Human Body : The Excretory System
Exercise
SECTION I
A. Name the following.
1. The structural and functional units of kidney.
= Nephron;
2. Straw coloured liquid that is removed by kidneys.
= Urine;
3. An organ that stores urine temporarily before it is released.
= Urinary Bladder;
4. The tube originating from renal pelvis.
= Ureters;
5. The bacterium causing UTI.
= E. Coli;
B. Choose the correct option.
1. Which of the following is the outer dark region of kidney?
a. Cortex. [✓]
b. Nephron. [ ]
c. Medulla. [ ]
d. Pelvis. [ ]
2. The excretory organs are
a. Kidneys and stomach. [ ]
b. Kidneys and lung. [✓]
c. Skin and nose. [ ]
d. Stomach and intestine. [ ]
3. The blood vessel carrying metabolic wastes into the kidney is
a. Renal vein. [ ]
b. Renal artery. [✓]
c. Aorta. [ ]
d. Vena cava. [ ]
4. The excess amino acid is changed into urea by
a. Gall bladder. [ ]
b. lungs. [ ]
c. Liver. [✓]
d. Pancreas. [ ]
5. Before being removed from the kidneys, the urine is collected in
a. Renal medulla. [ ]
b. Renal Pelvis. [✓]
c. Renal cortex. [ ]
d. Renal tubule. [ ]
C. Write true or false. Correct the false statements by changing the last word/s.
1. Apart from excretion, the other function of kidney is secretion. [F]
= Apart from excretion, the other function of kidney is osmoregulation.
2. The function of kidney is to filter urine. [F]
= The function of kidney is to filter blood.
3. The urinary bladder stores urine temporarily. [T]
4. The opening of urethra is controlled by a valve. [F]
= The opening of urethra is controlled by sphincter muscle.
5. High concentration of calcium oxalate can cause kidney stones. [T]
D. Choose the odd one out and give reasons for your choice.
1. ureter, urethra, bladder, cortex.
= Odd - cortex, it is the part of kidney. The others are the part of excretory system.
2. carbon dioxide, glucose, urea, uric acid.
= Odd - glucose, it is useful substance and absorbed by body. The others are waster materials or by product of glucose.
3. cortex, medulla, pelvis, ureter.
= Odd - ureter, it is the part of excretory system. The others are part of kidney.
4. kidney, skin, stomach, lung.
= Odd - stomach, it is the digestive organ. Others are excretory organs.
E. State the exact location of the following organs.
1. Kidneys.
= Located juts above the waist, one on each side of the backbone. The right kidney is positioned slightly lower than the left one.
2. Nephrons.
= Each kidney contains about a million nephrons. These nephrons are surrounded by capillaries.
3. Renal medulla.
= Inner part of the kidney.
4. Ureter.
= Ureters are a pair of tube-like structures that originate from the renal pelvis of both the kidneys.
5. Urethra.
= The urethra is a short muscular tube that arises from the lower end of the urinary bladder.
SECTION II
F. Define the following terms.
1. Excretion.
= Excretion is the process by which metabolic wastes are removed from the body of an organism.
2. UTI.
= Urinary track infection (UTI) is an infection that affects organs of the urinary system such as the bladder, ureter, and kidneys.
3. Urinary Bladder.
= The urinary bladder is a muscular bag-like structure present below the ureters in the lower abdomen.
4. Micturition.
= The process of expulsion of urine to the exterior is called micturition.
5. Nephrons.
= Microscopic filtering units or kidneys are called nephrons.
G. Differentiate between the following pair of words based on what is given in the bracket.
1. Ureter and urethra. (function)
= Ureters receive urine from the kidneys and transport it downwards towards the urinary bladder.
Urethra releases urine out of the body.
2. Excretion and respiration. (process)
= Excretion releases waste materials out of the body. On the other hand, respiration releases energy from food.
3. Lungs and skin. (excretory product)
= Lungs produce carbon dioxide skin produce sweat, which is a mixture of water, sodium salts, and nitrogenous wastes, such as urea.
4. Excretion and osmoregulation. (definition)
= Excretion is the process by which metabolic wastes are removed from the body of an organism.
Other than excretion, the kidney also helps in maintaining a balance between salt and water content in the body. This process is called osmoregulation.
5. Renal cortex and renal medulla. (location)
= Renal cortex is located in the outer part of the kidneys but renal medulla is located in the inner part of the kidneys.
H. Give reason for the following.
1. Metabolic wastes need to be removed from the body.
= Metabolic wastes need to be removed from the body because most of these wastes are toxic and if allowed to accumulate can be harmful to the body.
2. The flow of urine is regulated.
= The flow of urine is regulated to control the amount of water in the body.
3. It is advisable to drink sufficient water to avoid the formation of kidney stones.
= It is advisable to drink sufficient water to avoid the formation of kidney stones because water will prevent high concentration of mineral wastes, such as calcium oxalate and calcium phosphate, in the blood that is filtered by the kidneys.
4. The lungs are excretory organs.
= The lungs are excretory organs because carbon dioxide is removed from the bloodstream by lungs, which is then exhaled.
5. A person can live with one kidney.
= A person can live with one kidney. If one kidney fails to function, the other kidney enlarges and takes over the function of the damaged kidney.
I. Short answer questions.
1. Name the different excretory organs of human body.
= The different excretory organs of human body are - Lungs, Skin, Kidneys, and Liver.
2. List four different excretory wastes produced in human beings.
= Four different excretory wastes produced in human beings are - carbon dioxide, sweat, urine and bile pigments.
3. Which blood vessels carries metabolic wastes into kidney?
= Renal vein carries metabolic wastes into kidney.
4. Name two useful substances that are reabsorbed into the blood.
= Two useful substances that are reabsorbed into the blood are glucose and amino acids.
5. What is the cause of kidney stone formation?
= Kidney stone formation generally occurs when there is constantly high concentration of mineral wastes, such as calcium oxalate and calcium phosphate, in the blood that is filtered by the kidneys.
Insufficient water intake along with a diet rich in calcium are the main causes of kidney stones.
J. Long answer questions.
1. Draw a labelled diagram of the human excretory system.
=
Human Excretory System
2. Name the excretory organs other than kidneys and mention the excretory wastes produced by them.
= The excretory organs other than kidneys are -
❐ Lungs : During respiration, glucose is broken down in body cells to produce wastes in the form of carbon dioxide and water. The carbon dioxide is removed from the bloodstream by lungs, which is then exhaled.
❐ Skin : The skin contains numerous sweat and oil glands. The sweat glands secrete sweat, which is a mixture of water, sodium salts, and nitrogenous wastes, such as urea. It is excreted through sweat pores in the skin. The oil glands secrete sebum, which is a fatty substance that is also released to the skin surface. Sweating is important as it helps to regulate the body temperature and keeps the body cool.
❐ Liver : The excretory role of liver is formation of urea is transported to kidney through blood from where it is excreted. Other than this, the bile pigment, which are the excretory products from the breakdown of haemoglobin of old and worn out red blood cells, are produced in the liver. Bile pigments pass into the duodenum for removal from the body along with faeces.
3. Describe the internal structure of kidney.
= Each kidney is internally divided into two parts : an outer dark cortex and an inner lighter medulla. A wide, funnel-shaped cavity is present at the concave side of the kidneys. This cavity, called the renal pelvis, is the point where the kidney opens into tubes called the ureters.
4. Name the bacteria that causes urinary tract infection. What are the symptoms and preventive measures taken for UTI?
= The bacteria that causes urinary tract infection is E. Coli.
Urinary track infection causes pain in the pelvic region, burning sensation during urination, strong odour in urine, and increased urgency to urinate. If persistent or left untreated it may even damage the organs of the urinary system.
5. What should a person do if he is suffering from kidney stones? Can the stones be removed on their own?
= Drinking sufficient water (at least 8-10 glasses per day) is recommended to avoid the development of kidney stones. Limiting the intake of salt, oxalate-rich food, and animal protein may also help to prevent kidney stone formation.
Very small stones can pass through the ureters, causing little or no pain. However, when bigger stones block the ureters, obstructing the path of urine, it causes severe pain at the sides of the abdomen. Such complications require surgical removal of stones.
PICTURE STUDY
1. Study the picture given below and answer the questions that follow.
a. Name the parts labelled 1-5.
= 1 - Kidneys;
2 - Renal veins;
3 - Ureters;
4. Urinary bladder;
5. Urethra;
b. Which organ system do they constitute?
= They consist of excretory organ system.
c. What are the functions of the structures 1 and 4?
= The function of 1 is to filtering blood and producing urine. The function of 4 is to store urine temporarily and remove it later through a short tube, called the urethra.
d. Name the liquid expelled out from part 5. List two components present in the liquid.
= The liquid expelled out from the part 5 is urine.
Two components present in the liquid are - water and urea.
2. The figure given below is the internal structure of human kidney.
a. Which kidney, right or left, is placed slightly lower in human body?
= Right kidney, right or left, is placed slightly lower in human body.
b. Name the parts numbered 1 to 5.
= 1 - Renal cortex;
2 - Renal medulla;
3 - Renal artery;
4 - Ureter;
5 - Renal pelvis;
c. What are the structural and functional units of kidney?
= Nephrons are the structural and functional units of kidney.
d. Give the number and name of the part of kidney where urine is collected.
= The part of the kidney where urine is collected is renal pelvis. They are one in each kidney.
e. Name any two constituents of the blood that are reabsorbed by nephrons in the kidneys.
= Two constituents of the blood that are reabsorbed by nephrons in the kidneys are - glucose and amino acids.