Lecture 3:Leukocytes or white blood cells Flashcards
classify white blood cells?
We classify them from their specific nuclei
- Only true cells of formed elements of circulatory cells
White blood cells or WBCs
- 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
Types of white blood cells
- Vary in structure, function, and number
- Somewhat larger than erythrocytes
White blood cells, also called leukocytes, are cells that exist in
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.
There are five different types of WBCs and each has a different function. They include…
neutrophils,lymphocytes,basophils,eosinophils, andmonocytes
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
- For instance, an infection can stimulate your bone marrow to produce a higher number of neutrophils to fight off abacterialinfection.
- With allergies, there may be an increased number of eosinophils.
- An increased number of lymphocytes may be produced with aviralinfection.
- In certain diseases, such as leukemia, abnormal (immature or mature) white cells may rapidly multiply.
Why are leukocytes colourless
lack hemoglobin
How do you ID WBCs
by their nucleus shape
Look at the % of each in the blood and their functions
Leucocytes: 2 main types
- Polymorphonuclear granulocytes
2. Mononuclear Agranulocytes
Polymorphonuclear granulocytes
(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
Mononuclear Agranulocytes
(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
Leucocytes Ultimately originate from…
same undifferentiated multipotent stem cells in red bone marrow
produced only in bone marrow
Granulocytes and monocytes
Most new lymphocytes are actually produced by
lymphocytes already in lymphoid tissues such as lymph nodes and tonsils
Total number of white cells and percentage of each type may vary considerably, why?
to meet changing defense needs
Neutrophils
- 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
Eosinophils
- 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
Basophils
- 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
- Release is important in allergic reactions
Monophils
- 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”)
Lymphocytes
- 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
Self-assessment: quiz on white blood cells
https://www.proprofs.com/quiz-school/story.php?title=hematology-competency-assessment-2012
Hemopoiesis: how are all these formed elements produced?
