Introduction to the Structure and Function of Blood Flashcards
What is blood made up of?
It is made of plasma (fluid) and cells (such as red cells, white cells and platelets).
Describe Red Blood Cells (RBCs).
- they’re also known as erythrocytes
- they’re in the shape of biconcave discs
- they have no nucleus and do not contain DNA, RNA or mitochondria
Describe White Blood Cells (WBCs).
- they’re also known as leukocytes
- they’re colourless
- the two most common types of leukocytes are neutrophils and lymphocytes
Describe the structure of neutrophils.
- it is polymorphonuclear, so it has an irregular, multi-lobed nucleus
- it is a granulocyte, which means that it has prominent cytoplasmic granules which are toxic and used for killing microorganisms
List the three different types of granulocytes, and the differences between them.
NEUTROPHILS:
- weakly staining granules
- the commonest WBC
EOSINOPHILS:
- granules stain red with eosin
- make up 1-4% of WBCs
BASOPHILS:
- granules stain blue/purple with basic dyes
- make up <0.5% of WBCs
What are the two types of mononuclear cells?
The two types are monocytes (the largest type of WBC) and lymphocytes (it has a large nucleus, and not a lot of cytoplasm).
Describe platelets.
- they’re also known as thrombocytes
- they’re cytoplasmic fragments
- they have no nucleus
- they’re membrane-bound
- they contain granules
Where do blood cells come from?
Mature blood cells are produced from the stem cells in the bone marrow. The bone marrow contains many immature cells.
Describe blood plasma, including its ionic constituents.
It’s a fluid containing water, salts, proteins and organic molecules (eg. metabolites, carbohydrates, lipids, etc.)
Its ionic constituents are positive ions (such as sodium, potassium, calcium, magnesium and hydrogen ions) and negative ions (such as chloride, bicarbonate, phosphate, sulphate and organic anions).
What is the difference between plasma and serum?
Plasma is the fluid component of the whole blood.
Serum is the fluid left over after blood clotting factors have been removed from the plasma.
Describe the percentage of protein in the plasma.
Normally, the plasma is about 7-9% protein. It’s complex as there are thousands of different proteins, but over 90% of them is a single protein, albumin.
What are the three main functions of the blood?
- to TRANSPORT
- to DEFEND
- HOMEOSTASIS
What does the blood transport?
It carries oxygen/nutrients to tissues.
It removes CO2/other waste products from tissues.
It transports other substances (eg. hormones) from the sites of production to the sites of action.
Describe an erythrocyte’s role in oxygen transport and carbon dioxide removal.
Erythrocytes transport oxygen from the lungs to the body tissues. They also help in the removal of CO2 from body tissues to the lungs.
Most of the CO2 is carried as the bicarbonate ion (HCO3-) in the plasma. The red cell enzyme carbonic anhydrase helps the CO2 in two ways. It helps it to dissolve in plasma in the tissues, and it helps it come out of solution in the lungs.
Describe haemoglobin.
The major constituent in red blood cells is the protein Haemoglobin (Hb). Hb binds oxygen and carries it from the lungs to the tissues.
Hb is a protein tetramer made up of 4 polypeptide chains, 2 α and 2 β globin chains.
Each globin chain carries a haem molecule. Each haem holds a ferrous (Fe2+) iron atom. Oxygen binds reversibly to the iron atom by a coordination bond (dative bond). This is known as oxygenation, not oxidation.
There are two forms of haemoglobin:
- OXYHAEMOGLOBIN, when it is fully saturated with O2, making it bright red
- DEOXYHAEMOGLOBIN, when it has lost all of its O2, making it dark red
This is the basis of pulse oximetry. It measures the colour of the haemoglobin and determines if the patient is hypoxic (ie. if the patient is being deprived of adequate O2 supply).
