Lecture five- blood cells Flashcards
How many litres of blood does the average human have
5litres
Brief overview of what blood is made up of
- blood cells (45-55%)
- plasma- blood without cell components
- human plasma proteome (proteins like albumin, immunoglobin and clotting factors)
- serum (plasma without clotting factors and fibrinogen)
Separation of blood components. Explain how you would do this and what the sample would look like in the centrifuge tube.
- take sample
- spin it in the centrifuge tube
- the blood will split into two major components
- the lower level= haematocrit composed of blood cells
- upper level= plasma
- small layer between these containing platelets and white blood cells (lymphocytes)
What is plasma
blood without the cell components.
What can plasma be used for?
As a blood substitute. When blood isn’t available. To increase volume of blood during a surgery or after trauma. This controls bleeding and aids wound healing.
Many drugs will bind to ………. proteins. What does this do? How does this explain why less than 1% of drug is active?
bind to plasma proteins which supresses the drug. Only 1% of the drug is unbound and therefore active.
What is serum?
Plasma without the clotting factors and fibrinogen.
What are some uses of serum?
- extracted from blood to do diagnostic measurements.
- used in cosmetics
- used as growth media for cell culture
The three main types of blood cells. Name them
Erythrocytes (red blood cells), Leucocytes (white blood cells) and Platelets.
Role of Erythrocytes/ red blood cells
- carry oxygen around the body
- pH buffering of the blood- keep blood within the normal range of 7.2-7.4
Describe the structure and shape of Erythrocytes
- no nucleus- cannot grow, divide or form proteins
- contain haemoglobin- O2 binds to this and is carried around the body.
- biconcave shape- high surface area to volume ration. The shape of red blood cells can also distort/fold.
What is responsible for a person’s blood type?
The polysaccharides/ proteins on the surface membrane of red blood cells.
Name the process which produces red blood cells/ Erythrocytes
- Erythropoiesis.
Describe Erythropoiesis
- controlled by the hormone erythropoietin.
- EPO is secreted in small amounts by the kidney.
- If O2 levels are low, EPO production is triggered.
- More EPO= more red blood cells = more O2 can be carried around the body
Reasons for low O2 levels=
- high altitude
- lung disease- insufficient gas exchange
- insufficient pumping of heart
- Anaemia = decrease in the number of erythrocytes/ decreased concentration of haemoglobin per erythrocyte. This can be caused by low iron/B12 and genetic disorders like sickle cell anaemia.
What are platelets
- cell fragments with no nucleus
- involved in blood clotting
- derived from megakaryocytes
- production of platelets is controlled by thrombopoietin hormone produced by the liver.
Explain how thrombopoietin hormone controls platelet production
- protein binds to the platelet.
- if the platelet counts are normal, the TBO will bind to lots of platelets so the free TPO levels are low
- BUT if the platelet count is low then free TPO levels will be high in the serum as less are bound to platelets.
- High TPO level= platelet production is stimulated.
Give some disorders related to platelets
low platelet count causes excessive bleeding
antiplatelet drugs reduce risk of clotting and are used to treat patients with DVT, ischaemic stroke and heart attack.
Role of Leucocytes/ white blood cells
Important for the immune response- they are the host defence.
What is bone marrow? What comes from bone marrow?
Bone marrow is a spongy tissue found in the centre of bones. Blood cells come from bone marrow.
Bone marrow exists in two forms. Give them.
red marrow which contains blood cells AND yellow marrow containing cartilage, fat and bone cells.
What else does bone marrow contain that is important for healthy bones and joints?
collagen and glucosamine
In children the bone marrow from which bones generates blood cells?
most bones
In adults, the bone marrow from which bones generates blood cells?
bones of chest, base of skull, spinal vertebrae and upper sections of limbs.
Blood cells are derived from what stem cells?
hematopoietic stem cells
Haemopoietic stem cells differentiate into what two cells
myeloid progenitor cells or lymphoid progenitor cells (lymphocytes)
Myeloid progenitor cells differentiate into what 6 cells
- Megakaryocyte- which produces platelets.
- Eosinophil
Basophil
Erythrocytes
Monocytes- differentiate into dendritic/ macrophages
Neutrophil
Lymphoid progenitor cells differentiate into three types of cells
- T cell
- B cell - differentiate into plasma cells
- NK/ T killer cells
What happens if you have damaged bone marrow?
anaemic, susceptible to opportunistic infections due to weakened immune system, trouble clotting.
How may bone marrow be damaged?
radiation- eg. chemotherapy.
How can damage from chemo be prevented? if this doesn’t happen how can a patient get more bone marrow?
Sample of bone marrow is taken, the chemotherapy is given, the bone marrow is put back again. The bone marrow will therefore begin to regenerate. If this hasn’t happened, someone will receive bone marrow from a transplant.
Key functions of the blood (3 key functions)
- Transport= oxygen, carbon dioxide, nutrients and excretory products (taken to kidney)
- Regulation= delivery of hormones to target sites, diversion of blood in body homeostasis and temperature regulation. Eg. take blood to surface of skin to lose heat and maintain homeostasis, for example.
- Protection – leukocytes in infection, clotting mechanisms to prevent blood loss.
Leucocytes are involved in host immunity. What are the two different types and which white blood cells are involved in each?
- Innate immunity- myeloid cells. First line of defence against pathogens
- Adaptive immunity- lymphocytes. Highly specific to the pathogen (antigen specific). Longer lasting protection.
Monocytes/ macrophages and neutrophils come from myeloid cells. What is their role?
- phagocytic cells- they engulf protein.
- involved in innate immunity.
Eosinophils are a a product of …….. cells differentiating
myeloid cells
Eosinophil role
defence against parasitic infections. Key mediators in asthma.
Basophil cells are also a product of ………. cells differentiating
myeloid
what are basophil cells?
- they are circulating immune cells containing histamine
- involved in the pathogenesis of allergic reactions and inflammation.
Agranulocytes- what are they?
These are white blood cells which lack distinct granules in their cytoplasm.
Two cells which are agranulocytes
lymphocytes and monocytes.
monocytes develop into macrophages in the tissues which engulf bacteria and cell debris. They act as APCs to T cells in the adaptive immune system
- These cells also release cytokines
What are granulocytes?
cells with densely stained granules in cytoplasm. These granules contain enzymes which are released in the immune response.
- can be called polymorphonuclear leukocytes due to the nucleus shape
Three cells which are granulocytes
neutrophils, basophils and eosinophils.
Lymphocytes are as we know agranulocytes. Give the three types
- B cells (and plasma cells)- antibody production
- T helper cells- provide activation stimulus to other immune cells
- Natural T killer cells- lyse/kill virally infected cells and cancer cells
White blood cell/ Leucocyte disorders
Not enough leucocytes- due to HIV or chemo, for example: patient is immunosuppressed/immunocompromised and so is more susceptible to opportunistic infections.
Too many- due to allergies, inflammatory conditions, autoimmunity, for example: immune system is activated inappropriately. Therefore, immunosuppressive drugs are given.
