bodyfluidsandcirculation-181122151833.pptx

CIRCULATORY SYSTEM
This system is concerned with the circulation of body
fluids to distribute various substances to various body
parts. The circulatory system is also known as the
cardiovascular system.
It is an organ system that allows blood to circulate and
transport nutrients (such as electrolytes and amino
acids), oxygen, carbon dioxide, hormones, and blood
cells. These are circulated to and from cells in the
body to nourish it. The components of the human
circulatory system include the heart, blood, red and
white blood cells, platelets, and the lymphatic system.

CIRCULATORY SYSTEM
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Functions of Circulatory System

It transports nutrients from their sites of absorption to different tissues
and organs for storage, oxidation or synthesis of tissue components.

It also carries waste products of metabolism from different tissues to
the organs meant for their excretion from the body.

It transports respiratory gases between the respiratory organs and the
tissues.

It carries metabolic intermediates from one tissue to another for their
further metabolism; for example, blood carries lactic acid from muscles
to the liver for its oxidation.

It also transports informational molecules such as hormones, from
their sites of origin to the tissue

It uniformly distributes water, H+, chemical substances to all over the
body.

Types of Blood Circulation in Human
• The physiology of blood circulation was first described by Sir William Harvey in 1628.
The blood circulation in our body is divisible into 3 circuits –
• (i) Coronary circulation: It involves blood supply to the heart wall and also drainage
of the heart wall.
• (a) Coronary arteries: One pair, arising from the aortic arch just above the semilunar
valves. They break up into capillaries to supply oxygenated blood to the heart wall.
• (b) Coronary veins: Numerous, collecting deoxygenated blood from the heart wall
and drains it into right auricle through coronary sinus which is formed by joining of
most of the coronary veins.
• (ii) Pulmonary circulation: It includes circulation between heart and lungs. The right
ventricle pumps deoxygenated blood into a single, thick vessel called pulmonary
aorta which ascends upward and outside heart gets divided into longer, right and
shorter, left pulmonary arteries running to the respective lungs where oxygenation
of blood takes place.
• (iii) Systemic circulation: In this, circulation of blood occurs between heart and body
organs. The left ventricle pumps the oxygenated blood into systemic arch which
supplies it to the body organs other than lungs through a number of arteries.

BLOOD
Blood is a
connective
tissue which is
composed of a
fluid matrix
(plasma) and
formed
elements.

Plasma
• Plasma is a straw-coloured and viscous fluid.
• Plasma constitutes about 55% of the blood. About
90% of plasma is water and about 6-8% is composed
of proteins.
• The major plasma proteins are; fibrinogen, globulins
and albumins.
• Fibrinogen play important role in blood coagulation.
• Globulins are mainly involved in defense mechanism
and albumins help in osmotic balance.
• Small amounts of minerals; like Na+, Ca+ +, Mg+ +,
HCO3– and Cl–; are also present in plasma.
• Plasma also contains glucose, amino acids, lipids, etc.
• Factors for clotting of blood are present in the plasma
in an inactive form. Plasma without the clotting
factors is called serum.

Formed Elements
• The formed elements constitute about
45% of the blood. Erythrocytes,
leucocytes and platelets are
collectively called formed elements.

Erythrocytes or Red Blood Cells (RBCs)
• The RBCs are the most abundant cells in blood. In a
healthy adult, about 5 million to 5.5 million RBCs are
present per cubic mm of blood.
• RBCs are formed in the read bone marrow.
• In most of the mammals, nucleus is absent in the
RBCs. RBCs are biconcave in shape.
• The red colour is because of an iron containing protein
complex; called haemoglobin. In a healthy adult, each
100ml of blood contains 12-16 gm Hb.
• The average lifespan of RBCs is 120 days. RBCs are
finally destroyed in the spleen and hence, spleen isthe
graveyard of RBCs.
• RBCs play a significant role in transport of respiratory
gases.

Leucocytes or White Blood Cells (WBCs):
• The WBCs are nucleated and are relatively lesser in number than
RBCs.
• In a healthy adult about 6000-8000 WBCs are present per cubic
mm of blood.
• Leucocytes are generally short lived.
• There are two main categories of WBCs:
Granulocytes , e.g., neutrophils, eosinophils and basophils
Agranulocytes. e.g., Lymphocytes and monocytes.
• Neutrophils: Neutrophils are the most abundant cells among WBCs
and comprise about 60-65%.
Monocytes: Monocytes comprise about 6-8% of WBCs.
Neutrophils and monocytes are phagocytic cells.
Basophils: Basophils secrete histamine, serotonin, heparin, etc.
They are involved in inflammatory reactions.
Eosinophils: Eosinophils comprise 2-3% of WBCs. These resist
infections and are also associated with allergic reactions.
Lymphocytes: Lymphocytes comprise about 20-25% of WBCs.
There are two major types of lymphocytes, viz. B and T types. Both
the types are responsible for immune responses of the body.

Platelets
• Platelets are also known as
thrombocytes.
• They are cell fragments produced from
megakaryocytes. Megakaryocytes are
special cells in the bone marrow.
• Usually, one cubic mm of blood
contains 150,000-350,000 platelets.
• Platelets can release a variety of
substances. Most of these substances
are involved in blood coagulation.

BLOOD GROUPS
• Two such groupings – the ABO and Rh – are widely
used all over the world.
Importance of Blood Group: During blood
transfusion, the donor blood needs to be carefully
matched with the blood of a recipient. Transfusion
of unmatched blood can lead to severe problems
of clumping, i.e. destruction of RBC.
The blood group O can be donated to persons with
any other blood group and hence, an individual
with O group is called universal donor. A person
with AB blood group can accept blood from all
blood groups and hence, such an individual is
called universal recipient.

ABO Grouping
ABO grouping is based
on the presence or
absence of two surface
antigens on the RBCs,
viz. A and B.
Antigens are chemicals
which can induce
immune response. The
plasma also contains
two natural antibodies.
Antibodies are proteins
produced in response to
antigens.

Rh Grouping
The Rh antigen is similar to
one present in Rhesus
monkeys. It is also observed
on the surface of RBCs of
majority (nearly 80%) humans.
Such individuals are called Rh
positive (Rh +ve). A person
without Rh antigen is called Rh
negative (Rh –ve).
Significance of Rh Group: An
Rh -ve person, if exposed to
Rh +ve blood, will form
specific antibodies against the
Rh antigens. Hence, Rh group
should also be matched before
transfusions.

Coagulation
of Blood
Blood coagulates in response to
an injury or trauma.
Coagulation is a mechanism to
prevent excessive loss of blood
in case of injury.
Clot is a dark reddish brown
scum which is formed at the
site of an injury over a period
of time.
This is formed by a network of
threads called fibrins in which
dead and damaged formed
elements of blood are trapped.

Process of Blood
Clotting
Inactive fibrinogen is present in the
plasma. It is converted by the
enzyme thrombin into active fibrin.
Thrombin is formed from the
inactive prothrombin.
An enzyme complex,
thrombokinase, is responsible for
this conversion.
This complex is formed by a series
of linked enzymatic reactions . The
process involves a number of
factors present in the plasma in an
inactive state.
An injury stimulates the platelets
to release certain factors which
activate the mechanism of
coagulation.

BLOOD VASCULAR SYSTEM
• Higher animals have a well-developed circulatory system so that
transport of substances in the body can be done very effectively. In
them, the circulatory system consists of a central pumping organ called
as heart and various blood vessels (arteries, veins and capillaries).
Arteries conduct the blood from the heart to other tissues; veins bring
blood from other tissues to the heart. Some of the invertebrates and all
vertebrates possess this system. The circulatory system was first
discovered and demonstrated by William Harvey.
The blood vascular system may be of two types, the open and the
closed circulatory systems.

The Open and the Closed circulatory systems.
• Open circulatory system : In many advanced
invertebrates such as prawns, insects and
molluscs, the blood does not remain confined to
blood vessels but it flows freely through the body
cavity and channels called lacunae and sinuses in
the tissues. The body cavity is known as
hemocoele and the blood is hemolymph. In
insects, the tissues are in direct contact with the
blood. Hemolymph circulates in the whole body
due to the contractile activity of heart.

• Closed circulatory system : In closed circulatory system the
blood flows through proper blood vessels named arteries, veins
and blood capillaries. Arteries within the tissues divide into
arterioles, which then branch further to form capillaries.
Capillaries then unite to form venules, which come out of the
tissues and veins. Arteries have thick, elastic and muscular walls
which are made up of three concentric layers viz., tunica
externa, tunica media and tunica interna. All these layers have
got smooth or involuntary muscles. Capillaries are extremely
fine, thin blood vessels the walls of which are made of a single
layer of endothelial cells. The muscles and elastic fibers are
absent in them. These capillaries are highly permeable to water
and small macromolecules. Various nutrients, respiratory gases,
metabolites and other substances are exchanged between the
blood and tissues through these capillaries.

DIFFERENCES BETWEEN OPEN AND CLOSED
CIRCULARY SYSTEMS
Open circulatory system
(1) In open circulatory system
blood flows through large
open spaces and channels
called lacunae and sinuses
among the tissues.
(2) Tissues are in direct contact
with the blood.
(3) Blood flow is very slow and
blood has very low pressure.
(4) Exchange of gases and
nutrients takes place directly
between blood and tissues
Closed circulatory system
(1) In closed circulatory system
blood flows through a closed
system of chambers called
heart and blood vessels.
(2) Blood does not come in direct
contact with tissue.
(3) Blood flow is quite rapid and
blood has a high pressure
(4) Nutrients and gases pass
through the capillary wall to the
tissue fluid from where they are
passed on to the tissues.

Open circulatory system
(5) Less efficient as volume of
blood flowing through a
tissue cannot be controlled
as blood flows out in open
space.
(6) Open circulatory system is
found in higher invertebrates
like most arthropods such as
prawn, insects, etc., and in
some molluscs
(7) Respiratory pigment, if
present, is dissolved in
plasma; RBCs are not
present.
Closed circulatory system
(5) More efficient as volume of
blood can be regulated by the
contraction and relaxation of
the smooth muscles of the
blood vessels.
(6) closed circulatory system is
found in echinoderms, some
molluscs, annelids and all
vertebrates.
(7) Respiratory pigment is present
and may be dissolved in
plasma but is usually held in
RBCs.

ARTERIES AND VEINS
Structurally veins resemble arteries except that the three layers are very thin and
more elastic. In the veins the muscles and elastic connective tissues are poorly
developed. But the collagen fibers of the outer layer are very well developed. In
most of the veins the middle coat is extremely thin with practically no muscles. In
many veins semilunar valves are present in their lumen. These valves allow the
flow of the blood only in one direction i.e., towards the heart.

THE HEART
The heart is the central pumping organ of
the blood vascular system. It is a hollow
muscular structure and is made up of
cardiac muscles. It works throughout life
rhythmically without getting tired. It is
enclosed in a double membraneous sac
called pericardium that is filled with
pericardial fluid. Mainly there are two
chambers in a heart – auricle or atrium
that receives the deoxygenated blood
from various parts of the body; and a
ventricle that distributes the oxygenated
blood to the body. The number of these
chambers varies in different animals.

PISCES
Branchial heart,Thick,
muscular, made of cardiac
muscles, has two chambers (i)
auricle and (ii) ventricle. The
heart is called venous heart
since it pumps deoxygenated
blood to gills for oxygenation.
This blood goes directly from
gills to visceral organs (single
circuit circulation). A sinus
venosus and conus arteriosus
is present. Lung fishes have 2
auricles and 1 ventricle.
For example : Labeo,
Scoliodon, Neoceratodus,etc.

AMPHIBIANS
Heart consists of
(a) Two auricles
(b) Undivided ventricle
(c) Sinus venosus
(d) Truncus arteriosus
(conus + proximal part of aorta)
Right auricle receives blood from
all the visceral organs
(deoxygenated) via precaval and
post caval. Pulmonary artery
carries deoxygenated blood to
lungs for oxygenation. This blood
returns to left auricle via
pulmonary vein (Double circuit
circulation)
FOR EXAMPLE:Frog,Toad,etc.

REPTILES
Heart consists of :
(a) Left and right auricle
(b) Incompletely divided
ventricle
(Ventricle in crocodiles
gavialis and alligator is
completely divided)
(c) Sinus venosus
(d) Conus arteriosus
divided into right systemic,
left systemic and
pulmonary arch.
FOR EXAMPLE:
Lizards ,Snakes , Turtles,etc.

AVES
Heart consists of
(b) Left and right ventricle
(c) Complete separation
of arterial and venous
circulation
(d) Only right systemic
arch is present
(e) Sinus venosus and
truncus arterisious absent
FOR EXAMPLE:Pigeon,etc.

MAMMAL S
Heart consists of
(b) Left and right ventricle
(c) Complete separation
of arterial and venous
circulation
(d)They have left systemic
arch.
(e) Sinus venosus and
truncus arterisious absent
FOR EXAMPLE:
Human,Rabbit,etc.

 The mammalian heart including man is a hollow, cone-
shaped, muscular structure that lies in the thoracic cavity
above the diaphragm and in between the two lungs. It is
about the size of a fist measuring about 12 cm in length
and 9 cm in breadth. It weighs about 300 grams.
 It is a four chambered organ-two atria or auricles and two
ventricles. Deoxygenated blood is received into right
auricle by superior vena cava (from anterior region) and
inferior vena cava (from posterior region) of the body.
These vena cavae open directly into right auricle as there
is no sinus venosus.
 Right auricle also gets blood from coronary veins (from
the heart muscles itself). The right and left auricles are
separated by interauricular septum. Similarly, right and
left ventricles are also separated by interventricular
septum. Deoxygenated blood is then passed from the
right auricle to the right ventricle through the
atrioventricular aperture guarded by tricuspid valve
(having three flaps).

 The blood is then pumped into lungs for oxygenation
via pulmonary artery. After oxygenation, the blood is
brought back into left auricle via four pulmonary
veins. From left auricle, blood (now oxygenated)
goes to left ventricle through atrio-ventricular
aperture and this opening is regulated by bicuspid
(having two flaps) or mitral valve.
 The left ventricle has also got chordae tendinae and
papillary muscles which prevent the valves (both
bicuspid and tricuspid) from being pushed into
auricles at the time of ventricular contraction. Thus
the walls of left ventricle are thicker than the walls of
right ventricle.
 The oxygenated blood from left ventricle is then
distributed to all parts of the body with the help of
aorta. The openings of the aorta and other major
arteries are guarded by semilunar valves that prevent
the back flow of blood.

Differences between first and seconds heart sounds
First heart sound
(Lubb)
Second heart
sound (Dup)
(1) It is produced by
closure of bicuspid and
tricuspid valves at the
start of ventricular
systole.
(1) It is produced by
closure of semilunar
valves at the start of
ventricular diastole.
(2) It is low pitched,
less loud and of long
(2) It is higher pitched,
louder, sharper and of

CIRCULATION OF BLOOD THROUGH HEART
(1) The heart pumps blood to all parts of the body.
(2) The deoxygenated blood is drained into right auricle
through superior and inferior vena cava and coronary
sinus whereas the pulmonary veins carry oxygenated
blood from lungs to the left auricle. This is called as
Auricular circulation.
(3) About 70% of the auricular blood passes into the
ventricles during diastole. This phase is called diastasis.
(4) The rest of 30% of blood passes into the ventricles
due to auricular systole (contraction).
(5) In this way, blood reaches the ventricles and is called
ventricular filling.
(6) During ventricular systole (which starts first in left
ventricle than in right ventricle), the pressure increases
in the ventricles, thus, forcing the oxygenated blood
from left ventricle into systemic aorta and
deoxygenated blood from right ventricle into
pulmonary aorta.
(7) The systemic arch
distributes the oxygenated
blood to all the body parts
except lungs while pulmonary
aorta carries the
deoxygenated blood to lungs
for oxygenation.

HEART RATE AND PULSE
• In the resting condition, human heart beats at the rate of about 70 times
per minute. But, the heart beat rate increases during exercise, fever, and
emotions like anger and fear.
• During each heart beat, the blood is pumped from the ventricles of the
heart into the aorta to be distributed to all parts of the body. This happens
during the ventricular systole and is repeated every 0.8 seconds. The blood
from aorta then goes to other arteries of the parts. This causes a rhythmic
contraction in the aorta and its main arteries. It can be felt as regular jerks
or pulse in the regions where arteries are present superficially like wrist ,
neck and temples. This is known as arterial pulse.
• The pulse rate is, therefore, same as that of heart beat rate. This heart
beat rate differs from species to species. In general, the smaller the animal,
the greater the heart beat. Hence, larger animals have lower heart rates.
For example, an elephant has a normal heart beat rate of about 25 times
per minute, where as mouse has a normal heart beat rate of several
hundreds per minutes.

Automatic rhythmicity of the heart:
• The mammalian heart is a myogenic heart i.e., the heart beat originate from a
muscle (but it is regulated by nerves). In the right atrium near the region
where superior vena cava opens, a specialised muscle called sinu-auricular
node (SA-node) is present from where the heart beat originates. It is also
called as pace maker and is richly supplied with blood capillaries. A wave of
contraction (systole) originates from it and spreads over to the whole heart.
• At the junction of right atrium and right ventricle, a tissue called auriculo-
ventricular node (AV-node) is present that picks up the wave of contraction
propagated by SA-node. This is also known as bundle of His. Branches of this
spread over the ventricle forming the Purkinje system. The wave of contraction
spreads over the ventricle through AV-node and its Purkinje system.
• The heart is supplied with vagus (parasympathetic) and sympathetic nerve
fibers. The vagus nerve is inhibitory and so when stimulated slows down the
heart beat; while the sympathetic nerve is acceleratory and so when stimulated
fastens the heart beat. This happens because these nerves release chemicals
(hormones) when stimulated.

Fractions of cardiac output :
• Amount of pure blood going to an organ per minute
is called as fraction of the organ.
(i) Cardiac fraction – 200 ml/min.
(ii) Hepatic fraction – 1500 ml/min. (28% of blood as
liver is the busiest organ of body and has maximum
power of regeneration).
(iii) Renal fraction – 1300 ml/min (25% of blood)
(iv) Myofraction – 600-900 ml/min.
(v) Cephalic organs – 700-800 ml/min.

Arterial Blood Pressure:
The pumping action of the heart maintains a
pressure of blood in the arteries. This is called
Arterial blood pressure. It helps to pump blood at a
high velocity along the arteries in the closed
circulatory system. The blood pressure is far lower in
the open circulatory system.

Blood Flow in Veins:
The blood pressure is low in veins, because the blood flows
through narrow arterioles and capillaries to enter wider veins. At
many places in the body, this blood pressure is not sufficient to
drive the blood through the veins back to the heart. Veins have
thinner walls than arteries and are more easily compressed. There
are also many valves inside the veins. These valves permit the flow
of blood in the veins towards the heart and prevent blood flow in
the reverse direction. Contraction of muscles and changes of body
posture compresses the veins to move the blood inside them.
During this both cases, blood moves towards the heart only,
because the venous valves prevent the blood flow in the opposite
direction. This is a major process for venous blood flow.

Electrocardiogram
(ECG)
(i) Depolarisation waves: They represent
the generation of the potential difference.
These waves appear only when both
electrodes of galvanometer are in
different fields. When both the electrodes
are in same field, there are no deflection
and wave drops down to base line.
(ii) Repolarisation waves: They appear
when depolarisation is over and the
muscle fibre is returning to its original
polarity. When both electrodes are in
same polarity (means 100% repolarisation
and 100% depolarisation), there is no
deflection.
(a) P wave: Indicates impulse of
contraction generated by S.A. node and
its spread in atria causing atrial
depolarisation. The interval PQ represents
atrial contraction and takes 0.1 second.
b) QRS complex: Indicates spread of impulse of
contraction from A.V node to the wall of ventricles
through bundle of His and pukinje fibres causing
ventricular depolarisation. This complex also represents
repolarization of S.A. node.
The RS of QRS wave and ST interval show ventricular
contraction (0.3 seconds). QRS is related to ventricular
systole.
(c)T wave: Indicates repolarisation during ventricular
relaxation.

Lymph and Tissue Fluid
• It occurs in the spaces in between the cells of a tissue and is called as interstitial fluid or tissue
fluid.
• The exchange of any material (solid, liquid or a gas) that occurs between the blood and the
tissue cells always takes place through this fluid. Under the pressure of blood in the
capillaries some of the water and desired solutes are filtered out from the blood plasma into
the tissue spaces to form the tissue fluid.
• The composition of this tissue fluid is very similar to that of plasma except that it has much
less protein. Proteins are less because some of the proteins are not filtered out from the
capillary walls (impermeable).
• Some of the tissue fluid enters tiny channels called lymph vessels and the fluid collected in
them is called lymph and this system is known as lymphatic system. These lymph vessels
unite to form larger lymph vessels which ultimately drain into two large lymph vessels called
thoracic duct and the right lymphatic duct. These open into veins returning the lymph finally
into venous blood and so in the general circulatory system. This movement of lymph is
mainly due to the squeezing action of the surrounding muscles. So the lymphatic system is
slow and uncertain. Exercise increases the rate of lymph circulation.
Generally, the rate of lymph formation is equal to the rate of its return to the blood stream.
But sometimes, the formation rate of lymph exceeds the rate of its return to blood. The
increased volume of fluid around the cells then creates a swelling, called dropsy or oedema.

Functions of Lymph
•
1. It serves to return interstitial fluid into blood.
2. The plasma proteins macromolecules synthesized
by the liver cells, cannot pass into the blood vessels,
but can diffuse into the lymph vessels through their
wall and they come to the blood through lymph.
3. It also carries absorbed fats and lipids from the
small intestine to the blood in the form of chylomicron
droplet

Lymphatic System
• The lymphatic system is an extension of the circulatory system. It
consists of a fluid known as lymph, lymph capillaries and lymph ducts.
(a) Lymph: It can be defined as blood minus RBC's. In addition to the blood
vascular system all vertebrate possess a lymphatic system. It is
colourless or yellowish fluid present in the lymph vessels. It is a mobile
connective tissue like blood and is formed by the filtration of blood.
(b) Lymph capillaries: Small, thin, lined by endothelium resting on a
basement membrane and fine whose one end is blind and other end
unites to form lymphatic ducts.
(c) Lymphatic ducts or vessels: Numerous, present in various parts of
body. These vessels are like veins as they have all the three layers –
tunica externa, tunica media and tunica interna, and are provided with
watch pocket or semilunar valves but valves are more in number than
veins.

Disorders of Circulatory System:
1. High Blood Pressure (Hypertension): It is the term for blood pressurethat is
higher than normal of 120/80. In the instrument 120 is Systolic / pumping
pressure, 80 is Diastolic, resting pressure. If repeated check which shows 140/90
and higher shows Hypertension. It may leads to heart diseases and also affect
vital organs like brain and kidney.
2.Coronary Artery Disease (CAD) : it is also known as Atherosclerosis, due to
damage in the blood vessels of heart tissues. Basically it it due to, deposition
excess of Calcium, fat, cholesterol and fibrous tissues which makes the lumen of
arteries narrower.
3.Angina: It is also known as “angina pectoris”, it is symptom of acute chest pain
due to less oxygen supply to heart.
4.Heart Failure: It is the state when heart is not pumping blood effectively to other
organs of the body.

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