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INTERMEDIATE BIOLOGY
BODY FLUIDS AND CIRCULATION
-Circulation is the transport of nutrients, oxygen, CO2 and excretory products to the concerned
tissues or organs
...
) use water from their
surroundings
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-Circulatory system is 2 types- Open and Closed
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-E
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Arthropods and molluscs
...
-This is more
advantageous as the flow of fluid can be more precisely regulated
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g
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#All vertebrates have a muscular chambered heart
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• Amphibians: 3-chambered heart (2 atria + a ventricle)
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Ventricle is incompletely partitioned
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TYPES OF CIRCULATION
1)SINGLE CIRCULATION
-In fishes
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-Deoxygenated blood → to heart → to gills → oxygenated blood → to body parts →
deoxygenated blood → to heart
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-In this, left atrium gets oxygenated blood from gills/lungs/skin and right atrium gets
deoxygenated blood from other body parts
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- It pumps out mixed blood
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Right atrium gets
deoxygenated blood and passes to right ventricle and left atrium gets oxygenated blood and
passes to left ventricle
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HUMAN CIRCULATORY SYSTEM
BLOOD VASCULAR SYSTEM
Heart
Blood
Plasma
Formed elements
Blood vessels
Arteries
Veins
LYMPHATIC SYSTEM
Lymph
Lymph vessels
Lymph nodes
RBC
WBC
Platelets
Granulocytes
Agranulocytes
Capillaries
Neutrophils
Lymphocytes
Monocyte
Oeosinophils
Basophils
B- Lymphocytes
T-Lymphocytes
It includes Heart, Blood & Blood vessels
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BLOOD
Formed of plasma (55%) & formed elements (45%)
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PLASMA
Straw-coloured, slightly alkaline (pH 7
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Constituents of plasma
• Water (90-92%): It is a good solvent
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o Globulins: Act as antibodies (for defense of the body)
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Regulate blood pressure
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• Inorganic constituents: Na+, Ca2+, Mg2+, Cl-, HCO - etc
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Plasma without clotting factors is known as Serum
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FORMED ELEMENTS (RBC, WBC & PLATELETS)
Red Blood Cells (RBC) or Erythrocytes:
- Biconcave non-nucleated cells
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Red colour is due to
Haemoglobin (iron
containing protein)
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- Count: 5 - 5
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- Formed in: Red Bone marrow
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Worn-out RBCs are destroyed in spleen (graveyard of RBCs)
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White Blood Cells (WBC) or Leucocytes:
- Colourless nucleated cells
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- Formed in: Bone marrow, lymph glands, spleen
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- Function: Part of immune system
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GRANULOCYTES
They are 3 types:
A)NEUTROPHILS
-Hetrophils
-60-65%
-Soldier of the body
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B) EOSINOPHILS
-Acidophils
- 2-3%
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- Cause allergic reactions
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5-1%
-Secrete histamine,serotonin, heparin etc
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2
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Includes B- lymphocytes & T- lymphocytes
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B)MONOCYTES
-6-8%
- Largest WBC
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C)THROMBOCYTES(PLATELETS)
- Colourless non-nucleated cell fragments
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5 - 3
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- Formed in: Megakaryocytes in Bone marrow
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- Function: Blood clotting
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1)ABO GROUPING
-It is based on presence or absence of 2 surface antigens (chemicals that induce immune
response) on RBCs namely A
& B
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-Blood group Antigens Antibodies Can donate blood to
-Can receive blood from
(Donor’s group)
A
A
Anti-B
A & AB
A, O
B

B
Anti-A
B & 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
- Antigen A reacts with anti-A
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- If bloods with interactive antigens & antibodies are mixed
together, it causes clumping (agglutination) of RBCs
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-Persons with AB group are called Universal recipients because they can accept blood from all
groups
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- Rh+ve means the presence of Rh factor and Rh-ve means absence of Rh factor
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- Anti-Rh antibodies are not naturally found
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-So, a second transfusion of Rh+ve blood causes agglutination
-Therefore,Rh-group should be matched before transfusion
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- Rh antigens do not get mixed with maternal blood in first pregnancy because placenta
separates the two bloods
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-This induces the formation of Rh antibodies in maternal blood
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-This is fatal to the foetus or cause
severe anaemia and jaundice to the baby
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- It can be avoided by administering anti-Rh antibodies to the mother immediately after the first
delivery
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BLOOD VESSELS
Blood vessels are 3 types: Arteries, Veins & Capillaries
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-They contain oxygenated blood (except pulmonary artery)
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-Arteries are 3- layered- inner tunica intima (squamous endothelium), middle tunica media
(smooth muscles & elastic fibres) and outer tunica externa (fibrous connective tissue)
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- They contain deoxygenated blood (except pulmonary vein)
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- Veins are also 3-layered but
tunica media is comparatively thin
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-They are called capillaries
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3
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-It has the size of a clenched fist
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- The pericardial space (between pericardial membranes) is filled with pericardial fluid
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- Heart has 4 chambers- two upper atria (auricles) and two lower ventricles
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- The atria are separated by an inter-atrial septum and the ventricles are separated by
inter-ventricular septum
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- A tricuspid valve (3 muscular flaps or cusps) guards the opening between right atrium & right
ventricle
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-These valves allow the flow of blood only in one direction, i
...
from atria to ventricles
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-These openings have semi-lunar valves
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CONDUCTING SYSTEM OF HEART
- It includes nodal tissues, bundles & fibres
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-They are 2 types:
o SINO-ATRIAL NODE (SAN)
- in the right upper corner of the
right atrium
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- From the AVN, a bundle of fibrous atrio-ventricular bundle(AV bundle) passes through
atrio-ventricular septa and dividesinto right & left branches
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-In the ventricular wall, it breaks up into minute fibres (Purkinje fibres)
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- Nodal tissues generate action potential without any external stimuli, i
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it is autoexcitable
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-So, it is called the pacemaker
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- It involves 3 stages:
1
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- When the tricuspid and bicuspid valves open,blood from pulmonary vein and vena cava flows
into left & right ventricles respectively through left and right atria
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2
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As a result, both the atria contract
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-This increases the flow of blood into the
ventricles by about 30%
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VENTRICULAR SYSTOLE
-The action potential is conducted to

ventricular side by AVN & AV bundle from where bundle of His transmits it through the
ventricular musculature
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It is called ventricular systole
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Ventricular systole increases the ventricular pressure
causing
* Closure of tricuspid and bicuspid valves due to attempted backflow of blood into the atria
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So deoxygenated blood enters the pulmonary artery from right
ventricle and oxygenated blood enters the aorta from left ventricle
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* The tricuspid and bicuspid valves are opened by the pressure in the atria
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-A cardiac cycle is completed in 0
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• One heartbeat = a cardiac cycle
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• STROKE VOLUME
-It is the volume of blood pumped out by each ventricle during a cardiac cycle
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• CARDIAC OUTPUT
- It is the volume of blood pumped out by each ventricle per minute, i
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stroke volume x heart
rate (70 x 72)
- It is about 5000 ml (5 litres)
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• HEART SOUND
- During each cardiac cycle, 2 sounds are produced
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-The second sound (dub) is due to the closure of the semilunar valves
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ELECTROCARDIOGRAPH (ECG)
- It is an instrument used to obtain electrocardiogram
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- 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
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- An ECG consists of the following waves:
o P-WAVE
1 Represents the excitation (depolarization) of atria during atrial systole
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o T-WAVE
-Represents the repolarisation of ventricles
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-So, ECG has great clinical significance
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-It includes:
1)PULMONARY CIRCULATION: -Circulation b/w lungs and heart
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2)SYSTEMIC CIRCULATION
-Circulation b/w heart and various
body parts
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-Systemic circulation provides nutrients, O2 and other substances to the tissues and takes CO2
and other harmful substances away for elimination
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• CORONARY CIRCULATORY SYSTEM
It is a system of coronary
vesselsthat circulate blood to and from cardiac musculature
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- So, it is called myogenic heart
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- Sympathetic nerves of ANS increase the rate of heartbeat,the strength of ventricular
contraction and cardiac output
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- Adrenal medullary hormones increase the cardiac output
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- 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
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- Some tissue fluid enters lymphatic system and the tissue fluid in them is called lymph
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- Lymph is a colourless fluid containing lymphocytes
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- Tissue fluid helps to exchange nutrients, gases, etc
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-It carries plasma proteins synthesized in liver to the blood
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-Filtration of bacteria and foreign particles
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DISEASES OF CVS
1)HYPERRENSION
-High Blood Pressure
-The pressure of circulating blood on the walls of blood vessels is called
blood pressure
-Normal BP is 120/80 mm Hg
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-When the BP is higher than normal, it is called hypertension
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It leads to heart diseases and affects vital organs
(brain, kidney etc)
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-So the lumen
of arteries becomes
narrower and thereby affects the blood supply
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- It occurs due to improper
blood flow
- It is common among middle-aged and elderly
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-Congestion of
the lungs is the main symptom
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6)HEART ATTACK
- Sudden damage of heart muscle due to
inadequate blood supply

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