F2111 biology

blood smears

-place a clean glass slide on a flat surface add a drop of blood on one side of the slide

- take another clean slide holding at a 45 degree push carefully along the length of the first slide to produce a thin smear of blood

-the smear is put in alcohol and left to dry

Leishmans stain

1 Take an air dried blood smear on and glass slide and cover the smear with the undiluted stain

2 add just the enough number of drops to cover the smear, add enough to cover the film

3 Add twice the volume of pH 6.8 buffered water to dilute the stain

4 Allow to stain for 10–12 minutes

5 Wash off the stain with clean (or filtered) tap water . If the stain is tiped off instead of washing, this will leave a fine deposit covering the film. Wipe the back of the slide clean and stand it in a draining rack to dry. The stained smear should grossly appear neither too pink nor too blue

a haemocytometer is used to count the number of erythrocytes and leucocytes in a blood smear

1 Prepare a 1:1 dilution of the cell suspension in trypan blue

2 Load the hemocytometer:- Moisten and affix cover-slip to the hemocytometer. Ensure the cover-slip and hemocytometer are clean and grease-free (use alcohol to clean). A small amount of trypan blue-cell suspension is transferred to one of the chambers of the hemocytometer by carefully touching the cover slip at its edge with the pipette tip and allowing each chamber to fill by capillary action. The chamber is not overfill or under fill.

3 The square should contain 16 smaller squares. Count all the cells in the four 1 mm corner squares. If there are too many or few cells to count, repeat the procedure either concentrating or diluting the original suspension as appropriate.

Erythrocyte

-bi concave - allowing it to curl and fit into capillaries and it also has a shorter diffusion pathway

- no nucleus large surface area - can store more haemoglobin

-they have a large SA: V ratio - can transport more oxygen

Neutrophils

- digest bacteria by phagocytosis, they engulf the bacteria and tear it up using digestive juices

Lymphocytes

- large nucleus

- thin cytoplasm

- The nucleus of a lymphocyte stains dark purple/blue when exposed to a stain known as Wright's stain

- The three major types of lymphocyte are T cells, B cells and natural killer (NK) cells

neutrophils

- They have large amounts of Lysosomes, which contain enzymes that kill ingested cells. This makes their Cytoplasm appear Granular. They also have a Lobed Nucleus, which allows for greater flexibility.

Monocytes

- go round the tissue field of the body where they become larger and turn into macrophages there they can phagocytize bacteria throughtout the body, these cells also destroy dead damaged cells around the body.

- monocytes have lots of cytoplasm

- 'u' shaped nucleus

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