Physiology of blood Flashcards
Name the components of blood
1, White blood cells
- Red blood cells
- Platlets
- Plasma
- Buffy coat
What is the “Buffy coat” component of blood made up of?
Platlets and leukocytes
What percentage of blood is made up of platelets and leukocytes ?
less than 1%
What percentage of blood is made up of plasma?
55%
What percentage of blood is made up of the formed elements? ?
45%
What are the formed elements of blood?
- White blood cells
- Red blood cells
- Platelets
When blood is centrifuged what happens?
It splits up into its different elements
1st layer: Plasma
2nd layer: Buffy coat
3Rd: Erythrocytes
What is the function of blood?
- Delivers oxygen and removes carbon dioxide
- Maintains temperature, pH and fluid volume
- Provides protection from fluid loss
- Prevents infection
- Transports hormones and nutrients
- Transports waste products out of the body eg Urea
What is plasma made up of/
90% water
8% solutes
Name the solutes that make up plasma
Proteins like:
- Albumin (60%),
- Alpha and Beta globulins
- Gamma globulins,
- Fibrinogens
Gas
Electrolytes
Name the main protein the makes up plasma
Albumin
What is transported by the plasma?
- Organic nutrients eg carbohydrates, lipid, amino acids, vitamin
- Hormones
- Metabolic waste eg urea
What is haematopoiesis?
It is the process that forms blood
Which cells give rise to the formed elements of blood?
The haemocytoblasts (pluripotential hemopoietic stem cell (PHSC))
What is another name for haemocytoblasts?
pluripotential hemopoietic stem cell (PHSC)
How are haemocytoblasts transporter around the body?
They are pushed around by hormones and growth factors towards a certain pathway of differentiation depending on the body’s needs
Are Hemocytoblasts seen in blood films and cytology? why?
No as they are easily broken
Name the 2 different pathways Hemocytoblasts can take when differentiating
- The common myeloid progenitor
2. The common lymphoid progenitor
What does the common myeloid progenitor pathway lead to?
The formation of:
- Megakaryocytes which form platelet
- Erythrocytes
- Mast cells
- Myeloblasts which form basophil, neutrophils, eosinophils and monocytes
How are platelets formed from?
Megakaryocytes which is formed when Hemocytoblasts differentiate via the common myeloid progenitor pathway
What does the common lymphoid progenitor pathway lead to?
- Natural killer cells
2. Small lymphocytes which form t lymphocytes and B lymphocytes
What do red blood cells contain?
They contain haemoglobin
Why is haemoglobin important?
As it helps transport respiratory gases
How many red blood cells do we have?
Men have: 4.7-6.1 million per micro litre of blood
Females have: 4.2-5.4 million per micro litre of blood
How big are red blood cells?
Around 7.5 micrometers in diameter
What is special about the structure of red blood cells?
They lack mitochondria and don’t have a nucleus
What shape are ed blood cells and why is this important?
They are biconcave
This increases the surface area and increases flexibility
What is the benefit of red blood cells not having a mitochondria?
Give them more room to store ore haemoglobin
How are red blood cells produced?
Produced via haematopoiesis in bone
What is the lifespan of a red blood cell?
100-120 days
How are red blood cells destroyed?
Destroyed by macrophages in the spleen liver and bone §
Describe the structure of haemoglobin
It is made up of:
2 alpha chains
2 beta chains
1 iron containing haem group
What is erythropoiesis
How red blood cells form
What does erythropoiesis begin with?
Vitamin B12 and B9
Talk through the stages of erythropoiesis
- Hemocytoblast are activated by vitamin B12 and B9 to differentiate into Late normoblast
- Late normoblast leave the bone marrow
- The nuclei is lost and destroyed by macrophages forming a reticulocyte
- In 1-2 days the reticulocyte forms a erythrocyte (RBC)
- Eventually erythrocytes are destroyed by macrophages forming erythropoietin
What happens as Hemocytoblast differentiate?
The cell size decreases during maturation as RNA and DNA decreases
The nucleus gradually shrinks
The colour of the cell changes from blue to red
What are reticulocyte ?
An immature red blood cell
What percentage of circulating cells are reticulocyte ?
1%
What are erythrocyte ?
They are red blood cells
What is erythropoietin?
A hormone produced by destroyed red blood cells
Why is erythropoietin important?
As It pushes the Hemocytoblast to differentiate into late normoblast
Give some differences between Hemocytoblast and late normoblast
- Hemocytoblasts are bigger
- Hemocytoblast have ore RNA and DNA
- Hemocytoblast Has a bigger nucleus
- Hemocytoblast are red late normoblasts are blue
Where is erythropoietin released from?
The kidneys
When is erythropoietin released?
Realeased from the kidneys in repose to hypoxia
Wha can hypoxia be caused by
- Secondary to haemorrhage
- Loss of red blood cells
- Insufficient haemoglobin
- Reduced oxygen
- Increased damsons
What do erythropoietin stimulate?
Stimulates rapid maturation of committed red blood cells
What does the stimulation of erythropoietin lead to?
An increase in reticulocyte count circulating the body within 2 days
Why do men have more red blood cells than woman?
As testosterone enhances the production of erythropoietin leading to a higher RBC count in males
Talk through the stages of red cell death
- Macrophages break down RBCs into haem and globin
- Globing is broken down into amino acids and haem is broken down into down into Fe3+ (bound to transferrin) and biliverdin
- Iron is transported to the liver
- biliverdin is transported to the large intestine and ultimately exited out the body as faeces and urea
What do macrophages break RBCs into?
Haem and globin
Why is the iron broken down from haem bound to transferrin?
As iron is very reactive so when it binds to transferrin it not react with anything else
Talk through what happens to the iron element of haem when RBC death occurs?
Macrophages break down RBCs into haem
- Haem is broken down into Fe3+ which Is bound to transferrin
- This Fe3+ is transported to the liver and separated
- Then is reforms and moves out of liver where it travels around the body
Talk through what happens to the biliverdin element of haem when RBC death occurs?
- It is transported to the liver
- Then it is transported to the large intestine where is is changed by bacteria to form bilirubin
- bilirubin is then converted into urobilinogen and then Stercobilin
- urobilinogen is then transported to the kidney as urobilin
- urobilin leaves the kidneys as urea and Stercobilin leaves the body as faeces
What is anaemia?
It is a condition where a person has a decrease int eh number of red blood cells OR they have less than the normal quantity of haemoglobin in their blood
What anaemia due to?
- Excess blood loss
- Excess red blood cell destruction
- Deficient red blood cell production
What are the most common causes of iron deficient anaemia?
- Parasitosis
- Dietary deficiency
- Blood loss
- Malabsorption
- Pregnancy
Give some symptoms of iron deficient anaemia
- Tiredness
- Pale
- Light headedness
- Irritable
- Poor wound healing
- Beefy red tongue (glossitis)
- Burning mouth syndrome
- RAS
- Candidal infections
Name the different types of anaemia
- iron deficient anaemia
2. Pernicious Anaemia
What is Pernicious Anaemia?
It is vitamin B12 deficient anaemia
What is Pernicious Anaemia?
A lack of red blood cells due to a deficiency in vitamin B12
What can Pernicious Anaemia be due to?
Due to lack of intrinsic factors allowing absorption of vitamin B12
What can Pernicious Anaemia caused by?
- Autoimmune condition
- Tapeworms
- Poor diet
- Celiac
- Weight loss
- Neurological symptoms
- glossitis,
- angular cheilitis
How Is Pernicious Anaemia treated?
Treated with oral supplements and intramuscular B12 injections
What are Haemoglobinopathies
Conditions where there is something wrong with haemoglobin
Give examples of Haemoglobinopathies
- Sickle cell
2. Thalassaemia
What does sickle cell and Thalassaemia cause?
Leads to the production of abnormal RBSc that are broken down more quickly by the body
What can happen if you destroy more RBCs than you make?
You can get haemolytic anaemia
Is Sickle Cell Anaemia recessive or dominant?
Autosomal Recessive
What cases Sickle Cell Anaemia
Caused by a genetic mutation on chromosome 11 where the Glut protein is converted into Val at position 6
This produces a sickle component instead of a beta chain changing the shape of the RBC
How is sickle cel anaemia treated?
Treated with hydroxyurea to increase HbF production and prevent abnormal sickle cells being made
What does it mean if you are a Heterozygote for sickle cell anaemia
Means you have some sickle shaped RBC and some normal RBC
This is beneficial as it provides protection from malaria
Name the 2 different types of Thalassaemia
Alpha Thalassaemia
Beta Thalassaemia
What is alpha Thalassaemia
A reduction in alpha unit production
This leads to an excess of beta units
What is beta Thalassaemia?
A reduction in beta unit production
This leads to an excess of alpha units
Which type of Thalassaemia is more common?
Beta Thalassaemia
How many genes make up the alpha unit of RBCs?
2 genes so 4 alleles
How many genes make up the beta unit of RBCs?
1 gene so 2 alleles
If you lose one alpha unit allele what happens?
No problem
If you lose 2 alpha unit allele what happens?
May suffer from mild anaemia/microcytosis
If you lose 3 alpha unit allele what happens?
May suffer from severe anaemia
If you lose 4 alpha unit allele what happens?
Incompatible with life
What is microcytosis?
A condition where you have smaller red blood cells
Name the 5 different types of leukocytes from greater amount to least amount found in the blood
- Neutrophils (65%)
- Lymphocytes (25%)
- Monocytes (6%)
- Eosinophils (3%
- )Basophils (1%)
How big are leukocytes?
400-11000 cells mm^3
What happens when you have increased number of white blood cells
leukocytosis
When might someone have leukocytosis?
Seen in:
- Infections
- Neoplasia
- Autoimmune diseases
- Strenuous exercise
- Stress
- Allergies
What happens when you have a decreased number of white blood cells
You can get leukopenia