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13
Transportation in
Animals and Plants
LearningObjectives KNOWTHESE POINTS BEFORE YOU START
Heart isa muscular organ. Its walls are formed ofcardiac muscles.
Removal of toxic waste from the body of an organism is called excretion.
The students will be able to
know parts of circulatory
system, blood, blood
vessels and capillaries. Kidneys, skin, lungsand rectum are excretory organs. Kidneys filter out wastes
and excess of water from blood and remove them as urine.
know the working of
heart and circulation of Food manufactured by leaves is transported to the nongreen parts ofthe plant
through phloem. It is called translocation.
Loss of water from aerial parts of plant due to evaporation is called
transpiration.
blood.
know heartbeat and
about heart sounds
learn types of body
wastes and excretory
system in human beings. Now, study the chapter in detail.
know transport system in
plants.
+understand the process
of transpiration in plants.
TRANSPORT OF MATERIALS
All organisms have a way of transporting substances from one part of
the body to another. Complex animals and plants have well developed
transport system. It is responsible for the following functions:
Supply of nutrients and oxygen to every cell of the body.
Transport of substances formed in one part of the body to those
parts where they are needed, ike hormones and certain enzymes
in animals and food in plants.
Removal of harmful substances produced during different
biochemical processes like carbon dioxide, ammonia and urea,ete
from the place of formation to the region of excretion.
Plasma is the nonlivin liquid part of the
blood. It is
yellowish fuid that makes up
more than half of blood volume. It removes
carbon dioxide and wastes from the cells.
Mode of transport
transported are also different.
Transport in animals takes place by
Transport
in plants takes place by vascular
A n i m a l s
and plants have different modes
of
t r a n s p o r t
of substances. The substances
Plasma transports:
dissolved food to the cells,
oxygentothecells,
enzymes, hormones and
chemicals in the
body.
Blood cells or
corpuscles are the livingpart
of the blood. There are three kinds of blood
circulatory system.
system.
CIRCULATORY SYSTEM
Circa
irculatory system is the life support system
corpuscles.
Red blood corpuscles (RBCs) are
cells without nucleus. Their cytoplasm
has oxygen carrying pigment called
haemoglobin. It gives red colour to
these corpuscles (hence, red blood
corpuscles). It combines with oxygen to
form
oxyhaemoglobin,which transports
oxygen to all the body cells. RBCs live for
90 to 120 days (i.e., 3 to 4 months) only.
White blood corpuscles (WBCs) are
of different types. They have differently
shaped nuclei. They defend the body
against infection. They fight against
germs and also provide immunity against
infection. Normally, there is only one
WBC for every 600 RBCs. The white
blood corpuscle count goes up when there
is any infection in the body. WBCs are
called soldiers ofthe body.
Blood platelets are very minute cells
present in the blood. They help to stop
bleeding by clotting the blood.
that provides our body cells with food and
oxvgen. It takes away waste products from
the body cels.
Circulatory system is a system of vessels
which connects all the cells, tissues and
organs of the body together.
Parts of circulatory system
There are three main parts of the circulatory
system- blood, blood vessels and heart.
TABLE 13.1 ParTs OF CIRCULATORY SYSTEM AND
THEIR FUNCTIONS
Parts Function
Blood Fluid medium that transportssubstances
Blood vessels (arteries, Through them blood flows throughout
veins and capillaries) the body.
Heart Pumps the blood into blood vessels.
Blood
Blood is a fluid connective tissue. It is a
red-coloured viscous (thick and sticky) fluid
that flows in the blood vessels. Blood has
following functions:
It
supplies food and oxygen to every cell
of the body. Check PeINT 1
1. Name two functions of plasma.
2. What is the lifespan of RBCs?
3. When does the WBC count go up?
4. What are the functions of circulatory system?
It removes wastes from the cells.
It
helps in regulating body temperature.
* it
protects body against infection.
blo
The blood has two components-plasma and 5. What is haemoglobin?
blood cells or
corpuscles. 6. Which blood cells help in blood clotting?
Granules in Nuclei of different shapes
cytoplasm
Agranulocytes
Cytoplasm without granules
Granulocyte
Red Blood Corpuscles
White Blood Corpuscles Blood Platelets
Fig. 13.1 Bloodcorpuscles in human blood
Blood vessels
Activity
To count the pulse rate of a friend
Ask your friend or classmate to sit comfortably and
place the right hand on the table. Place your index
and middle fingers on the inner side of the wrist as
shown in figure and feel the throbbing movement of
blood flow. Start a stopwatch and count the number
Blood flows through a
system of tubes called
blood vessels. There are three kinds of blood
vessels arteries,veins and capillaries.
Arteries
Arteries carry blood away from the heart.
They have thick and muscular wall. The force
of heart pumping keeps the blood flowing
through arteries.
The blood in arteries is bright red in
colour because it contains a lot of oxygen
(oxyhaemoglobin is bright red in colour). In
arteries, blood flows with jerks and under
great force. We can feel the blood flow in
radial artery on the inner side of the wrist.
of throbs or beats in one minute.
Repeat the activity with other friends and record in
a table as given below:
Activity
To feel own pulse and count the pulse rate
S. o. Name of classmate Pulse rate/minute
Place the index and
middle fingers of the
right hand on the
inner side of the wrist
Note: The pulse rate increases during fever or high
blood pressure.
of your left hand. Press
lightly and feel the
throbbing movements.
The throbbing movements correspond to the blood
being pumped by the heart into the artery. This
throbbing is called pulse. The number of pulses or
throbs produced per minute is called pulse rate.
A normal healthy person has a pulse rate between
72-80 beats per minute.
The largest artery in the body is called aorta.
It arises from the left ventricle of heart.
This branches out into arteries. On entering
some body organ, each artery is divided into
smaller and smaller vessels which end into
fine capillaries.
Very thin wall
Wide lumen
Thick wall
Thin wall
Narrow lumen
Artery Vein Capillary
Fig. 13.2 Blood vessels
TABLE 13.2 DIFFERENCES BETWEEN
Veins
ARTERY, VEIN AND CAPILLAR
Veins carry blood from various body organs
to the heart. They have thin walls. The
valves present inside veins make the blood
to flow only towards the heart. The flow
of blood in veins is not jerky and the
blood is deoxygenated and so it is darker in
colour.
Artery Vein Capillary
1. Thick-walled with 1. Thin-walled with 1. Thin-walled
wide lumen.
narrow lumen. narrow tubes
with narrow
lumen.
2. Blood flows from|2. Capillaries join
body organs tothe
2. Blood flows from
heart to other artery with the
body parts. heart. vein and form a
network in the
You can see some of your veins because they
are just under the skin (1.e., superficial). They
are more prominent in old persons.
body organs.
3. Supplies blood to 3. Collects blood
frombody organs
and bringsitback
3. Helps in the
exchange of
food, oxygen and
body organs.
to heart. carbon dioxide
between blood
andtissues.
4. Situated just under4. Situated very deep
within the organs.
4. Situated deeper
under the skin. the skin.
|5. Carries oxygenated 5. Carries
blood (except
5. Carries both
types of blood.
deoxygenated
blood (except
pulmonary veins).
Valves pulmonaryarteries).
Fig. 13.3 A part of vein showing valves
Heart
Veins begin as capillaries. They join and
ejoin to form large veins that open into the
Tight auricle of heart.
Heart is a living pump. It is of the size of a
fist and is shaped like a cone. It lies between
the lungs in our thoracic (chest) cavity.
Its walls are formed of cardiac muscles.
Capillaries are the finest blood vessels. They These muscles contract and relax tirelessly
connect arteries with veins. The capillaries throughout life. Because of cardiac muscles,
the heart beats continuously and pumps blood
into the arteries to be transported to all parts
Capillaries
from blood to the cells and carbon dioxide of the body.
and waste products pass from cells to the Our heart is four-chambered. It has two
ave very thin walls (only one cell thick).
t the capillaries, food and oxygen pass
blood. auricles or atria and two ventricles. The
heart is divided into two halves by a thick Ventricles
ean
muscular septum. Each half has an auricle These are distributingchambersof thehe
TIcle
above and a ventricle below. The right halfof Their walls are thick. The right ventril
the heart has deoxygenated blood while the
left halfhas pure or oxygenated blood. The
receives deoxygenated blood trom right aurice
and pumps it to the lungs for
oxygenation
gest
septum prevents mixing of deoxygenated and
purification.The left ventricle is thelarge
oxygenated blood present in the right and left
heart chamber and has the thickestwalls..
receives oxygenated blood from left auric
and pumps it to the whole body.
There are four valves in the heart. Theu
control the direction of blood flow inthe
heart and into the blood vessels. Theyopen
and close about 100,000 times a day.
A tricuspid valve guards the opening of
right atrium into right ventricle.
A bicuspid valve guards the
openingoflft
halves of the heart.
ricle
Aorta
Right
Left
auricle
auricle
Right FLeft
ventricle atrium into left ventricle.
ventricle
Three semilunarvalves are
present at the
base ofpulmonary aorta and dorsal aorta
Fig. 13.4 Human heart
respectively.
Auricles or atria (sing. atrium) When atria contract, the cuspidvalves open.
Auricles are the receiving chambers of When ventricles contract, the pulmonaryand
the heart. Their walls are thinner than aortic semilunar valves open andcuspid valves
those of ventricles. The right auricle receives are slam shut.
deoxygenated blood from the whole body
while the left auricle receives oxygenated Working ofheart and circulation ofblood
When both atriaand ventricles are relaxed,
both the atria get filled with blood. The
right atrium receives deoxygenated blood
from various parts of the body and the left
atrium receives oxygenated blood trom
blood from lungs.
Aorta-
Pulmonary
artery
lungs by pulmonary veins.
Semilunar
valves Now both atria contractsimultaneouslyanu
their cuspid valves open up. Blood from let
atrium comes in the left ventricle and from
right atrium into right ventricle.
Both the atria relaxand ventriclescontra
The cuspid valves are slam shut and
semilunar valves open up.
Bicuspid
valves
Tricuspid-
Septum
valve
Thick
wall of
ventricle
Fig. 13.5 Internal structure of heart
30
Heartbeat and heart sounds
Right
pulmonary
artery
Aorta
The rhythmic contraction and relaxation of
auricles and ventricles is known as heartbeat.
Human heart beats about 72 times per
minute. One heart beat includes:
Pulmonary
Superior
trunk
Left auricle
vena cava-
Oxygenated
blood from
Right auricle-
a phase of contraction of heart muscles -
Systole.
a phase of relaxation of heart muscles and
general pause
-
Diastole.
During diastole, heart receives blood and
during systole, first atria contract to push
the blood into ventricles and then ventricles
lungs
Inferior
vena cava
Deoxygenated
blood-
-Left ventricle
Right
ventricle-
Fig. 18.6 Path of blood flow through heart
The oxygenated blood from left ventricle is contract to pump blood into their respective
pumped into aorta and is distributed to all blood vessels.
bodyparts by arteries. The deoxygenated
Thus, contraction ofatrial chambers and then
blood from right ventricle is pumped iinto ventricular chambers are the two phases of a
pulmonary aorta and is transported to lungs heartbeat. These two phases of heartbeat can
by the pulmonary arteries for oxygenation. be heard as lub and dub sounds. The sound
of heartbeat is caused by the contraction of
muscles and shutting down of valves.
In the lub phase, the ventricles contract
and cuspid valves close.
In the dub phase, the pulmonaryand aortic
Lungs
Lung
capillaries
Pulmonary vein
Lung capillaries valves close.
Pulmonary artery Aorta Can we hear lub-dub sound of heart?
Right auricle- -Left auricle
Heart
Left
Vena cava-
Right ventricle Yes, we can hear it by placing our ear
on the left side of the chest of our
friend.
ventricle
Capillary networks
in head, limbs and
internal organs
Activity
To make a model of stethoscope
Take a funnel having a diameter of 6-7
cm. Fix a rubber tube about 50 cm long
Fig. 13.7 Circulation of blood in humans
on the stem of funnel and stretch a
rubber sheet or a balloon on the mouth
SonethingMore of the funnel. Fix it with a rubber band.
The discoveryof blood circulation in the body was
made by Wiliam Harvey. He showed that blood
Circulates in the body in a closed system of vessels.
Place the open end of the tube on one
of your ears and mouth of the funnel on
your chest near the heart. You can hear a
thumping sound. These sounds are heart beats.
131
A normal heart repeats these lub-dub sounds
about 72 times per minute. Doctors use
stethoscope to hear this lub-dub sound.
Renal artery-
Renal vein- Kidney
Inferior
Activity Aorta
vena cava
To find out whether heartbeat rate remains
unchanged
Count the number of heartbeats in one minute
Ureter
when you are resting or sitting and relaxing. Then
run for about 4-5 minutes and record the rate of Urinary bladder
heartbeat. Compare the two observations. You can
repeat these observations with yourfriends also.
- Urethra
Urinary opening
Fig. 13.8 Human excretory system
Check PeINT 2-
Name the following.
1. The blood vessels that carry blood from heart to
other parts of the body.
2. The valve that guards the opening of right atrium on either side of backbone. The renal artery
Kidneys
Kidneys are brown-coloured bean-shaped
organs present in the abdominal cavity one
into ventricle.
brings blood to the kidneys and renal vein
3. The scientist who discovered circulation of blood.
takes it away. While passing through the
4. The blood vessel that receives blood from left
kidnevs, blood is filtered and excess of water
ventricle.
5. The instrument which is used to hear heartbeat. and nitrogenous wastes are removed in the
form of urine.
EXCRETION IN ANIMALS The urine is removed from the kidneys by
Numerous biochemical reactions occurrounda pair of tubes called ureters. It is collected
the clock in all living cels. They produce a and stored in the urinary bladder and is
variety of waste products like carbon dioxide, finally disposed off through urinary opening
located at the end of urethra. The urethra is
ammonia and other nitrogen compounds. If
they accumulate in the body, they may prove
to be toxic.
a muscular tube.
Something More
The process of removing toxic wastes from
the body is called excretion and the organs
Dialysis: Removal of wastes is important for all
living organisms. Normalkidneyfunction is essential
for good health. Human beings have two kidneys.
If one kidney is damaged, the other kidney fuiils
the excretory needs. But if both the kidneys are
damaged, the person cannot survive because of the
accumulation of toxic wastes in the body. Therefore
the nitrogenous wastes from the blood are periodicaly
removed by artificial kidney or the dlalysis machine.
The process of filtering blood and the remoyal o
wastes by the machine is called dialysis.
that remove these toxic wastes are called
excretory organs.
Types of body wastes
Table 13.3 given below shows three types of
wastes and the systems used to eliminate them.
Excretory system in human beings
Excretory system in humans has a pair of
An examination of urine gives an indicati0n
kidneys, a pair of ureters and a
urinary of the functioning of other organs in the
bladder and a urethra.
body. A doctor asks the patients to get ther
urine examined in order to diagnose certain Skin as
excretory organ
diseases. In case excess sugar, pus cells or other Sweat glands in the skin remove water, salts,
materials are found, it indicates that some
urea, etc. from the blood flowing through
organ of the body is not functioning properly. blood capillaries in the skin. They open on
The presence of sugar in urine indicates that the surface of skin by tiny pores. The fluid
the person is suffering from diabetes. In this that comes out of the body through these
disease, sugar level increases in blood instead pores is called sweat.
of moving into the cells to provide energy.
Some ofthe excess sugar is carried out ofthe
body through urine.
Why do we sweat in summer?
TABLE 13.3 Major TYPES OF BOoDY WASTESs
In summer when we feel hot due
to external heat, sweating and
evaporation of sweat makes the body
cool. Sweat evaporates from the
body surface. Evaporation needs heat
which is obtained from the body. So
we sweat in summer and also feel
Types of waste Example System too
eliminate them
Carbon dioxide Respiratory system
Digestivesystem
Gaseous waste
Solidwaste Faeces
Chemical waste (water,| Urine and sweat
salt,urea,etc.)
Excretory system
and skin
more thirsty.
Something More
Hair
We have 5.5 to 6.5 litres of blood circulating in
our body. Sweat
Kidneys clean all the blood in our body every
30 minutes.
pore
Receptors
About 200 litres of blood is fitered by kidneys
each day.
About 1.5to2.0itres of urine isexcretedin24 hours.
Urinecontains95% water, 2.5% urea and 2,5% of
other waste products. Sweat
Hair root gland
Blood
vessels
Activity Fig. 13.9 V.S. of skin
To test urine for the presence of glucose
Collect a small sample
of urine in a test tube.
Add a few drops of the
blue-coloured Benedict's
Why do our coloured clothes develop
white patches in the areas of under
arms?
solution to the urine.
Warm the mixture and
observe the change in
colour if any. Repeat the
above test with the urine
There is more sweating in underarm
area. The sweat contains salts. When
sweat from the clothes dries, the
water evaporates and salt is left
behind. This forms white patches on
Our clothes.
samples of your friends.
Record the change of
colour and discuss with your teacher.
Check PeINT 3 . Transport of water and minerals
The
Water is absorbed from soil by root hair, T
Fill in the blanks.
1.
Bean-shaped organ that removes nitrogenous are in close contact with water betweenthe
particles. Water and dissolved minerals
from root hair to the cells of root co
then to the xylem vessels.
wastes is called
mOove
2. Urea and uric acid are
3. The structural unit of kidney is
4. Artificial filtration of blood is carried out to
Cells of leaf
remove
TRANSPORT OF SUBSTANCES IN PLANTS Xylem vessel
in leaf
There are three different kinds of plants,
i.e., herbs, shrubs and trees. Though, the
complexity may vary but the mode of transport
in all the three types is the same. Plants have
a
well-developed transport system. It is called
vascular system. It has two main functions.
It transports water and minerals dissolved
in water from roots to all the aerial parts
of the plant
It transports the food synthesisedinleaves
to various parts ofthe plant right up to the
Xylem vessel in
the stem
Stoma
Film of water
Transpiration
Cells of
Soil particle root
Epidermis
Root hair Endodermis
roots.
Fig. 13.10 Path of water and minerals in plants
Vascular system
Vascular system consists of pipe-like vessels
arranged end to end. They extend from tips
of roots to the tips of leaves passing through
the stem. The vascular system is also called Scientists were also amazed to
conducting tissue. It is formed of two types
of cells also known as vessels - xylem vessels
and phloem vessels.
How can water move so high upto
the leaves of high trees?
see water reaching several metres
high in trees which were as tall as
15 metres. Two forces were found
responsible for this. Continuous
evaporation of water from the leaves
(transpiration) produces a suction
Xylem vessels
The xylemvessels transport water and dissolved force 1that pulls water upwards
minerals upwards from roots through stem to
the tips of leaves against the force of gravity.
This upward movement ofwater and minerals
is called ascent of sap.
(transpiration pull) in xylem vessels.
Continuous movement of water from
the root cells produces a
pushing
force. It pushes water upwards.
These vessels form a continuous network
Phloem vessels of channels through the stem and branch
These carry food synthesised by the leaves upto the tips of leaves, and transport wate
downwards to all the parts of a plant. and minerals to all the parts of a plant.
Translocation of food
The transport of food from leaves to all
other parts of plant is called translocation.
The food is manufactured in the mesophyll
cells of the leaf. From mesophyll cells, it
enters into the sieve tubes of phloem as
dilute (weak) solution and is transported
to all nongreen parts of the plant. Phloem
also transports amino acids and hormones
synthesised in the tips of shoots and roots.
Activity
To show that plants lose water by evaporation
Take two test tubes A and B and fill them with
water. Add few drops of eosin stain to colour the
water. Mark the level of water in both the tubes.
Pull out a small young plant from moist soil, wash
the roots and put it in test tube A.
Plug the opening of both the test tubes by cotton
wool, as shown in figure. Keep the set-up in open
and leave it undisturbed for 1-2 days.
Notice the change in the level of water in
test tube A. It has fallen down. But in test tube B
Transpiration
Transpiration is the loss ofwater from leaves
and other aerial parts of a plant into the air.
It occurs through stomata.
it remains unchanged. Where has water gone?
It has been absorbed by the roots and conducted
through stem and branches to leaves. You can see
that the midrib and branches of midrib have become
coloured.
Something More Young
plant
The midrib and its branches in leaves represent
the location of xylem and phloem. Cotton wool Cotton wool
Suction of water by plant roots is similar to sucking
of cold drink by using a straw.
Only 1-2% of water absorbed is used by the plant.
A lot of water is lost by plants by evaporation
throughstomata.
Testtube
-Water
Test tubeA Test tubeB
Why do plants lose so much of water?
Activity
Losing of water by transpiration
builds a suction force in the xylem
vessels of the plant. This helps to
pull water up to the top of a tree.
To demonstrate the evaporation of water
(transpiration) in plants
Take a well-watered potted
plant having broad leaves.
Cover the pot with a bell jar.
Leave the set-up in sunlight
for half an hour. Can you
see tiny drops of water on
When we keep cut flowers in water,
they remain fresh for few days,
otherwise they get dried up in few
the inner surface of the bell
hours. Why?
Flowers dry up due to loss of
water by evaporation. When kept
in water, their stem absorbs
water which is then transported to
flowers. The water lost by evaporation
is replaced by water absorbed and
the flowers remain fresh.
jar? From where have these
drops appeared?
These drops have appeared
by the condensation of
water vapour that has
evaporated from the leaves.

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Class 7 Chapter 13 Transportation

  • 1. 13 Transportation in Animals and Plants LearningObjectives KNOWTHESE POINTS BEFORE YOU START Heart isa muscular organ. Its walls are formed ofcardiac muscles. Removal of toxic waste from the body of an organism is called excretion. The students will be able to know parts of circulatory system, blood, blood vessels and capillaries. Kidneys, skin, lungsand rectum are excretory organs. Kidneys filter out wastes and excess of water from blood and remove them as urine. know the working of heart and circulation of Food manufactured by leaves is transported to the nongreen parts ofthe plant through phloem. It is called translocation. Loss of water from aerial parts of plant due to evaporation is called transpiration. blood. know heartbeat and about heart sounds learn types of body wastes and excretory system in human beings. Now, study the chapter in detail. know transport system in plants. +understand the process of transpiration in plants. TRANSPORT OF MATERIALS All organisms have a way of transporting substances from one part of the body to another. Complex animals and plants have well developed transport system. It is responsible for the following functions: Supply of nutrients and oxygen to every cell of the body. Transport of substances formed in one part of the body to those parts where they are needed, ike hormones and certain enzymes in animals and food in plants. Removal of harmful substances produced during different biochemical processes like carbon dioxide, ammonia and urea,ete from the place of formation to the region of excretion.
  • 2. Plasma is the nonlivin liquid part of the blood. It is yellowish fuid that makes up more than half of blood volume. It removes carbon dioxide and wastes from the cells. Mode of transport transported are also different. Transport in animals takes place by Transport in plants takes place by vascular A n i m a l s and plants have different modes of t r a n s p o r t of substances. The substances Plasma transports: dissolved food to the cells, oxygentothecells, enzymes, hormones and chemicals in the body. Blood cells or corpuscles are the livingpart of the blood. There are three kinds of blood circulatory system. system. CIRCULATORY SYSTEM Circa irculatory system is the life support system corpuscles. Red blood corpuscles (RBCs) are cells without nucleus. Their cytoplasm has oxygen carrying pigment called haemoglobin. It gives red colour to these corpuscles (hence, red blood corpuscles). It combines with oxygen to form oxyhaemoglobin,which transports oxygen to all the body cells. RBCs live for 90 to 120 days (i.e., 3 to 4 months) only. White blood corpuscles (WBCs) are of different types. They have differently shaped nuclei. They defend the body against infection. They fight against germs and also provide immunity against infection. Normally, there is only one WBC for every 600 RBCs. The white blood corpuscle count goes up when there is any infection in the body. WBCs are called soldiers ofthe body. Blood platelets are very minute cells present in the blood. They help to stop bleeding by clotting the blood. that provides our body cells with food and oxvgen. It takes away waste products from the body cels. Circulatory system is a system of vessels which connects all the cells, tissues and organs of the body together. Parts of circulatory system There are three main parts of the circulatory system- blood, blood vessels and heart. TABLE 13.1 ParTs OF CIRCULATORY SYSTEM AND THEIR FUNCTIONS Parts Function Blood Fluid medium that transportssubstances Blood vessels (arteries, Through them blood flows throughout veins and capillaries) the body. Heart Pumps the blood into blood vessels. Blood Blood is a fluid connective tissue. It is a red-coloured viscous (thick and sticky) fluid that flows in the blood vessels. Blood has following functions: It supplies food and oxygen to every cell of the body. Check PeINT 1 1. Name two functions of plasma. 2. What is the lifespan of RBCs? 3. When does the WBC count go up? 4. What are the functions of circulatory system? It removes wastes from the cells. It helps in regulating body temperature. * it protects body against infection. blo The blood has two components-plasma and 5. What is haemoglobin? blood cells or corpuscles. 6. Which blood cells help in blood clotting?
  • 3. Granules in Nuclei of different shapes cytoplasm Agranulocytes Cytoplasm without granules Granulocyte Red Blood Corpuscles White Blood Corpuscles Blood Platelets Fig. 13.1 Bloodcorpuscles in human blood Blood vessels Activity To count the pulse rate of a friend Ask your friend or classmate to sit comfortably and place the right hand on the table. Place your index and middle fingers on the inner side of the wrist as shown in figure and feel the throbbing movement of blood flow. Start a stopwatch and count the number Blood flows through a system of tubes called blood vessels. There are three kinds of blood vessels arteries,veins and capillaries. Arteries Arteries carry blood away from the heart. They have thick and muscular wall. The force of heart pumping keeps the blood flowing through arteries. The blood in arteries is bright red in colour because it contains a lot of oxygen (oxyhaemoglobin is bright red in colour). In arteries, blood flows with jerks and under great force. We can feel the blood flow in radial artery on the inner side of the wrist. of throbs or beats in one minute. Repeat the activity with other friends and record in a table as given below: Activity To feel own pulse and count the pulse rate S. o. Name of classmate Pulse rate/minute Place the index and middle fingers of the right hand on the inner side of the wrist Note: The pulse rate increases during fever or high blood pressure. of your left hand. Press lightly and feel the throbbing movements. The throbbing movements correspond to the blood being pumped by the heart into the artery. This throbbing is called pulse. The number of pulses or throbs produced per minute is called pulse rate. A normal healthy person has a pulse rate between 72-80 beats per minute. The largest artery in the body is called aorta. It arises from the left ventricle of heart. This branches out into arteries. On entering some body organ, each artery is divided into smaller and smaller vessels which end into fine capillaries.
  • 4. Very thin wall Wide lumen Thick wall Thin wall Narrow lumen Artery Vein Capillary Fig. 13.2 Blood vessels TABLE 13.2 DIFFERENCES BETWEEN Veins ARTERY, VEIN AND CAPILLAR Veins carry blood from various body organs to the heart. They have thin walls. The valves present inside veins make the blood to flow only towards the heart. The flow of blood in veins is not jerky and the blood is deoxygenated and so it is darker in colour. Artery Vein Capillary 1. Thick-walled with 1. Thin-walled with 1. Thin-walled wide lumen. narrow lumen. narrow tubes with narrow lumen. 2. Blood flows from|2. Capillaries join body organs tothe 2. Blood flows from heart to other artery with the body parts. heart. vein and form a network in the You can see some of your veins because they are just under the skin (1.e., superficial). They are more prominent in old persons. body organs. 3. Supplies blood to 3. Collects blood frombody organs and bringsitback 3. Helps in the exchange of food, oxygen and body organs. to heart. carbon dioxide between blood andtissues. 4. Situated just under4. Situated very deep within the organs. 4. Situated deeper under the skin. the skin. |5. Carries oxygenated 5. Carries blood (except 5. Carries both types of blood. deoxygenated blood (except pulmonary veins). Valves pulmonaryarteries). Fig. 13.3 A part of vein showing valves Heart Veins begin as capillaries. They join and ejoin to form large veins that open into the Tight auricle of heart. Heart is a living pump. It is of the size of a fist and is shaped like a cone. It lies between the lungs in our thoracic (chest) cavity. Its walls are formed of cardiac muscles. Capillaries are the finest blood vessels. They These muscles contract and relax tirelessly connect arteries with veins. The capillaries throughout life. Because of cardiac muscles, the heart beats continuously and pumps blood into the arteries to be transported to all parts Capillaries from blood to the cells and carbon dioxide of the body. and waste products pass from cells to the Our heart is four-chambered. It has two ave very thin walls (only one cell thick). t the capillaries, food and oxygen pass blood. auricles or atria and two ventricles. The
  • 5. heart is divided into two halves by a thick Ventricles ean muscular septum. Each half has an auricle These are distributingchambersof thehe TIcle above and a ventricle below. The right halfof Their walls are thick. The right ventril the heart has deoxygenated blood while the left halfhas pure or oxygenated blood. The receives deoxygenated blood trom right aurice and pumps it to the lungs for oxygenation gest septum prevents mixing of deoxygenated and purification.The left ventricle is thelarge oxygenated blood present in the right and left heart chamber and has the thickestwalls.. receives oxygenated blood from left auric and pumps it to the whole body. There are four valves in the heart. Theu control the direction of blood flow inthe heart and into the blood vessels. Theyopen and close about 100,000 times a day. A tricuspid valve guards the opening of right atrium into right ventricle. A bicuspid valve guards the openingoflft halves of the heart. ricle Aorta Right Left auricle auricle Right FLeft ventricle atrium into left ventricle. ventricle Three semilunarvalves are present at the base ofpulmonary aorta and dorsal aorta Fig. 13.4 Human heart respectively. Auricles or atria (sing. atrium) When atria contract, the cuspidvalves open. Auricles are the receiving chambers of When ventricles contract, the pulmonaryand the heart. Their walls are thinner than aortic semilunar valves open andcuspid valves those of ventricles. The right auricle receives are slam shut. deoxygenated blood from the whole body while the left auricle receives oxygenated Working ofheart and circulation ofblood When both atriaand ventricles are relaxed, both the atria get filled with blood. The right atrium receives deoxygenated blood from various parts of the body and the left atrium receives oxygenated blood trom blood from lungs. Aorta- Pulmonary artery lungs by pulmonary veins. Semilunar valves Now both atria contractsimultaneouslyanu their cuspid valves open up. Blood from let atrium comes in the left ventricle and from right atrium into right ventricle. Both the atria relaxand ventriclescontra The cuspid valves are slam shut and semilunar valves open up. Bicuspid valves Tricuspid- Septum valve Thick wall of ventricle Fig. 13.5 Internal structure of heart 30
  • 6. Heartbeat and heart sounds Right pulmonary artery Aorta The rhythmic contraction and relaxation of auricles and ventricles is known as heartbeat. Human heart beats about 72 times per minute. One heart beat includes: Pulmonary Superior trunk Left auricle vena cava- Oxygenated blood from Right auricle- a phase of contraction of heart muscles - Systole. a phase of relaxation of heart muscles and general pause - Diastole. During diastole, heart receives blood and during systole, first atria contract to push the blood into ventricles and then ventricles lungs Inferior vena cava Deoxygenated blood- -Left ventricle Right ventricle- Fig. 18.6 Path of blood flow through heart The oxygenated blood from left ventricle is contract to pump blood into their respective pumped into aorta and is distributed to all blood vessels. bodyparts by arteries. The deoxygenated Thus, contraction ofatrial chambers and then blood from right ventricle is pumped iinto ventricular chambers are the two phases of a pulmonary aorta and is transported to lungs heartbeat. These two phases of heartbeat can by the pulmonary arteries for oxygenation. be heard as lub and dub sounds. The sound of heartbeat is caused by the contraction of muscles and shutting down of valves. In the lub phase, the ventricles contract and cuspid valves close. In the dub phase, the pulmonaryand aortic Lungs Lung capillaries Pulmonary vein Lung capillaries valves close. Pulmonary artery Aorta Can we hear lub-dub sound of heart? Right auricle- -Left auricle Heart Left Vena cava- Right ventricle Yes, we can hear it by placing our ear on the left side of the chest of our friend. ventricle Capillary networks in head, limbs and internal organs Activity To make a model of stethoscope Take a funnel having a diameter of 6-7 cm. Fix a rubber tube about 50 cm long Fig. 13.7 Circulation of blood in humans on the stem of funnel and stretch a rubber sheet or a balloon on the mouth SonethingMore of the funnel. Fix it with a rubber band. The discoveryof blood circulation in the body was made by Wiliam Harvey. He showed that blood Circulates in the body in a closed system of vessels. Place the open end of the tube on one of your ears and mouth of the funnel on your chest near the heart. You can hear a thumping sound. These sounds are heart beats. 131
  • 7. A normal heart repeats these lub-dub sounds about 72 times per minute. Doctors use stethoscope to hear this lub-dub sound. Renal artery- Renal vein- Kidney Inferior Activity Aorta vena cava To find out whether heartbeat rate remains unchanged Count the number of heartbeats in one minute Ureter when you are resting or sitting and relaxing. Then run for about 4-5 minutes and record the rate of Urinary bladder heartbeat. Compare the two observations. You can repeat these observations with yourfriends also. - Urethra Urinary opening Fig. 13.8 Human excretory system Check PeINT 2- Name the following. 1. The blood vessels that carry blood from heart to other parts of the body. 2. The valve that guards the opening of right atrium on either side of backbone. The renal artery Kidneys Kidneys are brown-coloured bean-shaped organs present in the abdominal cavity one into ventricle. brings blood to the kidneys and renal vein 3. The scientist who discovered circulation of blood. takes it away. While passing through the 4. The blood vessel that receives blood from left kidnevs, blood is filtered and excess of water ventricle. 5. The instrument which is used to hear heartbeat. and nitrogenous wastes are removed in the form of urine. EXCRETION IN ANIMALS The urine is removed from the kidneys by Numerous biochemical reactions occurrounda pair of tubes called ureters. It is collected the clock in all living cels. They produce a and stored in the urinary bladder and is variety of waste products like carbon dioxide, finally disposed off through urinary opening located at the end of urethra. The urethra is ammonia and other nitrogen compounds. If they accumulate in the body, they may prove to be toxic. a muscular tube. Something More The process of removing toxic wastes from the body is called excretion and the organs Dialysis: Removal of wastes is important for all living organisms. Normalkidneyfunction is essential for good health. Human beings have two kidneys. If one kidney is damaged, the other kidney fuiils the excretory needs. But if both the kidneys are damaged, the person cannot survive because of the accumulation of toxic wastes in the body. Therefore the nitrogenous wastes from the blood are periodicaly removed by artificial kidney or the dlalysis machine. The process of filtering blood and the remoyal o wastes by the machine is called dialysis. that remove these toxic wastes are called excretory organs. Types of body wastes Table 13.3 given below shows three types of wastes and the systems used to eliminate them. Excretory system in human beings Excretory system in humans has a pair of An examination of urine gives an indicati0n kidneys, a pair of ureters and a urinary of the functioning of other organs in the bladder and a urethra. body. A doctor asks the patients to get ther
  • 8. urine examined in order to diagnose certain Skin as excretory organ diseases. In case excess sugar, pus cells or other Sweat glands in the skin remove water, salts, materials are found, it indicates that some urea, etc. from the blood flowing through organ of the body is not functioning properly. blood capillaries in the skin. They open on The presence of sugar in urine indicates that the surface of skin by tiny pores. The fluid the person is suffering from diabetes. In this that comes out of the body through these disease, sugar level increases in blood instead pores is called sweat. of moving into the cells to provide energy. Some ofthe excess sugar is carried out ofthe body through urine. Why do we sweat in summer? TABLE 13.3 Major TYPES OF BOoDY WASTESs In summer when we feel hot due to external heat, sweating and evaporation of sweat makes the body cool. Sweat evaporates from the body surface. Evaporation needs heat which is obtained from the body. So we sweat in summer and also feel Types of waste Example System too eliminate them Carbon dioxide Respiratory system Digestivesystem Gaseous waste Solidwaste Faeces Chemical waste (water,| Urine and sweat salt,urea,etc.) Excretory system and skin more thirsty. Something More Hair We have 5.5 to 6.5 litres of blood circulating in our body. Sweat Kidneys clean all the blood in our body every 30 minutes. pore Receptors About 200 litres of blood is fitered by kidneys each day. About 1.5to2.0itres of urine isexcretedin24 hours. Urinecontains95% water, 2.5% urea and 2,5% of other waste products. Sweat Hair root gland Blood vessels Activity Fig. 13.9 V.S. of skin To test urine for the presence of glucose Collect a small sample of urine in a test tube. Add a few drops of the blue-coloured Benedict's Why do our coloured clothes develop white patches in the areas of under arms? solution to the urine. Warm the mixture and observe the change in colour if any. Repeat the above test with the urine There is more sweating in underarm area. The sweat contains salts. When sweat from the clothes dries, the water evaporates and salt is left behind. This forms white patches on Our clothes. samples of your friends. Record the change of colour and discuss with your teacher.
  • 9. Check PeINT 3 . Transport of water and minerals The Water is absorbed from soil by root hair, T Fill in the blanks. 1. Bean-shaped organ that removes nitrogenous are in close contact with water betweenthe particles. Water and dissolved minerals from root hair to the cells of root co then to the xylem vessels. wastes is called mOove 2. Urea and uric acid are 3. The structural unit of kidney is 4. Artificial filtration of blood is carried out to Cells of leaf remove TRANSPORT OF SUBSTANCES IN PLANTS Xylem vessel in leaf There are three different kinds of plants, i.e., herbs, shrubs and trees. Though, the complexity may vary but the mode of transport in all the three types is the same. Plants have a well-developed transport system. It is called vascular system. It has two main functions. It transports water and minerals dissolved in water from roots to all the aerial parts of the plant It transports the food synthesisedinleaves to various parts ofthe plant right up to the Xylem vessel in the stem Stoma Film of water Transpiration Cells of Soil particle root Epidermis Root hair Endodermis roots. Fig. 13.10 Path of water and minerals in plants Vascular system Vascular system consists of pipe-like vessels arranged end to end. They extend from tips of roots to the tips of leaves passing through the stem. The vascular system is also called Scientists were also amazed to conducting tissue. It is formed of two types of cells also known as vessels - xylem vessels and phloem vessels. How can water move so high upto the leaves of high trees? see water reaching several metres high in trees which were as tall as 15 metres. Two forces were found responsible for this. Continuous evaporation of water from the leaves (transpiration) produces a suction Xylem vessels The xylemvessels transport water and dissolved force 1that pulls water upwards minerals upwards from roots through stem to the tips of leaves against the force of gravity. This upward movement ofwater and minerals is called ascent of sap. (transpiration pull) in xylem vessels. Continuous movement of water from the root cells produces a pushing force. It pushes water upwards. These vessels form a continuous network Phloem vessels of channels through the stem and branch These carry food synthesised by the leaves upto the tips of leaves, and transport wate downwards to all the parts of a plant. and minerals to all the parts of a plant.
  • 10. Translocation of food The transport of food from leaves to all other parts of plant is called translocation. The food is manufactured in the mesophyll cells of the leaf. From mesophyll cells, it enters into the sieve tubes of phloem as dilute (weak) solution and is transported to all nongreen parts of the plant. Phloem also transports amino acids and hormones synthesised in the tips of shoots and roots. Activity To show that plants lose water by evaporation Take two test tubes A and B and fill them with water. Add few drops of eosin stain to colour the water. Mark the level of water in both the tubes. Pull out a small young plant from moist soil, wash the roots and put it in test tube A. Plug the opening of both the test tubes by cotton wool, as shown in figure. Keep the set-up in open and leave it undisturbed for 1-2 days. Notice the change in the level of water in test tube A. It has fallen down. But in test tube B Transpiration Transpiration is the loss ofwater from leaves and other aerial parts of a plant into the air. It occurs through stomata. it remains unchanged. Where has water gone? It has been absorbed by the roots and conducted through stem and branches to leaves. You can see that the midrib and branches of midrib have become coloured. Something More Young plant The midrib and its branches in leaves represent the location of xylem and phloem. Cotton wool Cotton wool Suction of water by plant roots is similar to sucking of cold drink by using a straw. Only 1-2% of water absorbed is used by the plant. A lot of water is lost by plants by evaporation throughstomata. Testtube -Water Test tubeA Test tubeB Why do plants lose so much of water? Activity Losing of water by transpiration builds a suction force in the xylem vessels of the plant. This helps to pull water up to the top of a tree. To demonstrate the evaporation of water (transpiration) in plants Take a well-watered potted plant having broad leaves. Cover the pot with a bell jar. Leave the set-up in sunlight for half an hour. Can you see tiny drops of water on When we keep cut flowers in water, they remain fresh for few days, otherwise they get dried up in few the inner surface of the bell hours. Why? Flowers dry up due to loss of water by evaporation. When kept in water, their stem absorbs water which is then transported to flowers. The water lost by evaporation is replaced by water absorbed and the flowers remain fresh. jar? From where have these drops appeared? These drops have appeared by the condensation of water vapour that has evaporated from the leaves.