Molecules, Blood and Gas Exchange
Unit F211
The Blood(1.1.1)
Studying cells can provide valuable information about health.
Learning Objective
(1.1.1)a. describe how blood samples are taken and
blood smears (films) are made.
Blood_Test.3gp
Task
In your group, come up with a strategy to describe how blood samples are taken.
REMEMBER TO USE ALL KEY WORDS.
Learning Objective
(1.1.1)a. describe how blood samples are taken and blood smears
(films) are made.
d. describe the structure, as seen with a light microscope, of red blood cells (erythrocytes), neutrophils, lymphocytes, monocytes and macrophages as specialised cells with particular functions related to their structures.
Task
• In group of two, Read how to make a blood smear/ blood film.
• Practice making a blood film using the equipments provided.
Task
Now, write step by step method to make a blood film. You are to work individually.
Task
Compare your procedure with your partner. Use the book to mark your partner’s work.
Differential Stain
Erythrocytes• Biconcave discs.• Relatively large surface area
to volume ratio.• Cytoplasm is packed with a
pigment, a protein called haemoglobin.
• Mature erythrocytes have no nucleus. Very small and flexible.
Leucocytes
Neutrophils• Have small granules in the
cytoplasm.• Engulf microorganisms by
phagocytosis.
Lymphocytes• Have a large, darkly stained
nucleus surrounded by a thin layer of cytoplasm.
• There are two kinds of lymphocytes, T and B lymphocytes. Both look the same.
• B lymphocytes produce antibodies.
• T lymphocytes have several functions including cell destruction.
Monocytes• Are the largest kind of
leucocyte.• They have large, been-
shaped nucleus and clear cytoplasm.
• They spend 2-3 days in the circulatory system, then they move to the tissues.
• In the tissues, they become macrophages, engulfing micro organisms and other foreign materials
Identify the cells
Task
In groups of two, use the bio viewer, look at the blood films, identify the different blood cells and draw and label them.
Under each diagram, list at least two features with explanation.
Homework
• Read information from work sheets and answer questions 1.3-1.6.
• Due next Wednesday.
Calculating Magnification
• 1.1.1.g:
calculate the linear dimensions and magnification of drawings or photographs of
cells
How to calculate magnification?
Magnification=
Rearrange the formula to find the real size of the structure.
Size of the structure in the pictureReal size of the structure
Remember
A micrometer (µm) is one millionth of a meter. 1 1µm= 10-⁶ m
1 µm= 10 -³ mmAlways measure the structure in millimetres .
This means you can convert this to micrometers by multiplying by 1000, i.e. adding 3 zeros.
Task
Answer questions 1 and 2 from the spread.
Homework
Produce a booklet to explain to a patient about her/ his blood test. You should include how to take a blood sample, make a blood film and stain it, also, explain how to identify blood cells from the blood smear. You should include diagrams.
Due next Thursday.
Using a Haemocytometer
1.1.1 c
Learning Objectives
describe the use of a haemocytometer to count the numbers of erythrocytes and leucocytes (to include details of dilution);
Haemocytometer
Calculating the number of erythrocytes in 1mm³ of the original blood sample
The triple lined squares measure exactly 0.2 x 0.02 mmThe platform is exactly 0.1 mm below the cover slip. This means when you view one of the triple lined squares under the microscope, you are looking at a volume of exactly0.1x0.2x0.2 mm = 0.004mm³
Number of RBCs in the original sample in 1 mm³= 1/0.02 x number of cells counted in five triple lined squares x dilution .
Remember the dilution is 200
Calculating the number of leucocytes in 1mm³ of the original blood sample
Count the number of WBCs in the four corner squares. These squares measure exactly 1x1 mm. the depth of the chamber is 0.1mm. This means that each square has a volume of 1x1x0.1 = 0.1mm³
Number of WBCs in the original sample in 1 mm³= 1/0.4 x number of cells counted in four corner squares x dilution .
Remember the dilution is 20
Homework
Homework task: Pupils to write a detailedmethod in order to enable another studentto repeat the process and generate accurate
and reliable data
Lipids
1.1.2 t
(t) describe, with the aid of diagrams, the basic structure of glycerol and fatty acids;
(u) outline the formation of triglycerides by the condensation reactions between glycerol and fatty acids;
List the types of molecules you need to break down (digest) from your food.
Introduction to lipidsLipids are a diverse group of compounds that are insoluble in water but soluble in organic solvents such as ethanol.
The most common types of lipid are triglycerides (sometimes known as true fats or neutral fats), but other important lipids include waxes, steroids and cholesterol.
Like carbohydrates, lipids contain carbon, hydrogen and oxygen, but they have a higher proportion of hydrogen and a lower proportion of oxygen.
The structure of triglycerides
The structure of phospholipids