Unit 20: Biomedical science
Learning aim A: Understanding the principles of haematology and its use in
medical diagnosis
Title: Composition of human blood
Erythrocytes:
Type of red blood cell that deliver oxygen to the tissues in the body, the
oxygen is used for respiration by the cells to provide energy for contraction.
The red blood cells also transport carbon dioxide to the lungs to be exhaled.
Structure
The biconcave disc maximises surface area of cell membrane for oxygen to
diffuse across (facilitates oxygen transport), the shape allows red blood cells to
bend and flow smoothly through the capillaries. They do not contain organelles
and only contain haemoglobin.
Carbon dioxide binds to the haemoglobin in the red blood cells more easily
than oxygen as it displaces it more quickly due to carbons higher stability
constant and causes less oxygen to be transported by the red blood cells.
Red blood cells also make and store an enzyme called carbonic anhydrase
which is used as a catalyst.
Function
The main function of erythrocytes is to deliver oxygen to the tissues in the
body. The oxygen is used for respiration by the cells to provide energy for
contraction and release carbon dioxide. Red blood cells transport carbon
dioxide to the lungs to be exhaled.
Because red blood cells transport oxygen, it needs to be done efficiently. The
biconcave disc shape allows for this as the red blood cells can easily bend and
flow through capillaries to facilitate the transport of oxygen.
,The haemoglobin in red blood cells accepts carbon dioxide from surrounding
cells and releases oxygen to the tissues. This rapidly reverses in the lungs
where the haemoglobin bonds to oxygen and releases carbon dioxide.
The enzyme stored and made by red blood cells called carbonic anhydrase is
used as a catalyst for a reversible reaction that converts carbon dioxide to
bicarbonate ions. In the lungs, the bicarbonate ions enter the red blood cells
through the plasma and are converted back into carbon dioxide, which is then
exhaled.
Diagram of red blood cell (erythrocyte)
Leucocytes:
By engulfing pathogens, white blood cells protect the body against infections.
It lacks haemoglobin but has a nucleus.
Types of leucocytes: Monocytes, Lymphocytes, Neutrophils, Basophils,
Eosinophils
Monocytes
have longer lifespan to help break down bacteria, they have one large nucleus
Structure
Monocytes are the largest cells in the peripheral blood, with a diameter of 14-
20µm. Monocytes have an irregular cell shape, cytoplasmic vesicles, and an
oval shaped nucleus, and high nucleus to cytoplasm ratio of 3:1. The large,
, prominent nucleus remains folded rather than being multilobed. The
cytoplasm contains many cytoplasmic granules that are usually numerous
towards the plasma membrane.
The nucleus contains a chromatin net with strands that bridge tiny chromatin
clumps. These chromatin clumps are arranged on the inner side of the nuclear
membrane.
The surface of the monocyte contain surface blebs and ruffles which are of
functional significance.
The cytoplasm contains mitochondria that are numerous, elongated, and
small. The Golgi apparatus is also present together with the centrosome within
the nucleus.
The cell membrane of monocytes also have numerous microvilli that help with
locomotion and the adherence with other cells.
Function
Monocytes functions vary. Classical monocytes are 80% of the total monocyte
population. The remaining 20% are non-classical monocytes.
Some monocytes differentiate into macrophages that are more immediately
ready to recognise and attack a new threat. They can quickly migrate to the
site of inflammation to fight an infection.
Other monocytes differentiate into dendritic cells inside the tissues where they
work with T lymphocytes. Dendritic cells accumulate debris from the
breakdown of bacteria, viruses, and foreign material to the body. They present
these to the T-cells to form an immune response.
Lymphocytes
Make antibodies to fight against pathogens, they have a very large nucleus and
stains purple
Structure
Lymphocytes have a large nucleus and little to no eosinophilic cytoplasm.
Some lymphocytes have a clear perinuclear zone around the nucleus or in
some cases have a small clear zone to one side of the nucleus. A prominent
Learning aim A: Understanding the principles of haematology and its use in
medical diagnosis
Title: Composition of human blood
Erythrocytes:
Type of red blood cell that deliver oxygen to the tissues in the body, the
oxygen is used for respiration by the cells to provide energy for contraction.
The red blood cells also transport carbon dioxide to the lungs to be exhaled.
Structure
The biconcave disc maximises surface area of cell membrane for oxygen to
diffuse across (facilitates oxygen transport), the shape allows red blood cells to
bend and flow smoothly through the capillaries. They do not contain organelles
and only contain haemoglobin.
Carbon dioxide binds to the haemoglobin in the red blood cells more easily
than oxygen as it displaces it more quickly due to carbons higher stability
constant and causes less oxygen to be transported by the red blood cells.
Red blood cells also make and store an enzyme called carbonic anhydrase
which is used as a catalyst.
Function
The main function of erythrocytes is to deliver oxygen to the tissues in the
body. The oxygen is used for respiration by the cells to provide energy for
contraction and release carbon dioxide. Red blood cells transport carbon
dioxide to the lungs to be exhaled.
Because red blood cells transport oxygen, it needs to be done efficiently. The
biconcave disc shape allows for this as the red blood cells can easily bend and
flow through capillaries to facilitate the transport of oxygen.
,The haemoglobin in red blood cells accepts carbon dioxide from surrounding
cells and releases oxygen to the tissues. This rapidly reverses in the lungs
where the haemoglobin bonds to oxygen and releases carbon dioxide.
The enzyme stored and made by red blood cells called carbonic anhydrase is
used as a catalyst for a reversible reaction that converts carbon dioxide to
bicarbonate ions. In the lungs, the bicarbonate ions enter the red blood cells
through the plasma and are converted back into carbon dioxide, which is then
exhaled.
Diagram of red blood cell (erythrocyte)
Leucocytes:
By engulfing pathogens, white blood cells protect the body against infections.
It lacks haemoglobin but has a nucleus.
Types of leucocytes: Monocytes, Lymphocytes, Neutrophils, Basophils,
Eosinophils
Monocytes
have longer lifespan to help break down bacteria, they have one large nucleus
Structure
Monocytes are the largest cells in the peripheral blood, with a diameter of 14-
20µm. Monocytes have an irregular cell shape, cytoplasmic vesicles, and an
oval shaped nucleus, and high nucleus to cytoplasm ratio of 3:1. The large,
, prominent nucleus remains folded rather than being multilobed. The
cytoplasm contains many cytoplasmic granules that are usually numerous
towards the plasma membrane.
The nucleus contains a chromatin net with strands that bridge tiny chromatin
clumps. These chromatin clumps are arranged on the inner side of the nuclear
membrane.
The surface of the monocyte contain surface blebs and ruffles which are of
functional significance.
The cytoplasm contains mitochondria that are numerous, elongated, and
small. The Golgi apparatus is also present together with the centrosome within
the nucleus.
The cell membrane of monocytes also have numerous microvilli that help with
locomotion and the adherence with other cells.
Function
Monocytes functions vary. Classical monocytes are 80% of the total monocyte
population. The remaining 20% are non-classical monocytes.
Some monocytes differentiate into macrophages that are more immediately
ready to recognise and attack a new threat. They can quickly migrate to the
site of inflammation to fight an infection.
Other monocytes differentiate into dendritic cells inside the tissues where they
work with T lymphocytes. Dendritic cells accumulate debris from the
breakdown of bacteria, viruses, and foreign material to the body. They present
these to the T-cells to form an immune response.
Lymphocytes
Make antibodies to fight against pathogens, they have a very large nucleus and
stains purple
Structure
Lymphocytes have a large nucleus and little to no eosinophilic cytoplasm.
Some lymphocytes have a clear perinuclear zone around the nucleus or in
some cases have a small clear zone to one side of the nucleus. A prominent
