Excretion

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. 

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

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.

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.

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

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.

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.

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. 

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.

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.

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 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.

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.