Leukocytes and Their Functions
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Questions and Answers

What is the normal range of leukocytes in healthy adults per microliter of blood?

  • 1000 to 3000
  • 2000 to 5000
  • 4500 to 11,000 (correct)
  • 5000 to 15,000

Which of the following is NOT a type of granulocyte?

  • Neutrophils
  • Eosinophils
  • Basophils
  • Monocytes (correct)

Which statement about the life span of granulocytes is accurate?

  • They have a life span of only a few days. (correct)
  • They have a life span of months.
  • They can live for several weeks.
  • Their life span can vary significantly based on type.

What characterizes the nuclei of granulocytes?

<p>They have two or more distinct lobes. (A)</p> Signup and view all the answers

Which type of leukocyte primarily relies on glycolysis for energy?

<p>Granulocytes (B)</p> Signup and view all the answers

Which type of leukocyte does NOT contain specific granules?

<p>Lymphocytes (C)</p> Signup and view all the answers

What is the role of macrophages in relation to apoptotic granulocytes?

<p>They remove cellular debris. (C)</p> Signup and view all the answers

What type of granules do agranulocytes possess?

<p>Lysosomes (azurophilic granules) (C)</p> Signup and view all the answers

What is the primary function of neutrophils in the immune response?

<p>To actively phagocytize bacteria and small particles (D)</p> Signup and view all the answers

Which of the following describes the lifespan of neutrophils in connective tissues?

<p>1 to 4 days (C)</p> Signup and view all the answers

What unique morphological feature may be observed in female neutrophils?

<p>Drumstick-like appendage on one lobe (C)</p> Signup and view all the answers

What process refers to the movement of leukocytes out of the blood vessels into surrounding tissue?

<p>Diapedesis (D)</p> Signup and view all the answers

What type of granules do neutrophils have that are involved in their functional activities?

<p>Azurophilic primary granules and specific secondary granules (C)</p> Signup and view all the answers

Which leukocyte is less numerous and mainly associated with allergic responses and parasitic infections?

<p>Eosinophils (B)</p> Signup and view all the answers

What is a characteristic feature of eosinophils when viewed in blood smears?

<p>Bi-lobed nucleus with abundant pink or red granules (B)</p> Signup and view all the answers

What role do chemical mediators play in the function of neutrophils during an infection?

<p>They facilitate the chemotaxis of neutrophils towards infection sites (A)</p> Signup and view all the answers

What is the typical diameter range of circulating monocytes?

<p>12 to 15 μm (D)</p> Signup and view all the answers

Which cell is a precursor to macrophages?

<p>Monocyte (A)</p> Signup and view all the answers

What characteristic distinguishes monocytes from lymphocytes in terms of nucleus shape?

<p>Monocytes have a distinctly indented or C-shaped nucleus. (A)</p> Signup and view all the answers

How long is the life span of circulating platelets?

<p>10 days (A)</p> Signup and view all the answers

What type of cells do monocytes differentiate into once in connective tissue?

<p>Macrophages (D)</p> Signup and view all the answers

What is the primary function of platelets in the circulatory system?

<p>Promote blood clotting (A)</p> Signup and view all the answers

Which of the following cells are known to be antigen-presenting cells?

<p>Monocytes (B)</p> Signup and view all the answers

What is the range for normal platelet counts in blood?

<p>150,000 to 400,000/μL (A)</p> Signup and view all the answers

What role do eosinophils primarily play in the body?

<p>Modulating inflammatory responses (C)</p> Signup and view all the answers

Which leukocyte type is characterized by specific granules containing heparin?

<p>Basophils (C)</p> Signup and view all the answers

Which of the following is NOT a type of lymphocyte?

<p>Basophilic lymphocytes (A)</p> Signup and view all the answers

What is the primary function of natural killer (NK) cells?

<p>Destroying abnormal cells and pathogens (D)</p> Signup and view all the answers

How are lymphocytes primarily differentiated from one another?

<p>By distinctive surface molecules (CD markers) (B)</p> Signup and view all the answers

What features are uncommon for basophils compared to other leukocytes?

<p>Ability to remove antigen-antibody complexes (A)</p> Signup and view all the answers

What is a distinguishing feature of small lymphocytes?

<p>Spherical nuclei with condensed chromatin (C)</p> Signup and view all the answers

Which leukocyte type is primarily involved in the inflammatory response to allergies?

<p>Basophils (A)</p> Signup and view all the answers

Flashcards

Leukocytes (WBCs)

White blood cells, essential for immunity, that are classified into two main groups based on their cytoplasmic granules: granulocytes (with specific granules) and agranulocytes (without specific granules).

Granulocytes

Granulocytes contain two types of cytoplasmic granules: lysosomes (azurophilic granules) and specific granules with unique staining properties and functions. These cells have polymorphic nuclei with multiple lobes, giving the appearance of a segmented shape.

Agranulocytes

Agranulocytes lack specific granules but contain lysosomes (azurophilic granules). Their nuclei are typically spherical or indented, not segmented like granulocytes.

Neutrophils

A type of granulocyte characterized by segmented nuclei and the presence of specific granules that stain neutrally, giving them a pale, slightly pink appearance in blood smears.

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Eosinophils

A type of granulocyte distinguished by their bilobed nuclei and specific granules that stain strongly with acidic dyes, hence their reddish-orange appearance.

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Basophils

A type of granulocyte recognized by their segmented nuclei and specific granules that stain deeply with basic dyes, leading to a dark blue or purplish hue in blood smears.

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Monocytes

A type of agranulocyte with a large, round, indented nucleus and a pale, grayish cytoplasm. These cells differentiate into macrophages in tissues.

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Lymphocytes

A type of agranulocyte with a small, round nucleus and a scant cytoplasm. They play a crucial role in adaptive immunity, recognizing and responding to specific pathogens.

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Diapedesis

The process by which white blood cells exit blood vessels and enter surrounding tissues, moving towards sites of injury or infection.

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Chemotaxis

A chemical signaling process that attracts white blood cells to areas of inflammation or infection.

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Phagocytosis

The process by which cells engulf and destroy foreign particles or pathogens.

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Granules

Specialized storage compartments within cells that contain enzymes and other molecules used in cellular functions.

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Azurophilic Granules

Primary granules found in neutrophils that contain a variety of enzymes used in fighting infections.

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Specific Granules

Secondary granules found in neutrophils that contain enzymes and other molecules specifically involved in fighting bacteria.

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What are eosinophils?

A type of granulocyte responsible for killing parasitic worms, modulating inflammatory responses, and playing a key role in allergies. They're abundant in the intestinal lining and chronic inflammation sites like asthma lungs.

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What role do eosinophils play in immune defense?

A type of leukocyte that removes antigen-antibody complexes from interstitial fluid through phagocytosis.

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What are basophils?

A type of granulocyte with large, irregularly shaped granules that stain purple and contain heparin, histamine, and other inflammatory mediators.

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What are the features of basophils?

A type of leukocyte with a segmented nucleus and granules containing heparin, histamine, and other inflammatory mediators.

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What are lymphocytes?

A type of agranulocyte that includes lymphocytes, T cells, B cells, and natural killer (NK) cells. These cells are involved in adaptive immunity, recognizing and responding to specific pathogens.

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What are B lymphocytes?

A type of lymphocyte that matures in the bone marrow and produces antibodies to target specific antigens.

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What are T lymphocytes?

A type of lymphocyte that matures in the thymus and directly attacks infected cells or cancer cells.

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What are natural killer (NK) cells?

A type of lymphocyte that can kill infected cells or cancer cells without prior sensitization to specific antigens, providing an immediate defense mechanism.

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What are Monocytes?

These cells have a large, indented or C-shaped nucleus with less condensed chromatin than lymphocytes. Their cytoplasm is basophilic and contains many small lysosomes, giving it a bluish-gray color. Monocytes are precursor cells of macrophages, osteoclasts, microglia, and other cells of the mononuclear phagocyte system.

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What are Platelets?

Platelets are small, non-nucleated cell fragments that originate from megakaryocytes. They are essential for blood clotting and help repair minor tears in blood vessels, preventing blood loss. Typical platelet counts range from 150,000 to 400,000 per microliter of blood.

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What are the parts of a platelet?

The hyalomere is the outer, lightly stained zone of a platelet, while the granulomere is the darker, central zone containing granules.

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What is the function of the glycocalyx in platelets?

The glycocalyx, a thin layer surrounding the platelet plasma membrane, plays a crucial role in adhesion and activation during blood coagulation.

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What are megakaryocytes?

Megakaryocytes are giant, polyploid bone marrow cells that produce platelets by shedding fragments of their cytoplasm.

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What are azurophilic granules?

Azurophilic granules are lysosomes, primary granules within the cytoplasm of lymphocytes, that contain a variety of enzymes used in fighting infections.

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What is the mononuclear phagocyte system?

Mononuclear phagocyte system is a network of cells, including macrophages, osteoclasts, and microglia, that are derived from monocytes and play essential roles in immune defense of tissues.

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Study Notes

Leukocytes (White Blood Cells)

  • Leukocyte count varies by age, sex, and physiological condition
  • Healthy adults have 4500-11,000 leukocytes per microliter of blood
  • Leukocytes leave the bloodstream and migrate to tissues to carry out immune functions
  • Classified into granulocytes and agranulocytes based on cytoplasmic granules and nuclear morphology

Granulocytes

  • Spherical in blood plasma, amoeboid and motile in tissues
  • Estimated sizes observed in blood smears when spread, appearing slightly larger than in circulation
  • Include neutrophils, eosinophils, and basophils
  • Functionally differentiated cells with short lifespans (a few days)
  • Dependent on glycolysis for energy needs
  • Die by apoptosis in the connective tissue
  • Debris removed by macrophages without eliciting inflammation
  • Contain lysosomes (azurophilic granules)
  • Possess specific granules that bind to various stains (neutral, basic, or acidic)

Neutrophils (Polymorphonuclear Leukocytes)

  • 54-62% of circulating leukocytes
  • 12-15 µm in diameter
  • Nucleus with 2-5 lobes linked by thin extensions (drumstick-like appendage in females may appear on one lobe).
  • Inactive, spherical in circulation; become actively amoeboid during diapedesis (migration)
  • Phagocytic cells that target bacteria and small particles; arrive at infection sites using chemotaxis
  • Contain primary (azurophilic) and secondary (specific) granules.
  • Short-lived (1-4 days in tissues); lifespan in blood: 6-8 hours
  • Function in chemotaxis and phagocytosis.
  • Chemical mediators involved in neutrophil attraction to bacteria.

Eosinophils

  • 1-3% of circulating leukocytes
  • Similar size to neutrophils; bilobed nucleus
  • Characterized by large, acidophilic (red/pink staining) specific granules
  • Primarily target parasitic worms (helminths) and modulate inflammatory responses.
  • Abundant in connective tissue of the intestinal lining, lung tissues in asthma patients.
  • Also remove antigen-antibody complexes from interstitial fluids through phagocytosis.

Basophils

  • <1% of circulating leukocytes
  • 12-15 µm in diameter
  • Nucleus usually obscured by large, purple-staining specific granules.
  • Granules are smaller and more irregularly shaped
  • Contain heparin and other sulfated GAGs, as well as histamine and other inflammatory mediators

Agranulocytes

  • Do not contain specific granules, but contain azurophilic granules
  • Nucleus is spherical, or indented, but not lobulated
  • Include lymphocytes and monocytes

Lymphocytes

  • Most abundant agranulocyte; spherical nuclei
  • Present in blood smears, up to â…“ of leukocytes
  • Smallest leukocytes; large lymphocytes result from activation
  • Include T lymphocytes (helper and cytotoxic), B lymphocytes, and natural killer (NK) cells
  • Diversity of roles in immune defense against invading microorganisms and certain abnormal cells

Monocytes

  • Precursor cells for macrophages, osteoclasts, and microglia
  • 12-15 µm in diameter (macrophages larger)
  • Indented or C-shaped nucleus, less condensed than in lymphocytes
  • Basophilic cytoplasm; contains lysosomes or azurophilic granules
  • Phagocytic cells, part of the mononuclear phagocyte system

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Description

Test your knowledge on leukocytes, their classifications into granulocytes and agranulocytes, and their roles in the immune system. Understand the specific types of leukocytes, such as neutrophils, and their functions within the body. This quiz will help reinforce key concepts about blood cell counts and physiological roles.

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