Introduction to the structure and function of blood Flashcards
What are the four components of blood?
- Plasma (fluid)
- Red blood cells
- White blood cells
- Platelets
What are the three layers formed when you centrifuge blood? Name them from top to bottom.
1) Plasma
2) A layer of white blood cells called buffy coat (buffy is a pale yellow-brown colour)
3) Red cells at the bottom as they are denser than white blood cells
What is the importance of the shape RBCs / erythocytes have to their function?
1) The biconcave shape gives them a bigger surface area for the exchange of oxygen.
2) It allows for flexibility when they travel through narrow capillaries so that they dont rupture or cause blood clots
3) they do not have a nucleus, DNA, RNA or mitochondria (only very immature RBCs have RNA in the first 24 hours)
What is the diameter of a RBC? Extra points for knowing the centre and outer thickness
It is approximately 8um. But it can be anywhere between 6-8um in humans.
The central thickness is approx. 1um and the outer is approx. 2.4um.
What are granulocytes?
Granulocytes are a category of white blood cells characterised by the presence of granules in their cytoplasm.
What are the three different types of granulocytes?
- Neutrophils - they have weakly staining granules
- Eosinophils - they have a much more prominent pinkish-reddish granules
- Basophils - they have big purple granules in the cytoplasm (often you can’t see the nucleus because of the granules)
What do the granules in granulocytes contain?
The granules contain substances that are going to be released from the cells like antibacterial agents, inflammatory agents, etc.
What are mononuclear cells? What are the two types?
- Mononuclear cells have a single nucleus (rather than the multi-lobe nucleus of granulocytes).
- They have a large, regular sized nucleus.
The two types are:-
1) Monocytes:- they are the largest type of WBCs. They have a round or kidney shaped nucleus.
2) Lymphocytes:- they have a nucleus the same size as a RBC.
What is the function of platelets / thrombocytes.
They are clotting cells whose function is to react to bleeding from blood vessel injury by clumping, thereby initiating a blood clot.
Describe the structure of platelets / thrombocytes.
- They are a fragment of cytoplasm that don’t have a nucleus.
- They are membrane bound (they have a cell membrane around them like a nucleus).
- They have granules that are waiting to be secreted and contain substances that are involved in clotting and inflammation.
Where do blood cells come from?
- Mature blood cells are produced from stem cells in the bone marrow.
- The bone marrow contains many immature cells.
What is blood plasma?
• It is a fluid containing:-
◦ Water
◦ Salts
◦ Proteins
◦ Organic molecules
‣ E.g. metabolites, carbohydrates, lipids
What are the ionic constituents of blood plasma?
Ionic constituents are:-
• Positive ions (cations) such as -
◦ Sodium, potassium, calcium, magnesium and hydrogen ions
• Negative ions (anions) such as -
◦ Chloride, bicarbonate, phosphate, sulphate and organic anions.
What is the difference between plasma and serum?
- Plasma contains fibrinogen (an important blood clotting factor). This is not present in serum.
- Plasma is the fluid component of the whole blood, whereas serum is the fluid left after blood clotting factors have been removed from the plasma.
What is used to prevent blood from clotting?
Anticoagulants - they work by interfering with the chemicals needed to make clots or clotting factors.
What percentage of the plasma is protein? What is the most prevalent protein and what percentage is it?
- Usually about 7-9% of the plasma is protein.
- Its complex as there are thousands of different proteins.
- But more than 90% is a single protein called albumin.
What are the three main functions of the blood?
- Transport
- Immunity
- Homeostasis
What is the role of blood in transport?
- The blood carries oxygen / nutrients to tissues
- It removes CO2 / other waste products from tissues
- It also transports other substances (e.g. hormones) from sites of production to the sites of action.
Explain the role of erythrocytes in transport in blood
• 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 this CO2 is carried as bicarbonate ion (HCO3-) in the plasma.
◦ The red cell enzyme carbonic anhydrase helps CO2 in two ways:-
‣ It helps it (CO2) to dissolve in plasma in the tissues.
‣ It helps the CO2 to come out of solution in the lungs.
Describe the structure and function of haemoglobin.
• Hb binds to oxygen and carries it from the lungs to the tissues
• It is a protein tetramer made up of 4 polypeptide chains:-
◦ 2 alpha globin chains
◦ 2 beta globin chains
• Each globin chain carries a haem molecule.
• The haem holds a ferrous (Fe++) iron atom.
• Oxygen binds reversibly to the iron atom by coordination bond (dative covalent bond). This process is called oxygenation, not oxidation (as the Fe++ is not oxidised to Fe+++).
There are about 300,000,000 Hb molecules in each RBC, which takes up almost 50% of the space in each RBC.
What is the difference between oxygenation and oxidation?
- Oxygenation is a physical property that refers to the amount of dissolved oxygen in a system; or the process of increasing it.
- Oxidation is a chemical concept that originally referred to the addition of oxygen to an element or compound, but now is usually taken to mean the loss of electrons or an increase in oxidation state.
What are the two forms of haemoglobin (Hb)?
The two forms are:-
- Oxyhaemoglobin - When Hb is fully saturated with O2, making it bright red.
- Deoxyhaemoglobin - When Hb has lost all of its O2, making it dark red.