Review of White Blood Cells and Platelets (Nursing)

00:01 Now we'll talk about the white blood cells, these are our leukocytes.

00:04 These are nucleated independently modal structures.

00:07 They are highly differentiated and these are our cells of the immune system.

00:11 They compose the body's defense mechanisms.

00:14 They're generated in the bone marrow and normal values range between 4,000 and 11,000 (cells/mm3).

00:21 Leukopenia is a term we use to describe a low white blood cell count.

00:25 And leukocytosis describes a high white blood cell count.

00:29 There are three types: we have the granulocytes, the lymphocytes and the monocytes. We'll touch on each.

00:35 First the granulocytes. These are the most numerous.

00:39 The nucleus is gonna contain granules and this is where they get their name, and these are the mediators of our inflammatory response.

00:46 Basophils are the least common of these granulocytes and they can perform phagocytosis.

00:51 They can produce histamine and serotonin and these cells play a role in immune regulation and allergic responses.

00:58 Next we see eosinophils and these make up about 1 to 4% of the white blood cells and these play a role in the defense against parasitic infections.

01:07 These will increase called eosinophilia in the setting of parasites, asthma and certain tropical diseases.

01:15 So you can remember, "worms, wheezes and weird diseases" - we will see elevated eosinophils.

01:22 Our third is neutrophils and these can perform phagocytosis and are the most abundant type of granulocyte.

01:29 Now we'll cover the lymphocytes.

01:31 These are the immune response to a foreign substance in the body.

01:35 These are found in the lymph nodes, the spleen, the thymus, the tonsils and the lymphoid tissue of the GI tract.

01:42 They're going to enter the circulation freely through the thoracic lymph duct.

01:46 These can live a long time, up to 1 year.

01:49 These are part of the acquired or smart immune system, they have a memory.

01:55 There are three types, first the natural killer cells.

01:58 These are going to distinguish infected cells and tumors from normal uninfected cells by recognizing changes in a surface molecule called the MHC.

02:07 These become activated and release cytotoxic or cell-killing granules and then they destroy these altered cells.

02:15 Next are the B cells.

02:16 These are part of the humoral immunity and they're responsible for making large quantities of antibodies which can neutralize foreign objects like bacteria and viruses.

02:26 Last are the T-cells.

02:28 These are part of the cell-mediated immune response and these are going to directly attack antigens.

02:33 Lymphocytes are expressed as a percentage of the lymphocytes compared to the total number of white blood cells counted.

02:40 Lymphocytosis refers to an increased number, and usually this happens in the setting of a viral infection or in certain kinds of blood cancers or lymphoma.

02:50 Lymphocytopenia refers to a decreased number, and we see this in patients with HIV because this will destroy their T-cells.

02:59 Next, the monocytes.

03:00 Monocytes are the largest cells of the blood, they compose about 7% of the leukocytes.

03:06 They're phagocytic which means they ingest infectious agents and red blood cells.

03:11 They're found at the sites of chronic infection and these are made in the bone marrow and then they're gonna circulate around in the blood.

03:18 These are young and they're going to eventually develop into macrophages.

03:22 Here you see the timeline.

03:23 When they come out, they're just a monoblast, then they mature into a promonocyte into a monocyte which will further differentiate into a macrophage.

03:34 Next are the platelets.

03:35 These do not reproduce, these are small fragments of bone marrow cells.

03:40 Normal values range from about 150,000 to 400,000 and these are used for clotting.

03:46 They also are used to promote other clotting factors in the clotting cascades and these secrete vasoconstrictors.

03:55 Platelets attract neutrophils and monocytes to a site of inflammation.

03:59 They're also responsible for dissolving clots when they're no longer needed and they can digest and destroy bacteria.

04:06 They're also going to secrete growth factors to maintain the lining of the vessels.