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#	Question	Answer
1	What are the major forms of nitrogenous wastes excreted by animals?	Ammonia, urea, and uric acid.
2	Name the animals that are ammonotelic in nature.	Many bony fishes, aquatic amphibians, and aquatic insects.
3	Where is ammonia converted into urea in ureotelic animals?	In the liver.
4	Which excretory structures are found in Platyhelminthes?	Protonephridia or flame cells.
5	What are the functions of Malpighian tubules?	Removal of nitrogenous wastes and osmoregulation.
6	What is the average size of an adult human kidney?	10 - 12 cm long, 5 - 7 cm wide, and 2 - 3 cm thick.
7	Name the two zones inside the kidney.	Cortex and medulla.
8	What are the two main parts of a nephron?	Glomerulus and renal tubule.
9	Approximately how many nephrons are present in each kidney?	Nearly one million.
10	Into which structure do the DCTs of many nephrons open?	Collecting duct.
11	What are juxta medullary nephrons?	Nephrons with very long loops of Henle running deep into the medulla.
12	What is the first step in urine formation?	Glomerular filtration.
13	What are filtration slits or slit pores?	Minute spaces left between podocytes.
14	What is JGA?	A special sensitive region formed by cellular modifications in the distal convoluted tubule and afferent arteriole at their contact point.
15	How are nitrogenous wastes reabsorbed?	By passive transport.
16	What percentage of electrolytes and water are reabsorbed in the PCT?	70 - 80%.
17	What is the role of the collecting duct in blood homeostasis?	Maintenance of pH and ionic balance of blood.
18	What is the main function of the counter current mechanism?	Maintenance of concentration gradient in the medullary interstitium.
19	Which hormone is released due to excessive loss of body fluids?	Antidiuretic hormone (ADH) or vasopressin.
20	How can ADH increase blood pressure?	By causing constriction of blood vessels.
21	What type of substance is angiotensin II?	A powerful vasoconstrictor.
22	Which factor is released when blood flow to atria increases?	Atrial Natriuretic Factor (ANF).
23	Where is urine stored before release?	Urinary bladder.
24	How much urine does an adult human excrete on average per day?	1 to 1.5 litres.
25	What is ketonuria?	Presence of ketone bodies in urine.
26	Through what are bile pigments and other liver wastes eliminated?	Digestive wastes.
27	What is sebum?	Secretion of sebaceous glands providing oily covering to the skin.
28	What is the dialysing unit used in hemodialysis called?	Artificial kidney.
29	Through which vessel is purified blood returned to the body after dialysis?	Vein.
30	What are renal calculi?	Stones or insoluble masses of crystallised salts formed within the kidney.
31	What are the components of the human excretory system?	One pair of kidneys, one pair of ureters, a urinary bladder, and a urethra.
32	What are the three main processes involved in urine formation?	Filtration, reabsorption, and secretion.
33	Which structure regulates GFR?	Juxta Glomerular Apparatus (JGA).
34	How much can DCT and collecting duct concentrate the filtrate?	About four times.
35	Why are terrestrial animals generally ureotelic or uricotelic instead of ammonotelic?	To conserve water because ammonia requires large amounts of water for elimination.
36	Dialysis fluid contains all plasma constituents except _______.	Nitrogenous wastes.