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Questions and Answers
What is a distinguishing feature of WBCs (Leucocytes)?
What is a distinguishing feature of WBCs (Leucocytes)?
- Absence of nuclei
- Presence of nuclei (correct)
- Presence of hemoglobin
- High concentration in the bloodstream
Which of the following statements about WBCs is correct?
Which of the following statements about WBCs is correct?
- Their function includes immune response (correct)
- They contain hemoglobin for oxygen transport
- They are the most abundant cells in blood
- They are primarily responsible for nutrient delivery
What is true regarding the composition of WBCs (Leucocytes)?
What is true regarding the composition of WBCs (Leucocytes)?
- They contain specialized enzymes for defense (correct)
- They have a higher density than red blood cells
- They are composed mainly of plasma
- They lack nuclei but have large amounts of hemoglobin
Which characteristic does NOT apply to WBCs?
Which characteristic does NOT apply to WBCs?
In terms of blood composition, how do WBCs differ from RBCs?
In terms of blood composition, how do WBCs differ from RBCs?
Flashcards
WBC
WBC
White blood cells, also known as leucocytes or leukocytes, are essential components of the immune system. They lack hemoglobin, a protein that carries oxygen in red blood cells, and have nuclei, which distinguish them from other blood cells.
Leucocytes
Leucocytes
Leucocytes, also known as white blood cells or WBCs, are a type of blood cell that plays a crucial role in the immune system. They lack hemoglobin and possess nuclei, differentiating them from red blood cells.
Leukocytes
Leukocytes
Leukocytes, also known as white blood cells or WBCs, are a type of blood cell that plays a crucial role in the immune system. They lack hemoglobin and possess nuclei, differentiating them from red blood cells.
WBC function
WBC function
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WBC nuclei
WBC nuclei
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Study Notes
White Blood Cells (WBC)
- WBCs, also known as leukocytes or leucocytes, contain nuclei and lack hemoglobin
- Their count in blood ranges from 4,000 to 11,000 per mm³
- WBCs are less than 1% of total blood volume
Types of WBCs
- Granulocytes
- Contain numerous granules
- Nuclei are lobed
- Include:
- Neutrophils (40-70%), diameter 10-15 µm
- Eosinophils (1-4%), diameter 10-15 µm
- Basophils (0-2%), diameter 10-15 µm
- Agranulocytes
- Few or no granules
- Nuclei are large and spherical
- Include:
- Lymphocytes (20-40%), diameter 11-15 µm (large) or 7-10 µm (small)
- Monocytes (3-8%), diameter 14-18 µm
Leukopoiesis
- Production of WBCs
- Sites:
- Bone marrow (granulocytes, monocytes, and some lymphocytes)
- Lymph tissue (lymphocytes and plasma cells)
- Stimulators:
- Chemical messengers from bone marrow and mature WBCs (in areas of inflammation)
- Interleukins (e.g., IL-1, IL-2)
- Colony-stimulating factors (CSFs) (named for the WBC type they stimulate)
- Steps:
- Hemocytoblasts differentiate into myeloid and lymphoid stem cells
- Myeloid stem cells become myeloblasts or monoblasts
- Lymphoid stem cells become lymphoblasts
- Myeloblasts form eosinophils, neutrophils, and basophils
- Monoblasts develop into monocytes
- Lymphoblasts develop into lymphocytes
Leukocytosis and Leukopenia
- Leukocytosis: Increased WBC count (above 11,000/mm³)
- Physiological causes (e.g., extreme exercise, adrenaline injection, after meals, hot baths)
- Pathological causes (e.g., acute infection, acute hemorrhage, post-operative, tissue damage)
- Leukopenia: Decreased WBC count (below 4,000/mm³)
- Causes (e.g., toxicity of some drugs, typhoid fever, vitamin B12 and folic acid deficiency, bone marrow hypoplasia)
Neutrophils
- Lifespan: 6-12 hours
- First line of defense against bacteria and foreign particles
- Important roles: phagocytosis and inflammation
- Key characteristics:
- Margination
- Diapedesis
- Amoeboid movement
- Chemotaxis
- Opsonization
- Phagocytosis
- Degranulation
Granulocyte Degranulation
- Lysosomal enzymes in neutrophils fuse with phagocytic vesicles
- Destroy bacteria and neutrophils
- Removed by monocyte macrophages (reticuloendothelial system)
Other WBCs (Eosinophils, Basophils, Monocytes, Lymphocytes)
- Eosinophils:
- Fighting parasites
- Allergic inflammatory response
- Release plasminogen (dissolves blood clots)
- Basophils:
- Synthesize histamine (allergic/inflammatory mediator)
- Synthesize heparin (anticoagulant)
- Monocytes:
- Largest WBC type
- Function: Phagocytosis. Mature into macrophages in tissues
- Lymphocytes:
- Key cells of the immune system
- Two types:
- T Cells (helper, cytotoxic, suppressor and memory)
- B Cells (produce antibodies)
Tissue Macrophages
- Derived from monocytes
- Many types in various tissues (Kupffer cells in liver, alveolar macrophages in lungs)
- Important role in phagocytosis, filtering out bacteria and debris
Immunity
- The ability of the body to resist organisms and toxins that cause damage
- Two types of immunity
- Innate immunity (non-specific)
- First line of defense
- Does not require "prior exposure" to the antigen
- Acquired immunity (specific)
- Humoral immunity (antibodies)
- Cellular immunity (Tc lymphocytes)
Antibodies (Immunoglobulins)
- Gamma globulin plasma proteins
- Produced by B cells in response to antigens
- Five types: IgG, IgM, IgA, IgE, IgD.
Preprocessing of Lymphocytes
- Lymphocyte stem cells develop in bone marrow or fetal liver
- Processed in the thymus gland (T lymphocytes) and other lymphatic tissues (B lymphocytes).
Quiz Questions
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Description
Explore the fascinating world of white blood cells (WBCs), their types, and their critical role in the immune system. This quiz covers the characteristics of granulocytes and agranulocytes, as well as the process of leukopoiesis. Test your knowledge on WBCs and their functions in the human body.
