THE BLOOD • Globulins (38%)

• Blood is a fluid connective tissue. • Fibrinogen (7%)

The main function: • Other proteins (1%)
• Blood is the fluid that transports oxygen Water (91.5%
and nutrients to the cells and carries away Other Solute (1.5%)
carbon dioxide and other waste products. • Electrolytes
Characteristics • Nutrients
• Viscous (thicker) and sticky • Gases
• Temperature: 100.4°F (38°C) • Regulatory substances
• pH: 7.35-7.45 (Slightly alkaline) • Waste products
• Colour: Varies with oxygen content Formed Elements
- With 0, bright red • It consists of:
- Less 0, dark red PLATELETS
• Volume: 1,50,000 - 4,00,000
Adult male: 5-6 L Granulocytes
Adult female: 4 - 5 L • Neutrophils (60-70%)
Functions of Blood • Eosinophils (2-4%)
1. Transportation: • Basophils (0.5- 1%)
Lungs -> 02 -> Body cells WHITE BLOOD CELLS (WBCs)
Body cells -> CO, -> Lungs 5000-10,000
GI Tract -> Nutrients —> Body cells Agranulocytes
Endocrine glands -> Hormones — Body • Lymphocytes (20-25%)
cells • Monocytes (3-8%)
OXYGEN RED BLOOD CELLS (RBCs)
OXYGEN, REFRIGERATED LIQUID 4.8 - 5.8 million
Blood also transports heat and gathers Hematocrit
waste products from various organs for • The percentage of total blood volume
elimination from the body occupied by RBCs is called the hematocrit.
2. Regulation: • If hematocrit is 40, it indicates 40% of
• Circulating blood helps maintain the volume of blood is composed of RBCs.
homeostasis of all body fluids • Normal range
• Blood helps in maintaining the pH - Adult Female: 38-46%
• Blood helps in adjusting the body - Adult Male: 40 - 54%
temperatures like water. RED BLOOD CELLS (Erythrocytes)
• Blood osmotic pressure influences water • These blood cells contain the oxygen
contents of cells and interaction of ions & carrying protein hemoglobin, which is a
proteins. pigment that gives whole blood its red
3. Protection color.
• Blood clotting protects from excessive • Shape: Biconcave discs
bleeding. • Diameter: 7-8 um
• WBCs protects against infection • RBCs have NO NUCLEUS
"Blood proteins, including antibodies, • The cytosol of RBCs contains hemoglobin
interferons and complement help protect molecules
from diseases • Life span: 100 - 120 days (80 -90 days in
Blood plasma: A straw coloured fluid infants)
Blood plasma is made up of:
Proteins (7%)
• Albumin (54%) RBC Physiology
• Highly specialized for their oxygen Under some circumstances Hb releases
transport function. the NO, which causes vasodilation, which
• Due to no nucleus, lot of internal space is an increase in blood vessel diameter
is available for oxygen transportation. that occurs when the smooth muscles in
• RBCs don't have mitochondria and the vessel walls relaxes.
generate ATP anaerobically (without Vasodilation improves blood flow and
oxygen) enhances oxygen delivery to cells near the
• The biconcave disc shape also increases site of Nitric Oxide release
the surface area for diffusion of gas • RBCs also contain the enzyme Carbonic
molecules into and out of RBC Anhydrase (CA), which catalyses the
• Each RBC contains about 280 million conversion of carbon dioxide and water to
hemoglobin molecules. carbonic acid, which in turns dissociates
Hemoglobin (Hb) into Ht and HCO;
It is the iron containing protein in the
blood. This reaction is important for two reasons:
Normal Hb value: 13 to 17gm/dI (male) 1. It allows about 70% of CO, to be
12 to 15 gm/dI (Female) transported in blood plasma from tissue
Structure: cells to the lungs in the form of HCO3
• Hb molecule consist of a protein called 2. It also serves as an important buffer in
globin. extracellular fluid.
• Hb has four polypeptide chains (2 alpha RBC Life Cycle
and 2 beta chain) • RBCs live for only about 120 days, due
• The four chains are bound by non- to the wear and tear they undergo while
protein pigment called heme. passing through capillaries.
• Each heme ring has an iron ion (Fe?+) • Without nucleus and other organelles,
• Iron ion combines with Oxygen molecule RBCs cannot repair themselves.
• Heme - Oxygen molecule bond is • Damaged RBCs are removed from
reversible circulation and destroyed by fixed
• As blood flows through tissue capillaries phagocytic macrophages in the spleen and
Iron- Oxygen reaction reverses liver.
• Oxygen is released first into interstitial • The breakdown products are recycled
space and then cells. and used in various metabolic processes.
• Hemoglobin also transports 23% of the Erythropoiesis and destruction/ recycling
total carbon dioxide from metabolism. of RBCs
• Erythropoiesis: The production or
Blood flowing through tissue capillaries formation of RBCs in the red bone marrow.
pick up carbon dioxide, some of which • Erythropoietin: Hormone that regulate
combines with amino acid in the globin RBCs production
chain. • Removal of damaged RBCs take place in
As blood flows through lungs the carbon Spleen, Liver and Bone marrow
dioxide is released from hemoglobin and • Macrophages are specialized cells
then exhaled. involved in phagocytosis of damaged or
• Hemoglobin also plays a role in the old RBCs
regulation of blood flow and blood WHITE BLOOD CELLS
pressure. • White blood cells are also called
Gaseous hormone Nitric Oxide (NO) Leukocytes
produced by endothelial cells that line
blood vessels binds to hemoglobin.
• WBCs have nuclei and a full complement Eosinophils helps in controlling
of other organelles but they lack inflammation. (e.g. Mosquito bite, asthma,
hemoglobin. skin allergy)
• WBCs are classified into two: Basophil
i. Granular leukocytes or Granulocytes • Granules are round with various sizes.
i. Agranular leukocytes or Agranulocytes • They stain blue-purple with basic dyes.
Granular Leukocytes • Nucleus has two lobes
• Staining with Leishman's stain makes it • Cytoplasmic granules are packed with
possible to easily identify different types of heparin, histamine and other substances
leukocytes. that promote inflammation.
• Leukocytes with clearly visible granules • Count: 0.5 - 1% of total WBCs.
with distinctive colouration that can be • Functions
recognized under a light microscope are - Contains the anti-coagulant heparin,
granular leukocytes or granulocytes. which prevents blood from clotting.
• Three type: - They also contain histamines which are
- Neutrophil released during an allergic reaction to
- Eosinophil enable inflammation
- Basophil Agranular Leukocytes
Neutrophil • Even though they are called agranular,
• The granules of neutrophil are smaller they have some amount of granules that
than those of other granulocytes. are not visible under a microscope.
• They are stained pale lilac. • 20-50% of WBCs are agranulocytes.
• The nucleus have 2 to 5 lobes connected • They are of t
by thin strands. Lymphocyte (T-Cell, B-Cell, Natural Killer
• Granules consist of lysosomes with cell)
enzymes for phagocytosis. • The nucleus stains dark and is round or
• They are attracted to area with infection slightly divided.
by chemicals called chemotaxins. • The cytoplasm stains sky blue
• Life span: Average 5 days • The larger the cell more cytoplasm is
• Neutrophils count = 2500-8000 per mm visible.
(55-70%) • Two types according to cell diameter
• Function: Small, fast and active - Small: 6-9 um - Large: 10-14 um
scavengers • Count: 20-40% of all WBCs (1000 - 4800
- Protect the body against bacterial in 1ul of blood)
infection. Function:
- Remove dead cells and its remains. - Mediate immune responses, antigen-
Eosinophil antibody reactions.
• Consist of large uniform sized granules. - B cells develop into plasma cells, which
• They stain Red-orange with acidic dyes. secrete antibodies.
• Nucleus often has two lobes connected - T cells attack invading viruses, cancer
by thick strands of chromatin. cells and transplanted tissues
• Count: 30-500 per mm3 (2-4% of total - NK cells attack wide variety of infectious
WBCs) microbes
• Function: - Phagocytosis after developing into
- Elimination of parasites like worms, using macrophages.
toxic chemicals stored in the granules. Monocyte
- Accumulation of eosinophil occurs in • Nucleus is usually kidney- shaped or
allergic reactions (hypersensitivity). horseshoe- shaped
• Cytoplasm is blue- grey and has a foamy • About 1/3rd of platelets is stored in the
appearance due to very fine granules spleen to be released incase to control
(lysosomes) excessive bleeding
• Largest WBCs accounts for 100-700 per Haemostasis : The stopping of blood flow
mm3 (2 - 8% of all leukocytes) • When a blood vessel is damaged, there
• Monocytes develop in macropahges will be loss of blood.
Functions • This loss of blood is stopped and healing
- Phagocytosis after transforming to of the damaged vessel takes place
macrophages through stages.
- Produces Interleukin 1 which: • Platelets play an important role in
+ acts on the hypothalamus causes haemostasis through coagulation or blood
increase in body clotting
temperature during microbial infection. Stages of Haemostasis:
+ Stimulate globulin production by liver + 1. Vasoconstriction
Enhances production of T- Lymphocytes 2. Platelet plug formation
The Reticuloendothelial system (The 3. Coagulation (Blood clotting)
Monocyte- macrophage system) 4. Fibrinolysis
• Consist of body's complement of Vasoconstriction
monocytes and macrophages Platelets come in contact with damaged
• Some macrophage are mobile and some blood vessel
are fixed. |
• The macrophages provide effective Platelets become sticky and adhere to the
defence at key body locations. damaged walls
• The collection of fixed macrophages are |
shown in the figure in the next slide. Platelets release Serotonin
• Macrophages produce chemicals called | causes
cytokines, interleukin 1. Constriction (narrows) of blood vessel
• Important role in specific and non- Reduces or stopping blood flow
specific immune system.
Platelets (Thrombocytes) Platelet plug formation
• Irregular disc shaped cells Adherent platelet clump together
• 2 - 4 um in diameter | releases
• Does not have nucleus Adenosine Diphosphate (ADP) and other
• Cytoplasm is packed with granules substances
containing substances which help in |causes
clotting. Attraction of more platelets to the injured
• Cessations or Ending of bleeding is site
called haemostasis. |positive feedback
• Normal count: 1,50,000 to 4,00,000 per More platelets accumulate at site of
mm3 vascular damage
Smooth |within 6 minutes of injury
platelet Forms a temporary seal (Platelet plug)
Spiky platelet 3. Coagulation (Blood Clotting)
• The hormone thrombopoietin from the • This is a complex process that also
liver stimulates platelet production. involves a positive feed back system.
• Life span: 8 - 11 days (unused platelets • Coagulation is aided by 12 clotting
destroyed by macrophages in the spleen) factors.
• There are three pathways for
coagulation
- Extrinsic pathway (activated within
seconds)
- Intrinsic pathway (activated in 3 -
6minutes)
- Common pathway (activated after Ext
and Int pathway)