PhysiologyLesson 4 of 6 in the course The Cardiovascular System: Blood

Leukocytes and Platelets: Classification, Function, and Disorders

5 flashcards · 5 quiz questions · 5 match pairs · 4 fill-in sentences · English

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Summary

Leukocytes, or white blood cells, defend the body against infection and abnormal cells and help remove debris. This lesson introduces their shared characteristics, how they move through tissues, and the two major groups used to classify them.

Leukocytes and erythrocytes both originate from hematopoietic stem cells in bone marrow, but they differ in important ways. A typical microliter of blood contains about 5,000–10,000 leukocytes, far fewer than erythrocytes. Leukocytes are generally larger, and they are the only formed elements that are complete cells, with a nucleus and organelles. There are several types of leukocytes, and most live for hours or days rather than the much longer lifespan typical of erythrocytes.

All flashcards

What are leukocytes?
Leukocytes are white blood cells that defend against microorganisms and abnormal body cells and help clear debris.
What is diapedesis?
Diapedesis, or emigration, is the process by which a leukocyte passes between cells in a small blood vessel wall and enters tissue.
What does positive chemotaxis mean?
It is the directed movement of leukocytes toward chemical signals released at sites such as infection or injury.
What is a differential leukocyte count?
It is an assessment of the types and percentages of leukocytes in a blood sample, which can help with diagnosis and treatment decisions.
How do granular and agranular leukocytes differ?
Granular leukocytes have abundant, visible cytoplasmic granules; agranular leukocytes have fewer and less obvious granules.

Quiz questions

  1. Which leukocyte type can attack parasitic worms and help counteract histamine?Answer: Eosinophils
  2. What is the name for specific immunity mediated by antibodies produced by plasma cells?Answer: Humoral immunity
  3. Platelets are cytoplasmic fragments released by which bone marrow cells?Answer: Megakaryocytes
  4. What can result from an abnormally low platelet count?Answer: Impaired clotting and excessive bleeding
  5. Which pattern characterizes acute leukemia?Answer: Overproduction of immature leukocytes

Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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