Lecture 3:Leukocytes or white blood cells

Question 1

classify white blood cells?

Answer 1

We classify them from their specific nuclei

- Only true cells of formed elements of circulatory cells

Question 2

White blood cells or WBCs

Answer 2

• Mobile units of body’s immune defense system
• Immune system:
  > Made up of leukocytes, their derivatives, and variety of plasma
  proteins
  > Recognizes and destroys or neutralizes materials within body
  that are foreign to “normal self”
  > Functions:
• Defends against invading pathogens
• Identifies and destroys cancer cells that arise in body
• Functions as a “cleanup crew” that removes worn-out cells and
  tissue debris

Question 3

Types of white blood cells

• Vary in structure, function, and number
• Somewhat larger than erythrocytes

Question 4

White blood cells, also called leukocytes, are cells that exist in

Answer 4

the blood, thelymphatic system, andtissuesand are an important part of the body’s natural defense (immune) system.
They help protect against infections and also have a role ininflammation, andallergic reactions.

Question 5

There are five different types of WBCs and each has a different function. They include…

Answer 5

neutrophils,lymphocytes,basophils,eosinophils, andmonocytes

Question 6

WBCs are present in the blood at relatively stable numbers. However, these numbers may temporarily shift higher or lower depending on what is going on in the body

Answer 6

1. For instance, an infection can stimulate your bone marrow to produce a higher number of neutrophils to fight off abacterialinfection.
2. With allergies, there may be an increased number of eosinophils.
3. An increased number of lymphocytes may be produced with aviralinfection.
4. In certain diseases, such as leukemia, abnormal (immature or mature) white cells may rapidly multiply.

Question 7

Why are leukocytes colourless

Answer 7

lack hemoglobin

Question 8

How do you ID WBCs

Answer 8

by their nucleus shape

Question 9

Look at the % of each in the blood and their functions

Question 10

Leucocytes: 2 main types

Answer 10

1. Polymorphonuclear granulocytes

2. Mononuclear Agranulocytes

Question 11

Polymorphonuclear granulocytes

Answer 11

(many-shaped nucleus; granule-containing cells)
- Neutrophils: Granules are neutral and show no dye preference

• Eosinophils: Granules have an affinity for the red dye eosin
• Basophils: Granules have an affinity for a basic blue dye

Question 12

Mononuclear Agranulocytes

Answer 12

(single-nucleus; cells lacking granules)
- Monocytes: Have oval or kidney-shaped nucleus

• Lymphocytes: Smallest of the leukocytes; usually have large spherical nucleus that occupies most of the cell

Question 13

Leucocytes Ultimately originate from…

Answer 13

same undifferentiated multipotent stem cells in red bone marrow

Question 14

produced only in bone marrow

Answer 14

Granulocytes and monocytes

Question 15

Most new lymphocytes are actually produced by

Answer 15

lymphocytes already in lymphoid tissues such as lymph nodes and tonsils

Question 16

Total number of white cells and percentage of each type may vary considerably, why?

Answer 16

to meet changing defense needs

Question 17

Neutrophils

Answer 17

• Most abundant leukocyte (60-70%)
• Phagocytic specialists
• Release web of extracellular fibers called neutrophil extracellular
  traps (NETs) that contain bacteria-killing chemicals
• Can also destroy bacteria by phagocytosis
• Functions:
  > First defenders on scene of bacterial invasion
  > Very important in inflammatory responses
  > Scavenge to clean up debris

Question 18

Eosinophils

Answer 18

• Increase in circulating eosinophils (eosinophilia) is associated with:
  > Allergic conditions such as asthma and hay fever
  > Internal parasite infestations, such as worms
  [Attach to worm and secrete substances to kill it]
• Make up 1-4% of Leukocytes

Question 19

Basophils

Answer 19

• Least numerous and most poorly understood of the leukocytes
  0.25-0.5% of leukocytes
• Quite similar structurally and functionally to mast cells
• Synthesize and store:
  > Histamine:
  
  • Release is important in allergic reactions
    > Heparin:
  • Speeds up removal of fat particles from blood after fatty meal
  • Can also prevent clotting of blood samples drawn for chemical
  • analysis
  • Used extensively as anticoagulant drug

Question 20

Monophils

Answer 20

• Emerge from bone marrow while still immature and circulate for day
  or two before settling down in various tissues in body
• Mature and enlarge in resident tissue and become known as
  macrophages
  > Life span can range from several months to years
• Become professional phagocytes
• Continue to mature and enlarge, becoming macrophages
  (“large eaters”)

Question 21

Lymphocytes

Answer 21

• Provide immune defense against targets for which they are
  specifically programmed
• Live about 100 to 300 days
• 2 types of lymphocytesB lymphocytes
  > Produce antibodies which circulate in blood
  - Responsible for antibody-mediated or humoral immunityT lymphocytes
  > Do not produce antibodies
  > Directly destroy specific target cells by releasing chemicals
  that punch holes in the victim cell (cell-mediated immunity)
  > Target cells include body cells invaded by viruses and cancer
  cells

Question 22

Self-assessment: quiz on white blood cells

https://www.proprofs.com/quiz-school/story.php?title=hematology-competency-assessment-2012

Question 23

Hemopoiesis: how are all these formed elements produced?

Answer 23