WBCs & Platelets | A&P II

Granule

Membrane-bound structure in a cell

2 types of leukocytes

Granulocytes & agranulocytes

Types of granulocytes

Neutrophil, eosinophil, basophil

Types of agranulocytes

Lymphocyte, monocyte

Types of WBCs in order from most → least common

Neutrophils, lymphocytes, monocytes, eosinophils, basophils

What is DLC (acronym & clinical use)

Differential leukocyte count, provides the percentages of each type of WBC to help understand multiple aspects someone’s immune health

Diapedesis

The process in which WBCs squeeze through blood vessels to enter surrounding tissues

WBCs are capable of ____ movement through the use of ____

Amoeboid; pseudopodia

Positive chemotaxis

Attraction towards chemical stimuli allowing WBCs to respond to infection, injury, etc

Neutrophils are also called:

Polymorphonuclear cells

Neutrophil visual description

Multilobed nucleus, mostly light pink with fine dark blue granules

Which WBC is known as the “first responder”

Neutrophils

Which WBC is the most abundant, making up 50-70% of WBCs?

Neutrophils

What do neutrophils do upon encountering pathogens?

Phagocytosis

What occurs after a neutrophil phagocytoses (engulfs) a pathogen?

Degranulation: the neutrophil release defensins from its granules to destroy the pathogen

What occurs after degranulation in a neutrophil?

It releases prostaglandins and leukotrienes to signal for reinforcements from other WBCs

Once neutrophils have exhausted their function and lived out their 1-2 day lifespan:

They pool with killed bacteria and other debris to form pus

Which of these is a neutrophil?

A

High neutrophil count indicates:

Recent (acute) infection

Eosinophil visual description

Red cytoplasm, coarse granules, bilobed nucleus (earmuff shape)

Eosinophils make up __% of WBCs

2-4%

Eosinophil function:

Defend from parasitic infections and regulate allergic reactions & inflammation

Why can’t eosinophils perform phagocytosis and what is their alternative?

They attack parasites that are too large to engulf, so they release the toxic compounds from their granules onto their targets

Eosinophils temper ____ (effect) to counterbalance _____ (cell)

Inflammation; neutrophils

Which one of these is an eosinophil?

B

What is the rarest type of WBC? (<1%)

Basophils

Basophil visual description:

Almost completely dark blue/purple with granules difficult to see

Which one of these is a basophil?

C

Basophil granules contain:

Histamine & heparin

What type of cell are basophils similar to & what is the key difference?

Mast cells: fixed in tissues rather than circulating in blood

How does histamine (released by both basophils and mast cells) affect the blood vessels?

Vasodilation

Heparin is released by basophils and functions to:

prevent blood clotting

What is the second most common type of WBC and what % do they make up?

Lymphocytes; 20-30%

Lymphocytes visual description

Smallest WBC; large spherical nucleus surrounded by thin ring of cytoplasm

What are two of the common types of lymphocytes and where are they produced?

T-cells: thymus

B-cells: bone marrow

Memory lymphocytes are:

Long lived lymphocytes that can remember specific pathogens for your entire life, allowing them to multiply rapidly to defend against it

Which of the following is a lymphocyte?

D

Which WBC is late to respond but stays for a longer period of time to fight an infection?

Monocyte

Monocytes, once they migrate into body tissues, are activated and become:

Macrophages

Which is the largest WBC at ~20 microns?

Monocyte

Monocytes make up ___% of WBCs

2-8%

Monocyte visual description

Largest WBC; kidney bean shaped nucleus

Platelets are also called:

Thrombocytes

Platelets are not true cells but fragments of :

Megakaryocyte

Megakaryocyte

Giant cells in bone marrow with extensions in bloodstream that break off, forming platelets

After platelets circulate for ____ days, they are removed by the ____

9-12; spleen

Typical platelet count range per microliter

150k-500k

Term for production of platelets

Thrombocytopoiesis

Platelets’ primary function is:

Preventing blood loss

What are 3 main ways platelets prevent blood loss?

1. Releasing factors like ADP, thromboxane, etc

2. Form platelet plugs to temporarily patch damaged vessel walls

3. Clot retraction to shrink break in vessel walls

The term for low platelet count (<150k/µL) is ____ and results in ___

Thrombocytopenia: results in excessive bleeding, causing hematoma (bruise) formation

The term for high platelet count (>500k/µL) is ____ and results in ___

Thrombocytosis: excessive clotting, restricting blood flow & oxygen

All blood cells come from this stem cell:

Hemocytoblast