Excretion and Excretory System

The cup-shaped part of nephron which receives the glomerular filtrate is called Bowman’s capsule.

The blood in kidneys is filtered by nephrons, the functional units of the kidney. Each nephron begins in a renal corpuscle, which is composed of a glomerulus enclosed in a Bowman's capsule.

Several collecting ducts unite to form larger ducts that empty urine into a calyx at the tip of the renal pyramid. 

The outlet of urine from the body is through urethra.
Urine produced in the kidneys passes through the ureters into the urinary bladder where it is released through the urethra. Ureters are the long tubes, which connect the kidneys with the urinary bladder. Urinary bladder is muscular sac where urine is stored until the pressure of the expanded bladder leads to urge to pass it out through the urethra.
Anus is the excretory opening at the end of the digestive tract, it controls the excretion of faeces produced during digestion.

Nitrogenous waste substances such as ammonia, urea and uric acid are produced during protein metabolism according to the species. Amino acids are the breakdown products of proteins in the body. Ammonia is the most toxic and requires large amount of water for its excretion. It is excreted as waste product in protozoans, e.g. amoeba, paramecium, sponges, hydra, liver fluke, earthworm, etc. Uric acid is also excreted as waste product by the most insects (e.g. cockroach), land snails (e.g. helix), land reptiles (e.g. lizards), snakes and birds. 

Renal artery gives rise to a bunch of capillaries called glomerulus.

Nephron is the basic functional unit of kidneys. Each human kidney possesses about one million structural and functional units called nephrons.

Along with the removal of waste, kidneys also maintain constant blood pressure. One of the major roles of the kidneys is maintaining the proper levels of electrolytes (such as sodium and potassium) in the body. The amount of electrolytes in the body influences the amount of fluid in the body. When electrolyte levels are high, the body retains more water, which in turn increases the volume of the blood. More blood volume results in higher blood pressure. Thus, the kidneys maintain blood pressure by indirectly controlling the amount of blood in the body. 

Kidneys are multicellular organs. They filter approximately 1100-1200 ml of blood per minute. The amount of filtrate formed by the kidney per minute is called Glomerular filtrate rate (GFR). GFR, in healthy individual, is approximately 125 ml per minute, i.e. 180 litres per day. Thus, kidney needs to have million nephrons.

Urine produced in the kidneys pass through ureters into urinary bladder.
Kidneys filter out waste products from the blood. Just as CO₂ is removed from the blood in the lungs, Nitrogenous wastes like urea or uric acid are removed from blood in the kidneys. This process is called excretion. Excretory system of human beings includes a pair of kidneys, a pair of ureters, a urinary bladder and a urethra. Kidneys are located in the abdomen, one on either side of the backbone. Urine produced in the kidneys passes through the ureters into the urinary bladder where it is released through the urethra. Ureters are the long tubes, which connect the kidneys with the urinary bladder. Urinary bladder is a muscular sac where urine is stored until the pressure of the expanded bladder leads to urge to pass it out through the urethra.
Vena cava is a large vein, which brings blood from the various parts of body to the heart.
Aorta is the largest artery and it arises from the left ventricle and supplies oxygenated blood (not in case of pulmonary artery) to various parts of body.

Kidneys filter out nitrogenous waste from blood. Also, they help in removal of excess of water from the body. Kidneys are the vital organs for survival. Several factors like infections, injury or restricted blood flow to kidneys, reduce the activity of kidneys. This leads to accumulation of poisonous wastes in the body. The composition of blood is disrupted. It may even lead to death of an organism.

Apart from kidneys, liver and skin also help in elimination of nitrogenous excretion. Liver, the largest gland in our body secretes bile containing substances like bilirubin, biliverdin, cholesterol, degraded steroid hormones, vitamins and drugs. Formation of urea also takes place in liver. Most of these substances eliminate through digestive wastes. The sweat and oil glands in the skin also eliminate substances through their secretions, e.g. sweat produced by the sweat glands comprises water, NaCl, small amounts of urea, lactic acid etc. Similarly, oil glands in the skin eliminate certain sterols, hydrocarbons and waxes. Lungs, however, do not excrete nitrogenous wastes, but remove large amounts of carbon dioxide and significant amounts of water every day.

The nature (pH) of urine is acidic as uric acid is found in it, and it imparts acidic character to urine. Uric acid is an organic acid, which reacts with strong alkali to form urate ion. The urine so formed is a light yellow coloured watery fluid, which is slightly acidic (pH 6.0) and has a characteristic odour.

The shape of human kidney is bean shaped. Kidneys are reddish brown, bean shaped structures situated in the abdomen. 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 grams.

Hemodialysis is the separation of certain substances from blood by use of a selectively permeable membrane.

In unicellular organisms, e.g. amoeba, paramecium, there are no separate excretory organs. They excrete out waste through general body surface through simple diffusion. The biological process involved in the removal of harmful metabolic wastes from the body is called excretion. These metabolic wastes include the nitrogenous materials. Different organisms use varied strategies for this. Many unicellular organisms remove these wastes by simple diffusion.
Diffusion is the movement of particles from the region of high concentration to the region of low concentration.
Filtration – It is a physical process used to separate solids from liquid or gases.
Reabsorption occurs in kidney, which selectively reabsorbs substances like glucose, protein, sodium, which had already been secreted in the renal tubule. These reabsorbed substances return to blood.
Translocation is the transport of soluble products of photosynthesis by the food conducting tissues, called phloem.
Therefore, simple diffusion is the correct answer.

 Excess water is excreted from plants through the stomata in leaves.  Plants can get rid of excess water by transpiration and guttation.

The organ that temporarily stores urine before it passes out of the body is urinary bladder. Excretory system of human beings includes a pair of kidneys, a pair of ureters, a urinary bladder and a urethra. Kidneys are located in the abdomen, one each on either side of the backbone. Urine produced in the kidneys passes through the ureters into the urinary bladder where it is released through the urethra. Ureters are the long tubes, which connect the kidneys with the urinary bladder. Urinary bladder is muscular sac where urine is stored until the pressure of the expanded bladder leads to urge to pass it out through the urethra.
While gall bladder is a pear shaped sac like structure and is attached to the liver. It stores bile secreted by the liver.
Uterus is part of human female reproductive system. It is hollow muscular and pear shaped structure.

Renal vein carries away the filtered blood from the kidneys.
Nephron is the structural and functional unit in kidneys. Each nephron is made up of 2 main parts: malphigian body and renal tubule. Malphigian body comprises a cup-shaped Bowman's capsule and a network of blood capillaries, the glomerulus. The renal artery, after entering the kidney, divides and redivides forming various afferent renal arterioles. An afferent arteriole enters a Bowman's capsule to form glomerulus. The efferent renal arteriole has narrower lumen than the afferent renal arteriole. Thereafter, an efferent renal arteriole leaves the glomerulus. The efferent renal arteriole breaks up into capillaries around the tubules. All the capillaries, in turn, unite to form renal venules and the latter together form the renal vein, which leaves the kidney. Thus, after the process of filtration in the glomerulus, renal vein has the clean or filtered blood.

Renal artery brings the dirty blood containing waste substances <span style="font-family:" arial;="" font-size:="" small;="">into the kidney. 
The renal artery, after entering the kidney, divides and redivides forming various afferent renal arterioles. This renal artery brings dirty blood containing waste substances. 

Shedding of body parts for getting rid of waste material is a characteristic of plants. Plants store the wastes in some organs like leaves or stalk, which ultimately die and are shed. In various other creatures like birds, mammals and amphibians, there is shedding of feathers or outer skin or even wings. This is different from the shedding of leaves or stalks in plants, which occur to get rid of wastes which are stored in them.

The process by which metabolic wastes are eliminated from the body is called excretion.
Metabolism includes the sum of all the chemical reactions that take place in our body. The breakdown of proteins produces nitrogenous wastes like ammonia, urea and uric acid. The elimination of such wastes from the body is termed as excretion.
Nutrition is a process by which the organisms obtain those substances, which are utilized for their growth and maintenance and for meeting their energy meets.
Filtration - It is a physical process used to separate solids from liquid or gases.
Transportation - It is the movement of water and minerals in various parts of the plant body.

The component of glomerular filtrate not reabsorbed in the tubular part of nephron is urea. Glucose and amino acids are reabsorbed to minimize the loss from the body. Also, much water is reabsorbed in the tubular part of the nephron so as to produce concentrated urine. Urea, being the chief excretory product, is not reabsorbed and is excreted out of the body.

Filtration of blood occurs in Bowman's capsule. The filtration of blood is carried out by blood capillaries (glomerulus). On an average, 1100-1200 ml of blood is filtered by the kidneys per minute. The glomerular capillary blood pressure causes filtration of blood through membranes and almost all the constituents of the plasma, except proteins, are passed through the lumen of Bowman's capsule (cup-shaped part of nephron, which receives the glomerular filtrate).
Tissue fluid is the fluid that surrounds the cells in an organism. It is aqueous in nature and is composed of amino acids, sugars, fatty acids, hormones, salts as well as waste products from the cells. Lymph is also a part of tissue fluid.
Cerebrospinal fluid is the fluid that surrounds our brain. It acts like cushion and protects our brain.

Vacuoles are the membrane-bound organelles of plant cells. These store food or waste products.

Antidiuretic hormone promotes the reabsorption of water from the nephron during urine formation. It acts on the distal convoluted tubule, collecting ducts and increases the reabsorption of water from it. Calcitonin is the hormone produced from the thyroid glands. 

Resins and gums are the excretory products of plants that are stored in xylem (water and minerals conducting channel). Resin is a viscous, thick and sticky liquid, secreted by some plants especially by coniferous trees. Gums are mucilaginous substances secreted by the plants.
Cellulose is the most abundant component of plant cell walls. Lignin is a component of cell walls, which binds cellulose fibres, confers strength and hardens the wood.

Each human kidney has about one million structural and functional units called nephrons. Each nephron is made up of 2 main parts: malphigian body and renal tubule. Malphigian body comprises a cup shaped Bowman's capsule and a network of blood capillaries (glomerulus). The renal artery, after entering the kidney, divides and redivides forming various afferent renal arterioles. This renal artery brings dirty blood containing waste substances. An afferent arteriole enters Bowman's capsule to form glomerulus. The efferent renal arteriole has narrower lumen than the afferent renal arteriole. Thereafter, an efferent renal arteriole leaves the glomerulus. The efferent renal arteriole breaks up into capillaries around the tubules. All the capillaries, in turn, unite to form renal venules and the latter together form the renal vein, which leaves the kidney.
Vasa recta are the capillaries around this loop of Henle. The vasa recta help to retain reabsorbed ions and urea.

Ureters are the long tubes which connect the kidneys with the urinary bladder. 

Each human kidney has about one million structural and functional units called nephrons. Each nephron is made up of 2 main parts: malphigian body and renal tubule. Malphigian body comprises a cup shaped Bowman's capsule and a network of blood capillaries, the glomerulus. The renal artery after entering the kidney divides and redivides forming various afferent renal arterioles. An afferent arteriole enters a Bowman's capsule to form glomerulus. The efferent renal arteriole has narrower lumen than the afferent renal arteriole. Thereafter, an efferent renal arteriole leaves the glomerulus. The efferent renal arteriole breaks up into capillaries around the tubules. All the capillaries, in turn, unite to form renal venules and the latter together form the renal vein, which leaves the kidney. Vasa recta are the capillaries around this loop of Henle. The vasa recta help to retain reabsorbed ions and urea.

The structural and functional unit in kidneys is nephron. Each nephron is made up of two main parts: Malpighian body and renal tubule. Renal tubule is the tubular part of the nephron. Malpighian body comprises cup shaped Bowman's capsule and a network of blood capillaries (glomerulus). The Bowman's capsule leads into the renal tubule, which leads to proximal convoluted tubule (PCT) and then to descending limb of loop of Henle, further to ascending limb and then to distal convoluted tubul, which further leads to collecting duct . Urine formation involves the filtration of blood, which is carried out by blood capillaries (glomerulus). On an average, 1100-1200 ml of blood is filtered by the kidneys per minute. The glomerular capillary blood pressure causes filtration of blood through membranes, and almost all the constituents of the plasma, except the proteins, are passed through the lumen of Bowman's capsule (cup shaped part of nephron, which receives the glomerular filtrate). From here, the glomerular filtrate enters the tubular part of nephron, i.e. renal tubule.

Ureters are long tubes which connect the kidneys with the urinary bladder. Urinary bladder is a muscular sac where urine is stored until the pressure of the expanded bladder leads to urge to pass it out through the urethra.

 Plants get rid off excess water by the process called transpiration. Transpiration is the loss of water in the vapour form from the exposed surfaces of plants like leaves, stem, etc. Waste products may be stored in leaves that fall off. Also, there are other waste products, which are stored as resins and gums in old xylem (water conducting system). Translocation is the means to transport food from leaves to other parts of the plant or transport of water from the roots to other parts of the plant.

Excretory system of human beings includes a pair of kidneys, a pair of ureters, a urinary bladder and a urethra. Kidneys are located in the abdomen, one on either side of the backbone.
Diaphragm is a tissue of internal muscle that separates thorax and abdomen of mammals. Abdomen comprises digestive organs like stomach, small intestine, large intestine with caecum and appendix, liver, gall bladder, pancreas and spleen; organs of urinary system like kidneys and ureters.

Water droplets are formed by the process of transpiration. 
The liquid that comes out of tree bark is actually the excretory wastes like resins, gums, alkaloids (wastes obtained from nitrogenous substances), rubber, etc. Plants do not have special excretory system. They excrete out these waste materials through the bark. Cell sap is the liquid that is stored in the cell vacuole and composed of water and sugars.

The final urine is prepared from the primary urine by reabsorption. After the glomerular filtration, absorption of selected materials occurs from the filtrate into the blood. About 65-80% filtrate is reabsorbed from here. Solutes like glucose, amino acids are absorbed so that these do not appear in urine. Also, considerable amount of water is absorbed. Hence, concentrated urine is produced.
Ultra filtration is the process that takes place in the Bowman’s capsule. On an average, 1100-1200 ml of blood is filtered by the kidneys per minute. The blood pressure of glomerular capillary causes filtration of blood through membranes and almost all the constituents of the plasma, except the proteins, are passed through the lumen of Bowman’s capsule (Cup shaped part of nephron, which receives the glomerular filtrate, is called Bowman’s capsule). Therefore, it is considered as a process of ultrafiltration.
Dialysis is the separation of certain substances from blood by use of a selectively permeable membrane. The pores in the membrane allow some substances to pass through, however, prevent others.

Oxygen is generated as a waste during photosynthesis in plants.

The process of removal of waste products of metabolism is very essential to life. Plants get rid of excretory gases through the pores (stomata) on the surface of the leaves.

Filtration of blood occurs in the kidneys in a cup shaped part of nephron, which receives the glomerular filtrate is called Bowman’s capsule.
 

Waste products are stored as resins in old xylem plants. Some plant wastes are very useful to human beings, e.g. rubber, latex, gum, resins and essential oils like eucalyptus or sandalwood oil.