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Questions and Answers
What is the lifespan of granulocytes once they are released into the blood?
What is the lifespan of granulocytes once they are released into the blood?
- 10-20 hours
- Months
- 4-8 hours (correct)
- Days to weeks
What happens to granulocytes during severe tissue infections?
What happens to granulocytes during severe tissue infections?
- They have no immune function
- They become macrophages
- Their lifespan is extended
- They proceed more rapidly to the infected area (correct)
How long do monocytes stay in the blood before entering tissues?
How long do monocytes stay in the blood before entering tissues?
- 4-5 days
- Weeks
- A few hours
- 10-20 hours (correct)
In what form can tissue macrophages live for months?
In what form can tissue macrophages live for months?
What are granulocytes also known as?
What are granulocytes also known as?
What are the types of granulocytes?
What are the types of granulocytes?
What is the primary function of tissue macrophages?
What is the primary function of tissue macrophages?
What is the lifespan of platelets?
What is the lifespan of platelets?
What can the B-cells mature into?
What can the B-cells mature into?
How long can lymphocytes live?
How long can lymphocytes live?
Where do leukocytes originate in the body?
Where do leukocytes originate in the body?
What do pluripotent hematopoietic stem cells differentiate into?
What do pluripotent hematopoietic stem cells differentiate into?
What distinguishes leukocytes from red blood cells?
What distinguishes leukocytes from red blood cells?
What is lymph?
What is lymph?
Which type of progenitor stem cell differentiates into erythrocytes and megakaryocytes?
Which type of progenitor stem cell differentiates into erythrocytes and megakaryocytes?
What is the lifespan of lymphocytes depending on the body's need?
What is the lifespan of lymphocytes depending on the body's need?
Which of the following is NOT a part of the lymphatic system?
Which of the following is NOT a part of the lymphatic system?
How do leukocytes travel in the body?
How do leukocytes travel in the body?
How frequently are platelets replaced within the bloodstream?
How frequently are platelets replaced within the bloodstream?
Which of the following describes leukocytes?
Which of the following describes leukocytes?
Which type of blood cell lineage includes monocytes and granulocytes?
Which type of blood cell lineage includes monocytes and granulocytes?
What is the average number of white blood cells in a cubic millimeter of blood?
What is the average number of white blood cells in a cubic millimeter of blood?
Which component connects the lymphatic system to the blood circulatory system?
Which component connects the lymphatic system to the blood circulatory system?
Which of the following is a true statement about leukocytes?
Which of the following is a true statement about leukocytes?
Which statement about lymphocyte circulation is accurate?
Which statement about lymphocyte circulation is accurate?
What type of blood cell does the term 'diapedesis' refer to?
What type of blood cell does the term 'diapedesis' refer to?
What types of harmful agents does the immune system defend against?
What types of harmful agents does the immune system defend against?
Which of the following is NOT a key factor for the immune system's protective functions?
Which of the following is NOT a key factor for the immune system's protective functions?
How does the immune system respond to pathogens introduced at various sites in the body?
How does the immune system respond to pathogens introduced at various sites in the body?
What allows the immune system to effectively locate and destroy microbes?
What allows the immune system to effectively locate and destroy microbes?
What is the role of phagocytes in the immune system?
What is the role of phagocytes in the immune system?
Which type of immune cell is involved in recognizing and presenting antigens?
Which type of immune cell is involved in recognizing and presenting antigens?
What characteristic is crucial for the rapid response of the immune system?
What characteristic is crucial for the rapid response of the immune system?
Which factor contributes significantly to the immune system's ability to adapt and respond to many different microbes?
Which factor contributes significantly to the immune system's ability to adapt and respond to many different microbes?
Which of the following elements is considered a molecular component of the immune system?
Which of the following elements is considered a molecular component of the immune system?
What does the immune system primarily do in response to altered self-cells, such as cancer?
What does the immune system primarily do in response to altered self-cells, such as cancer?
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Study Notes
Overview of the Immune System
- The immune system defends against various harmful agents: bacteria, single-celled eukaryotes, multicellular organisms (worms and fungi), viruses, and altered self-cells (cancer, autoimmune diseases).
- The system employs diverse mechanisms, including intracellular and extracellular attacks and toxin release.
- Optimal immune function relies on rapid, varied cell responses, organized lymphoid tissues, and the ability of cells to migrate to infection sites.
Cellular Components of the Immune System
- White Blood Cells (WBCs) are the main cells in the immune system, circulating in blood and lymph, and responsible for protection against infections.
- WBCs are formed partially in the bone marrow and lymph tissue, unlike red blood cells which carry oxygen.
- WBC types include granulocytes, monocytes, and lymphocytes, each with distinct roles and morphologies.
Classification of Leukocytes
- Granulocytes: A type of WBC with granules.
- Neutrophils: Lifespan of 4-8 hours in blood, 4-5 days in tissues.
- Eosinophils: Lifespan similar to neutrophils.
- Basophils: Rare, with a similar lifespan to eosinophils.
- Monocytes: Short transit time of 10-20 hours in blood; develop into macrophages in tissues, where they can live for months.
- Lymphocytes: Continuous circulation in the body; lifespan varies from weeks to months based on the body's demand.
Immune Cell Organization
- WBCs reside in various locations: circulating in blood, lymphatic vessels, lymph nodes, and lymphoid organs like the spleen and tonsils.
- Tissues harbor scattered immune cells, providing localized defense mechanisms.
White Blood Cell Lifespan
- Granulocytes:
- Circulate for 4-8 hours then last 4-5 days in tissues; lifespan shortened during severe infections.
- Monocytes:
- Live 10-20 hours in blood; become macrophages in tissues and can survive for months.
- Lymphocytes:
- Constantly circulate through the body, maintaining immunity over time.
Blood Cell Counts
- Average white blood cell count is 7,400/mm³ (normal range: 4,500-11,000/mm³).
- Neutrophils comprise 40-60% of WBCs, essential for acute immune responses.
Hematopoietic Process
- All WBCs originate from Pluripotent Hematopoietic Stem Cells (PHSC) in bone marrow.
- PHSC differentiates into committed pre-cursor stem cells for various blood cells, including myeloid and lymphoid lineages.
- Myeloid lineage includes granulocyte and monocyte precursors; lymphoid lineage includes B- and T- lymphocytes.
Platelets
- Play a critical role in hemostasis and are replaced approximately every 10 days, with around 30,000 produced daily per microliter of blood.
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