Excretory system- Shankarlal Chhetri
Self test questions
1. Given below is a list of substances—select the ones that need to be got rid off from the
Glucose, excess water, amino acid, urea, carbon dioxide, excess common salt, glycogen,
uric acid.
Ans: excess common salts, excess water, urea, carbon dioxide, uric acid.
2. Undigested and unabsorbed food which passes out is termed as excreta in popular
language. Is it a kind of excretion?
Ans: No! all the undigested food are not directly involved in the cellular metabolism,
excretion refers to the all the activities that are taking place in the cellular metabolism.
All wastes that has been produced from the each cells are collected by the circulatory
system and majors separation happens in the kidney and others surfaces of the body.
Name the following:
The tube arising from the notch of the kidney on the median side and connecting
behind with the urinary bladder.
Ans: ureter
The tube that passess the urine to the outside of the body.
Ans: Urethra
The inner lighter coloured region of the kidney.
Knot-like mass of blood capillary inside Bowmann’s capsule.
Ans: Glomerulus
The structural and functional unit of kidney
Ans:Nephron/uriniferous tubule
State if the following statements are true or false.
i) The blood flows through glomerulus under great pressure
Ans: True
ii) Glomerulus filtrate consists of many substances such as water, salts, glucose and white blood
Ans: True
iii) Sodium Chloride contained in glomerulus filtrate is fully reabsorbed in the renal tubule
Ans: False
Excretory system- Shankarlal Chhetri
iv) Besides the normal constituents, the urine may pass out excess vitamins but not the antibodies
Ans: False
v) Excessive uric acid and urine may produce Kidney stones [Ans: True]
Review questions:
1. Select the correct answer out of the four available choices given under each.
a) Excretion primarily involves
Removal of all byproducts during catabolism
Removal of by products during anabolism
Removal of nitrogenous wastes
Throwing out excess water.
Ans: Removal of nitrogenous wastes
b) Maximum amount of water from the glomerulus filtrate is absorbed in
Proximal convoluted tubule
Descending limbs of loop of Henle
Ascending limb of loop of Henle
Distal convoluted tubule
Ans: proximal convoluted tubule
c) Sodium reabsorption occurs in kidney tubules under the influences of
Amount of sodium in the blood
Amount of sodium in the urine
The hormone rennin
Ans: ADH
d) Which one of the following is not an excretory activity?
Removal of carbon dioxide
Removal of faecal matter
Removal of sweat due to perspiration
Removal of urea
Ans: Removal of faecal matter
e) In Human urea is formed in
Body tissue
Excretory system- Shankarlal Chhetri
Ans: Liver
2. Name the following:
a. The organ which produces urea [ liver]
b. The outer part of kidney containing the Bowmann’s Capsule [ Malphigian capsule]
c. The tuft of capillaries in a nephron [ Glomerulus]
d. The part where the term urine is first use for the fluid in it. [Ureter]
e. The vein in which urea concentration is maximum [ Renal vein]
Define the following terms:
a. Ultrafiltration
 The blood flows through the glomerulus under great pressure which is much greater
than in the capillaries elsewhere. The reason for this greater pressure is that the efferent
arteriole is narrower than the afferent incoming arteriole. This high pressure hydrostatic
pressure causes the liquid parts of the blood to filter out form the glomerulus into the
renal tubule. This filtration under extraordinary force is called ultrafiltration.
b. Micturition
 urine is expelled from urinary bladder through urethra by relaxation of urinary bladder
into urinary bladder into urethra under impulse form the nervous system. Such a process
is called micturition.
c. Renal pelvix
 the front end of the ureter is somewhat expanded into the kidney and is called pelvis.
d. Urea
 urea is highly poisonous nitrogenous wastes produced as results of the metabolites
waste from the cells. If allowed to accumulate in the blood to a certain level it causes
e. Osmoregulation
 the kidney while removing wastes like urea from the blood also regulates its
composition. i.e. the percentage of water and salts. This function is called
3. Look at the figure given below. It is a section of Human Kidney as seen from the front.
Excretory system- Shankarlal Chhetri
a. Is it the left kidney or the right one? Give reason for your answer.
Ans: It is right kidney
b. Is it longitudinal section or a cross section?
Ans: it is longitudinal section
c. Name the part numbered 1-6
1 Pelvis
2Renal Artery
4 cortex
5 Papilla
6 Pyramid
Write down the functional activity of the given organs.
Glomerulus ultrafiltration
Henle’s loop selection reabsorption
Ureter collect the urine and transfer to urinary bladder
Renal artery carries impure blood for filtration
Urethra excrete out the wastes as urine
Given below are two sets of five terms. Rewrite the terms in correct order to be in logical
a) Afferent arteriole, renal vein, capillary network, glomerulus, efferent arteriole.
Ans: Afferent arteriole, capillary network, glomerulus, efferent arteriole, renal vein
b) Renal artery, urethra, ureter, kidney, urinary bladder
Ans: Renal artery, kidney, ureter, urinary bladder, urethra.
6. Why is excretion necessary? Name the common excretory substances in our body.
Ans: A large number of waste products are formed during the metabolic activities in the
body. These products become toxic or harmful if retained inside. Large amounts of
carbond dioxide and water are produced by metabolism of carbohydrates, fats and
protein. Nitrogenous wastes such as ammonia, urea, uric acid etc.. Are formed protein
and other complex nitrogenous compound.
The wastes are carbon dioxide, water and nitrogenous waste.
7. What is uriniferous tubule? How does it function?
Ans: The kidney is composed of an enormous number of minute tubules called
uriniferous tubules; these are the structural as well as functional units of the kidney. The
blood flows through the glomerulus under great pressure which is much greater than in
Excretory system- Shankarlal Chhetri
the capillaries elsewhere, this high pressure causes the liquid part of the blood to filter out
from the glomerulus into the renal tubule. This filtration under force is ultrafiltration.
During ultrafiltration almost all the liquid part of the blood comes out the glomerulus and
passes into the funnel-shaped cavity of the Bowmann’s capsule, the fluid entering the
renal tubule is called the glomerulus filtrate consist of water, urea, salts, glucose and
other plasma. Thus blood proceeding away from the glomerulus is relatively thick. The
glomerular filtrate entering the renal tubule is not urine. It is an extremely dilute solution
containing a lot of usable materials including glucose and some salts such as those of
sodium. As the filtrate passes down the tubule, much of the water is reabsorption is only
to the extent of that the normal concentration of the blood is not disturbed. This is called
selective absorption.
Certain substance like K+ions in the normal course, and large number of foreign
chemicals including drug like penicillin are passed into the forming urine in the distal
convoluted tubule. This passage involves the activity of the cells of the tubular wall, and
hence it is called tubular secretion.
8. Why is it necessary to maintain a normal osmotic concentration of the blood?
Ans: The kidney while removing wastes like urea from the blood also regulates its
composition, i.e. the percentage of water and salts. This function is osmoregulation and
its implies the regulation of osmotic pressure of the blood.
9. If you donate one kidney to a needy patient, would it cause any harm to you? Give
Ans: if one kidney is donated for the needy patient, another kidney is sufficient for
excretory needs and the person can lead a normal life. There is no harm in donating a
single kidney, however, both malfunctioning kidney may lead to the death.
10. In summer the urine is slightly thicker than in winter. Explain why?
Ans: we urinated fewer times in summer tank in winter and the urine passed is generally
thicker, the reason is obvious, we lose a considerable part of water through perspiration
and the kidneys have to reabsorb more water from the ureine making it more
11. Differentiate between the following pairs of terms:
a. Bowman’s Capsule and Malpighian capsule
b. Renal cortex and renal Medulla
c. Renal Pelvis and Renal medulla
d. Renal pelvis and papilla
e. Urea and urine
Excretory system- Shankarlal Chhetri
Bowman’s capsule
It is thin-walled cup, something like a
hollow ball pressed deep on one side. Its
hollow internal space continuous into the
Renal cortex
Malpighian Capsule
The Bowman’s capsule and the
glomerulus together are called
Malpighian capsule or just renal capsule
Renal Medulla
It is outer region of LS of kidney with
dark cortex.
Inner lighter region of LS of Kidney
which is composed of a finely striped
substance arranged in several pyramid.
Renal Pelvis
The front end of the ureter is somewhat
expanded into the kidney is called Pelvis
Renal medulla
Inner lighter region of LS of Kidney
which is composed of a finely striped
substance arranged in several pyramid.
Renal pelvis
The front end of the ureter is somewhat
expanded into the kidney is called Pelvis
The apex of each pyramid prject into the
Pelvis of the Kidney
It is chief nitrogenous that our body
needs to be got rid off.
It is ultimate products of urine containing
some salts and all metabolic wates
12 . What is dialysis? Under what condition is it carried out?
Ans: If therer is failure of both the kidneys would lead to death. Artificial Kidney is a
dialysis Machine. The patient’s blood is led from the radial artery in his arm through
the machine where the urea and excess salts are removed and the purified blood is
returned to a vein in the same arm. In cases of permanent damge to the kidney
dialysis is to be repeated for about twelves hours twice a week.
13. Name the main nitrogenous metabolic waste excreted out by mammals.
Ans: these include urea, uric acid, Ammonia.
Excretory system- Shankarlal Chhetri
14. Given alongside is the figure of certain organs and associated parts in the human
body. Study the same and answer the question that follow;
a. Name all the organ system shown completely or Partially
Ans: Excretory system and circulatory system
b. Name the parts numbered 1-6
2Proximal convoluted tubule
3Henle’s loop
4 Bowman’s Capsule
5 Distal convoluted tubule
6 Ureter
c. Name the structural and functional unit of the part marked ‘1’
Ans: uriniferous tubule
d. Name the two main organic constituent of the fluid that flows down the part
labelled ‘3’
Ans: Glucose & Vitamin
e. Name the two major steps involved in the formation of the fluid that passes down
the the part labelled ‘3’
Ans: Tubular secretion & Selective Reabsorption.
15. Fill in the blanks in the following passages to make a meaningful description
In a Nephron, the ………blood …………flows through
the…Glomerulus………under great pressure. The reason for this great pressure is
Excretory system- Shankarlal Chhetri
that the…………efferent arteriole……(outgoing)…….is narrower than the
……………afferent arteriole……(incoming). This high pressure causes the
Liquid………….part of the blood to filter out from the ……Glomerulus….into
16. The following diagram represented a mammalian kidney tubule and its blood supply.
Parts indicated by the guidelines 1-8 are as follows
Math the items in Column I with those in Column II
Bowman’s Capsule
a. Renal artery
Contains more CO2 and less Urea
b. Regulates amount of water excreted
Antidiuretic Hormone
c. Renal vein
Contains more urea
d. Glomerulus
Ans: Bowman’s capsule Glomerulus
Contains more CO2 and less Urea Renal Vein
Antidiuretic Hormone Regulates amount of water excreted
Contains more urea Renal Artery.

Excretory system- Shankarlal Chhetri