabsorption of Na+ and water from the distal parts of the tubule. This also leads to an increase in blood pressure and GFR.
This complex mechanism is generally known as the Renin-Angiotensin mechanism.
An increase in blood flow to the atria of the heart can cause the release of Atrial Natriuretic Factor (ANF). ANF can cause vasodilation (dilation of blood vessels) and thereby decrease the blood pressure. ANF mechanism, therefore, acts as a check on the renin-angiotensin mechanism.

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Atrial natriuretic factor (ANF) is a 28 amino acid polypeptide hormone secreted mainly by the heart atria in response to atrial stretch. ANF acts on the kidney to increase sodium excretion and GFR, to antagonize renal vasoconstriction, and to inhibit renin secretion.

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What does ANF in heart do? This hormone, described in 1981 as atrial natriuretic factor (ANF), is diuretic (natriuretic), hypotensive, and has an inhibitory effect on renin and aldosterone secretion. Thus, ANF probably intervenes in the short- and long-term control of water and electrolyte balance and of blood pressure.

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Which is the antagonistic hormone of ANF? Anantin--a peptide antagonist of the atrial natriuretic factor (ANF).

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Peritubular capillaries
In the renal system, peritubular capillaries are 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. Peritubular capillaries surround the cortical parts of the proximal and distal tubules, while the vasa recta go into the medulla to approach the loop of Henle. About one-fifth of the blood plasma is filtered into Bowman's capsule as the blood passes through the glomerular capillaries; four-fifths continues into the peritubular capillaries. Ions and minerals that need to be saved in the body are reabsorbed into the peritubular capillaries through active transport, secondary active transport, or transcytosis. The ions that need to be excreted as waste are secreted from the capillaries into the nephron to be sent towards the bladder and out of the body. Essentially, the peritubular capillaries reabsorb useful substances such as glucose and amino acids and secrete certain mineral ions and excess water into the tubule. The majority of exchange through the peritubular capillaries occurs because of chemical gradients osmosis and hydrostatic pressure. Movement of water into the peritubular capillaries is due to the loss of water from the glomerulus during filtration, which increases the colloid osmotic pressure of the blood. This blood leaves the glomerulus via the efferent arteriole, which supplies the peritubular capillaries. The higher osmolarity of the blood in the peritubular capillaries creates an osmotic pressure which causes the uptake of water. Other ions can be taken up by the peritubular capillaries via solvent drag. Water is also driven into the peritubular capillaries due to the higher fluid pressure of the interstitium, driven by reabsorption of fluid and electrolytes via active transport, and the low fluid pressure of blood entering the peritubular capillaries due to the narrowness of the efferent arteriole.

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19. Extract(71-75 ) Micturition-

Urine formed by the nephrons is ultimately carried to the urinary bladder where it is stored till a voluntary signal is given by the central nervous system (CNS).
This signal is initiated by the stretching of the urinary bladder as it gets filled with urine. In response, the stretch receptors on the walls of the bladder send signals to the CNS. The CNS passes on motor messages to initiate the contraction of smooth muscles of the bladder and simultaneous relaxation of the urethral sphincter causing the release of urine.
The process of release of urine is called micturition and the neural mechanisms causing it is called the micturition reflex.
An adult human excretes, on an average, 1 to 1.5 litres of urine per day. The urine formed is a light yellow coloured watery fluid which is slightly acidic (pH-6.0) and has a characterestic odour.
On an average, 25-30 gm of urea is excreted out per day. Various conditions can affect the characteristics of urine.
Analysis of urine helps in clinical diagnosis of many metabolic discorders as well as malfunctioning of the kidney.
For example, presence of glucose (Glycosuria) and ketone bodies (Ketonuria) in urine are indicative of diabetes mellitus.
19. Extract(76-80 )
Role of other organs in excretion Other than the kidneys, lungs, liver and skin also help in the elimination of excretory wastes.
Our lungs remove large amounts of CO2 (18 litres/day) and also significant quantities of water every day.
Liver, the largest gland in our body, secretes bile-containing substances like bilirubin, biliverdin, cholesterol, degraded steroid hormones, vitamins and drugs.

Most of these substances ultimately pass out alongwith digestive wastes. The sweat and sebaceous glands in the skin can eliminate certain substances through their secretions. Sweat produced by the sweat glands is a watery fluid containing NaCl, small amounts of urea, lactic acid, etc.
Though the primary function of sweat is to facilitate a cooling effect on the body surface, it also helps in the removal of some of the wastes mentioned above.
Sebaceous glands eliminate certain substances like sterols, hydrocarbons and waxes through sebum.

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Sebum is an oily, waxy substance produced by your body's sebaceous glands. Sebum is an oily and slightly waxy substance found on the skin. It is mostly produced on the face and scalp, but it can also occur on the rest of the skin, except on the palms or soles of the feet.
What causes sebum? Sebum is produced by sebaceous glands when they disintegrate. The gland cells last about a week, from formation to discharge. The sebaceous glands produce lipids, triglycerides, which are broken down by bacterial enzymes (lipases) in the sebaceous duct to form smaller compounds, free fatty acids.
Sweat and Sebum – Differences.
Sweat Sebum Secretion Sweat is secreted by sweat glands. Sebum is secreted by sebaceous glands or oil glands. Composition Sweat is composed of water and salts. Sebum is composed of oil, fatty acids, waxes and cholesterol. Odour Sweat is of a bad odour. Sebum is odourless. Type of secretion Sweat is fluid in nature. Sebum is oily in nature. Discharged from Sweat is discharged from the surface of the skin. Sebaceous glands associated with the hair follicles secrete sebum. Involved in Thermoregulation. Lubrication. Present in Present only in specific regions of the body like eyelids, ear, armpits, etc. Present throughout the body except for palms and soles.
This secretion provides a protective oily covering for the skin. Do you know that small amounts of nitrogenous wastes could be eliminated through saliva too?

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Fill in the blanks:
76. Other than the kidneys, ………, …………… and ……… also help in the elimination of excretory wastes.
77. Our lungs remove large amounts of CO2 which is ……….litres/day.
78. ……………., the largest gland in our body, secretes bile-containing substances like ………….. , ………… , cholesterol, degraded steroid hormones, vitamins and drugs.
79. The ………… and …………… glands in the skin can eliminate certain substances through their secretions. Sweat produced by the ………... glands is a watery fluid containing NaCl, small amounts of urea, lactic acid, etc. Though the primary function of sweat is to facilitate a …………… effect on the body surface, it also helps in the removal of some of the wastes.
80. ……….. glands eliminate certain substances like sterols, hydrocarbons and waxes through sebum. This secretion provides a protective oily covering for the skin. Small amounts of nitrogenous wastes could be eliminated through ………?

19. Extract(80-83). Disorders of the excretory system-
Malfunctioning of kidneys can lead to accumulation of urea in blood, a condition called uremia, which is highly harmful and may lead to kidney failure. In such patients, urea can be removed by a process called hemodialysis.
Blood drained from a convenient artery is pumped into a dialysing unit after adding an anticoagulant like heparin.
The unit contains a coiled cellophane tube surrounded by a fluid (dialysing fluid) having the same composition as that of plasma except the nitrogenous wastes.
The porous cellophane membrance of the tube allows the passage of molecules based on concentration gradient.
As nitrogenous wastes are absent in the dialysing fluid, these substances freely move out, thereby clearing the blood. The cleared blood is pumped back to the body through a vein after adding anti-heparin to it.
This method is a boon for thousands of uremic patients all over the world. Kidney transplantation is the ultimate method in the correction of acute renal failures (kidney failure).
A functioning kidney is used in transplantation from a donor, preferably a close relative, to minimise its chances of rejection by the immune system of the host.
Modern clinical procedures have increased the success rate of such a complicated technique.
Renal calculi: Stone or insoluble mass of crystallised salts (oxalates, etc.) formed within the kidney.
Glomerulonephritis: Inflammation of glomeruli of kidney.
80. Malfunctioning of kidneys can lead to accumulation of urea in blood, a condition called ………. which is highly harmful and may lead to kidney failure. In such patients, urea can be removed by a process called hemodialysis.
81. In hemodialys Blood drained from a convenient artery is pumped into a dialysing unit after adding an anticoagulant like ……..
82. In Renal calculi stone or insoluble mass of crystallised salts like ………… are formed within the kidney.
83. Inflammation of glomeruli of kidney is called ………….. 00
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