Blood is a connective tissue that distributes oxygen and nutrients throughout the body while also protecting against infection. It is composed of plasma and formed elements, which include red blood cells, white blood cells, and platelets. Red blood cells contain hemoglobin and distribute oxygen, while white blood cells protect the body against infection and disease. Platelets help the blood clot to prevent blood loss from injuries. The document provides detailed information on the composition and functions of blood and its components.

1. Dr. Moattar Raza Rizvi
NRS237, Physiology

2. Distributes
•Oxygen and nutrients (removes waste products)
•Hormones delivered to target organs
Regulates
•Body temperature, pH
Protects
•Against blood/fluid loss via hemostasis
(coagulation)
•Against infection via contribution to inflammatory
and immune responses.

3. • Sticky
• Opaque
• Salty-metallic taste
• Color varies according to oxygen content
• More dense than water and 5x more viscous
• pH: 7.35-7.45 (reservoir for bicarbonate ions)
• Temperature: 38°C
• Volume (4-6 litres; adult).

4. • Blood is the body’s only fluid tissue (a
connective tissue)
• 2 major components
– Liquid = plasma (55%)
– Formed elements (45%)
• Erythrocytes, or red blood cells (RBCs)
• Leukocytes, or white blood cells (WBCs)
• Platelets or Thrombocytes

5. Withdraw blood
and place in tube
1 2 Centrifuge
Plasma
(55% of whole blood)
Formed
elements
Buffy coat:
leukocyctes and
platelets
(<1% of whole blood)
Erythrocytes
(45% of whole blood)
• Hematocrit
• Males: 47% ± 5%
• Females: 42% ± 5%

6. • Hematocrit
• Males: 47% ± 5%
• Females: 42% ± 5%

7. • Blood plasma components:
– Water = 90-92%
– Proteins = 6-8%
• Albumins; maintain osmotic pressure and viscosity of
the blood
• Globulins
– Alpha and beta globulins are used for transport purposes
– Gamma globulins are the immunoglobulins (IgG, IgA, etc)
• Fibrinogen; a clotting protein
– Organic nutrients – glucose, carbohydrates, amino acids
– Electrolytes – sodium, potassium, calcium, chloride,
bicarbonate
– Nonprotein nitrogenous substances – lactic acid, urea,
creatinine
– Respiratory gases – oxygen and carbon dioxide

9. • Formed elements comprise 45% of blood
• Erythrocytes, leukocytes, and platelets make up the
formed elements
– Only WBCs are complete cells
– RBCs have no nuclei or organelles, and platelets are just
cell fragments
• Most formed elements survive in the bloodstream for
only a few days
• Most blood cells do not divide but are renewed by
cells in bone marrow

10. • Biconcave disc
– Folding increases surface area (30% more surface area)
– Plasma membrane contains spectrin
• Give erythrocytes their flexibility
• Anucleate, no centrioles, no organelles
– End result - no cell division
– No mitochondria means they generate ATP anaerobically
• Filled with hemoglobin (Hb) - 97% of cell contents
– Hb functions in gas transport
• Hb + O2 HbO2 (oxyhemoglobin)
• Most numerous of the formed elements
– Females: 4.3–5.2 million cells/cubic millimeter
– Males: 5.2–5.8 million cells/cubic millimeter

12. • Erythrocytes are dedicated to respiratory gas transport
• Hemoglobin reversibly binds with oxygen and most
oxygen in the blood is bound to hemoglobin
– Hb functions in gas transport
• Hb + O2 HbO2 (oxyhemoglobin)
• Composition of hemoglobin
– A protein called globin
• made up of two alpha and two beta chains
– A heme molecule
• Each heme group bears an atom of iron, which can bind to one
oxygenmolecule
• Each hemoglobin molecule thus can transport four molecules of
oxygen

14. • Oxyhemoglobin – hemoglobin bound to oxygen
– Oxygen loading takes place in the lungs
• Deoxyhemoglobin – hemoglobin after oxygen diffuses
into tissues (reduced Hb)
• Carbaminohemoglobin – hemoglobin bound to carbon
dioxide
– Carbon dioxide loading takes place in the tissues

15. The life span of an erythrocyte is 100–120 days
Travels about 750 miles in that time
Iron is transported from liver in
blood plasma by beta-globulins
as transferrin
RBC Destruction
1.RBC damaged by squeezing through
capillaries
2.Macrophages phagocytize damaged RBC
in spleen/liver
3.Hemoglobin decomposes – heme &
globin
4.Heme decomposes – iron & biliverdin
5.Iron is stored to be used later
6.Some biliverdin converted to bilirubin
7.Biliverdin/bilirubin excreted in bile as
pigments
8.Globin broken down into amino acids

16. Imbalance
Reduces O2
levels in blood
Erythropoietin
stimulates red
bone marrow
Enhanced
erythropoiesis
increases RBC
count
Normal blood oxygen levels Stimulus: Hypoxia due to
decreased RBC count,
decreased availability of O2
to blood, or increased
tissue demands for O2
Imbalance
Start
Kidney (and liver to a
smaller extent) releases
erythropoietin
Increases
O2-carrying
ability of blood

17. • Hematopoiesis – blood cell formation
• Production of Erythrocytes: Erythropoiesis
– Occurs in the red bone marrow (myeloid tissue)
• Axial skeleton and girdles
• Epiphyses of the humerus and femur
• Marrow contains immature erythrocytes

18. • The % volume occupied by red blood cells is known as the
hematocrit.
• Volume occupied by white blood cells is relatively small.

20. • Leukocytes, the only blood components that are complete cells:
– Larger than RBC – Up to 3 times larger
• Two major types of leukocytes
– Granulocytes: Neutrophils, Eosinophils, Basophils
– Agranulocytes: Monocytes, Lymphyocytes
• Normal WBC Count 4,800 - 10,000/cubic millimeter
• Number and percentage of each WBC helps diagnose certain
diseases
– Leukocytosis – WBC count over 11,000/mm3
• Normal response to bacterial or viral invasion
– Leukopenia - a decrease in WBC count below 4,800/mm3
– Leukemia - a cancer of WBC

21. • Diapedesis: Can squeeze through
small spaces and leave blood
circulation
• Functions of WBC – Fighting
Foreign Microorganisms
• Functions of WBC – Fighting Foreign Microorganisms
• WBC release chemicals that dilate blood vessels
• Inflammatory response
• More blood to area – redness, swelling
• Damaged cells release chemicals that attract other WBCs
• Positive chemotaxis
• Pus forms from bacteria, WBCs, and damaged cells
• Until all foreign microorganisms are “dead”

22. Are all phagocytic cells
Cell Type Characteristic features Major Functions
Neutrophils Account for 65-75% of total
WBC’s
Multilobed nucleus
AKA “polys” or PMN’s
(polymorphonuclear)
Ingest and destroy invading
microorganisms
Participate in acute
inflammation
Eosinophils Eosinophils account for 1–4%
of WBCs
Bilobed nucleus
Phagocytic especially against
parasitic infection
large multicellular parasites such as
tapeworms and hookworms
Basophils Account for 0.5-1% of all
WBCs
Have U- or S-shaped nuclei
Migrate to tissues to become
mast cells; release of histamine
contributes to inflammation
Helps in allergic reactions

23. Cell Type Characteristic features Major Functions
Monocyte Monocytes account for 3–7%
of leukocytes
They are the largest
leukocytes
They have purple-staining,
U- or kidney-shaped nuclei
They leave the circulation, enter
tissue, and differentiate into
macrophages which protect
against viruses, certain
intracellular bacterial parasites,
and chronic infections.
Lymphocyte Account for 20-25% or more
of WBCs and:
Have large, dark-purple,
circular nuclei with a thin
rim of blue cytoplasm
Most important cells of the
immune system
There are two types of
lymphocytes: T cells and B cells
T cells - attack foreign cells
directly
B cells give rise to plasma cells,
which produce antibodies

24. • Not complete cells, fragments
• No nucleus
• Less than half the size of RBC
• Lives for about 10 days
• Platelet Counts: 150,000 450,000 per L blood‐ μ
• Their granules contain serotonin, Ca2+
, enzymes, ADP,
and platelet-derived growth factor (PDGF)
• Platelets function in the clotting mechanism by forming
a temporary plug that helps seal breaks in blood vessels
• Platelets not involved in clotting are kept inactive by
Nitric Oxide (NO) and prostaglandins

26. • RBC membranes have glycoprotein antigens on their
external surfaces
• These antigens are:
– Unique to the individual
– Recognized as foreign if transfused into another individual
– Promoters of agglutination and are referred to as
agglutinogens
• Presence or absence of these antigens is used to
classify blood groups

27. • The ABO blood groups consists of:
– Two antigens (A and B) on the surface of the RBCs
– Two antibodies in the plasma (anti-A and anti-B)
• An individual with ABO blood may have various
types of antigens and spontaneously preformed
antibodies
• Agglutinogens and their corresponding antibodies
cannot be mixed without serious hemolytic reactions
Blood Group AB is Universal Recipient
Blood Group O is Universal Donor

28. • There are 4 blood types
– A, B, AB, O
– Type A has “A” antigen, and B antibodies
– Type B has “B” antigen, and A antibodies
– Type AB has “A” and “B” antigen, and NO antibodies
– Type O has NO antigen and “A” and “B” antibodies

29. Named after the rhesus monkeys in which it
was first studied
• Many Rh factors, mostly antigen
• Presence of the Rh agglutinogens on RBCs is indicated as Rh+
;
85% of population is +
• Lack of antigen indicated as Rh -; 15% of popn.
• Anti-Rh antibodies are not spontaneously formed only in Rh–
individuals

30. • Rh antibodies created in Rh‐ individuals in response
to Rh antigens on Rh+ RBC
• If an Rh‐ individual receives Rh+ blood
• First time : usually ok
• Second time : RBC have become sensitized to
Rh+ blood; Rh antibodies will attack and
agglutinate the Rh+ RBC

33. When a blood vessel ruptures, local
vasoconstriction (decrease in the
caliber of blood vessels) occurs to
decrease blood flow to the area.
When a blood vessel ruptures, local
vasoconstriction (decrease in the
caliber of blood vessels) occurs to
decrease blood flow to the area.
Platelets and clotting factors
become activated when exposed
to the collagen layer of the
damaged blood vessel.
Platelets and clotting factors
become activated when exposed
to the collagen layer of the
damaged blood vessel.
Platelets clump together
(aggregate) by binding to the
collagen, forming a loose
platelet plug.
Platelets clump together
(aggregate) by binding to the
collagen, forming a loose
platelet plug.

35. • Three Coagulation Pathways
– Extrinsic pathway: release of chemicals from broken
blood vessel or damaged tissue
• Begins in the vessel wall
• Outside bloodstream
– Intrinsic pathway: blood contact with foreign surfaces in
absence of tissue
• Begins with circulating proenzymes
• Within bloodstream
– Common pathway
• Where intrinsic and extrinsic pathways converge

36. Hemostasis
• The Extrinsic Pathway
– Damaged cells release tissue factor (TF)
– TF + other compounds = enzyme complex
– Activates Factor X

37. • The Intrinsic Pathway
– Activation of enzymes by collagen
– Platelets release factors (e.g., PF–3)
– Series of reactions activates Factor X
Hemostasis

38. • The Common Pathway
– Forms enzyme prothrombinase
– Converts prothrombin to thrombin
– Thrombin converts fibrinogen to fibrin
Hemostasis

39. • Stimulates formation of tissue factor
– Stimulates release of PF-3
– Forms positive feedback loop (intrinsic and
extrinsic)
• Accelerates clotting
Hemostasis

40. The Coagulation Phase of Hemostasis
Hemostasis

41. The Coagulation Phase of Hemostasis
Hemostasis

42. • Calcium Ions, Vitamin K, and Blood Clotting
– Calcium ions (Ca2+
) and vitamin K are both essential
to the clotting process
Hemostasis

43. • Clotting: Area Restriction
– Anticoagulants (plasma proteins)
• Antithrombin-III
• Alpha-2-macroglobulin
– Heparin
– Protein C (activated by thrombomodulin)
– Prostacyclin
Hemostasis

44. • Clotting can be prevented by Ca+2
chelators (e.g.
sodium citrate or EDTA)
• or heparin which activates antithrombin III (blocks
thrombin)
• Coumarin blocks clotting by inhibiting activation of
Vit K
• Vit K works indirectly by reducing Ca+2
availability

45. Complete the following questions:
1.Diapedesis is the process by which the WBC’s comes out of blood
capillaries.
2.Erythropoiesis is the formation of red blood cells.
3.Erythrocytopenia is the decrease in the number of RBC.
4.Hematocrit is the percentage of blood cells in the blood.
5.Instrument used to determine RBC count Hematocytometer
6.Hemolysis is breaking of RBC.
7.Hemometer instrument used to know percentage of hemoglobin in
blood.
8.Leukocytosis is increase in number of WBC’s
9.Erythrocytosis is increase in number of RBC’s.
10.Leukopenia is decrease in number of WBC’s.
11.Red blood cells in human does not contain nucleus and
mitochondria
12.Give the terms used for decrease in RBC and WBC count.
13.Blood is fluid connective tissue

46. 1. Write the functions of blood?
2. Write the composition of blood?
3. Write the different types of White blood cells?
4. What is hemoglobin and its function?
5. What is the life span of RBC?
6. Write the functions of platelets?
7. Name the different types of blood groups in our body.
8. Name the antigens and antibodies present in blood group A, B,
AB and O?
9. Name any 3 blood anticoagulants?
10. Name the plasma proteins found in blood with function?
11. Define blood coagulation? The property of blood to change
from fluid to get state within a few minutes after it comes in
contact with air is blood coagulation.
12. What is the role of vitamin K? Vitamin K is essential for the
formation of blood clot.