The Blood Applied Physiology

1. THE BLOOD
(APPLIED PHYSIOLOGY)
Prof.Nagamani.T

2. CONTENTS (4 HRS)
 Blood–Functions, Physical characteristics
 Formation of blood cells
 Erythropoiesis– Functions of RBC, RBC life cycle
 WBC– types, functions
 Platelets– Function and production of platelets
 Clotting mechanism of blood, clotting time,bleeding time,
PTT
 Hemostasis– role of vasoconstriction ,platelet plug
formation in hemostasis, coagulation factors, intrinsic
and extrinsic pathways of coagulation
 Blood groups and types
 Functions of reticuloendothelial system, immunity
 Application in nursing

3. INTRODUCTION
 Blood is one of the most important components of life.
Almost any animal that possesses a circulatory system
has blood.
 Our body consists of 4-6 litres of blood with an average
pH of 7.35 to 7.45
 Every tissue in the body requires an adequate supply of
oxygen, nutrients and hormones.
 The waste products should be removed from the
tissues from time to time.
 These functions are carried out by the blood
 The heart and blood vessels are the mechanism by
which a constant circulation is maintained through out
the body.

4. WHAT IS BLOOD
 Blood is a fluid connective tissue that consists of
plasma, blood cells and platelets. It circulates
throughout our body delivering oxygen and
nutrients to various cells and tissues. It makes up
8% of our body weight. An average adult possesses
around 5-6 litres of blood.

5. COMPOSITION OF BLOOD
 Composition of Blood: Plasma, RBCs, WBCs and
platelets

7. COMPONENTS OF BLOOD
 There are many cellular structures in the
composition of blood. When a sample of blood is
spun in a centrifuge machine, they separate into the
following constituents:
 Plasma, buffy coat and erythrocytes. Thus blood
contains RBC, WBC, platelets and plasma.

8. PLASMA
 The liquid state of blood can be contributed to
plasma as it makes up ~55% of blood.
 It is pale yellow in colour and when separated.
 Blood plasma consists of salts, nutrients, water and
enzymes.
 Blood plasma also contains important proteins and
other components necessary for overall health.
 Hence, blood plasma transfusions are given to
patients with liver failure and life-threatening
injuries.

9. Components of Blood Plasma
 Blood plasma has several protein components.
Proteins in blood plasma are:
 Serum globulin
 Serum albumin
 Fibrinogen
 The serum contains only globulin and albumin.
Fibrinogen is absent in serum because it is
converted into fibrin during blood clotting.

10. TYPES OF BLOOD CELLS
 Blood consist of cells known as formed elements of
blood. These cells have their own functions and
roles to play in the body. The blood cells which
circulate all
 Red blood cells (Erythrocytes)
 White blood cells (Leucocytes)
 Thrombocytes ( Platelets)

11. RED BLOOD CELLS (ERYTHROCYTES)
 Red blood cells consist of Haemoglobin, a protein.
They are produced by the bone marrow to primarily
carry oxygen to the body and carbon dioxide away
from it.
 RBCs are biconcave cells without nucleus in
humans; also known as erythrocytes. RBCs contain
the iron-rich protein called haemoglobin; give blood
its red colour.
 RBCs are the most copious blood cells produced in
bone marrows. Their main function is to transport
oxygen from and to various tissues and organs.

12. WHITE BLOOD CELLS (LEUCOCYTES)
 White blood cells are responsible for fighting foreign
pathogens (such as bacteria, viruses, and fungi) that
enter our body. They circulate throughout our body and
originate from the bone marrow.
 Leucocytes are colourless blood cells. They are
colourless because it is devoid of haemoglobin.
 They are further classified as granulocytes and
agranulocytes. WBCs mainly contribute to immunity and
defence mechanism.
Types of White Blood Cells
 There are five different types of White blood cells and
are classified mainly based on the presence and
absence of granules.
 Granulocytes
 Agranulocytes

13. TYPES OF WHITE BLOOD CELLS

14. GRANULOCYTES
 They are leukocytes, with the presence of granules in
their cytoplasm. The granulated cells include-
eosinophil, basophil, and neutrophil.
Eosinophils
 They are the cells of leukocytes, which are present in
the immune system.
 These cells are responsible for combating infections in
parasites of vertebrates and for controlling mechanisms
associated with allergy and asthma.
 Eosinophil cells are small granulocyte, which are
produced in the bone marrow and makes 2 to 3 per
cent of whole WBCs. These cells are present in high
concentrations in the digestive tract.

15. Basophils
 They are the least common of the granulocytes,
ranging from 0.5 to 1 per cent of WBCs.
 They contain large cytoplasmic granules, which play
a vital role in mounting a non-specific immune
response to pathogens, and allergic reactions by
releasing histamine and dilating the blood vessels.
 These white blood cells have the ability to be stained
when exposed to basic dyes, hence referred to as
basophil.
 These cells are best known for their role in asthma
and their result in inflammation and
bronchoconstriction in the airways.
 They secrete serotonin, histamine and heparin.

16. Neutrophils
 They are normally found in the bloodstream.
 They are predominant cells, which are present in pus.
 Around 60 to 65 per cent of WBCs are neutrophils with a
diameter of 10 to 12 micrometres.
 The nucleus is 2 to 5 lobed and the cytoplasm has very
fine granules.
 Neutrophil helps in the destruction of bacteria with
lysosomes, and it acts as a strong oxidant.
 Neutrophils are stained only using neutral dyes. Hence,
they are called so.
 Neutrophils are also the first cells of the immune system to
respond to an invader such as a bacteria or a virus.
 The lifespan of these WBCs extends for up to eight hours
and is produced every day in the bone marrow.

17. AGRANULOCYTES
 They are leukocytes, with the absence of granules in
their cytoplasm. Agranulocytes are further classified into
monocytes and lymphocytes.
Monocytes
 These cells usually have a large bilobed nucleus, with a
diameter of 12 to 20 micrometres.
 The nucleus is generally half-moon shaped or kidney-
shaped and it occupies 6 to 8 per cent of WBCs.
 They are the garbage trucks of the immune system.
 The most important functions of monocytes are to
migrate into tissues and clean up dead cells, protect
against bloodborne pathogens and move very quickly to
the sites of infections in the tissues.
 These white blood cells have a single bean-shaped
nucleus, hence referred to as Monocytes.

18. Lymphocytes
 They play a vital role in producing antibodies.
 Their size ranges from 8 to 10 micrometres.
 They are commonly known as natural killer cells.
 They play an important role in body defence.
 These white blood cells are colourless cells formed
in lymphoid tissue, hence referred to as
lymphocytes.
 There are two main types of lymphocytes – B
lymphocytes and T lymphocytes.
 These cells are very important in the immune
systems and are responsible for humoral and cell-
mediated immunity.

19. PLATELETS (THROMBOCYTES)
 Tiny disc-shaped cells that help regulate blood flow
when any part of the body is damaged, thereby
aiding in fast recovery through clotting of blood.
 Thrombocytes are specialized blood cells produced
from bone marrow.
 Platelets come into play when there is bleeding or
haemorrhage.
 They help in clotting and coagulation of
blood. Platelets help in coagulation during a cut or
wound.

21. FUNCTIONS OF BLOOD
 Blood is a fluid connective tissue connecting blood
cells, plasma and platelets.
 It circulates all through the circulatory system of
humans, delivering nutrients and oxygen to different
cells and tissues.
 It also passes metabolic waste products away from
the very same cells.
 On an average, blood constitutes about 8% of the
mass of the body, and an adult’s body has around
5-6 litres of blood.

22.  Blood comprises blood cells suspended in the
blood plasma.
 Plasma accounts for 55% of the volume of the
blood, it mainly comprises glucose, proteins,
hormones, mineral ions, carbon dioxide and even
the blood cells.
 In plasma, albumin is the chief protein, and it
operates to control the colloidal osmotic pressure of
blood.
 Mainly, blood cells are RBCs (red blood cells),
WBCs (white blood cells) and platelets.

23.  In the vertebrate blood, the most abundantly found
blood cell is red blood cells.
 It contains an iron-containing protein –
haemoglobin, promoting oxygen transport by
associating reversibly to this respiratory gas, and
highly increasing their blood solubility.
 On the contrary, carbon dioxide is usually
transported extracellularly as bicarbonate ions are
transported in the plasma.

24. IMPORTANT FUNCTIONS OF BLOOD
Defense – Role of Blood in Defense
 There are different forms of WBCs protecting from
exterior threats such as the pathogenic bacteria which
enter the bloodstream in a wound. Various other WBCs
find and destroy the internal threats like the cells having
mutated DNA, which can grow and multiply to become
carcinogenic, or even the body cells infected with the
viruses.
 Blood platelets and some of the proteins that are
dissolved in plasma interact to produce clots blocking
the ruptured sites of blood vessels when the vessels
get damaged, leading to bleeding. Hence, the body is
prevented from any further loss of blood.

25. Transportation – Role of Blood in Transportation
 The food we consume has nutrients that are absorbed
in the digestive tract. Most of the nutrients directly pass
from the bloodstream to the liver, which is processed
and released into the bloodstream to deliver to the cells
of the body.
 Oxygen diffuses into the blood that moves from the
lungs to the heart, which then is pumped to the entire
body. Additionally, the blood picks the by-products and
cellular wastes too, and passes them to different
structures to be eliminated.

26. Homeostasis – Role of Blood in Maintaining
Homeostasis
 The body temperature is regulated through the
negative-feedback loop. When blood passes through
the vessels of the skin, heat can be dissipated to the
environment and the blood getting back to the body can
be cooler. On the contrary, on a colder day, blood gets
diverted from the skin to preserve a warmer tone. If
conditions are extreme, it can lead to frostbite.
 Also, blood aids in maintaining the balance of chemicals
in the body. The pH of tissues is regulated by the buffers
found in the blood, such as proteins and associated
compounds. Further, blood also aids in regulating the
water content of the cells.

27.  Blood aids in eliminating urea, lactic acid and carbon
dioxide
 Involved in immunological functions, such as circulation
of the white blood cells, identifying foreign particles by
the antibodies
 It responds to broken blood vessels, coagulation,
converting blood from liquid to a semisolid gel that
stops bleeding
 Involved in hydraulic functions
 Performs messenger functions, even that of
transporting hormones and signalling tissue damage

30. FUNCTIONS OF WBC
 There are five types of white blood cells:
 Neutrophils: Help protect your body from infections by
killing bacteria, fungi and foreign debris.
 Lymphocytes: Consist of T cells, natural killer cells and
B cells to protect against viral infections and produce
proteins to help you fight infection (antibodies).
 Eosinophils: Identify and destroy parasites, cancer
cells and assists basophils with your allergic response.
 Basophils: Produce an allergic response like coughing,
sneezing or a runny nose.
 Monocytes: Defend against infection by cleaning up
damaged cells.

35. FUNCTIONS OF PLATELETS

36. FORMATION OF BLOOD CELLS (HEMATOPOIESIS)
 Hematopoiesis/ hemopoiesis is the production, Development
and the maturation of Blood cells.
 Blood cells formation, or hematopoiesis, occurs in red bone
marrow, or myeloid tissue.
 The cellular components of blood are developed from the
Hematopoietic stem cells also known as Pluripotent Stem
cells or totipotent stem cells which further differentiate and
mature into typical blood cells.
 The Pluripotent stem cells give rise to two types of Stem cells
or lineages –
* Myeloid stem cells/Lineage – Differentiate in the Redbone
marrow and form Erythrocytes, Granulocytes (Neutrophils,
Eosinophils, and Basophils), Monocytes and Thrombocytes
* Lymphoid stem cells/Lineage – differentiates in the Redbone
marrow and then migrates to the lymphoid tissue. They form
T- and B- Lymphocytes.

37.  The immature cell divides, matures and eventually
becomes a mature RBC, WBC or Platelet.
It includes;
 The production of erythrocytes is called as
Erythropoiesis; the leukocytes are called as
Leucopoiesis and that of platelets is Thrombopoiesis.
 Leucopoiesis is further subdivided into –
* Granulopoiesis – formation of granulocytes
* Monopoiesis – formation of monocytes
* Lymphopoiesis – formation of lymphocytes

38. ERYTHROPOISES
(FORMATION OF RED BLOOD CELLS
 It is the process of formation, development, and maturation of red blood
cells.
 Life span. 100 to 120 days.
 Lost RBCs. Lost cells are replaced more or less continuously by the
division of hemocytoblasts in the red bone marrow.
 Immature RBCs. Developing RBCs divide many times and then begin
synthesizing huge amounts of hemoglobin.
 Reticulocyte. Suddenly, when enough hemoglobin has been
accumulated, the nucleus and most organelles are ejected and the cell
collapses inward;
 Mature erythrocytes. Within 2 days of release, they have rejected the
remaining ER and have become fully functioning erythrocytes; the entire
developmental process from hemocytoblast to mature RBC takes 3 to 5
days.
 Erythropoietin. The rate of erythrocyte production is controlled by a
hormone called erythropoietin; normally a small amount of erythropoietin
circulates in the blood at all times, and red blood cells are formed at a
fairly constant rate.
 Control of RBC production. An important point to remember is that it is
not the relative number of RBCS in the blood that controls RBC
production; control is based on their ability to transport enough oxygen
to meet the body’s demands.

39. SITE OF HEMATOPOIESIS
 The site of Hematopoiesis depends on the age of the
person as follows –
 In human embryo – Yolk sac is the main site of
Hematopoiesis
 By the 3rd to 7th month of Intra-uterine life –
Hematopoiesis occurs in liver and spleen.
 By the 7th month till birth – it starts in the bone
marrow.
 From birth till maturity – occurs in bone marrow,
spleen, and liver.
 In adults – Hematopoiesis occurs in the Central
skeleton (Vertebrae, Sternum, Ribs, Skull, Sacrum,
and pelvis), proximal ends of the long bones like
Femur, Tibia, and Humerus.

40.  Regulation of Erythropoiesis – Erythropoietin is
the hormone produced mainly by the kidneys, helps
to regulate the process of Erythropoiesis so that the
number of RBCs is sufficient to sustain adequate
tissue oxygen levels.

42.  Reticulocytes are called as the juvenile RBCs or
Immature RBCs.
 Reticulocytes spend 1-2 days in the marrow then 1-
2 days in circulation where it gets mature into
Erythrocytes and attains biconcave shape.
 Normal range of Reticulocytes –
 Adults – 0.5 – 2.5%
 Infants – 2 – 6%

43. STRUCTURE OF ERYTHROCYTES
 Erythrocytes, also referred to as Red Blood Cells
(RBCs) is a significant cellular component of blood.
These cells circulate in the blood carrying oxygen
from the lungs to all the tissues of the body. It is
responsible for imparting blood with its
characteristic colour.
 Mature erythrocytes in humans are rounded, small
and biconcave, as though dumbbell-shaped. As the
cell is flexible, it can reform to take up a bell shape
when it passes through the super tiny blood
vessels.

46.  RBCs or erythrocytes exhibit a diameter of 7-8 µm
possessing an atypical structure in comparison to
most other body cells of humans. The RBC
structure resembles a donut, they are biconcave
wherein their periphery is thicker than their central
portion. Courtesy to this feature, the total surface of
the cell membrane is maximized enabling exchange
of gases and their transport.
 These cells are anuclear and do not have any other
intracellular organelles as they are lost in
erythropoiesis. There are two main structures –
cytoplasm engirdled by a cell membrane.

47.  Cytoplasm – It is filled with haemoglobin which in
turn contains acidophilia causing erythrocytes to
stain intense red with eosin on the samples of
tissues stained with hematoxylin and eosin.
 Cell membrane – This membrane is a lipid layer
containing two types of membrane proteins –
peripheral and integral.
 The RBC membrane is a two-dimensional structure
comprising a cytoskeleton and a lipid bilayer bound
together. The lipid bilayer has different types of
cholesterol, phospholipids, sphingolipids, and
integral membrane proteins like the glycophorin.

48.  The peripheral membrane proteins extend into the
cytoplasm only, as they are found on the inner surface
of the plasma membrane. The proteins are
interconnected by several intracellular filaments which
form a complex mesh-like cytoskeletal network through
the inner cell membrane. This network is responsible for
imparting strength and elasticity to RBCs enabling its
even passage into the thinnest and smallest capillaries
without any breakage/leakage.
 Integral membrane proteins are innumerable, stretching
throughout the thickness of the cell membrane. It binds
haemoglobin serving as anchor points for the
cytoskeletal network of RBCs. Additionally, they express
antigens of ABO blood groups. Erythrocyte surface
antigens are necessary for blood transfusions.

49. RED BLOOD CELLS – FUNCTION
Basic and important functions of RBCs:
 Delivers oxygen from the lungs to the tissues all
through the body ( exchange of gases)
 Facilitates carbon dioxide transport
 Acts as a buffer and regulates hydrogen ion
concentration
 Contributes to blood viscosity
 Carries blood group antigens and Rh factor

50. LEUKOPOIESIS
 It is the process of formation or production of leucocytes
which normally occurs in the blood-forming tissue of the
bone marrow. There are 3 independent series, which
leads to the formation of 3 different types of white cells –
 Granulocytes – Granulopoiesis
 Lymphocytes – Lymphopoiesis
 Monocytes – Monopoiesis/ Monocytopoiesis
 The formation of White Blood cells is regulated by –
 Stimulation by cytokines and Colony stimulating factor.
 Produced by Macrophages & T – lymphocytes.
 Activated by coming in contact with foreign organisms.

51. GRANULOPOIESIS
 Granulopoiesis is the process of formation or
production of Granulocytes that are the type of White
blood cells that contains the granules in their
cytoplasm, which begins at the Myeloblast and passes
through the stages of a Promyelocyte, Myelocyte,
Metamyelocyte and Band cells and ultimately results
in the formation of 3 types of Granulocytes –
Neutrophils, Eosinophils & the Basophils.

53. LYMPHOPOIESIS
 Lymphopoiesis is the process of formation or
production of Lymphocytes, a type of white blood
cells that lack the granules in their cytoplasm, which
begins at the Lymphoblast and passes through the
stage of Prolymphocyte and ultimately results in the
formation of mature Lymphocytes.

55. MONOPOIESIS/ MONOCYTOPOIESIS
 Monopoiesis or Monocytopoiesis is the process of
formation of production of Monocytes, a type of White
blood cells that lack the granules in their cytoplasm,
which begins at the Monoblast, passes through the
stage of Promonocyte and ultimately results in the
formation of mature Monocytes.

56. THROMBOPOIESIS
 Thrombopoiesis is the formation or production of
Thrombocytes or Platelets in the bone marrow
which is formed by fragmentation of mature
Megakaryocyte membrane projections, begins at
Megakaryoblast and passes through the stages of
Promegakaryocyte and then the Megakaryocytes
ultimately results in the formation of mature
Thrombocytes or Platelets.

57. HAEMOGLOBIN
 Haemoglobin (Hb) is a type of globular protein present
in red blood cells (RBCs), which transports oxygen in
our body through blood.
 The standard abbreviation for Haemoglobin is “Hb”
 The haemoglobin level is measured in g/dL of the
blood.
 In a healthy individual, the level ranges from 12 to 20
g/dL. Generally Hb level in males is greater compared
to females. The normal level in males is 13.5 to 17.5
g/dL and in females, it is 12 to 15.5 g/dL.

58.  Haemoglobin develop in the cells of the bone marrow.
Eventually, they turn into red blood cells.
 Hence, Haemoglobin is a hemeprotein found in only in
red blood cells (RBC) or the erythrocytes of blood. They
are said to occupy 1/3rd of the volume of RBCs. 90-
95% of the dry weight of red blood cells is by
haemoglobin.
Functions:
 Transport of oxygen: Every 100 ml of oxygenated
blood carries 5 ml of O2 to the tissues.
 Transport of Carbon dioxide: Every 100 ml of
deoxygenated blood carries 4 ml of CO2 to the alveoli.

59. Types of Haemoglobin
 The main types of Haemoglobin are –
 Haemoglobin A: Most common form of
Haemoglobin found in the adult human being. It is a
combination of two alpha and two beta chains.
 Haemoglobin A2: It is indicative of 2-3% of
Haemoglobin found in the adult human being and is
a combination of two alpha and two delta chains.
 Haemoglobin F: It is seen in newborns blood (1% in
its Haemoglobin) and is the combination of two
alpha and two gamma chains.

60. Diseases related to Haemoglobin
 Haemoglobin deficiency leads to the lower oxygen-carrying
capacity of the blood. It can be due to nutritional deficiency,
cancer, kidney failure or any genetic defects.
 Higher than normal haemoglobin level is associated with
various heart and pulmonary diseases.
 Sickle cell anaemia – It is due to a defect in the
haemoglobin gene.
 Thalassemia – It is caused due to less production of
haemoglobin. There are two types of thalassemia, 𝜶-
thalassemia and 𝞫-thalassemia. It is also caused due to
defective genes and severity depends on how many genes
are missing or defective.
 Haemoglobin level is commonly used as a diagnostic tool.
The HbA1c level, i.e. glycosylated Hb or Hb linked with
sugar is a marker for average glucose level in the blood of a
diabetic patient.

61. CLOTTING MECHANISM OF BLOOD
Blood Coagulation
 It is defined as the process by which a blood clot forms
and potentially leads to hemostasis, the cessation of
blood loss from a damaged vessel, followed by repair.
 Blood coagulation or clotting is an important
phenomenon to prevent excess loss of blood in case of
injury or trauma.
 The blood clot or ‘coagulum’ is formed by a network of
fibrin threads. In this network, deformed and dead
formed elements (erythrocytes, leukocytes and platelets)
get trapped.

62.  Prothrombin is the inactive form of thrombin that is
present in the plasma. Thrombokinase converts
prothrombin to active thrombin which in turn activates
fibrinogen to fibrin. All these clotting factors help in
blood coagulation.
 An injury stimulates platelets or thrombocytes to
release various factors that initiate the blood clotting
cascade. Calcium ions play an important role in blood
coagulation.

64. FACTORS INVOLVED IN BLOOD COAGULATION
 Coagulation of blood occurs through a series of
reactions due to the activation of a group of
substances called clotting factors.
 There are 13 clotting factors identified and named
after the scientists who discovered them or as per
the activity.
 Only factor IX or Christmas factor is named after
the patient in whom it was discovered.

66. BLOOD COAGULATION PATHWAY
 The process of blood coagulation leads to haemostasis, i.e.
prevention of bleeding or haemorrhage.
 Blood clotting involves activation and aggregation of
platelets at the exposed endothelial cells, followed by
deposition and stabilisation of cross-linked fibrin mesh.
 Primary haemostasis involves platelet aggregation and
formation of a plug at the site of injury, and secondary
haemostasis involves strengthening and stabilisation of
platelet plug by the formation of a network of fibrin threads.
 The secondary haemostasis involves two coagulation
pathways, the intrinsic pathway and the extrinsic pathway.
Both pathways merge at a point and lead to the activation of
fibrin, and the formation of the fibrin network.

67. PLATELET ACTIVATION
 The blood circulating in the blood vessel does not clot
under normal circumstances. The blood coagulation
process is stimulated when there is any damage to the
endothelium of blood vessels.
 It leads to platelet activation and aggregation.
 When collagen is exposed to the platelets due to injury,
the platelets bind to collagen by surface receptors.
 This adhesion is stimulated by the von Willebrand
factor released from endothelial cells and platelets.
 This forms additional cross-linking and activation of
platelet integrins, which facilitate tight binding and
aggregation of platelets at the site of injury. This leads
to primary haemostasis.

68. BLOOD COAGULATION CASCADE/ PROCESS
 The process of coagulation is a cascade of enzyme
catalysed reactions wherein the activation of one
factor leads to the activation of another factor and
so on.
The three main steps of the blood coagulation
cascade are as follows:
 Formation of prothrombin activator
 Conversion of prothrombin to thrombin
 Conversion of fibrinogen into fibrin

69. 1. Formation of prothrombin activator
 The formation of a prothrombin activator is the first step in the blood
coagulation cascade of secondary haemostasis. It is done by two
pathways, viz. extrinsic pathway and intrinsic pathway.
Extrinsic Coagulation Pathway
 It is also known as the tissue factor pathway. It is a shorter pathway.
The tissue factors or tissue thromboplastins are released from the
damaged vascular wall. The tissue factor activates the factor VII to
VIIa. Then the factor VIIa activates the factor X to Xa in the
presence of Ca2+.
Intrinsic Coagulation Pathway
 It is the longer pathway of secondary haemostasis. The intrinsic
pathway begins with the exposure of blood to the collagen from the
underlying damaged endothelium. This activates the plasma factor
XII to XIIa.
 XIIa is a serine protease, it activates the factor XI to XIa. The XIa
then activates the factor IX to IXa in the presence of Ca2+ ions.
 The factor IXa in the presence of factor VIIIa, Ca2+ and
phospholipids activate the factor X to Xa.

70. 2. Conversion of prothrombin to thrombin
 Prothrombin or factor II is a plasma protein and is the
inactive form of the enzyme thrombin. Vitamin K is
required for the synthesis of prothrombin in the liver.
 The prothrombin activator formed above converts
prothrombin to thrombin.
 Thrombin is a proteolytic enzyme. It also stimulates its
own formation, i.e. the conversion of prothrombin to
thrombin.
 It promotes the formation of a prothrombin activator by
activating factors VIII, V and XIII.

71. 3. Conversion of fibrinogen into fibrin
 Fibrinogen or factor I is converted to fibrin by thrombin.
 Thrombin forms fibrin monomers that polymerise to form
long fibrin threads.
 These are stabilised by the factor XIII or fibrin stabilising
factor.
 The fibrin stabilising factor is activated by thrombin to
form factor XIIIa.
 The activated fibrin stabilising factor (XIIIa) forms cross-
linking between fibrin threads in the presence of
Ca2+ and stabilises the fibrin meshwork.
 The fibrin mesh traps the formed elements to form a
solid mass called a clot.

72. CLOTTING TIME
 Clotting time is a general term for the time required
for a sample of blood to form a clot, or, in medical
terms, coagulate.
 The Clotting Time Blood Test helps determine the time
it takes for a sample of blood to form a blood clot while
in a glass test tube of standard size. It was once
regularly used to diagnose clotting disorders
Normal clotting time (CT)
 The expected range is 3 to 8 minutes.
 The glass tube method clotting time is 5 to 15 minutes.
 The siliconized tube’s clotting time is 19 to 60 minutes
(reference: Interpretation of diagnostic test by Jacques
Wallach M.D.)

73. BLEEDING TIME (BT)
 Bleeding time is the functional test of primary hemostasis that
checks how quickly the blood clots stop the bleeding.
 This test diagnoses bleeding problems related to the
abnormalities of:
 Platelets functions. Platelets response to vascular injury.
 Vascular response to injury.
 Blood vessel elasticity also influences the bleeding time.
 The ability of the blood vessels to constrict.
 Bleeding times is the best single screening test for acquired
causes like uremia or congenital functional or structural
disorder of platelets.
NORMAL Values Of Bleeding G Time (BT)
 Bleeding time normal: 3 to 6 minutes
 Borderline: 7 to 11 minutes.
 Abnormal value: 10 to 15 minutes

74. PROTHROMBIN TIME (PT)
 The prothrombin time (PT) test measures how long
it takes for a blood clot to form based on a protein
produced by the liver called prothrombin.
 With the PT test, the reference range is between 10
to 12 seconds

75. PARTIAL THROMBOPLASTIN TIME (PTT)
 The partial thromboplastin time (PTT) test also
measures the speed of clotting but differs from the
PT test in that it aims to establish how blood clots
within a blood vessel (intrinsic pathway).
 PTT test, the reference range is between 25 and 33
seconds.

76. HEMOSTASIS
 Platelets are key players in hemostasis, the
process by which the body seals a ruptured blood
vessel and prevents further loss of blood. Although
rupture of larger vessels usually requires medical
intervention, hemostasis is quite effective in dealing
with small, simple wounds.
 There are three steps to the process: vascular
spasm, the formation of a platelet plug, and
coagulation (blood clotting). Failure of any of these
steps will result in hemorrhage—excessive
bleeding.

77. STAGES OF HEMOSTASIS
 When a blood vessel is injured, a series of
reactions initiate, resulting in hemostasis, which
occurs in three stages;
• Vasoconstiction
• Platelet plug formation
• Coagulation of blood ( Blood Clotting)

78. VASOCONSTRICTION
 When a vessel is severed or punctured, or when
the wall of a vessel is damaged, vascular spasm
occurs.
 This vascular spasm occurs to reduce pressure to
the damaged area of the vessel, and minimize
blood loss.
 This phenomenon typically lasts for up to 30
minutes, although it can last for several hours.

79. FORMATION OF THE PLATELET PLUG
 In the second step, platelets, which normally float free in the plasma,
encounter exposed connective tissue found inside the damaged vessel.
 This causes platelets to clump together, become sticky, and bind to the
exposed collagen and endothelial lining.
 This process is assisted by a glycoprotein in the blood plasma called von
Willebrand factor, which helps stabilize the growing platelet plug.
 As platelets collect, they simultaneously release chemicals from their
granules into the plasma that further contribute to hemostasis. Among
the substances released by the platelets are:
 Adenosine diphosphate (ADP) – helps additional platelets to adhere to
the injury site, reinforcing and expanding the platelet plug
 Serotonin – maintains vasoconstriction
 Prostaglandins and phospholipids – maintain vasoconstriction and help
to activate further clotting chemicals
 A platelet plug temporarily seals a small opening in a blood vessel, which
allows the body time to make more sophisticated and durable repairs.

80. COAGULATION
 These sophisticated and durable repairs made beyond
the plug formation are collectively called coagulation,
the formation of a blood clot.
 The process is sometimes characterized as a
cascade, because one event prompts the next as in a
multi-level waterfall.
 The result is the production of a gelatinous but robust
clot made up of a mesh of an insoluble protein called
fibrin, which is derived from a plasma protein called
fibrinogen.
 This mesh traps platelets and blood cells

82. BLOOD GROUPS AND TYPES

83.  Karl Landsteiner, an Austrian scientist discovered the
ABO blood group system in the year 1900.
 In his experiments, he mixed different blood types and
noted that the plasma from certain blood type produced
agglutinates or formed clusters which were caused by
the absence of molecules on red blood cells and
resulting in antibodies to defeat that molecule.
 He then made a note of the agglutination and divided
the blood types into 4 different groups.
 For the discovery of ABO blood group, he was awarded
the Nobel Prize.
 The blood grouping system is pivotal in blood
transfusion.
 Our immune system recognizes another blood type as
foreign and attacks it if introduced in the body causing
a transfusion reaction.

84. ABO AND RH BLOOD GROUPS
 During the blood transfusion, the two most important
group systems examined are the ABO-system and
the Rhesus system.
 The ABO blood group system consists of 4 types of
blood group – A, B, AB, and O and is mainly based on
the antigens and antibodies on red blood cells and in
the plasma. Both antigens and antibodies are protein
molecules in which antigens are present on the surface
of Red Blood Cells and antibodies are present in the
plasma which is involved in defending mechanisms.
 On the other hand, the Rh blood group system consists
of 50 defined blood group antigens. In the Rh system,
the most important antigens are D, C, c, E, and e.

85. 1. ABO BLOOD GROUP SYSTEM
 The basis of ABO grouping is of two antigens- Antigen A
and Antigen B. The ABO grouping system is classified
into four types based on the presence or absence of
antigens on the red blood cells surface and plasma
antibodies.
 Group A – contains antigen A and antibody B.
 Group B –contains antigen B and antibody A.
 Group AB –contains both A and B antigen and no
antibodies (neither A nor B).
 Group O – contains neither A nor B antigen and both
antibodies A and B.

86.  The ABO group system is important during blood
donation or blood transfusion as mismatching of blood
group can lead to clumping of red blood cells with
various disorders.
 It is important for the blood cells to match while
transfusing i.e. donor-recipient compatibility is
necessary.
 For example, a person of blood group A can receive
blood either from group A or O as there are no
antibodies for A and O in blood group A.
 Individuals of blood group O are called as universal
donors, whereas individuals of blood group AB
are universal recipients.

88. 2. RH BLOOD GROUP SYSTEM
 In addition to the ABO blood grouping system, the other
prominent one is the Rh blood group system.
 About two-thirds of the population contains the third
antigen on the surface of their red blood cells known
as Rh factor or Rh antigen; this decides whether the
blood group is positive or negative.
 If the Rh factor is present, an individual is rhesus
positive (Rh+ve); if an Rh factor is absent individual
is rhesus negative (Rh-ve) as they produce Rh
antibodies.
 Therefore, compatibility between donor and individual is
crucial in this case as well.

89. THE RETICULOENDOTHELIAL SYSTEM (RES)
 The RES is also known as the
mononuclear phagocyte system. This system consists of
cellular and noncellular components.
 The reticuloendothelial system (RES) is a heterogeneous
population of phagocytic cells in systemically fixed
tissues that play an important role in the clearance of
particles and soluble substances in the circulation
and tissues, and forms part of the immune system.
 Substances that are cleared include immune
complexes, bacteria, toxins, and exogenous antigens

90.  The RES: Consists of the phagocytic cells located in
reticular connective tissue, primarily monocytes
and macrophages. Since phagocytosis is their primary
role, mononuclear phagocytic system has been
suggested as an alternative name.
The composition of the reticuloendothelial system
includes
 Kupffer cells of the liver
 Microglia of the brain
 Alveolar macrophages
 Bone marrow
 Lymph nodes
 Macrophages in the intestine and other tissues.

91. REGULATION OF THE RES
The reticuloendothelial system is also under the leading role of the
nervous system and is regulated by chemicals in the body fluids.
The state of the cerebral cortex has a great influence on the
activity of macrophages in the reticular endothelium.
 The more the cortex is excited, the more activity in the
reticuloendothelial system is inhibited. eg when a person's
painful cerebral cortex is in an excited state, the function of the
reticuloendothelial system is inhibited.
 If the cerebral cortex is in a state of inhibition, such as
during sleep or anesthesia, activity on phagocytic cells is
enhanced.
 The chemical regulation of endocrine and vitamins also has a
certain effect on the function of the reticuloendothelial system.
eg. Experiments have shown that in the absence of vitamin C or
injection of adrenaline, the phagocytic activity of the
reticuloendothelial system becomes sluggish, the phagocytic
capacity is also weakened, and the production of collagen fibers
is also poor

92. FUNCTIONS OF THE RETICULO-ENDOTHELIAL SYSTEM:

93.  i. Phagocytosis: They engulf foreign particles, bacteria
and parasites and in this way, act as a great defensive
mechanism.
 ii. Formation of Antibodies: The antitoxic and
antibacterial bodies are manufactured by this system.
This is also a great protective mechanism.
 iii. Formation of R.B.C: Red blood cells develop from
the R.E. cells. Turnbull holds that they develop from the
extravascular R.E. cells (haemocytoblasts).
 iv. Formation of Leucocytes: The granulocytes,
lymphocytes and monocytes—are all derived from the
R.E. system.
 v. Destruction of Red Cells and White Cells: The
senile red cells and white cells are engulfed and
destroyed by the R.E. cells. In adult life, it takes place
chiefly in the spleen and liver.

94.  vi. Scavengers of Tissue Debris and Bacteria in
Infections Processes: The R.E. cells help in the
scavenging process.
 vii. Formation of Bile Pigments: The R.E. cells
manufacture bilirubin from haemoglobin.
 viii. Storage Function: A large amount of lipids,
cholesterol and iron are stored in the R.E. cells.
 ix. Manufacture of Plasma Proteins: Serum globulin
and certain other plasma proteins are manufactured, to
some extent, by the R.E. cells.
 x. Formation of Tissue Cells:
Since the cells of this system are undifferentiated, they
can be converted into ordinary connective tissue cells,
such as fibroblasts, under suitable stimulus. This is seen
during repair stage of inflammatory process.

95. IMMUNITY
 Immunity is the ability of the body to defend itself
against disease-causing organisms.
 Everyday our body comes in contact with several
pathogens, but only a few results into diseases.
 The reason is, our body has the ability to release
antibodies against these pathogens and protects
the body against diseases. This defence
mechanism is called immunity.

97. TYPES OF IMMUNITY
There are two major types of immunity:
 Innate Immunity or Natural or Non-specific Immunity.
 Acquired Immunity or Adaptive Immunity.
Innate Immunity
 This type of immunity is present in an organism by birth.
 This is activated immediately when the pathogen
attacks. Innate immunity includes certain barriers and defence
mechanisms that keep foreign particles out of the body.
 This immunity helps us by providing the natural resistance
components including salivary enzymes, natural killer cells,
intact skin and neutrophils, etc. which produce an initial
response against the infections at birth prior to exposure to a
pathogen or antigens.
 It is a long-term immunity in which our body produces the
antibodies on its own. Our body has few natural barriers to
prevent the entry of pathogens.

98. Barriers in Innate Immunity:
 Physical Barriers: These include the skin, body
hair, cilia, eyelashes, respiratory tract, and
gastrointestinal tract. The skin acts as a physical
barrier, preventing pathogen entry. Mucus in the
nose and ears also traps pathogens.
 Physiological Barriers: Stomach acid breaks
down food molecules, killing many germs. Saliva
and tears have antibiotic properties.
 Cellular Barriers: Leukocytes (white blood cells),
neutrophils, lymphocytes, basophils, eosinophils,
and monocytes play a role. They are present in
blood and tissues.
 Cytokine Barriers: Cells secrete interferons when
invaded by viruses. Interferons coat infected cells,
preventing nearby cells from getting infected.

99. Cells Involved In Innate Immunity
 Phagocytes: These circulate through the body and look for any
foreign substance. They engulf and destroy it defending the body
against that pathogen.
 Macrophages: These have the ability to move across the walls of
the circulatory system. They release certain signals as cytokines to
recruit other cells at the site of infections.
 Mast Cells: These are important for healing wounds and defence
against infections.
 Neutrophils: These contain granules that are toxic in nature and
kill any pathogen that comes in contact.
 Eosinophils: These contain highly toxic proteins that kill any
bacteria or parasite in contact.
 Basophils: These attack multicellular parasites. Like the mast
cells, these release histamine.
 Natural Killer Cells: These stop the spread of infections by
destroying the infected host cells.
 Dendritic Cells: These are located in the tissues that are the
points for initial infections. These cells sense the infection and
send the message to the rest of the immune system by antigen
presentation.

100. Acquired Immunity
 Acquired immunity or adaptive immunity is the immunity
that our body acquires or gains over time. Unlike the
innate immunity, this is not present by birth.
 The ability of the immune system to adapt itself to disease
and to generate pathogen-specific immunity is termed as
acquired immunity. It is also known as adaptive immunity.
 An individual acquires the immunity after the birth, hence
is called as the acquired immunity.
 It is specific and mediated by antibodies or lymphocytes
which make the antigen harmless.
 The main function of acquired immunity is to relieve the
victim of the infectious disease and also prevent its attack
in future.

101. Types of Acquired Immunity
 Active Immunity : Active immunity involves the direct
response to a foreign antigen within the body. In the
case of the acquired or adaptive immune system, the
body remembers the pathogens it has encountered in
the past. This is a direct result of the active immune
system.
 Active immunity occurs when we are in contact with the
pathogen or its antigen.
 Passive Immunity: Passive immunity involves the
immune response by the antibodies attained from
outside the body. The primary response by the body to
a pathogen it encounters for the first time is rather
feeble, so the first encounter is always a little harsh on
the body.

102. Features of Acquired Immunity
 Specificity: Our body has the ability to differentiate
between different types of pathogens, whether it is
harmful or not, and devise ways to destroy them.
 Diversity: Our body can detect vast varieties of
pathogens, ranging from protozoa to viruses.
 Differentiate between self and non-self: Our body has
the unique ability to differentiate between its own cells
and foreign cells. It immediately starts rejecting any
foreign cell in the body.
 Memory: Once our body encounters a pathogen, it
activates the immune system to destroy it. It also
remembers what antibodies were released in response
to that pathogen, so that, the next time it enters, a similar
procedure is followed by the body to eliminate it.

103. Cells Involved in Acquired Immunity
 The acquired immunity involves two types of cells: B-cells and T-cells
B-cells
 They develop in the bone marrow.
 These cells are activated on their encounter with foreign agents. These foreign
particles act as foreign markers.
 The B-cells immediately differentiate into plasma cells which produce
antibodies specific to that foreign particle or so-called antigen.
 These antibodies attach to the surface of the antigen/foreign agent.
 These antibodies detect any antigen in the body and destroy it.
 The immunity dependent on B-cells is called humoral immunity.
T-cells
 They originate in the bone marrow and develop in the thymus.
 T-cells differentiate into helper cells, cytotoxic cells, and regulatory cells. These
cells are released into the bloodstream.
 When these cells are triggered by an antigen, helper T-cells release cytokines
that act as messengers.
 These cytokines initiate the differentiation of B-cells into plasma cells which
release antibodies against the antigens.
 The cytotoxic T-cells kills the cancer cells.
 Regulatory T-cells regulate immune reactions.

104. APPLICATION IN NURSING
 Phlebotomy
 Collection of blood sample for blood grouping &
typing
 Blood Transfusion
 Procedure for Administration of Blood Products
& Blood Components
 Patient Observation During Transfusion
 Monitor for Acute & delayed transfusion
reactions
 Document reaction & Report to Physician

105. IMPORTANT QUESTIONS
 Blood Groups
 RES
 Types of Immunity
 Hemostasis
 Blood Clotting Mechanism
 Types of blood cells
 WBC
 Composition of blood
 Functions of RBC
 Functions of WBC
 Platelets

106. THANK YOU