Blood – Complete Study Notes for Nursing Exams (Hemoglobin, Types, and Hematopoiesis)

Blood – Complete Study Notes for Nursing Exams: Blood is a vital fluid connective tissue that plays a crucial role in transporting oxygen, nutrients, hormones, and waste products throughout the human body. Understanding its composition, function, and components like hemoglobin and hematopoiesis is essential for nursing students and aspirants preparing for competitive exams.

Blood – Complete Study Notes for Nursing Exams

What is Blood?

Blood is a liquid connective tissue responsible for delivering essential nutrients and oxygen to tissues and removing carbon dioxide and metabolic wastes.
Its red color is due to the presence of hemoglobin (Hb) in red blood cells.
It comprises RBCs, WBCs, platelets, and plasma.

Blood is a liquid connective tissue that transports nutrients, oxygen, and waste products between the body’s organs and tissues.

It appears red due to the presence of hemoglobin.

Normal blood volume:

Males: 5–6 liters
Females: 4.5–5.5 liters

The normal blood pH ranges between 7.35 to 7.45.

All blood cells (RBCs, WBCs, platelets) are generated in the bone marrow, particularly in long bones in adults.

Site of Hematopoiesis

Age Group	Site of Hematopoiesis
Fetus (0–2 months)	Yolk sac
Fetus (2–7 months)	Liver, spleen
Fetus (>7 months)	Bone marrow
Adults	Bone marrow of ribs, vertebrae, sternum, sacrum, pelvis, proximal ends of femur

Hemoglobin

Hemoglobin (Hb) is an iron-containing protein responsible for oxygen transport in RBCs.
Structure:
- Made of globin (protein with 4 polypeptide chains: 2 alpha + 2 non-alpha).
- Contains heme (iron), which converts to bilirubin for excretion.

Normal levels:

Males: 13–18 g/dL or 135–180 g/mL
Females: 12–16 g/dL or 120–150 g/mL

Types of Hemoglobin

Type	Polypeptide Chains	Remarks
HbA (Adult)	2 alpha, 2 beta (α₂β₂)	>95%, normal adult Hb
HbA2	2 alpha, 2 delta (α₂δ₂)	~2–3%, normal adult Hb
HbF (Fetal)	2 alpha, 2 gamma (α₂γ₂)	~3%, normal fetal Hb
Gower 1 & 2, Portland	Various	Found only in embryonic period

Additional Notes:

HbF has higher oxygen affinity than HbA, aiding oxygen transfer from mother to fetus.
HbA1c: Glucose-bound Hb, used for monitoring blood glucose over 90 days (important in diabetes).

Hemoglobin Derivatives

Oxyhemoglobin: Hb + O₂ → Bright red
Carbaminohemoglobin: Hb + CO₂ → Dark red
Carboxyhemoglobin: Hb + CO → Toxic form, interferes with O₂ transport

Hematocrit (HCT)

Indicates the percentage of RBCs in total blood volume.
Varies based on age, sex, and ethnicity.

Normal Ranges:

Males: 41%–50%
Females: 36%–44% (slightly lower)

Clinical Relevance:

Low HCT: Suggests anemia due to reduced RBCs.
High HCT: May occur in dehydration or polycythemia (excess RBCs).

Composition of Blood

Blood constitutes 55% plasma and 45% blood cells.
Plasma is the liquid part of the blood which consists of 92% water, 8% proteins, and other electrolytes, hormones, and nutrients.
- Albumin (60-65%): Maintains the body’s colloid osmotic or oncotic pressure.
- Globulin (35%): Helps in maintaining immunity of the body and is a type of immunoglobulin (Ig).
- Fibrinogen (4%): Necessary for blood clot formation.

Blood – Complete Study Notes for Nursing Exams (Hemoglobin, Types, and Hematopoiesis)

Blood Cells

Red Blood Cells (RBCs):

Also known as erythrocytes.
Normal value: 4.5 to 6.2 million/mcl in males and 4.2 to 5.5 million/mcl in females.
Formed in bone marrow of long bones such as sternum, ribs, iliac crest, femur, and clavicle.
Process of formation: Erythropoiesis takes 7 to 9 days in bone marrow.
Decrease in the number of RBCs is called erythrocytopenia or erythropenia.

White Blood Cells (WBCs):

Also known as leukocytes.
Two types:
- Granulocytes: Includes neutrophils, eosinophils, and basophils.
- Agranulocytes: Includes monocytes or macrophages and lymphocytes (T-Cell & B-Cell).
Normal value of WBCs: 4000 to 11000 cells/mm³.
WBCs are produced in bone marrow and spleen.

Platelets:

Also known as thrombocytes.
The smallest cells of the blood (2-4 µm in diameter).
Normal platelet count: 1,50,000–4,00,000 per microliter of blood.
Platelets function in blood clot formation to prevent bleeding.

Blood Components Summary

Parameter	Normal Value
Red Blood Cells (RBCs)	Males: 4.5-6.2 million/mm³ Females: 4.2-5.5 million/mm³
White Blood Cells (WBCs)	4500–11,000/mm³
Platelets	1,50,000–4,00,000/mm³
Hemoglobin	Males: 13-16 g/dL Females: 12-16 g/dL
Hematocrit	Males: 41-50% Females: 36%-44%

Neutrophils and Macrophages:

These are immune cells responsible for phagocytosis, meaning they ingest and destroy harmful microorganisms.
Neutrophils are the first responders to infections and their lifespan is 5-7 days.
Macrophages are involved in the long-term defense and tissue repair.

Hemoglobin Types

Type of Hemoglobin	Polypeptide Chains	Remarks
Hemoglobin A (HbA)	2 alpha, 2 beta (α₂β₂)	Normal adult Hb
Hemoglobin A2 (HbA2)	2 alpha, 2 delta (α₂δ₂)	Normal adult Hb
Fetal Hb (HbF)	2 alpha, 2 gamma (α₂γ₂)	Normal fetal Hb

HbA1c is the glycosylated form of HbA, used to monitor blood glucose levels in diabetic patients.

Human Blood Clotting

Stages of Blood Clotting

Vasoconstriction: Also called vascular spasm, this is the narrowing of blood vessels to prevent excessive bleeding.
Platelets Plug Formation Stage: Platelets adhere to damaged endothelium to form a platelet plug (primary hemostasis). This process is activated by a glycoprotein or Von Willebrand factor.
Blood Coagulation Phase:
- Extrinsic clotting mechanism: Processed by damaged tissues.
- Intrinsic clotting mechanism: Processed by release of chemicals/clotting factors.

Blood Clotting Factors

Factor	Name	Nature	Source	Pathway & Functions
I	Fibrinogen	Plasma Protein	Liver	Common pathway, converted to fibrin (insoluble vehicle of clotting)
II	Prothrombin	Plasma Protein	Liver	Common pathway, converted to thrombin (converts fibrinogen to fibrin)
III	Tissue factor (TF)	Plasma membrane glycoprotein	Tissue cells	Activates extrinsic pathway
IV	Calcium (Ca²⁺)	Inorganic ion	Plasma	Needed for essential stages of coagulation process, always present
V	Proaccelerin	Plasma protein	Liver, platelets	Common pathway
VI	Proconvertin	Plasma protein	Liver	Both extrinsic and intrinsic pathways
VII	Antihemophilic factor (AHF)	Plasma protein	Liver, lung capillaries	Intrinsic pathway, deficiency results in hemophilia A
VIII	Plasma thromboplastin component (PTC)	Plasma protein	Liver, lung capillaries	Intrinsic pathway, deficiency results in hemophilia B
IX	Stuart factor	Plasma Protein	Liver	Common pathway
X	Plasma thromboplastin antecedent (PTA)	Plasma Protein	Liver	Intrinsic pathway, deficiency results in hemophilia C
XI	Hemophilic factor	Plasma Protein	Liver	Intrinsic pathway, initiates clotting in vitro, activation initiates inflammation
XII	Fibrin stabilizing factor (FSF)	Plasma protein	Liver, bone marrow	Cross-links fibrin, forming a stable clot

Trick for Remembering the Blood Clotting Factors

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Important Points to Remember

Vitamin K and Calcium must be present in the blood for liver to produce prothrombin.
Factor number VII, IX, and X are Vitamin K dependent (important for normal coagulation).
End product of blood coagulation process or hemostasis is Fibrin.
Plasmin is formed by Plasminogen, and the endothelium formed then fibrin is destroyed by plasmin.

Blood Groups

A, B, AB, and O blood groups were discovered by Karl Landsteiner in 1901.
ABO blood grouping system is based on antigens and antibodies present in RBCs.
The associated anti-A and anti-B antibodies are usually IgM antibodies.

Should Remember

Rh Factor is also known as Rhesus Factor and was discovered by Karl Landsteiner in 1937.
According to Rh factor system, persons who have Rh positive are known as Rh+, while those who do not have this factor are known as Rh-.