Body Fluids N Circulation

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WHAT IS CIRCULATION?
• Circulation is the transport of nutrients,

oxygen, CO2 and excretory products to the
concerned tissues or organs.
• For circulation, simple organisms (sponges,
coelenterates etc) use water from their
surroundings.
• Complex organisms use body fluids (blood &
lymph) for circulation.
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TYPES OF CIRCULATORY SYSTEM
Circulatory system
Open type Closed type
1. Open circulatory system

• Here, the blood pumped by the heart passes through large vessels into
open spaces or cavities called sinuses.
• E.g. Arthropods and molluscs.
TYPES OF CIRCULATORY SYSTEM
Circulatory system
Open type Closed type
2. Closed circulatory system

• Here, blood pumped by the heart is circulated through blood vessels.
• It is more advantageous as the flow of fluid can be precisely regulated.
• E.g. Annelids and chordates.
HEART OF VERTEBRATES
All vertebrates have a muscular chambered heart.
Fishes Amphibians Reptiles (except Crocodiles,

2-chambered 3-chambered crocodiles) birds &
3-chambered mammals
(an atrium + a (2 atria + a
ventricle). ventricle). (incomplete 4-chambered.
partition for
ventricle).
CIRCULATORY PATHWAYS
Patterns of Circulation in Vertebrates
Single circulation
Patterns of Incomplete double

circulation circulation
Double circulation
1. Single circulation
• It is seen in fishes.
• Heart receives impure blood only (venous
heart).
• Deoxygenated blood from heart → oxygenated
by gills → supplied to body parts →
deoxygenated blood → to heart.
2. Incomplete double circulation
• It is seen amphibians & reptiles.

• Left atrium receives oxygenated blood from
gills/lungs/skin. Right atrium gets deoxygenated
blood from other body parts. However, they get
mixed up in the single ventricle.
• Ventricle pumps out mixed blood.
3. Double circulation
• It is seen in birds & mammals.

• Left atrium receives Oxygenated blood. It passes
on to left ventricle.
• Right atrium receives Deoxygenated blood. It
passes on to right ventricle.
• Ventricles pump it out separately without any
mixing up.
HUMAN CIRCULATORY SYSTEM
Blood vascular system Lymphatic system
Heart Blood Blood vessels Lymph
Lymph vessels
Plasma Formed elements Arteries
Veins Lymph nodes

RBC WBC Platelets
Capillaries
Granulocytes Agranulocytes
Neutrophils Lymphocytes Monocyte

Oeosinophils
B- Lymphocytes
Basophils T-Lymphocytes
1. BLOOD VASCULAR SYSTEM
A. BLOOD
COMPOSITION OF BLOOD
a. Plasma b. Formed elements
55% 45%
Straw-coloured and Include cells
slightly alkaline (pH 7.4) (RBC, WBC and Platelets )
fluid matrix.
A. BLOOD
Constituents of plasma Functions
Solvent. Transports vitamins, hormones,
Water (90-92%)
enzymes, nutrients etc.
Plasma Fibrinogen For blood coagulation (clotting)
proteins Globulins Act as antibodies (for defense of the body)
(6-8 %) Albumins Osmotic balance & regulation of blood pressure. Plasma
Glucose, amino acids, without
For energy production and growth
lipids, cholesterol clotting
Inorganic: (Na+, K+, Mg2+, Regulation of osmosis etc. factors is
Cl-, HCO3- , Ca2+ ) Ca2+ For blood clotting and muscle contraction called
Gases (CO2, O2, N2 etc) For transport Serum.
A. BLOOD
Red Blood Cells

(RBC) or
Erythrocytes
White Blood Cells
FORMED
(WBC) or
ELEMENTS
Leucocytes
Platelets
(Thrombocytes)
A. BLOOD
Features of RBC (Erythrocytes)
Colour Red (due to haemoglobin)
Lifespan 120 days
Count 5 - 5.5 millions/mm-3
Formed in Red bone marrow
Normal Hb level in blood:
Biconcave in shape. 12-16 gm/ 100 ml
Structure
No nucleus, mitochondria etc.
Worn-out RBCs are destroyed
Functions CO2 and O2 transport in spleen (graveyard of RBCs)
A. BLOOD
Features of WBC (Leucocytes)

Colour Colourless
Lifespan 1-15 days
Count 6000-8000 /mm-3
Bone marrow, lymph
Formed in
glands, spleen
Structure Nucleated. Different types
Functions Part of immune system
A. BLOOD
Features of Platelets (Thrombocytes)

Colour Colourless
Lifespan 7 days
Count 1.5 - 3.5 lakhs/mm-3
Formed in Megakaryocytes in Bone marrow
Non-nucleated cell fragments.
Structure
Release clotting substances.
Functions Blood clotting
A. BLOOD
Types of WBC % Functions
Neutrophils (Heterophils) 60-65% Phagocytosis. Soldier of the body.
Granulocytes
Resist infections.
Eosinophils (Acidphils) 2-3%
Cause allergic reactions.
Secrete histamine, serotonin, heparin.
Basophils (Cyanophils) 0.5-1%
Cause inflammatory reactions.
Agranulocytes
Monocytes (Largest WBC) 6-8% Phagocytosis

B-
Lymphocytes lymphocytes Immune responses of the body.
(Smallest WBC, 20-25%
T- Secrete antibodies.
largest nucleus)
lymphocytes
A. BLOOD
Blood coagulation
• It is a mechanism for haemostasis

(prevention of blood loss through
injuries).
• It involves the following events:
A. BLOOD
Blood coagulation
A. BLOOD
Blood Grouping
A+ B+ AB+ O+
A- B- AB- O-
• Blood groups were discovered by

Carl Land Steiner.
• It includes ABO grouping & Rh
Grouping.
A. BLOOD
Blood Grouping 1. ABO grouping
• It is based on presence or
absence of 2 surface antigens
(chemicals that induce immune
response) on RBCs namely A & B.
• Similarly, plasma contains 2
antibodies (proteins produced in
response to antigens) namely
anti-A & anti-B.
A. BLOOD
ABO Blood Grouping
Can receive
Blood Antigens Antibodies in Can donate
blood from
group on RBC plasma blood to
(Donor’s group)
A A Anti-B A and AB A, O
B B Anti-A B and AB B, O
AB A, B Nil AB only A, B, AB & O
O Nil Anti-A & Anti-B A, B, AB & O O only
A. BLOOD
• Antigen A reacts with anti-A.

• Antigen B reacts with anti-B.
• Mixing of bloods with interactive
antigens & antibodies causes
clumping (agglutination) of RBCs.
A. BLOOD
• O group persons are called

O-group: Universal donors as they can
Universal donate blood to persons with any
Donor AB-group: blood group.
Universal • AB group persons are called
Recipient Universal recipients because they
can accept blood from all groups.
A. BLOOD
Blood Grouping 2. Rh grouping
• Rhesus (Rh) factor is an antigen

found on RBC.
• Rh+ve means the presence of Rh
factor and Rh-ve means absence of
Rh factor.
• Nearly 80% of humans are Rh+ve.
A. BLOOD
Blood Grouping 2. Rh grouping
• Anti-Rh antibodies are not
naturally found. So Rh-ve person
can receive Rh+ve blood only once
but it causes the development of
anti-Rh antibodies in his blood. So
a second transfusion of Rh+ve
blood causes agglutination.
• Therefore, Rh-group should be
matched before transfusion.
A. BLOOD
Blood Grouping Erythroblastosis foetalis
• It is an Rh incompatibility between
the Rh-ve blood of a pregnant
mother and Rh+ve blood of the
foetus.
• Rh antigens do not get mixed with
maternal blood in first pregnancy
because placenta separates the two
bloods.
A. BLOOD
• But at the time of first delivery,

there is a possibility of exposure of
the maternal blood to small
amounts of the Rh+ve blood from
the foetus.
• This induces the formation of Rh
antibodies in maternal blood.
A. BLOOD
• In case of her subsequent

pregnancies, Rh antibodies from
mother leak into the foetal blood
(Rh+ve) and destroy the foetal
RBCs. This is fatal to foetus or
cause severe anaemia and jaundice
to the baby. This condition is called
Erythroblastosis foetalis.
A. BLOOD
• Erythroblastosis foetalis can be

avoided by administering anti-Rh
antibodies to the mother
immediately after the delivery of
first child.
B. BLOOD VESSELS
Arteries
Types of
Veins
Blood vessels
Capillaries
B. BLOOD VESSELS
1. Arteries
• They carry blood from heart
to other tissues.
• They contain oxygenated
blood (except pulmonary
artery).
• Their smaller branches are
called arterioles.
B. BLOOD VESSELS
1. Arteries
Arteries have 3 layers:
 Tunica intima: Squamous
endothelium. Inner layer.
 Tunica media: Smooth
muscles & elastic fibres.
Middle layer.
 Tunica externa: Fibrous
connective tissue with
collagen fibres. Outer layer.
B. BLOOD VESSELS
2. Veins • They carry blood towards
heart.
• They contain deoxygenated
blood (except pulmonary vein)
• Their smaller branches are
called venules.
• Veins are also 3-layered but
tunica media is comparatively
thin.
B. BLOOD VESSELS
3. Capillaries
• In tissues, arterioles divide

into thin walled and single
layered vessels. They are
called capillaries.
• They unite into venules.
C. HEART
Structure of Heart • Heart is a mesodermally derived
organ located in mediastinum.
• It is protected by double-layered
pericardium.
• The pericardial space (between
pericardial membranes) is filled
with pericardial fluid. It reduces
the friction between the heart
walls, and surrounding tissues.
C. HEART
Structure of Heart • Heart is 4 chambered- 2 upper
atria (auricles) & 2 lower
ventricles.
• The walls (cardiac muscles) of the
ventricles are much thicker than
that of the atria.
• Atria are separated by inter-atrial
septum.
• Ventricles are separated by inter-
ventricular septum.
C. HEART
Structure of Heart • In b/w atrium and ventricle there is
a thick fibrous atrio-ventricular
septum with an opening.
• A tricuspid valve (3 muscular flaps
or cusps) guards the opening
between right atrium and right
ventricle.
• A bicuspid (mitral) valve guards the
opening between left atrium and
left ventricle.
C. HEART
Structure of Heart
• These valves allow the flow of
blood only in one direction, i.e.
from atria to ventricles.
• The openings of right & left
ventricles into pulmonary artery
and aorta respectively are
provided with the semi-lunar
valves. They prevent backwards
flow of blood.
C. HEART
Conducting System • Human heart is myogenic, i.e. normal
activities of heart are auto regulated by
nodal tissues (a specialized cardiac
musculature present in heart wall).
• It consists of
o Sino-atrial node (SAN) in the right upper
corner of the right atrium.
o Atrio-ventricular node (AVN) in the lower
left corner of the right atrium close to the
atrio-ventricular septum.
C. HEART
Conducting System • From the AVN, a bundle of fibrous atrio-
ventricular bundle (AV bundle) passes
through atrio-ventricular septa and
divides into a right & left branches.
• Each branch passes through the
ventricular walls of its side.
• In the ventricular wall, it breaks up into
minute fibres (Purkinje fibres). These
fibres along with the bundles are known
as bundle of His.
C. HEART
Conducting System
• Nodal tissues generate action potential
without any external stimuli, i.e. it is
autoexcitable.
• SAN initiates and maintains contraction
of heart by generating action potentials
(70-75/min). So it is called the
pacemaker.
C. HEART
Joint diastole
Phases of
Atrial systole
Cardiac cycle
Ventricular
systole
C. HEART
Cardiac Cycle 1. Joint Diastole
• Firstly, all chambers of heart are in
relaxed state (joint diastole).
• When the tricuspid & bicuspid valves
open, blood from pulmonary vein and
vena cava flows into left & right
ventricles respectively through left &
right atria.
• Semilunar valves are closed at this stage.
C. HEART
Cardiac Cycle 2. Atrial (Auricular) systole
• The SAN generates an action potential.

It stimulates both the atria to undergo
contraction (atrial systole).
• This increases the flow of blood into
the ventricles by about 30%.
C. HEART
Cardiac Cycle 3. Ventricular Systole
• Action potential is conducted to

ventricular side by AVN & AV bundle
from where bundle of His transmits it
through the ventricular musculature.
• It causes contraction of ventricles
(ventricular systole). During this, the
atria undergo diastole.
C. HEART
Cardiac Cycle 3. Ventricular Systole
Ventricular systole increases the ventricular
pressure. It causes the following events:
• Closure of tricuspid and bicuspid valves
due to attempted backflow of blood into
the atria.
• Semilunar valves open. So deoxygenated
blood enters the pulmonary artery from
right ventricle and oxygenated blood
enters the aorta from left ventricle.
C. HEART
Cardiac Cycle
The ventricles now relax (ventricular
diastole) and the ventricular pressure
falls. It causes the following events:
 Closure of the semilunar valves. It
prevents the backflow of blood into
the ventricles.
 Tricuspid & bicuspid valves are
opened by the pressure in the atria.
C. HEART
Cardiac Cycle • Ventricles & atria again undergo joint
diastole and the above processes are
repeated. This is called cardiac cycle.
• A cardiac cycle= atrial systole +
ventricular systole + diastole
• A cardiac cycle is completed in 0.8
seconds.
• One heartbeat = a cardiac cycle.
• So number of normal heartbeat:
70-75 times/min (average: 72/min).
C. HEART
Cardiac Cycle Stroke volume & Cardiac output
• Stroke volume: Volume of blood

pumped out by each ventricle during a
cardiac cycle. It is about 70 ml.
• Cardiac output: Volume of blood
pumped out by each ventricle per
minute, i.e. stroke volume x heart rate
(70 x 72). It is about 5000 ml (5 litres).
• Cardiac output of an athlete is very high.
C. HEART
Cardiac Cycle Heart Sounds
• During each cardiac cycle, 2 prominent

sounds are produced.
• First sound (lub) is due to the closure
of tricuspid & bicuspid valves.
• Second sound (dub) is due to the
closure of the semilunar valves.
• One heartbeat = a lub + a dub.
C. HEART
Regulation of Cardiac activity • Human heart is myogenic
because normal activities of
heart are auto regulated by
nodal tissues.
• Medulla oblongata regulates
cardiac activity through ANS.
• Sympathetic nerves of ANS
increase the rate of heartbeat,
the strength of ventricular
contraction and cardiac output.
C. HEART
Regulation of Cardiac activity
• Parasympathetic nerves of ANS

decrease the heart beat,
conduction of action potential
and the cardiac output.
• Adrenal medullary hormones
increase the cardiac output.
DOUBLE CIRCULATION
• In man, blood flows through the

heart twice for completing its circuit.
This is called double circulation.
• It includes,
 Pulmonary circulation
 Systemic circulation
DOUBLE CIRCULATION
1. Pulmonary Circulation
• It is the circulation b/w lungs and
heart.
• Deoxygenated blood pumped into
the pulmonary artery is passed on
to lungs from where oxygenated
blood is carried by pulmonary
veins into the left atrium.
DOUBLE CIRCULATION
• It is the circulation b/w heart & various
2. Systemic Circulation
body parts.
• Oxygenated blood is passed through
aorta, arteries, arterioles & capillaries
and is reached the tissues.
• Deoxygenated blood collected from
tissues by venules, veins & vena cava is
carried to the right atrium.
• Systemic circulation provides nutrients,
O2 and other substances to the tissues
and takes CO2 and other harmful
substances away for elimination.
DOUBLE CIRCULATION
Pulmonary & Systemic

circulations
HEPATIC PORTAL SYSTEM
• It is a system which includes

the hepatic portal vein that
carries blood from intestine to
the liver before it is delivered
to the systemic circulation.
CORONARY CIRCULATORY SYSTEM
Coronary Coronary
Arteries Veins
It is a system of coronary vessels that circulate blood to and from the

cardiac musculature.
2. LYMPHATIC SYSTEM
• It includes Lymph, Lymph vessels & Lymph

nodes.
• As the blood passes through the
capillaries in tissues, some water and
soluble substances are filtered out from
plasma to the intercellular spaces, to form
tissue (interstitial) fluid. It has the same
mineral distribution as that in plasma.
2. LYMPHATIC SYSTEM
• Exchange of nutrients, gases,

etc between the blood &
cells occur through this fluid.
• Some tissue fluid enters
lymphatic system (a system
of lymph vessels and lymph
glands) and the tissue fluid
in them is called lymph.
• Lymph drains back to the
major veins.
2. LYMPHATIC SYSTEM
FUNCTIONS OF LYMPH
• It is the middleman between blood & tissues.

• It carries plasma proteins synthesized in liver
to the blood.
• Transports digested fats (through lacteals in
the intestinal villi), fat soluble vitamins,
hormones etc.
• Filtration of bacteria and foreign particles.
• Lymph nodes produce WBC (lymphocytes) &
antibodies.
• It helps in the defensive mechanism of body.
ELECTROCARDIOGRAPH (ECG)
• It is an instrument used to obtain

electrocardiogram (it is a graphical
representation of the electrical activity of
the heart during a cardiac cycle).
• To get an ECG, a patient is connected to
the machine with 3 electrical leads (one to
each wrist and to left ankle) that monitor
heart activity. For a detailed evaluation of
heart’s function, multiple leads are
attached to the chest region.
ELECTROCARDIOGRAPH (ECG)
An ECG consists of the following waves:
• P-wave: Represents the excitation
(depolarization) of atria which causes
atrial systole.
• QRS-complex: Represents
depolarization of ventricles (Ventricular
systole).
• T-wave: Represents the repolarisation
of ventricles.
Deviation in the ECG indicates the abnormality or disease. So ECG has

great clinical significance.
DISORDERS OF CIRCULATORY SYSTEM
1. Hypertension (High Blood Pressure)
• Here, the blood pressure is higher than

normal systolic (pumping) pressure
(120 mm Hg) and normal diastolic
(resting) pressure (80 mm Hg), i.e.
above 120/80 mm Hg.
• If the BP is 140/90 or above, it is
hypertension.
• It leads to heart diseases and affects
vital organs (brain, kidney etc).
2. Coronary Artery Disease (CAD) or Atherosclerosis
• It is the deposition of Ca, fat,

cholesterol and fibrous tissue
in coronary arteries.
• It makes the lumen of arteries
narrower and thereby affect
the blood supply.
3. Angina (angina pectoris)
• An acute chest pain due to O2

deficiency to heart muscles.
• It occurs due to improper blood
flow.
• It is common among middle-aged
and elderly.
4. Heart Failure (congestive heart failure)
• It is the condition in which heart is not

pumping blood enough to meet the
needs of the body.
• Congestion of the lungs is the main
symptom.
• Heart failure is not same as cardiac
arrest (heart stops beating) or a heart
attack (sudden damage of heart muscle
due to inadequate blood supply).
Prepared by: K.C. MUHAMMED ALI
Visit: bankofbiology.blogspot.com
Site of injury Clumped platelets & tissues
Release
Thromboplastin
Forms
Thrombokinase (Prothrombinase) enzyme
Ca2+ Hydrolyses
Prothrombin Thrombin
Fibrinogen (soluble) Fibrin (insoluble)

Traps
Dead & damaged formed Clot
elements (coagulum)

Body Fluids N Circulation

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This presentation is prepared by

• Circulation is the transport of nutrients,

Open type Closed type

1. Open circulatory system

Open type Closed type

2. Closed circulatory system

Fishes Amphibians Reptiles (except Crocodiles,

Patterns of Incomplete double

2. Incomplete double circulation

• It is seen amphibians & reptiles.

• It is seen in birds & mammals.

Blood vascular system Lymphatic system

Heart Blood Blood vessels Lymph

Veins Lymph nodes

Neutrophils Lymphocytes Monocyte

Red Blood Cells

Features of WBC (Leucocytes)

Features of Platelets (Thrombocytes)

Monocytes (Largest WBC) 6-8% Phagocytosis

• It is a mechanism for haemostasis

• Blood groups were discovered by

AB A, B Nil AB only A, B, AB & O

O Nil Anti-A & Anti-B A, B, AB & O O only

• Antigen A reacts with anti-A.

• O group persons are called

• Rhesus (Rh) factor is an antigen

• But at the time of first delivery,

• In case of her subsequent

• Erythroblastosis foetalis can be

• In tissues, arterioles divide

• The SAN generates an action potential.

• Action potential is conducted to

• Stroke volume: Volume of blood

• During each cardiac cycle, 2 prominent

• Parasympathetic nerves of ANS

• In man, blood flows through the

Pulmonary & Systemic

• It is a system which includes

It is a system of coronary vessels that circulate blood to and from the

• It includes Lymph, Lymph vessels & Lymph

• Exchange of nutrients, gases,

• It is the middleman between blood & tissues.

• It is an instrument used to obtain

Deviation in the ECG indicates the abnormality or disease. So ECG has

• Here, the blood pressure is higher than

• It is the deposition of Ca, fat,

• An acute chest pain due to O2

• It is the condition in which heart is not

Fibrinogen (soluble) Fibrin (insoluble)

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