Blood histology

Describe the 3 layers blood will form in a tube with anticoagulant

1. The yellow top layer = plasma; 55%

2. The middle layer = buffy coat = leukocytes

3. The red bottom layer = RBC

What is hematocrit and the normal values for female and male

• The volume of formed elements per unit volume of blood.

• Females: 35-45%

• Males: 40-50%

Define blood serum

fluid portion of blood remaining after a clot forms [plasma minus fibrinogen and other clotting proteins]

List out and descrbie the five major plasma proteins

• Albumin – establish the blood colloid osmotic pressure, a force responsible for maintenance of blood and interstitial fluid volumes.

• Globulins;

  • a and b-globulins:

    • from the liver

    • transport substances such as lipid soluble vitamins or iron and other metal ions.

  • y-globulins

    • from plasma cells and include antibodies

• Clotting proteins – Produced in the liver; involved in clot formation.

  • Major ones: Prothrombin and fibrinogen

• Complement proteins – involved in inflammation and destruction of foreign microorganisms

• Plasma lipoproteins

  • Chylomicrons – transport triglycerides to liver.

  • (VLDL) – transport triglycerides from liver to body cells.

  • LDL – transport cholesterol from liver to body cells

What are the marrow cavities? Differentiate between red and yellow marrow

• cavities of long bones and spaces of spongy bone

• Red: where hematopoeisis occurs; adults have limited locations of red marrow as opposed to new borns

• Yellow: Where hematopoesis cease; contains adipose

Describe the basic procedure of peripheral blood smears and the three types of dyes used

normally studied in the light microscope by evenly smearing a drop of blood across a glass slide, air-drying, and then staining with a mixture of dyes.

Dyes used:

1. Methylene blue – stains acidic cellular components blue

2. Eosin – stains alkaline components pink

3. Azures - oxidation of methylene blue; azurophilic
   structures in blood cells bind azures → red to violet appearance.

   • Lysosomes of leukocytes often appear as azurophilic granules

Describe the shape of red blood cells and its organelles; describe the characteristics of the cytoskeleton

Does not have a nucleus; biconcave disks

No organelles; does have cytoskeletal network

• adjacent to cell membrane

• meshwork of spectrin (filamentous protein) and actin

• ankyrin secures meshwork to plasmalemma proteins

• determines cell shape but also allows flexibility

What are the four major proteins found in RBC

1. hemoglobin

2. carbonic anhydrase

3. band 3

   1. exchanges intracellular bicarbonate for extracellular Cl-.

   2. binding site for ankyrin

4. proteins involved in glucose metabolism

What are the 3 granulocytes? What are the two agranulocytes?

Granulocytes:

1. Neutrophils

2. Eosinophils

3. Basophils

Agranulocytes:

1. Lymphocytes

2. Monocytes

Describe histology and function of neutrophils

• distinct nucleus: Three lobes (could be five) connected by small strand of chromatin

• Cytoplasm; Contains:

  • small granules barely seen by microscope;

  • Azurophilic granules

  • stains lightly eosinophic

• Function: Fighting infection via its granules

  1. Chemotatic agents call neutrophils over

  2. Phagocytosis

  3. Destroy eaten materials via:

     1. enzyme

     2. oxygen free radicals (O₂ -)

     3. lactoferrin (binds to Fe which bacteria needs

Describe histology and function of Eosinophils

large, refractive granules that stain with eosin

• membrane-bound,

• staining characteristic arises from crystalline core composed of major basic protein.

• crystalline core + eosinophilia= granules a ruby-like appearance in smears

Functions:

• membrane receptors for histamine, leukotrienes, and eosinophil chemotactic factor.

  • bind = migration to site of parasitic worm invasion, allergic reaction, or inflammation

• Majorly responsible for killing parasitic worms

• Near crystalline core, has enzymes for inactivation of inflammation response intiators (ex: histamine/leukotrienes)

Describe histology and function of basophils

• lobed nucleus (usually masked by basophilic granules)

• less numerous violet-colored granules/ more irregular shape than other granulocytes

Functions:

1. granules contain

   1. Heparin (anticoagulant)

   2. Histamine: vasocilation, bronchial smooth muscle contraction, leakiness of blood vessels

   3. Chemotactic factors: attracts eosinophils and neutrophils

2. IgE binds to Basophils → antigen binds to IgE on Basophils:

   1. Granule contents (as described above) release

   2. Basophil produces leukotrienes

Describe the histology and functions of Lymphocytes

• round cells with a dense, round nucleus,

• thin rim of basophilic cytoplasm surrounding predominating nucleus

Functions:

• T-cells:

  • precursor lymph → thymus → maturation of T Cells

  • responsible for Cellular Immune Response

• B-Cells:

  • Precursor lymph matures in Bone Marrow

  • Responsible for Humoral Immune Response

    • B cells → plasma cells → antibodies

• Null cells:

  • could be circulating stem cells

  • Could be Natural Killer Cells (NKs)

    • kill virus-infected cells

NOTE: both T/B cells go to peripheral lymph organs to produce clones

Describe the histology and functions of monocytes

• large, kidney-shaped nucleus; stains light due to less condensed chromatin

Function: migrate into connective tissue where they differentiate into macrophages

Describe the histology and functions of Megakaryocytes; Where does it exist?

• appears multinucleate but actual: single, large lobulated nucleus

• present in bone marrow; not present in peripheral blood.

• Demarcation membranes: membrane invaginations → shed as platelets

NOTE: Demarcation = the action of fixing the boundary or limits of something.

Describe the histology and functions of platelets

• non-nucleated fragments of the megakaryocytes

• dense granular central region and clear peripheral region

• membrane has numerous receptors and thick glycocalx

Function:

1. control hemorrhage of damaged blood vessels.

2. Vessel damage:

   1. platelets activation → release contents of granules

   2. adhere to damage site and to each other

      1. aka, forming platelet plug

   3. Complex cascade of events follows → blood clot